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Yang, Zhouming, Xin Liu, Jinyun Guo, Yaowei Xia e Xiaotao Chang. "An Enhanced Method for Detecting and Repairing the Cycle Slips of Dual-Frequency Onboard GPS Receivers of LEO Satellites". Journal of Sensors 2020 (26 de novembro de 2020): 1–17. http://dx.doi.org/10.1155/2020/8817626.
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Cycle slip detection and repair play important roles in the processing of data from dual-frequency GPS receivers onboard low-Earth orbit (LEO) satellites. To detect and repair cycle slips more comprehensively, an enhanced error method (EEM) is proposed. EEM combines single-frequency and narrow-lane carrier phase observations to construct special observations and observation equation groups. These special observations differ across time and satellite (ATS). ATS observations are constructed by three steps. The first step is differencing single-frequency and narrow-lane observations through a time difference (TD). The second step is to select a satellite as a reference satellite and other satellites as nonreference satellites. The third step is to difference the single-frequency TD observations from the reference satellite and the narrow-lane TD observations from the nonreference satellites by a satellite difference. If cycle slips occur at the reference satellite, the correction values for these ATS observations can be significantly enlarged. To process all satellites, the EEM selects each satellite as a reference satellite and builds the corresponding equation group. The EEM solves these observation equation groups according to the weighted least-squares adjustment (LSA) criterion and obtains the correction values; these correction values are then used to construct the χ 2 values corresponding to different equation groups, and the EEM subsequently carries out a chi-square distribution test for these χ 2 . The satellite corresponding to the maximum χ 2 will be marked. Then, the EEM iteratively processes the other satellites. Cycle slips can be estimated by rounding the float solutions of changes in the ambiguities of cycle slip satellites to the nearest integer. The simulation test results show that the EEM can be used to detect special cycle slip pairs such as (1, 1) and (9, 7). The EEM needs only observation data in two adjacent epochs and is still applicable to observation epochs with continuous cycle slips.
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Li, Gongqiang, Jing Liu, Hai Jiang e Chengzhi Liu. "Research on the Efficient Space Debris Observation Method Based on Optical Satellite Constellations". Applied Sciences 13, n.º 7 (24 de março de 2023): 4127. http://dx.doi.org/10.3390/app13074127.
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The increasing amount of space debris poses a major threat to the security of space assets. The timely acquisition of space debris orbital data through observations is essential. We established a mathematical model of optical satellite constellations for space debris observation, designed a high-quality constellation configuration, and designed a space debris tracking observation scheduling algorithm. These tools can realize the efficient networking of space debris from a large number of optical satellite observation facilities. We designed a constellation consisting of more than 20 low-Earth orbit (LEO) satellites, mainly dedicated to the observation of LEO space objects. According to the observation scheduling method, the satellite constellation can track and observe more than 93% of the targets every day, increase the frequency of orbital data updates, and provide support for the realization of orbital space debris cataloguing. Designing optical satellite constellations to observe space debris can help realize the advance perception of dangerous collisions, timely detect dangerous space events, make key observations about high-risk targets, greatly reduce the false alarm rate of collisions, and provide observational data support for space collisions.
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Wu, Qianyu, Jun Pan e Mi Wang. "Dynamic Task Planning Method for Multi-Source Remote Sensing Satellite Cooperative Observation in Complex Scenarios". Remote Sensing 16, n.º 4 (10 de fevereiro de 2024): 657. http://dx.doi.org/10.3390/rs16040657.
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As the number and variety of remote sensing satellites continue to grow, user demands are becoming increasingly complex and diverse. Concurrently, there is an escalating requirement for timeliness in satellite observations, thereby augmenting the complexity of task processing and resource allocation. In response to these challenges, this paper proposes an innovative method for dynamic task planning in multi-source remote sensing satellite cooperative observations tailored to complex scenarios. In the task processing phase, this study develops a preprocessing model suitable for various types of targets, enabling the decomposition of complex scenes into multiple point targets for independent satellite observation, thereby reducing the complexity of the problem. In the resource allocation phase, a dynamic task planning algorithm for multi-satellite cooperative observation is designed to achieve dynamic and optimized scheduling of the processed point targets, catering to the needs of multi-source remote sensing satellites. Empirical validation demonstrated that this method effectively implements dynamic adjustment plans for point targets, comprehensively optimizing the number of observation targets, computation time, task priority, and satellite resource utilization, significantly enhancing the dynamic observation efficiency of remote sensing satellites.
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Bloßfeld, Mathis, Julian Zeitlhöfler, Sergei Rudenko e Denise Dettmering. "Observation-Based Attitude Realization for Accurate Jason Satellite Orbits and Its Impact on Geodetic and Altimetry Results". Remote Sensing 12, n.º 4 (19 de fevereiro de 2020): 682. http://dx.doi.org/10.3390/rs12040682.
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For low Earth orbiting satellites, non-gravitational forces cause one of the largest perturbing accelerations. During a precise orbit determination (POD), the accurate modeling of the satellite-body attitude and solar panel orientation is important since the satellite’s effective cross-sectional area is directly related to the perturbing acceleration. Moreover, the position of tracking instruments that are mounted on the satellite body are affected by the satellite attitude. For satellites like Jason-1/-2/-3, attitude information is available in two forms—as a so-called nominal yaw steering model and as observation-based (measured by star tracking cameras) quaternions of the spacecraft body orientation and rotation angles of the solar arrays. In this study, we have developed a preprocessing procedure for publicly available satellite attitude information. We computed orbits based on Satellite Laser Ranging (SLR) observations to the Jason satellites at an overall time interval of approximately 25 years, using each of the two satellite attitude representations. Based on the analysis of the orbits, we investigate the influence of using preprocessed observation-based attitude in contrast to using a nominal yaw steering model for the POD. About 75% of all orbital arcs calculated with the observation-based satellite attitude data result in a smaller root mean square (RMS) of residuals. More precisely, the resulting orbits show an improvement in the overall mission RMS of SLR observation residuals of 5.93% (Jason-1), 8.27% (Jason-2) and 4.51% (Jason-3) compared to the nominal attitude realization. Besides the satellite orbits, also the estimated station coordinates benefit from the refined attitude handling, that is, the station repeatability is clearly improved at the draconitic period. Moreover, altimetry analysis indicates a clear improvement of the single-satellite crossover differences (6%, 15%, and 16% reduction of the mean of absolute differences and 1.2%, 2.7%, and 1.3% of their standard deviations for Jason-1/-2/-3, respectively). On request, the preprocessed attitude data are available.
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Zhang, Xiaozhen, Yao Kong, Xiaochun Lu e Decai Zou. "Contribution of Etalon Observation to Earth Rotation Parameters under a New Observation Scenario". Applied Sciences 12, n.º 10 (13 de maio de 2022): 4936. http://dx.doi.org/10.3390/app12104936.
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The standard products of the International Laser Ranging Service (ILRS) are mainly based on the two laser geodynamics satellites (LAGEOS) due to the sparse observations of the Etalon satellites. With improvements in the ability to track high-altitude satellites, ILRS conducted a 3-month Etalon tracking campaign. In this paper, we study the contribution of more Etalon observations in the new observation scenario to weekly ILRS products, such as station coordinates, Earth rotation parameters (ERPs) and satellite orbit. We compare the ILRS products estimated from LAGEOS-only solutions and LAGEOS+Etalon solutions. In the new observation scenario of 2019, the numbers of observations of Etalon satellites are 1.4 and 1.7 times larger than those in 2018. It is shown that the quality of station coordinates, and the satellite orbit of LAGESOS satellites are only slightly affected by the increase in Etalon observations of the campaign. However, for station 1868, which is dedicated to high-altitude satellites, the root mean square (RMS) values of the residuals in the N, E, and U components are improved by 3.1 cm, 2.1 cm and 2.3 cm, respectively. The internal precision of orbit for Etalon-1/2 satellites in tangle and normal directions are improved by 1.5 cm and 2.9 cm, respectively. Most remarkably, the standard deviations for Xp, Yp and LOD can be improved by 6.9%, 14.3% and 5.1%, respectively, compared with the International Earth Rotation System (IERS)-14-C04 series. With our research, the ILRS could increase efforts on Etalon satellite tracking without affecting the routine observations of LAGEOS satellites.
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Li, Min, Tianhe Xu, Haibo Ge, Meiqian Guan, Honglei Yang, Zhenlong Fang e Fan Gao. "LEO-Constellation-Augmented BDS Precise Orbit Determination Considering Spaceborne Observational Errors". Remote Sensing 13, n.º 16 (12 de agosto de 2021): 3189. http://dx.doi.org/10.3390/rs13163189.
