Journal articles on the topic 'Aircraft Reachable Ground Footprint'
To see the other types of publications on this topic, follow the link: Aircraft Reachable Ground Footprint.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 32 journal articles for your research on the topic 'Aircraft Reachable Ground Footprint.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Albaali, Abdul Ghani, Rita Haddad, Motasem Saidan, and Majid Zeki Hameed. "Carbon Footprint of Royal Jordanian Airlines Ground and Air Operations." Journal of Public Administration and Governance 2, no. 4 (November 11, 2012): 11. http://dx.doi.org/10.5296/jpag.v2i4.2663.
Full textAbstract:
Aviation is different from other energy-using activities. Currently it makes about 2% of the global CO2 emission but it is rising fast. This will negatively affecting on the environment and urges us to pay more attention to the risks of travelling on environment The principal aviation emissions include the greenhouse gases carbon dioxide (CO2), water vapor (H2O), nitrogen oxides (NOx), sulphur oxides (SOx), and soot. The emissions affect the climate through various mechanisms. CO2 has a long atmospheric residence time of about 100 years. It is well mixed throughout the atmosphere and affects the global climate as a green house gas. Aircraft engines represent an increasing and potent source of greenhouse gas emissions, due in part to the unprecedented growth in air travel. This study highlights for the first time the importance and carbon footprint of Royal Jordanian Airlines aircraft fuel in producing CO₂ airborne emissions as well as emissions generated during the flight due to the use of wide variety of products and equipment.
2
Baxter, Glenn. "Assessing the Carbon Footprint and Carbon Mitigation Measures of a Major Full-Service Network Airline: A Case Study of Singapore Airlines." International Journal of Environment, Agriculture and Biotechnology 7, no. 5 (2022): 081–107. http://dx.doi.org/10.22161/ijeab.75.9.
Full textAbstract:
In this qualitative longitudinal case study, Singapore Airlines carbon footprint is examined for the period covering the company’s 2010/11 to 2021/22 financial years. The study’s qualitative data was examined by document analysis. The case study found that Singapore Airline’s carbon footprint is comprised of its Scope 1 direct emissions that are produced from the provision of its passenger and air cargo services together with the carbon dioxide (CO2) emission produced from the ground service equipment and vehicles used in its ground operations. The carbon footprint also includes its Scope 2 indirect emissions, which are produced from the airline’s consumption of electricity at its Singapore hub. Singapore Airlines has implemented a very comprehensive environmental policy and has pledged to achieve net zero carbon emissions by 2050. The largest source of carbon dioxide (CO2) emissions is from the airline’s passenger services. Singapore Airlines has implemented extensive carbon dioxide (CO2) emissions reduction measures that have focused on the reduction in aircraft weight, and highly efficient fuel management procedures. Other key carbon dioxide (CO2) emissions reduction measures include improved operational procedures, the optimization of air space management in collaboration with key air traffic control agencies, the use of cleaner energy vehicles, an extensive range of energy efficiency measures in its buildings and facilities, the use of sustainable aviation fuels, and the use of more energy efficient ground power sources. In addition, the acquisition and operation of the state-of-the art, next generation aircraft, such as the Airbus A350-900XWB and the Boeing 787-10 have helped the airline to mitigate its carbon footprint.
3
Gautam, Deepak, Christopher Watson, Arko Lucieer, and Zbyněk Malenovský. "Error Budget for Geolocation of Spectroradiometer Point Observations from an Unmanned Aircraft System." Sensors 18, no. 10 (October 15, 2018): 3465. http://dx.doi.org/10.3390/s18103465.
Full textAbstract:
We investigate footprint geolocation uncertainties of a spectroradiometer mounted on an unmanned aircraft system (UAS). Two microelectromechanical systems-based inertial measurement units (IMUs) and global navigation satellite system (GNSS) receivers were used to determine the footprint location and extent of the spectroradiometer. Errors originating from the on-board GNSS/IMU sensors were propagated through an aerial data georeferencing model, taking into account a range of values for the spectroradiometer field of view (FOV), integration time, UAS flight speed, above ground level (AGL) flying height, and IMU grade. The spectroradiometer under nominal operating conditions (8 ∘ FOV, 10 m AGL height, 0.6 s integration time, and 3 m/s flying speed) resulted in footprint extent of 140 cm across-track and 320 cm along-track, and a geolocation uncertainty of 11 cm. Flying height and orientation measurement accuracy had the largest influence on the geolocation uncertainty, whereas the FOV, integration time, and flying speed had the biggest impact on the size of the footprint. Furthermore, with an increase in flying height, the rate of increase in geolocation uncertainty was found highest for a low-grade IMU. To increase the footprint geolocation accuracy, we recommend reducing flying height while increasing the FOV which compensates the footprint area loss and increases the signal strength. The disadvantage of a lower flying height and a larger FOV is a higher sensitivity of the footprint size to changing distance from the target. To assist in matching the footprint size to uncertainty ratio with an appropriate spatial scale, we list the expected ratio for a range of IMU grades, FOVs and AGL heights.