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The precise orbit determination (POD) accuracy of the Chinese BeiDou Navigation Satellite System (BDS) is still not comparable to that of the Global Positioning System because of the unfavorable geometry of the BDS and the uneven distribution of BDS ground monitoring stations. Fortunately, low Earth orbit (LEO) satellites, serving as fast moving stations, can efficiently improve BDS geometry. Nearly all studies on Global Navigation Satellite System POD enhancement using large LEO constellations are based on simulations and their results are usually overly optimistic. The receivers mounted on a spacecraft or an LEO satellite are usually different from geodetic receivers and the observation conditions in space are more challenging than those on the ground. The noise level of spaceborne observations needs to be carefully calibrated. Moreover, spaceborne observational errors caused by space weather events, i.e., solar geomagnetic storms, are usually ignored. Accordingly, in this study, the actual spaceborne observation noises are first analyzed and then used in subsequent observation simulations. Then, the observation residuals from the actual-processed LEO POD during a solar storm on 8 September 2017 are extracted and added to the simulated spaceborne observations. The effect of the observational errors on the BDS POD augmented with different LEO constellation configurations is analyzed. The results indicate that the noise levels from the Swarm-A, GRACE-A, and Sentinel-3A satellites are different and that the carrier-phase measurement noise ranges from 2 mm to 6 mm. Such different noise levels for LEO spaceborne observations cause considerable differences in the BDS POD solutions. Experiments calculating the augmented BDS POD for different LEO constellations considering spaceborne observational errors extracted from the solar storm indicate that these errors have a significant influence on the accuracy of the BDS POD. The 3D root mean squares of the BDS GEO, IGSO, and MEO satellite orbits are 1.30 m, 1.16 m, and 1.02 m, respectively, with a Walker 2/1/0 LEO constellation, and increase to 1.57 m, 1.72 m, and 1.32 m, respectively, with a Walker 12/3/1 constellation. When the number of LEO satellites increases to 60, the precision of the BDS POD improves significantly to 0.89 m, 0.77 m, and 0.69 m for the GEO, IGSO, and MEO satellites, respectively. While 12 satellites are sufficient to enhance the BDS POD to the sub-decimeter level, up to 60 satellites can effectively reduce the influence of large spaceborne observational errors, i.e., from solar storms.
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Kitajima, Natsumi, Rie Seto, Dai Yamazaki, Xudong Zhou, Wenchao Ma e Shinjiro Kanae. "Potential of a SAR Small-Satellite Constellation for Rapid Monitoring of Flood Extent". Remote Sensing 13, n.º 10 (18 de maio de 2021): 1959. http://dx.doi.org/10.3390/rs13101959.
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Constellations of small satellites equipped with synthetic aperture radar (SAR) payloads can realize observations in short time intervals independently from daylight and weather conditions and this technology is now in the early stages of development. This tool would greatly contribute to rapid flood monitoring, which is usually one of the main missions in upcoming plans, but few studies have focused on this potential application and a required observation performance for flood disaster monitoring has been unclear. In this study, we propose an unprecedented method for investigating how flood extents would be temporally and spatially observed with a SAR small-satellite constellation and for evaluating that observation performance via an original index. The virtual experiments of flood monitoring with designed constellations were conducted using two case studies of flood events in Japan. Experimental results showed that a SAR small-satellite constellation with sun-synchronous orbit at 570 km altitude, 30-km swath, 15–30° incidence angle, and 20 satellites can achieve 87% acquisition of cumulative flood extent in total observations. There is a difference between the results of observation performance in two cases because of each flood’s characteristics and a SAR satellite’s observation system, which implies the necessity of individual assessments for various types of rivers.
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Zhao, You, Peng Qi Gao, Ming Shen, Xiao Zhong Guo, Da Tao Yang e Huan Huan Yu. "Design of Computer Communication and Network in APOSOS Project". Advanced Materials Research 271-273 (julho de 2011): 700–705. http://dx.doi.org/10.4028/www.scientific.net/amr.271-273.700.
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Asia-Pacific Optical Satellite Observation System (APOSOS) is based on members of Asia-Pacific Space Cooperation Organization (APSCO). Its aim is to develop a regional or even global satellite tracking system basically composed of optical trackers. The system will be used to track objects of interest or space-debris for the safety of spacecraft launch mission or the intactness of operational satellites. APOSOS is composed of Asia-Pacific optical satellite observation center, APSCO member state node, sub-node and observation telescope. Asia-Pacific optical satellite observation center manage the whole observation network. Every member state node answers for the organization of observation with their country’s facility according to the observation plan released by observation center. The sub-node transmits observational data to corresponding member state node first. Then the member state node transmits the data summarized to the observation center. This paper will briefly introduce the APOSOS project first and present the design of computer communication and network in APOSOS project in detail.
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Ko, Haneul, e Yeunwoong Kyung. "Resource- and Neighbor-Aware Observation Transmission Scheme in Satellite Networks". Sensors 23, n.º 10 (19 de maio de 2023): 4889. http://dx.doi.org/10.3390/s23104889.
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The observation satellite can exploit its own storage and computational resources to reduce the transmission delay. However, too excessive usage of these resources can have negative effects on the queuing delay at the relay satellite and/or on conducting other tasks at each observation satellite. In this paper, we proposed a new resource- and neighbor-aware observation transmission scheme (RNA-OTS). In RNA-OTS, each observation satellite decides whether to use its resources and the resources of the relay satellite at each time epoch by considering its resource utilization and transmission policies of neighbor observation satellites. For the optimal decision of each observation satellite in a distributed manner, the operation of observation satellites is modeled by means of a constrained stochastic game, and a best-response-dynamics-based algorithm is devised to find the Nash equilibrium. The evaluation results demonstrate that RNA-OTS can decrease the delay to deliver the observation to the destination by up to 87% compared to a relay-satellite-based scheme while guaranteeing a sufficiently low average utilization of the resources of the observation satellite.
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Yang, Sen, Xiaoyang Meng, Xingying Zhang, Lu Zhang, Wenguang Bai, Zhongdong Yang, Peng Zhang, Zhili Deng, Xin Zhang e Xifeng Cao. "Study on the Ground-Based FTS Measurements at Beijing, China and the Colocation Sensitivity of Satellite Data". Atmosphere 12, n.º 12 (29 de novembro de 2021): 1586. http://dx.doi.org/10.3390/atmos12121586.
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The Fourier Transform Spectrometer (FTS) at the Beijing Satellite Meteorological Ground Station observed XCO2 (the dry carbon dioxide column) from 2 March 2016 to 4 December 2018. The validation results of ground-based XCO2, as well as GOSAT, OCO-2, and TanSat XCO2, show that the best temporal matching setting for ground-based XCO2 and satellite XCO2 is ±1 h, and the best spatial matching setting for GOSAT is 0.5° × 0.5°. Consistent with OCO-2, the best spatial matching setting of TanSat is 5° × 5° or 6° × 6°. Among GOSAT, OCO-2, and TanSat, the satellite observation validation characteristics near 5° × 5° from the ground-based station are obviously different from other spatial matching grids, which may be due to the different observation characteristics of satellites near 5° × 5°. To study the influence of local CO2 sources on the characteristics of satellite observation validation, we classified the daily XCO2 observation sequence into concentrated, dispersive, increasing, and decreasing types, respectively, and then validated the satellite observations. The results showed that the concentrated and decreasing sub-datasets have better validation performance. Our results suggest that it is best to use concentrated and decreasing sub-datasets when using the Beijing Satellite Meteorological Ground Station XCO2 for satellite validation. The temporal matching setting should be ±1 h, and the spatial matching setting should consider the satellites observation characteristics of 5° × 5° distance from the ground-based station.
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Zhao, Qiang, Le Yu, Zhenrong Du, Dailiang Peng, Pengyu Hao, Yongguang Zhang e Peng Gong. "An Overview of the Applications of Earth Observation Satellite Data: Impacts and Future Trends". Remote Sensing 14, n.º 8 (13 de abril de 2022): 1863. http://dx.doi.org/10.3390/rs14081863.
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As satellite observation technology develops and the number of Earth observation (EO) satellites increases, satellite observations have become essential to developments in the understanding of the Earth and its environment. However, the current impacts to the remote sensing community of different EO satellite data and possible future trends of EO satellite data applications have not been systematically examined. In this paper, we review the impacts of and future trends in the use of EO satellite data based on an analysis of data from 15 EO satellites whose data are widely used. Articles that reference EO satellite missions included in the Web of Science core collection for 2020 were analyzed using scientometric analysis and meta-analysis. We found the following: (1) the number of publications and citations referencing EO satellites is increasing exponentially; however, the number of articles referencing AVHRR, SPOT, and TerraSAR is tending to decrease; (2) papers related to EO satellites are concentrated in a small number of journals: 43.79% of the articles that were reviewed were published in only 13 journals; and (3) remote sensing impact factor (RSIF), a new impact index, was constructed to measure the impacts of EO satellites and to predict future trends in applications of their data. Landsat, Sentinel, MODIS, Gaofen, and WorldView were found to be the most significant current EO satellite missions and MODIS data to have the widest range of applications. Over the next five years (2021–2025), it is expected that Sentinel will become the satellite mission with the greatest influence.
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Martellato, Elena, Alice Maria Piccirillo, Giampaolo Ferraioli, Alessandra Rotundi, Vincenzo Della Corte, Pasquale Palumbo, Emanuele Alcaras et al. "A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation". Remote Sensing 14, n.º 9 (26 de abril de 2022): 2066. http://dx.doi.org/10.3390/rs14092066.
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In this paper, we present several study cases focused on marine, oceanographic, and atmospheric environments, which would greatly benefit from the use of a deployable system for small satellite observations. As opposed to the large standard ones, small satellites have become an effective and affordable alternative access to space, owing to their lower costs, innovative design and technology, and higher revisiting times, when launched in a constellation configuration. One of the biggest challenges is created by the small satellite instrumentation working in the visible (VIS), infrared (IR), and microwave (MW) spectral ranges, for which the resolution of the acquired data depends on the physical dimension of the telescope and the antenna collecting the signal. In this respect, a deployable payload, fitting the limited size and mass imposed by the small satellite architecture, once unfolded in space, can reach performances similar to those of larger satellites. In this study, we show how ecology and Earth Observations can benefit from data acquired by small satellites, and how they can be further improved thanks to deployable payloads. We focus on DORA—Deployable Optics for Remote sensing Applications—in the VIS to TIR spectral range, and on a planned application in the MW spectral range, and we carry out a radiometric analysis to verify its performances for Earth Observation studies.
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Martellato, Elena, Alice Maria Piccirillo, Giampaolo Ferraioli, Alessandra Rotundi, Vincenzo Della Corte, Pasquale Palumbo, Emanuele Alcaras et al. "A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation". Remote Sensing 14, n.º 9 (26 de abril de 2022): 2066. http://dx.doi.org/10.3390/rs14092066.
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In this paper, we present several study cases focused on marine, oceanographic, and atmospheric environments, which would greatly benefit from the use of a deployable system for small satellite observations. As opposed to the large standard ones, small satellites have become an effective and affordable alternative access to space, owing to their lower costs, innovative design and technology, and higher revisiting times, when launched in a constellation configuration. One of the biggest challenges is created by the small satellite instrumentation working in the visible (VIS), infrared (IR), and microwave (MW) spectral ranges, for which the resolution of the acquired data depends on the physical dimension of the telescope and the antenna collecting the signal. In this respect, a deployable payload, fitting the limited size and mass imposed by the small satellite architecture, once unfolded in space, can reach performances similar to those of larger satellites. In this study, we show how ecology and Earth Observations can benefit from data acquired by small satellites, and how they can be further improved thanks to deployable payloads. We focus on DORA—Deployable Optics for Remote sensing Applications—in the VIS to TIR spectral range, and on a planned application in the MW spectral range, and we carry out a radiometric analysis to verify its performances for Earth Observation studies.
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Yang, Y., Y. Zhao e L. Zhang. "EVALUATING THE INFLUENCE OF SATELLITE OBSERVATION ON INVERSING NOX EMISSION AT REGIONAL SCALE". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W9 (25 de outubro de 2019): 211–17. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w9-211-2019.
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Abstract. In order to explore the influence of satellite observation data on the top-down NOx estimates at regional scale, the top-down NOx emissions for Yangtze River Delta (YRD) region at 9 km spatial resolution were developed with Peking University Ozone Monitoring Instrument NO2 product (POMINO) v1 and POMINO v2 satellite observation data in January and July of 2016. The differences of top-down NOx estimates derived from the two satellites were quantitative evaluated, and the reasons were comprehensively analyzed. The total NOx emissions based on POMINO v2 in January and July was 27% and 45% higher than those derived with POMINO v1, respectively. It indicated that the difference of top-down estimate derived from different satellite observation in summer was larger than that in winter. Considering that the difference between the two observations in January was similar to that in July, it was mainly because that the sensitivity of NO2 concentration to emissions was larger in summer than in winter. Top-down estimates derived from the two satellite observation were evaluated with air quality model (AQM) and ground observation. The model performances derived from top-down NOx emission based on POMINO v1 were better than those based on POMINO v2. The probable reason was that the NO2 vertical column densities (VCD) in POMINO v1 was closer to available ground-based MAX-DOAS observations during cloudless days and the satellite observation of cloudless was usually selected to inversing NOx emission.
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Tsuchiya, Kiyoshi, Kohei Arai e Tamotsu Igarashi. "Marine observation satellite". Remote Sensing Reviews 3, n.º 2 (janeiro de 1987): 59–101. http://dx.doi.org/10.1080/02757258709532089.
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Jiang, Yuhang, Feng Gao, Shaoqing Zhang, Wei Cheng, Chang Liu e Shudong Wang. "MCSPF-Net: A Precipitation Forecasting Method Using Multi-Channel Cloud Observations of FY-4A Satellite by 3D Convolution Neural Network". Remote Sensing 15, n.º 18 (15 de setembro de 2023): 4536. http://dx.doi.org/10.3390/rs15184536.
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Accurate precipitation forecasting plays an important role in disaster prevention and mitigation. Currently, precipitation forecasting mainly depends on numerical weather prediction and radar observation. However, ground-based radar observation has limited coverage and is easily influenced by the environment, resulting in the limited coverage of precipitation forecasts. The infrared observations of geosynchronous earth orbit (GEO) satellites have been widely used in precipitation estimation due to their extensive coverage, continuous monitoring, and independence from environmental influences. In this study, we propose a multi-channel satellite precipitation forecasting network (MCSPF-Net) based on 3D convolutional neural networks. The network uses real-time multi-channel satellite observations as input to forecast precipitation for the future 4 h (30-min intervals), utilizing the observation characteristics of GEO satellites for wide coverage precipitation forecasting. The experimental results showed that the precipitation forecasting results of MCSPF-Net have a high correlation with the Global Precipitation Measurement product. When evaluated using rain gauges, the forecasting results of MCSPF-Net exhibited higher critical success index (0.25 vs. 0.21) and correlation coefficients (0.33 vs. 0.23) and a lower mean square error (0.36 vs. 0.93) compared to the numerical weather prediction model. Therefore, the multi-channel satellite observation-driven MCSPF-Net proves to be an effective approach for predicting near future precipitation.
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Chandrashekar, M. G., V. Jayaramn, C. B. S. Dutt e B. Manikiam. "Earth Observation System Plans of India". International Astronomical Union Colloquium 123 (1990): 531. http://dx.doi.org/10.1017/s0252921100077617.
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AbstractOperational methodologies are available to retrieve several parameters related to the land, air and oceans from satellite data which is capable of providing well calibrated data/observations over large areas giving a synoptic view on a repetitive and reliable basis. The capability of satellites to provide data in various spectral, spatial and temporal scales is of great advantage in studying the dynamic aspects of earth atmosphere system. The present day capabilities of satellites include spatial resolutions ranging from 10 m and above and repetition of a few hours (geosynchronous Satellite) to few days. Higher spatial resolutions and all weather capabilities (through microwave sensing) are becoming available in the immediate future. Towards utilising the potentials of space based systems, India has been operating INSAT series of satellite for weather monitoring and 1RS series of satellites for natural resources monitoring/management. The INSAT is a series of geostationary satellites stationed over Indian region to provide meteorological observations on a continuous basis in visible and thermal regions in addition to providing services for disaster warning related to Cyclones and remote location data collection platforms. The space based observations on meteorology over the past 5 years is proving to be a valuable data base for studies related to monsoon dynamics and tropical cyclones.
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Nashimoto, Masashi, Masayuki Tanaka, Masashi Chiba, Kohei Hayashi, Yutaka Komiyama e Takashi Okamoto. "The Missing Satellite Problem outside of the Local Group. II. Statistical Properties of Satellites of Milky Way–like Galaxies". Astrophysical Journal 936, n.º 1 (29 de agosto de 2022): 38. http://dx.doi.org/10.3847/1538-4357/ac83a4.
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Abstract We present a new observation of satellite galaxies around seven Milky Way (MW)–like galaxies located outside of the Local Group (LG) using Subaru/Hyper Suprime-Cam imaging data to statistically address the missing satellite problem. We select satellite galaxy candidates using magnitude, surface brightness, Sérsic index, axial ratio, FWHM, and surface brightness fluctuation cuts, followed by visual screening of false positives such as optical ghosts of bright stars. We identify 51 secure dwarf satellite galaxies within the virial radius of nine host galaxies, two of which are drawn from the pilot observation presented in Paper I. We find that the average luminosity function of the satellite galaxies is consistent with that of the MW satellites, although the luminosity function of each host galaxy varies significantly. We observe an indication that more massive hosts tend to have a larger number of satellites. Physical properties of the satellites such as the size–luminosity relation are also consistent with the MW satellites. However, the spatial distribution is different; we find that the satellite galaxies outside of the LG show no sign of concentration or alignment, while that of the MW satellites is more concentrated around the host and exhibits a significant alignment. As we focus on relatively massive satellites with M V < −10, we do not expect that the observational incompleteness can be responsible here. This trend might represent a peculiarity of the MW satellites, and further work is needed to understand its origin.
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Meng, Fan Qin, Xu Hai Yang, Ji Kun Ou e Pei Wei. "Method of Determining Satellite Clock Error by Using Observation Data of Satellite-Ground and Inter-Satellite". Advanced Materials Research 718-720 (julho de 2013): 474–79. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.474.