4
El-Madany, T., H. Geiß, A. Schmidt, and O. Klemm. "Regionalization of turbulent fluxes by combining aircraft measurements with footprint analysis." Biogeosciences Discussions 6, no. 4 (July 14, 2009): 7017–51. http://dx.doi.org/10.5194/bgd-6-7017-2009.
Full textAbstract:
Abstract. This paper presents a method for the regionalization of turbulent fluxes by combining airborne flux measurements and footprint analysis. Eddy covariance measurements were performed with a small environmental research aircraft in May 2008 over the "Münsterland" region in northwest Germany. This region is dominated by agricultural patches that are typically a few hectares in size. An analytic footprint model was tested and applied to relate the fluxes, as measured on the aircraft during day time conditions, to different vegetation types on the ground. The geo referenced footprint areas were merged with high resolution land use data (30×30 m), resulting in a quantification of different land use types inside the respective footprints. The fluxes of the sampled area in the Münsterland of 1510 km2 were scaled up to the area of the "Westfälische Bucht" (6054 km2), since the land use composition are comparable to a large extent. The mean fluxes calculated of 99 flight segments and used for the regionalization were found −0.69 mg m−2 s−1 for carbon dioxide and +0.17 g m−2 s−1 for water vapor.
5
Vellinga, O. S., R. W. A. Hutjes, J. A. Elbers, A. A. M. Holtslag, and P. Kabat. "Regional carbon dioxide and energy fluxes from airborne observations using flight-path segmentation based on landscape characteristics." Biogeosciences Discussions 6, no. 6 (November 11, 2009): 10479–517. http://dx.doi.org/10.5194/bgd-6-10479-2009.
Full textAbstract:
Abstract. This paper presents an analysis of regional fluxes obtained with a small aircraft over heterogeneous terrain in the South West of France, during the large scale field experiment CERES'07. We use a method combining variable flight-path segmentation with basic airborne footprint analysis. The segmentation is based on topography, land use and soil type, using a.o. satellite imagery and digital maps. The segments are delineated using an average footprint length, based on all flights, and segment lengths, which are variable in space but not in time. The method results in segment averaged carbon and energy fluxes, which are shown to be representative of regional fluxes. Our analysis is focussed on the carbon dioxide, heat and evaporative fluxes around solar noon. We will show that spatial and seasonal variations in the fluxes can be linked to the underlying landscape. In addition, a comparison between the airborne data and ground flux data is made to support our results. However, due to the incompleteness of ground data for some predominant vegetation types (even in such a data dense context), upscaling of ground data to regional fluxes was not possible. Without the comparison, we are still able to demonstrate that aircraft can provide direct and meaningful estimates of regional fluxes of energy and carbon dioxide.
6
Vellinga, O. S., B. Gioli, J. A. Elbers, A. A. M. Holtslag, P. Kabat, and R. W. A. Hutjes. "Regional carbon dioxide and energy fluxes from airborne observations using flight-path segmentation based on landscape characteristics." Biogeosciences 7, no. 4 (April 21, 2010): 1307–21. http://dx.doi.org/10.5194/bg-7-1307-2010.
Full textAbstract:
Abstract. This paper presents an analysis of regional fluxes obtained with a small aircraft over heterogeneous terrain in the south-west of France, during the large scale field experiment CERES'07. We use a method combining variable flight-path segmentation with basic airborne footprint analysis. The segmentation is based on topography, land use and soil type, using a.o. satellite imagery and digital maps. The segments are delineated using an average footprint length, based on all flights, and segment lengths, which are variable in space but not in time. The method results in segment averaged carbon and energy fluxes, which are shown to be representative of regional fluxes. Our analysis is focussed on carbon dioxide, heat and evaporative fluxes around solar noon. We will show that spatial and seasonal variations in the fluxes can be linked to the underlying landscape. In addition, a comparison between the airborne data and ground flux data is made to support our results. However, due to the incompleteness of ground data for some predominant vegetation types (even in such a data dense context), upscaling of ground data to regional fluxes was not possible. Without the comparison, we are still able to demonstrate that aircraft can provide direct and meaningful estimates of regional fluxes of energy and carbon dioxide.
7
Lents, Charles E. "Hybrid Electric Propulsion." Mechanical Engineering 142, no. 06 (June 1, 2020): 54–55. http://dx.doi.org/10.1115/1.2020-jun5.
Full textAbstract:
Abstract Electrified propulsion holds the promise of reducing aviation’s CO2 emissions footprint through three means: access to green grid electric energy, improvements in aircraft performance through new airframe and propulsion system architectures and enabling further optimization of the gas turbine cycle. Charging an aircraft battery pack with green electric energy and using this energy to drive electric propulsors results in a zero emissions vehicle. This is practical for light aircraft and short missions. Boosting a Jet-A burning gas turbine with green electric energy (again stored in a ground charged battery), in either a parallel or series turbo-electric architecture can yield a net reduction in CO2 emissions, as long as the fuel burn required to carry the weight of a discharged battery pack does not overcome the reduction in fuel burn afforded by the ground charged battery. Several studies have indicated that a net savings is possible with cell level energy densities approach ∼ 500 whr/kg, a reasonable target for the 2030 time frame. Electrified propulsion can also enable unique aircraft configurations, employing a veryhigh efficiency prime mover (gas turbine) designed for running only a generator at peak efficiency, and/or distributing the propulsors throughout the aircraft, for improvement in L/D and propulsive efficiency.
8
Plass, Simon, Robert Poehlmann, Romain Hermenier, and Armin Dammann. "Global Maritime Surveillance by Airliner-Based AIS Detection: Preliminary Analysis." Journal of Navigation 68, no. 6 (May 20, 2015): 1195–209. http://dx.doi.org/10.1017/s0373463315000314.
Full textAbstract:
Demands on security, safety, and environmental protection in worldwide shipping are steadily increasing. Shipboard broadcast transponders based on the Automatic Identification System (AIS) can be easily detected close to coastal or waterway areas. Satellite-based AIS receivers detect globally but are limited in high-density traffic areas. This paper investigates the challenges and performance of AIS detection on aircraft at altitudes between 8 500 m and 10 000 m. During flight trials over sea and land, AIS signals were recorded. Post-processing of the recorded data allows the evaluation but also faces challenges due to the nature of overlapping AIS signals at the aircraft. A comparison of detected signals at the aircraft with received AIS signals on the ground is given, including the evaluation of the reception footprint of the aircraft. Finally, a concept for worldwide AIS detection via airliners is presented. The study shows the potential for global complementary surveillance coverage via airliner-based AIS detection.
9
Baxter, Glenn. "Mitigating Aircraft Auxiliary Power Unit Carbon Dioxide (CO2) Emissions During the Aircraft Turnaround Process from the Use of Solar Power at the Airport Gate: The Case of Moi International Airport, Kenya." International Journal of Environment, Agriculture and Biotechnology 7, no. 1 (2022): 014–22. http://dx.doi.org/10.22161/ijeab.71.2.
Full textAbstract:
One of the most pervasive trends in the global airport industry in recent times has been the adoption of green renewable technologies. Many airports around the world have now installed photovoltaic (PV) solar systems as a key environmental measure. One of the critical areas of energy management at an airport is the provision of power and cooling at the gate, which is used during the aircraft turnaround process. Historically, the aircraft auxiliary power unit (APU) was the primary power source during the aircraft turnaround process. In recent times, airports have transitioned to the use of fixed electrical ground power (FEGP) and preconditioned air to mitigate the emissions from use of aircraft auxiliary power unit (APUs). Based on an instrumental case study research approach, this study has examined how Moi International Airport in Kenya has mitigated the airport’s carbon footprint by using a green, renewable energy system. The study’s qualitative data was examined by document analysis. The case study revealed that Moi International Airport has installed a photovoltaic (PV) solar system with a 500kW capacity that is used to primarily provide solar power at the airport’s apron area. The photovoltaic (PV) solar system has delivered Moi International Airport with an important environmental related benefit as it has enabled the airport to reduce it carbon footprint, as the photovoltaic (PV) solar system has reduced the airport’s carbon dioxide (CO2) emissions by an estimated 1,300 tonnes per annum.