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We have done some simulate analysis on GPS data in this paper. The main research is method of determining satellite clock error by usining observation data of satellite-ground and inter-satellite under the condition of regional station arrangement. The research method is as follows: when the satellite in the visible area of regional observation network, we can get satellite clock error directly by satellite-ground time comparison, and predict the satellite clock error in invisible area. When the satellite in the invisible area of regional observation network, if this satellite can establish inter-satellite links with other satellites in the visible area, then the satellite clock error can be determined by time comparison of satellite-ground and inter-satellite; If there is no inter-satellite link between this satellite and other satellites in the visible area, then we can only predict the satellite clock error by given data. The simulation conditions of this paper are as follows: the system error of satellite-ground is 0.5 ns, the random error is 0.5 ns; the system error of inter-satellite is 1 ns, the random error is 0.5 ns. In this case, we can obtain the satellite clock error of PRN02 in an orbital period by method of this paper, and the accuracy is about 1.3 ns.
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Qin, Dan, Yongjun Jia, Mingsen Lin e Shanwei Liu. "Performance Evaluation of China’s First Ocean Dynamic Environment Satellite Constellation". Remote Sensing 15, n.º 19 (30 de setembro de 2023): 4780. http://dx.doi.org/10.3390/rs15194780.
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China’s first dynamic environment satellite constellation includes the HY-2B, HY-2C, and HY-2D satellites. In this study, the along track SLA, SWH, and SSWS of this satellite constellation were evaluated. SLA parameters are evaluated using self-crossing and dual-crossing methods. The SSWS and SWH data were evaluated by comparing with NDBC buoy and other available satellites’ data. The evaluation revealed that the standard deviation of the SLA from the HY-2B/C/D satellites’ single mission crossovers was 3.29 cm, 3.51 cm, and 3.72 cm, respectively. In addition, at the dual-crossovers of the Jason-3 satellite and the HY-2B satellite, the HY-2B satellite, and the HY-2C/D satellites, the standard deviation was determined to be 3.40 cm, 3.48 cm, and 4.25 cm, respectively. The accuracy of the SWH products of the HY-2B/C/D satellite radar altimeters was observed to be 0.23 m, 0.25 m, and 0.26 m, respectively. The accuracy of the SSWS data of the HY-2B/C/D satellite radar altimeters was observed to be 1.48 m/s, 1.59 m/s, and 1.35 m/s, respectively. In addition, this study also analyzed and compared the observation efficiency of the dynamic environment satellite constellation with the following six satellites: Sentinel-3(A, B), Jason-3, Sentinel-6A, Saral, and Cryosat-2. Observation efficiency refers to selection of any point on the globe to find a minimum radius of at least one observation point within a circle in a 14-day period. The analysis results demonstrated that observation efficiency of China’s first dynamic environment satellite constellation was comparable to that of the six satellites.
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Wu, Juntao, Mingkun Su, Jun Gong, Lingsa Pan, Jiale Long e Fu Zheng. "Analysis of the Influence of Flood on the L4 Combination Observation of GPS and GLONASS Satellites". Atmosphere 14, n.º 6 (26 de maio de 2023): 934. http://dx.doi.org/10.3390/atmos14060934.
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With global warming, extreme weather such as floods and waterlogging occurs more frequently and seriously in recent years. During the flood, the surrounding environment of the GNSS (Global Navigation Satellite System) station will change as the volume of water increases. Considering the multipath error is directly relevant to the observation environment, thus, the influence of flood on the L4 combination observation (a geometry-free ionosphere-free linear combination of carrier phase) which is related to the multipath error of GPS (Global Positioning System) and GLONASS satellites is investigated in depth. In addition, the ground track repetition periods of GPS and GLONASS satellites are analyzed in the sky plot to illustrate the rationality of chosen reference day. Based on the results of the satellite sky plot, one and eight days are adopted to demonstrate the influence of flood on L4 combination observation for GPS and GLONASS satellites, respectively. Real data sets collected at the ZHNZ GNSS observation station during the flood from DOY (Day of Year) 193 to DOY 204, 2021 are used. Experimental results show that the flood has a significant impact on the L4 combination observation of GPS and GLONASS satellites, and the fluctuation of L4 under flood performs much larger than that of without flood. For GPS satellites, the maximum RMS (root mean square) increase rate of L4 under flood is approximately 186.67% on the G31 satellite. Even for the minimum RMS increase rate, it can reach approximately 23.52%, which is the G02 satellite. Moreover, the average RMS increase rate of GPS and GLONASS satellites can reach approximately 109.53% and 43.65%, respectively. In addition, the influence of rainfall and hardware device are also investigated, which can further demonstrate that the fluctuation of L4 is mainly caused by the flood but not by the rainfall and hardware device elements. Thus, based on the above results, the influence of flood on L4 observation should be taken into account during the applications of L4 used, such as the retrieval of soil moisture and vegetation water content based on GNSS L4 combination observations
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Zhang, Qinghua, Yongxing Zhu e Zhengsheng Chen. "An In-Depth Assessment of the New BDS-3 B1C and B2a Signals". Remote Sensing 13, n.º 4 (21 de fevereiro de 2021): 788. http://dx.doi.org/10.3390/rs13040788.
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An in-depth and comprehensive assessment of new observations from BDS-3 satellites is presented, with the main focus on the Carrier-to-Noise density ratio (C/N0), the quality of code and carrier phase observations for B1C and B2a signal. The signal characteristics of geosynchronous earth orbit (GEO), inclined geosynchronous satellite orbit (IGSO) and medium earth orbit (MEO) satellites of BDS-3 were grouped and compared, respectively. The evaluation results of the new B1C and B2a signals of BDS-3 were compared with the previously B1I/B2I/B3I signals and the interoperable signals of GPS, Galileo and quasi-zenith satellite system (QZSS) were compared simultaneously. As expected, the results clearly show that B1C and B2a have better signal strength and higher accuracy, including code and carrier phase observations. The C/N0 of the B2a signal is about 3 dB higher than other signals. One exception is the code observation accuracy of B3I, which value is less than 0.15 m. The carrier precision of B1C and B2a is better than that of B1I/B2I/B3I. Despite difference-in-difference (DD) observation quantity or zero-base line evaluation is adopted, while B1C is about 0.3 mm higher carrier precision than B2a. The BDS-3 MEO satellite and GPS, Galileo, and QZSS satellites have the same level of signal strength, code and phase observation accuracy at the interoperable frequency, namely 1575.42 MHz and 1176.45 MHz which are very suitable for the co-position application.
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Zhang, Xiao, Yang, Liu, Chang e Zhou. "An Effectiveness Evaluation Model for Satellite Observation and Data-Downlink Scheduling Considering Weather Uncertainties". Remote Sensing 11, n.º 13 (8 de julho de 2019): 1621. http://dx.doi.org/10.3390/rs11131621.
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Low Earth orbit (LEO) satellites play an important role in human space activities, and market demands for commercial uses of LEO satellites have been increasing rapidly in recent years. LEO satellites mainly consist of Earth observation satellites (EOSs), the major commercial applications of which are various sorts of Earth observations, such as map making, crop growth assessment, and disaster surveillance. However, the success rates of observation tasks are influenced considerably by uncertainties in local weather conditions, inadequate sunlight, observation dip angle, and other practical factors. The available time windows (ATWs) suitable for observing given types of targets and for transmitting data back to ground receiver stations are relatively narrow. In order to utilize limited satellite resources efficiently and maximize their commercial benefits, it is necessary to evaluate the overall effectiveness of satellites and planned tasks considering various factors. In this paper, we propose a method for determining the ATWs considering the influence of sunlight angle, elevation angle, and the type of sensor equipped on the satellite. After that, we develop a satellite effectiveness evaluation (SEE) model for satellite observation and data-downlink scheduling (SODS) based on the Availability–Capacity–Profitability (ACP) framework, which is designed to evaluate the overall performance of satellites from the perspective of time resource utilization, the success rate of tasks, and profit return. The effects of weather uncertainties on the tasks’ success are considered in the SEE model, and the model can be applied to support the decision-makers on optimizing and improving task arrangements for EOSs. Finally, a case study is presented to demonstrate the effectiveness of the proposed method and verify the ACP-based SEE model. The obtained ATWs by the proposed method are compared with those by the Systems Tool Kit (STK), and the correctness of the method is thus validated.
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Solíz, J., M. Quiroga e R. Puma-Guzmán. "DESIGN OF A SPACE MISSION FOR THE ACQUISITION OFTERRESTRIAL IMAGES FOR BOLIVIA". Revista Mexicana de Astronomía y Astrofísica Serie de Conferencias 52 (5 de outubro de 2020): 21–22. http://dx.doi.org/10.22201/ia.14052059p.2020.52.08.