10
Mosberg, Bengt, Johan Rignér, Pernilla Ulfvengren, and Per Näsman. "Approximation of pilot operational behavior affecting noise footprint in steep approaches." Noise Control Engineering Journal 68, no. 2 (March 20, 2020): 179–98. http://dx.doi.org/10.3397/1/376816.
Full textAbstract:
Landing aircraft create noise that disturbs residents living close to airports. One method to reduce such noise is to fly the final approach at a steeper glide slope than the normal 3.0 glide slope, thus increasing the distance between the source of the noise and the ground. If this is performed, there is a risk that the operational behavior of the pilot counteracts the noise reduction possible to achieve, due to the fact that the pilot must manage the aircraft's speed on a steeper glide slope. For practical reasons, there are few live trials and studies on pilot behavior during steeper approaches. In this project, a method to approximate pilot operational behavior during slightly steeper approaches, using flight data recorder data from standard approaches, was developed. The method exploits the fact that flying an approach in tailwind conditions creates the same operational challenges for a pilot as flying a steeper than normal approach does. The method was applied to 1159 flights. The results indicate that the pilots' operational behavior will change when glide slope angle increases. Extension of final flap and landing gear in steeper approaches will take place at a greater height but closer to the airport than for standard 3.0 ILS approaches. The result can be a reduction of the noise from arriving aircraft by up to 2 dB in some areas beneath the approach path if a 3.5 glide slope angle is used.
11
Choi, Sungyeon, Lok N. Lamsal, Melanie Follette-Cook, Joanna Joiner, Nickolay A. Krotkov, William H. Swartz, Kenneth E. Pickering, et al. "Assessment of NO<sub>2</sub> observations during DISCOVER-AQ and KORUS-AQ field campaigns." Atmospheric Measurement Techniques 13, no. 5 (May 19, 2020): 2523–46. http://dx.doi.org/10.5194/amt-13-2523-2020.
Full textAbstract:
Abstract. NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ, conducted in 2011–2014) campaign in the United States and the joint NASA and National Institute of Environmental Research (NIER) Korea–United States Air Quality Study (KORUS-AQ, conducted in 2016) in South Korea were two field study programs that provided comprehensive, integrated datasets of airborne and surface observations of atmospheric constituents, including nitrogen dioxide (NO2), with the goal of improving the interpretation of spaceborne remote sensing data. Various types of NO2 measurements were made, including in situ concentrations and column amounts of NO2 using ground- and aircraft-based instruments, while NO2 column amounts were being derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This study takes advantage of these unique datasets by first evaluating in situ data taken from two different instruments on the same aircraft platform, comparing coincidently sampled profile-integrated columns from aircraft spirals with remotely sensed column observations from ground-based Pandora spectrometers, intercomparing column observations from the ground (Pandora), aircraft (in situ vertical spirals), and space (OMI), and evaluating NO2 simulations from coarse Global Modeling Initiative (GMI) and high-resolution regional models. We then use these data to interpret observed discrepancies due to differences in sampling and deficiencies in the data reduction process. Finally, we assess satellite retrieval sensitivity to observed and modeled a priori NO2 profiles. Contemporaneous measurements from two aircraft instruments that likely sample similar air masses generally agree very well but are also found to differ in integrated columns by up to 31.9 %. These show even larger differences with Pandora, reaching up to 53.9 %, potentially due to a combination of strong gradients in NO2 fields that could be missed by aircraft spirals and errors in the Pandora retrievals. OMI NO2 values are about a factor of 2 lower in these highly polluted environments due in part to inaccurate retrieval assumptions (e.g., a priori profiles) but mostly to OMI's large footprint (>312 km2).
12
Lian, Weiqi, Shaoning Li, Guo Zhang, Yanan Wang, Xinyang Chen, and Hao Cui. "Accuracy Verification of Airborne Large-Footprint Lidar based on Terrain Features." Remote Sensing 12, no. 5 (March 9, 2020): 879. http://dx.doi.org/10.3390/rs12050879.