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The importance of having a terrestrial observation satellite consists of the need of governments and private entities to have recent images of a specific area, for the use of cartography, illicit plantations, mining, petroleum deposits, natural disasters, etc. Therefore, having up-to-date images of the national territory should be a priority. This analysis and design of mission focuses on the design of the orbit of the satellite, studying what type of orbit is appropriate for a future Earth observation satellite. The simulation of the orbit is carried out in this work through the study of the perturbations that most affect low-altitude satellites. The calculation of the satellite's revisit time will be based on areas of potential study interest for both the government and private companies settled in the country.
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Cui, Jintian, e Xin Zhang. "Application of a Multi-Satellite Dynamic Mission Scheduling Model Based on Mission Priority in Emergency Response". Sensors 19, n.º 6 (23 de março de 2019): 1430. http://dx.doi.org/10.3390/s19061430.
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Emergency observations are missions executed by Earth observation satellites to support urgent ground operations. Emergency observations become more important for meeting the requirements of highly dynamic and highly time-sensitive observation missions, such as disaster monitoring and early warning. Considering the complex scheduling problem of Earth observation satellites under emergency conditions, a multi-satellite dynamic mission scheduling model based on mission priority is proposed in this paper. A calculation model of mission priority is designed for emergency missions based on seven impact factors. In the satellite mission scheduling, the resource constraints of scheduling are analyzed in detail, and the optimization objective function is built to maximize the observation mission priority and mission revenues, and minimize the waiting time for missions that require urgency for execution time. Then, the hybrid genetic tabu search algorithm is used to obtain the initial satellite scheduling plan. In case of the dynamic arrival of new emergency missions before scheduling plan releases, a dynamic scheduling algorithm based on mission priority is proposed to solve the scheduling problem caused by newly arrived missions and to obtain the scheduling plan of newly arrived missions. A simulation experiment was conducted for different numbers of initial missions and newly arrived missions, and the scheduling results were evaluated with a model performance evaluation function. The results show that the execution probability of high-priority missions increased because the mission priority was taken into account in the model. In the case of more satellite resources, when new missions dynamically arrived, the satellite resources can be reasonably allocated to these missions based on the mission priority. Overall, this approach reduces the complexity of the dynamic adjustment and maintains the stability of the initial scheduling plan.
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Kim, Dongwoo, e Taejin Chung. "Design of an Elliptical Orbit for High-Resolution Optical Observation at a Very Low Altitude over the Korean Peninsula". Journal of Astronomy and Space Sciences 40, n.º 1 (março de 2023): 35–44. http://dx.doi.org/10.5140/jass.2023.40.1.35.
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Surveillance and reconnaissance intelligence in the space domain will become increasingly important in future battlefield environments. Moreover, to assimilate the military provocations and trends of hostile countries, imagery intelligence of the highest possible resolution is required. There are many methods for improving the resolution of optical satellites when observing the ground, such as designing satellite optical systems with a larger diameter and lowering the operating altitude. In this paper, we propose a method for improving ground observation resolution by using an optical system for a previously designed low orbit satellite and lowering the operating altitude of the satellite. When the altitude of a satellite is reduced in a circular orbit, a large amount of thrust fuel is required to maintain altitude because the satellite’s altitude can decrease rapidly due to atmospheric drag. However, by using the critical inclination, which can fix the position of the perigee in an elliptical orbit to the observation area, the operating altitude of the satellite can be reduced using less fuel compared to a circular orbit. This method makes it possible to obtain a similar observational resolution of a medium-sized satellite with the same weight and volume as a small satellite. In addition, this method has the advantage of reducing development and launch costs to that of a small-sized satellite. As a result, we designed an elliptical orbit. The perigee of the orbit is 300 km, the apogee is 8,366.52 km, and the critical inclination is 116.56°. This orbit remains at its lowest altitude to the Korean peninsula constantly with much less orbit maintenance fuel compared to the 300 km circular orbit.
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Zhang, Shengyu, Zhencai Zhu, Haiying Hu e Yuqing Li. "Research on Task Satellite Selection Method for Space Object Detection LEO Constellation Based on Observation Window Projection Analysis". Aerospace 8, n.º 6 (31 de maio de 2021): 156. http://dx.doi.org/10.3390/aerospace8060156.
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Aiming at the task planning and scheduling problem of space object detection LEO constellation (SODLC) for detecting space objects in deep space background, a method of SODLC task satellite selection based on observation window projection analysis is proposed. This method projects the spatial relative relationships of the SODLC observation blind zone, observation range, and the initial spatial position of the objects onto the surface of the earth for detectable analysis of satellites and targets and binds the dynamic observation conditions to the satellite trajectory after projection calculation of the visible relationship between target changes. On this basis, combined with the features of SODLC with high orbital symmetry, the task satellite selection is divided into two steps: orbit plane selection and task satellite selection. The orbit planes are selected based on the longitude range of the ascending node with the geographic location of the targets, and the task satellites are selected according to the relative motion relationship between the satellites and the targets together with the constraints of observable conditions. The selection method simplifies the calculation process of scheduling and selecting task satellites. Simulation analysis prove the method has better task satellite selection efficiency. The method has high practical value for task planning and scheduling for event-driven SODLC.
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Kidd, Chris, Vincenzo Levizzani e Peter Bauer. "A review of satellite meteorology and climatology at the start of the twenty-first century". Progress in Physical Geography: Earth and Environment 33, n.º 4 (agosto de 2009): 474–89. http://dx.doi.org/10.1177/0309133309346647.
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The observation of the atmosphere by satellite instrumentation was one of the first uses of remotely sensed data nearly 50 years ago. Since then a range of satellites have carried many different meteorological sensors capable of monitoring the dynamics of the atmosphere and the capture and retrieval of information about atmospheric parameters for use in meteorological and climatological applications. The utilization of satellite observations for meteorology and climatology is essential since the atmosphere is a global feature, and conventional observations of it are primarily land-based. Satellites, with their synoptic view, provide much information benefiting numerical weather prediction models to improve weather forecasting and the ability to monitor weather systems, in particular those that pose a threat to humankind, over the entire Earth. Development of new observational capabilities has led to new insights into atmospheric processes and their interaction, allowing the consequences of anthropogenic activities, such as climate change, to be monitored.
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Paek, S. W., S. Kim, L. Kronig e O. de Weck. "Sun-synchronous repeat ground tracks and other useful orbits for future space missions". Aeronautical Journal 124, n.º 1276 (10 de março de 2020): 917–39. http://dx.doi.org/10.1017/aer.2020.21.
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ABSTRACTThe development of oceanography and meteorology has greatly benefited from satellite-based data of Earth’s atmosphere and ocean. Traditional Earth observation missions have utilised Sun-synchronous orbits with repeat ground tracks due to their advantages in visible and infrared wavelengths. However, diversification of observation wavelengths and massive deployment of miniaturised satellites are both enabling and necessitating new kinds of space missions. This paper proposes several unconventional satellite orbits intended for use in, but not limited to, Earth observation. This ‘toolbox’ of orbits and taxonomy thereof will thus support the definition of design requirements for the individual satellites in nano-satellite constellations developed by national space agencies, industries and academia.
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Chen, Hao, Shu Yang, Jun Li e Ning Jing. "Exact and Heuristic Methods for Observing Task-Oriented Satellite Cluster Agent Team Formation". Mathematical Problems in Engineering 2018 (6 de agosto de 2018): 1–23. http://dx.doi.org/10.1155/2018/2103625.
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With the development of aerospace science and technology, Earth Observation Satellite cluster which consists of heterogeneous satellites with many kinds of payloads appears gradually. Compared with the traditional satellite systems, satellite cluster has some particular characteristics, such as large-scale, heterogeneous satellite platforms, various payloads, and the capacity of performing all the observation tasks. How to select a subset from satellite cluster to perform all observation tasks effectively with low cost is a new challenge arousing in the field of aerospace resource scheduling. This is the agent team formation problem for observation task-oriented satellite cluster. A mathematical scheduling model is built. Three novel algorithms, i.e., complete search algorithm, heuristic search algorithm, and swarm intelligence optimization algorithm, are proposed to solve the problem in different scales. Finally, some experiments are conducted to validate the effectiveness and practicability of our algorithms.
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Takenaka, Hideaki, Taiyou Sakashita, Atsushi Higuchi e Teruyuki Nakajima. "Geolocation Correction for Geostationary Satellite Observations by a Phase-Only Correlation Method Using a Visible Channel". Remote Sensing 12, n.º 15 (1 de agosto de 2020): 2472. http://dx.doi.org/10.3390/rs12152472.
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This study describes a high-speed correction method for geolocation information of geostationary satellite data for accurate physical analysis. Geostationary satellite observations with high temporal resolution provide instantaneous analysis and prompt reports. We have previously reported the quasi real-time analysis of solar radiation at the surface and top of the atmosphere using geostationary satellite data. Estimating atmospheric parameters and surface albedo requires accurate geolocation information to estimate the solar radiation accurately. The physical analysis algorithm for Earth observations is verified by the ground truth. In particular, downward solar radiation at the surface is validated by pyranometers installed at ground observation sites. The ground truth requires that the satellite observation data pixels be accurately linked to the location of the observation equipment on the ground. Thus, inaccurate geolocation information disrupts verification and causes complex problems. It is difficult to determine whether error in the validation of physical quantities arises from the estimation algorithm, satellite sensor calibration, or a geolocation problem. Geolocation error hinders the development of accurate analysis algorithms; therefore, accurate observational information with geolocation information based on latitude and longitude is crucial in atmosphere and land target analysis. This method provides the basic data underlying physical analysis, parallax correction, etc. Because the processing speed is important in geolocation correction, we used the phase-only correlation (POC) method, which is fast and maintains the accuracy of geolocation information in geostationary satellite observation data. Furthermore, two-dimensional fast Fourier transform allowed the accurate correction of multiple target points, which improved the overall accuracy. The reference dataset was created using NASA’s Shuttle Radar Topography Mission 1-s mesh data. We used HIMAWARI-8/Advanced HIMAWARI Imager data to demonstrate our method, with 22,709 target points for every 10-min observation and 5826 points for every 2.5 min observation. Despite the presence of disturbances, the POC method maintained its accuracy. Column offset and line offset statistics showed stability and characteristic error trends in the raw HIMAWARI standard data. Our method was sufficiently fast to apply to quasi real-time analysis of solar radiation every 10 and 2.5 min. Although HIMAWARI-8 is used as an example here, our method is applicable to all geostationary satellites. The corrected HIMAWARI 16 channel gridded dataset is available from the open database of the Center for Environmental Remote Sensing (CEReS), Chiba University, Japan. The total download count was 50,352,443 on 8 July 2020. Our method has already been applied to NASA GeoNEX geostationary satellite products.
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He, Lei, e Dong Liang Qin. "Ballistic Measurement and Parameter Estimation of Ballistic Missile with Early Warning Satellite". Advanced Materials Research 712-715 (junho de 2013): 1960–64. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.1960.
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Space infrared early warning satellite is an important platform for detecting ballistic missile launch and trajectory. This paper established observation satellite motion model, and the motion state of the satellite at any time was gotten based on its initial information by numerical integration methods. According the theory of double satellites location and satellite observation data of ballistic missile, the observation trajectory of ballistic missile was fitted. The trajectory was used to build the motion model of ballistic missile, and the position, speed and other parameters of the ballistic missile can be inferred. Finally, simulation experiment was conducted.
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Balsamo, G., J.-F. Mahfouf, S. Bélair e G. Deblonde. "A Land Data Assimilation System for Soil Moisture and Temperature: An Information Content Study". Journal of Hydrometeorology 8, n.º 6 (1 de dezembro de 2007): 1225–42. http://dx.doi.org/10.1175/2007jhm819.1.
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Abstract A Canadian Land Data Assimilation System (CaLDAS) for the analysis of land surface prognostic variables is designed and implemented at the Meteorological Service of Canada for the initialization of numerical weather prediction and climate models. The assimilation of different data sources for the production of daily soil moisture and temperature analyses is investigated in a set of observing system simulation experiments over North America. A simplified variational technique is adapted to accommodate different observation types at their appropriate time in a 24-h time window. The screen-level observations of temperature and relative humidity, from conventional synoptic surface observations (SYNOP)/aviation routine weather report (METAR)/surface aviation observation (SA) reports, are considered together with presently available satellite observations provided by the Aqua satellite (microwave C-band), Geostationary Operational Environmental Satellite (GOES) [infrared (IR)], and observations available in the future by the Soil Moisture and Ocean Salinity (SMOS) satellite mission (microwave L-band). The aim of these experiments is to assess the information content brought by each observation type in the land surface analysis. The observation systems are simulated according to their spatial coverage, temporal availability, and nominal or expected errors. The results show that the observable with the largest dynamical response to perturbations of the control variable carries the greatest information content into the analysis. The observational error and the observation frequency counterbalance this feature in the analysis. If one considers a single observation both for soil moisture and soil temperature analysis, then satellite measurements (L-band, C-band, and IR in decreasing order of importance) are the primary source of information. When observation availability is considered and the highest temporal frequency of screen-level observations is used (1 h), a large amount of information is extracted from SYNOP-like reports. The screen-level observations are shown to provide valuable soil moisture information mainly during the daytime, while during nighttime these observations (and particularly screen-level temperature) are mostly useful for the soil temperature analysis. The results are presented with perspectives for future operational developments and preliminary assimilation experiments are performed with hourly screen-level observations.
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Liu, Sikai, e Jun Yang. "A Satellite Task Planning Algorithm Based on a Symmetric Recurrent Neural Network". Symmetry 11, n.º 11 (6 de novembro de 2019): 1373. http://dx.doi.org/10.3390/sym11111373.
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The intelligent satellite, iSAT, is a concept based on software-defined satellites. Earth observation is one of the important applications of intelligent satellites. With the increasing demand for rapid satellite response and observation tasks, intelligent satellite in-orbit task planning has become an inevitable trend. In this paper, a mixed integer programming model for observation tasks is established, and a heuristic search algorithm based on a symmetric recurrent neural network is proposed. The configurable probability of the observation task is obtained by constructing a structural symmetric recurrent neural network, and finally, the optimal task planning scheme is obtained. The experimental results are compared with several typical heuristic search algorithms, which have certain advantages, and the validity of the paper is verified. Finally, future application prospects of the method are discussed.
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Papiya, Sumaiya Janefar, Dr Bobby Barua e Mehnaz Hossain. "Prospects Challenges of Bangabandhu Satellite-2". International Journal of Advanced Networking and Applications 14, n.º 02 (2022): 5342–52. http://dx.doi.org/10.35444/ijana.2022.14204.
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The development of the Bangabandhu Satellite-1 has changed the direction of Bangladesh's satellite communication research. Bangladesh's dream project was the Bangabandhu Satellite 1. This satellite's primary goal is to maintain effective internet and communication services in remote places. First of all, we must concentrate to the depth of satellite communication system and its process to reach any conclusion. Our main goal of the research is to recognize a feasibility review on Bangabandhu satellite-2. So, for the feasibility studies we reviewed the most promising technical parts of Bangabandhu satellite-1. Here, we only focused the certain parts of the satellite such as coding, modulation, battery, purpose of ground station and the benefits of the satellite communication system. Then we moved on the main parts of the Bangabandhu satellite-2. As, Bangabandhu satellite-1 was Geosynchronous equatorial orbit (GEO) communication satellite and Bangabandhu satellite-2 will be Low Earth Orbit (LEO) observation satellite (LEO) so, some of configurations between them might be changed. Furthermore, we largely focused on Facts, efficiency, performance and noticeable difference between two satellites.
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Lee, Jeeho, Eunseo Park, Man-Soo Choi, Daniel Kucharski, Yu Yi e Jong-Uk Park. "Spin Axis Determination of Defunct GLONASS Satellites Using Photometry Observation". Journal of Astronomy and Space Sciences 38, n.º 1 (março de 2021): 45–53. http://dx.doi.org/10.5140/jass.2021.38.1.45.
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GLONASS, a satellite navigation system developed in Russia since 1976, is defunct and orbits in an unstable attitude. The satellites in these problems are not managed and there is no precise information, which can increase the risk of collisions with other space objects. In this study, detailed attitude dynamic have to be analyzed through photometry data, which requires spin period and spin axis. The light curve data is obtained by observing through the photometer at the Graz station and the power spectrum is calculated to obtain the cycle of the satellite. The geometric relationship between observer and sun is analyzed for GLONASS-50 satellite. The box-wing model is applied to obtain the phase reflection of the satellite and obtain the Irradiation of the satellite through this information. In Light Curve and Irradiation, the spin axis is calculated for each peak points with the distance square minimum technique. The spin axis of the GLONASS-50 satellite is RA = 116°, Dec = 92°.
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Li, Zhiliang, Limin Zhao, Yun Liu, Xingfeng Chen, Hang Chen, Fengjie Zheng, Yunli Zhang et al. "Autonomous Mission Planning Method for Optical Imaging Satellites Based on Real-Time Cloud Cover Information". Remote Sensing 14, n.º 11 (31 de maio de 2022): 2635. http://dx.doi.org/10.3390/rs14112635.
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Cloud cover is an important factor limiting the earth observation efficiency of optical imaging satellites. Existing solutions include avoiding cloudy observation time windows by onboard cloud detectors and ground monitors, which are difficult to improve satellite observation efficiency in time. In order to solve the problem, firstly, a Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites cooperation scheme by using cloud cover information provided by GEO meteorological satellite to guide the imaging of LEO optical satellites is proposed, and the operation flow and key elements in this scheme are analyzed. Secondly, Fengyun-4 GEO meteorological satellite and its cloud mask (CLM) products are analyzed. Thirdly, an autonomous mission planning algorithm based on real-time cloud cover information is proposed. Computational results have demonstrated the effectiveness of the proposed GEO–LEO satellites cooperation scheme by taking the actual orbit and payload data of Fengyun-4 and Gaofen-1/2 satellites as examples.
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Darbeheshti, Neda, Henry Wegener, Vitali Müller, Majid Naeimi, Gerhard Heinzel e Martin Hewitson. "Instrument data simulations for GRACE Follow-on: observation and noise models". Earth System Science Data 9, n.º 2 (17 de novembro de 2017): 833–48. http://dx.doi.org/10.5194/essd-9-833-2017.
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Abstract. The Gravity Recovery and Climate Experiment (GRACE) mission has yielded data on the Earth's gravity field to monitor temporal changes for more than 15 years. The GRACE twin satellites use microwave ranging with micrometre precision to measure the distance variations between two satellites caused by the Earth's global gravitational field. GRACE Follow-on (GRACE-FO) will be the first satellite mission to use inter-satellite laser interferometry in space. The laser ranging instrument (LRI) will provide two additional measurements compared to the GRACE mission: interferometric inter-satellite ranging with nanometre precision and inter-satellite pointing information. We have designed a set of simulated GRACE-FO data, which include LRI measurements, apart from all other GRACE instrument data needed for the Earth's gravity field recovery. The simulated data files are publicly available via https://doi.org/10.22027/AMDC2 and can be used to derive gravity field solutions like from GRACE data. This paper describes the scientific basis and technical approaches used to simulate the GRACE-FO instrument data.
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Yoshida, Mayumi, Keiya Yumimoto, Takashi M. Nagao, Taichu Y. Tanaka, Maki Kikuchi e Hiroshi Murakami. "Satellite retrieval of aerosol combined with assimilated forecast". Atmospheric Chemistry and Physics 21, n.º 3 (10 de fevereiro de 2021): 1797–813. http://dx.doi.org/10.5194/acp-21-1797-2021.
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Abstract. We developed a new aerosol satellite retrieval algorithm combining a numerical aerosol forecast. In the retrieval algorithm, the short-term forecast from an aerosol data assimilation system was used as an a priori estimate instead of spatially and temporally constant values. This method was demonstrated using observation of the Advanced Himawari Imager onboard the Japan Meteorological Agency's geostationary satellite Himawari-8. Overall, the retrieval results incorporated strengths of the observation and the model and complemented their respective weaknesses, showing spatially finer distributions than the model forecast and less noisy distributions than the original algorithm. We validated the new algorithm using ground observation data and found that the aerosol parameters detectable by satellite sensors were retrieved more accurately than an a priori model forecast by adding satellite information. Further, the satellite retrieval accuracy was improved by introducing the model forecast instead of the constant a priori estimates. By using the assimilated forecast for an a priori estimate, information from previous observations can be propagated to future retrievals, leading to better retrieval accuracy. Observational information from the satellite and aerosol transport by the model are incorporated cyclically to effectively estimate the optimum field of aerosol.
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Jung, Byoung-Joo, Hyun Mee Kim, Thomas Auligné, Xin Zhang, Xiaoyan Zhang e Xiang-Yu Huang. "Adjoint-Derived Observation Impact Using WRF in the Western North Pacific". Monthly Weather Review 141, n.º 11 (25 de outubro de 2013): 4080–97. http://dx.doi.org/10.1175/mwr-d-12-00197.1.
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Abstract An increasing number of observations have contributed to the performance of numerical weather prediction systems. Accordingly, it is important to evaluate the impact of these observations on forecast accuracy. While the observing system experiment (OSE) requires considerable computational resources, the adjoint-derived method can evaluate the impact of all observational components at a lower cost. In this study, the effect of observations on forecasts is evaluated by the adjoint-derived method using the Weather Research and Forecasting Model, its adjoint model, and a corresponding three-dimensional variational data assimilation system in East Asia and the western North Pacific for the 2008 typhoon season. Radiance observations had the greatest total impact on forecasts, but conventional wind observations had the greatest impact per observation. For each observation type, the total impact was greatest for radiosonde and each Advanced Microwave Sounding Unit (AMSU)-A satellite, followed by surface synoptic observation from a land station (SYNOP), Quick Scatterometer (QuikSCAT), atmospheric motion vector (AMV) wind from a geostationary satellite (GEOAMV), and aviation routine weather reports (METARs). The fraction of beneficial observations was approximately 60%–70%, which is higher than that reported in previous studies. For several analyses of Typhoons Sinlaku (200813) and Jangmi (200815), dropsonde soundings taken near the typhoon had similar or greater observation impacts than routine radiosonde soundings. The sensitivity to the error covariance parameter indicates that reducing (increasing) observation (background) error covariance helps to reduce forecast error in the current analysis framework. The observation impact from OSEs is qualitatively similar to that from the adjoint method for major observation types. This study confirms that radiosonde observations provide primary information on the atmospheric state as in situ observations and that satellite radiances are an essential component of atmospheric observation systems.
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Tregloan-Reed, J., A. Otarola, E. Ortiz, V. Molina, J. Anais, R. González, J. P. Colque e E. Unda-Sanzana. "First observations and magnitude measurement of Starlink’s Darksat". Astronomy & Astrophysics 637 (30 de abril de 2020): L1. http://dx.doi.org/10.1051/0004-6361/202037958.
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Aims. We measured the Sloan g′ magnitudes of the Starlink’s STARLINK-1130 (Darksat) and 1113 low Earth orbit (LEO) communication satellites to determine the effectiveness of the Darksat darkening treatment at 475.4 nm. Methods. Two observations of the Starlink’s Darksat LEO communication satellite were conducted on 2020/02/08 and 2020/03/06 using Sloan r′ and g′ filters, respectively. A second satellite, STARLINK-1113, was observed on 2020/03/06 using a Sloan g′ filter. The initial observation on 2020/02/08 was a test observation conducted when Darksat was still in the process of manoeuvring to its nominal orbit and orientation. Based on the successful test observation, the first main observation took place on 2020/03/06, along with an observation of the second Starlink satellite. Results. The calibration, image processing, and analysis of the Darksat Sloan g′ image gives an estimated Sloan g′ magnitude of 7.46 ± 0.04 at a range of 976.50 km. For STARLINK-1113, an estimated Sloan g′ magnitude of 6.59 ± 0.05 at a range of 941.62 km was found. When scaled to a range of 550 km and corrected for the solar and observer phase angles, a reduction by a factor of two is seen in the reflected solar flux between Darksat and STARLINK-1113. Conclusions. The data and results presented in this work demonstrate that the special darkening coating used by Starlink for Darksat has darkened the Sloan g’ magnitude by 0.77 ± 0.05 mag when the range is equal to a nominal orbital height (550 km). This result will serve members of the astronomical community who are actively modelling the satellite mega-constellations to ascertain their actual impact on both amateur and professional astronomical observations. Both concurrent and subsequent observations are planned to cover the full optical and NIR spectrum using an ensemble of instruments, telescopes, and observatories.
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He, Yongming, Lei He, Yuan Wang, Yu Xiao, Yingwu Chen e Lining Xing. "Autonomous Mission Replanning Method for Imaging Satellites Considering Real-Time Weather Conditions". Journal of Computational and Theoretical Nanoscience 13, n.º 10 (1 de outubro de 2016): 6967–73. http://dx.doi.org/10.1166/jctn.2016.5654.
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During the observations made by imaging satellites, meteorological factors are likely to change frequently. The vagaries of weather conditions and significant effects on the actual observation results mean that there is an urgent need to apply more intelligence to satellite mission planning. Thus, this paper describes an autonomous replanning method for imaging satellites that considers the real-time weather conditions. Considering the characteristics of different input data, this method replans the low-yield task set and fine-tunes others to improve profitability. Moreover, the proposed method can heuristically select the appropriate adjustment rule to achieve autonomous satellite mission planning. A series of simulations with various task quantities and in different environments shows that the proposed method can respond effectively to real-time weather changes, and can steadily improve the total profits in a variety of weather conditions during Earth observation activities.
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Zheng, Zhonggang, Qingmei Li e Kun Fu. "Evaluation Model of Remote Sensing Satellites Cooperative Observation Capability". Remote Sensing 13, n.º 9 (29 de abril de 2021): 1717. http://dx.doi.org/10.3390/rs13091717.
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This paper proposed a new remote sensing observation capability evaluation model (RSOCE) based on analytic hierarchy process to quantitatively evaluate the capability of multi-satellite cooperative remote sensing observation. The analytic hierarchical process model is a combination of qualitative and quantitative analysis of systematic decision analysis method. According to the objective of the remote sensing cooperative observation mission, we decompose the complex problem into several levels and a number of factors, compare and calculate various factors in pairs, and obtain the combination weights of different schemes. The model can be used to evaluate the observation capability of resource satellites. Taking the optical remote sensing satellites, such as China’s resource satellite series and GF-4, as examples, this paper verifies and evaluates the model for three typical tasks: point target observation, regional target observation, and moving target continuous observation. The results show that the model can provide quantitative reference and model support for comprehensive evaluation of the collaborative observation capability of remote sensing satellites.
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Zhao, Yulong, Yuan Zhang, Yan Wang e Xianjun Pan. "Research on user requirements preprocessing of imaging reconnaissance satellites". Journal of Physics: Conference Series 2551, n.º 1 (1 de julho de 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2551/1/012007.
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Abstract Aiming at how to solve the problem of optimal matching between imaging reconnaissance user requirements and satellite resources, this paper conducts research on the preprocessing of imaging reconnaissance satellite requirements. First, considering the remote sensor type and resolution of imaging satellites, a requirement-resource matching matrix is constructed to realize the preliminary matching between user requirements and imaging reconnaissance satellite resources. Secondly, starting from the time constraints, by calculating the observation time window of requirement and resources, the time requirements of satellite resources and user requirements are matched. Finally, in order to solve the problem that the same observation task can be completed by multiple imaging satellites, a conflict resolution method based on resource consumption is proposed, which effectively improves the preprocessing ability of user requirements.
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Cucurull, L., e R. A. Anthes. "Impact of Infrared, Microwave, and Radio Occultation Satellite Observations on Operational Numerical Weather Prediction". Monthly Weather Review 142, n.º 11 (24 de outubro de 2014): 4164–86. http://dx.doi.org/10.1175/mwr-d-14-00101.1.
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Abstract A comparison of the impact of infrared (IR), microwave (MW), and radio occultation (RO) observations on NCEP’s operational global forecast model over the month of March 2013 is presented. Analyses and forecasts with only IR, MW, and RO observations are compared with analyses and forecasts with no satellite data and with each other. Overall, the patterns of the impact of the different satellite systems are similar, with the MW observations producing the largest impact on the analyses and RO producing the smallest. Without RO observations, satellite radiances are over– or under–bias corrected and RO acts as an anchor observation, reducing the forecast biases globally. Positive correlation coefficients of temperature impacts are generally found between the different satellite observation analyses, indicating that the three satellite systems are affecting the global temperatures in a similar way. However, the correlation in the lower troposphere among all three systems is surprisingly small. Correlations for the moisture field tend to be small in the lower troposphere between the different satellite analyses. The impact of the satellite observations on the 500-hPa geopotential height forecasts is much different in the Northern and Southern Hemispheres. In the Northern Hemisphere, all the satellite observations together make a small positive impact compared to the base (no satellite) forecasts. The IR and MW, but not the RO, make a small positive impact when assimilated alone. The situation is considerably different in the Southern Hemisphere, where all the satellite observations together make a much larger positive impact, and all three observation types (IR, MW, and RO) make similar and significant impacts.
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Feng, Yanxiang, Ruipeng Zhang, Sida Ren, Shuailin Zhu e Yikang Yang. "A Distributed Approach for Time-Dependent Observation Scheduling Problem in the Agile Earth Observation Satellite Constellation". Remote Sensing 15, n.º 7 (24 de março de 2023): 1761. http://dx.doi.org/10.3390/rs15071761.
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The increasing number of agile earth observation satellites (AEOSs) in orbit have advanced maneuverable capabilities, enabling the AEOS constellation to provide richer observation services. Therefore, observation scheduling in the AEOS constellation is crucial for improving the performance of satellite remote sensing systems. This paper focuses on the problem of distributed observation scheduling in the AEOS constellation, where a period of transition time is required between two consecutive observations, and this constraint depends on the start time of observations. We define a new fitness function that not only maximizes the profit sum but also considers system load balancing. Based on the fundamental idea of a distributed performance impact (PI) algorithm, we develop a PI-based distributed scheduling method (PIDSM) that runs concurrently on all AEOSs via local inter-satellite link (ISL)-based communications. The PIDSM iterates between two phases: target inclusion and consensus and target removal. The first phase aims to select the optimal task for each AEOS, while the second phase reaches a consensus over all AEOSs and removes targets that may decrease overall fitness. Experimental results demonstrate that the PIDSM can schedule more targets, reduce communication overhead, and achieve higher fitness values than existing algorithms. Sensitivity analyses further validate the effectiveness of the PIDSM.
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Budnikova, P. A., N. V. Emelyanov e B. S. Safonov. "Refinement of the motion model of the Linus satellite of the asteroid (22) Kalliope". Seriya 3: Fizika, Astronomiya, n.º 2_2023 (2 de junho de 2023): 2320802–1. http://dx.doi.org/10.55959/msu0579-9392.78.2320802.
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The aim of this article is to analyze the dynamics of the Linus satellite of the asteroid (22) Kalliope. New results have been obtained, and now they are being published. New observations of the satellite were made at the Caucasus Mountain Observatory of the SAI from October 2021 to March 2022. The obtained astrometric results are presented in the article. Based on the updated set of observations, the parameters of the satellite’s orbit were re-determined. An increase in the accuracy of ephemeris with the addition of new observations is shown. A new attempt was made to determine the precession of the satellite’s orbit caused by the compression of a rapidly rotating asteroid. The goal was to determine the dynamic compression of the central body. The entire observation interval is divided into groups. From the observations of each group the position of the axis of the satellite’s orbit was found. Changing the position of the axis gives the desired precession. Studies on several examples show that the position of the axis from such groups of observations is determined very unreliably. The reason lies in the strong correlation between the determined parameters with limited observational accuracy. Ways of studying precession are outlined by joint determination of dynamic parameters on the basis of all available observations.
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Zhao, Hang, Yamin Zhang, Qiangqiang Jiang, Xiaofeng Wei, Shizhong Li e Bo Chen. "Software-Defined Satellite Observation: A Fast Method Based on Virtual Resource Pools". Remote Sensing 15, n.º 22 (16 de novembro de 2023): 5388. http://dx.doi.org/10.3390/rs15225388.
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In recent years, the proliferation of remote sensing satellites has dramatically increased the demands of Earth observation and observing efficiency. Designing a promising satellite resource scheduling method is a pivotal way to meet the requirements of this scenario. However, with hundreds or more satellites involved, the existing optimization methods struggle to address the NP-hard resource scheduling problem effectively. In this paper, an approach named software-defined satellite observation (SDSO) is proposed. First, adopting the new design ideology, we define a unified specification based on a discrete spatial grid to describe the observation capability of all satellites. The observation resources are virtualized using the virtual resource pool technique and then stored in the database in advance, implementing on-demand acquisition for observation resources. Next, we designed a model of the remote sensing satellite resource scheduling problem based on a virtual resource pool and designed a solution method for searching information within the virtual resource pool. Finally, the experimental results show that the computational efficiency of the proposed SDSO methodology has a substantial advantage over the traditional methods. Meanwhile, with the growing number of satellites involved in scheduling, there is only a slight degradation in the execution performance of our method, while the time complexity of optimization-based approaches increases exponentially.
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Kidd, C., e V. Levizzani. "Status of satellite precipitation retrievals". Hydrology and Earth System Sciences 15, n.º 4 (5 de abril de 2011): 1109–16. http://dx.doi.org/10.5194/hess-15-1109-2011.
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Abstract. Satellites offer an unrivalled vantage point to observe and measure Earth system processes and parameters. Precipitation (rain and snow) in particular, benefit from such observations since precipitation is spatially and temporally highly variable and with satellites overcoming some of the deficiencies of conventional gauge and radar measurements. This paper provides an overall review of quantitative precipitation estimation, covering the basis of the satellite systems used in the observation of precipitation, the dissemination and processing of this data, and the generation, availability and validation of these precipitation estimates. A selection of applications utilising these precipitation estimates are then outlined to exemplify the utility of such products.
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Lu, Qifeng, e William Bell. "Characterizing Channel Center Frequencies in AMSU-A and MSU Microwave Sounding Instruments". Journal of Atmospheric and Oceanic Technology 31, n.º 8 (1 de agosto de 2014): 1713–32. http://dx.doi.org/10.1175/jtech-d-13-00136.1.
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Abstract Passive microwave observations from the Microwave Sounding Unit (MSU) and the Advanced Microwave Sounding Unit-A (AMSU-A) have been exploited widely for numerical weather prediction (NWP), atmospheric reanalyses, and climate monitoring studies. The treatment of biases in these observations, with respect to models as well as between satellites, has been the focus of much effort in recent years. This study presents evidence that shifts, drifts, and uncertainties in pass band center frequencies are a significant contribution to these biases. Center frequencies for AMSU-A channels 6–14 and MSU channel 3 have been analyzed using NWP fields and radiative transfer models, for a series of operational satellites covering the period 1979–2012. AMSU-A channels 6 (54.40 GHz), 7 (54.94 GHz), and 8 (55.50 GHz) on several satellites exhibit significant shifts and drifts relative to nominal pass band center frequencies. No significant shifts were found for AMSU-A channels 9–14, most probably as a consequence of the active frequency locking of these channels. For MSU channel 3 (54.96 GHz) most satellites exhibit large shifts, the largest for the earliest satellites. For example, for the first MSU on the Television and Infrared Observation Satellite-N (TIROS-N), the analyzed shift is 68 MHz over the lifetime of the satellite. Taking these shifts into account in the radiative transfer modeling significantly improves the fit between model and observations, eliminates the strong seasonal cycle in the model–observation misfit, and significantly improves the bias between NWP models and observations. The study suggests that, for several channels studied, the dominant component of the model–observation bias results from these spectral errors, rather than radiometric bias due to calibration errors.