Full textAbstract:
Accuracy verification of airborne large-footprint lidar data is important for proper data application but is difficult when ground-based laser detectors are not available. Therefore, we developed a novel method for lidar accuracy verification based on the broadened echo pulse caused by signal saturation over water. When an aircraft trajectory crosses both water and land, this phenomenon and the change in elevation between land and water surfaces can be used to verify the plane and elevation accuracy of the airborne large-footprint lidar data in conjunction with a digital surface model (DSM). Due to the problem of echo pulse broadening, the center-of-gravity (COG) method was proposed to optimize the processing flow. We conducted a series of experiments on terrain features (i.e., the intersection between water and land) in Xiangxi, Hunan Province, China. Verification results show that the elevation accuracy obtained in our experiments was better than 1 m and the plane accuracy was better than 5 m, which is well within the design requirements. Although this method requires specific terrain conditions for optimum applicability, the results can lead to valuable improvements in the flexibility and quality of lidar data collection.
13
Li, Jinhua, Yun Zheng, Menachem Rafaelof, Hok K. Ng, and Stephen A. Rizzi. "AIRNOISEUAM: An Urban Air Mobility Noise-Exposure Prediction Tool." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 6 (August 1, 2021): 474–85. http://dx.doi.org/10.3397/in-2021-1488.
Full textAbstract:
A new software tool called AIRNOISEUAM is introduced that models the noise exposure of Urban Air Mobility (UAM) operations. Given relevant UAM aircraft performance models, mission profiles, and Noise-Power-Distance data, AIRNOISEUAM predicts the noise exposure footprint for receptors on the ground. The performance of AIRNOISEUAM using a Robinson R66 helicopter model and a six-passenger quadrotor model, and a diverse set of scenarios from NASA’s UAM human-in-the-loop simulations is compared to that of the industry-standard tool with the same inputs. The predicted noise exposure results from both tools are found to be nearly identical. AIRNOISEUAM offers a fast-time, flexible interface and modular design to facilitate the dynamic requirements of the aviation research community.
14
Tuladhar, Sandeep, Tri Ratna Bajracharya, and Shree Raj Shakya. "Evaluation and mitigation analysis of carbon footprint for an airline operator: Case of Nepal airlines corporation." Journal of Innovations in Engineering Education 4, no. 1 (March 5, 2021): 18–33. http://dx.doi.org/10.3126/jiee.v4i1.34817.
Full textAbstract:
This paper deals with evaluation and analysis of carbon footprint of an airline operator, Nepal Airlines Corporation (NAC) by using its actual flight and maintenance data from 2016 to 2019. NAC is a multi-fleet operator, of both turboprop and turbofan aircrafts. Carbon footprint in terms of Carbon Dioxide (CO2) emission has been calculated for NAC’s airline operations per individual aircraft, fleet-type and operating sector (i.e., international and domestic), and total ground handling operations. In each of the study years, contribution to NAC’s total CO2 production from its domestic fleet was found out to be very small (below 6% of yearly total), even though its fleet number outnumbered that of international fleet. This indicates better optimization opportunities for international-sector (turbofan) aircrafts than domestic-sector (turboprop) aircrafts. Reductions in fuel on-board as per prescribed levels, better airport slot management and selection of long-haul flight destinations have been identified as potential mitigation strategies for CO2 emission from international sector. Smaller aircrafts operating in domestic sectors are more prone to variations in occupancy rate and as such, NAC could focus on optimizing its commercial strategy to improve its CO2/passenger rate in domestic sector.
15
Eberle, Brian F., and Jonathan D. Rogers. "Real-Time Trajectory Generation and Reachability Determination in Autorotative Flare." Journal of the American Helicopter Society 65, no. 3 (July 1, 2020): 1–17. http://dx.doi.org/10.4050/jahs.65.032008.
Full textAbstract:
Autorotation maneuvers inherently offer little margin for error in execution and induce high pilot workload, particularly as the aircraft nears the ground in an autorotative flare. Control augmentation systems may potentially reduce pilot workload while simultaneously improving the likelihood of a successful landing by offering the pilot appropriate cues. This paper presents an initial investigation of a real-time trajectory generation scheme for autorotative flare based on time-to-contact theory. The algorithm exhibits deterministic runtime performance and provides a speed trajectory that can be tracked by a pilot or inner-loop controller to bring the vehicle to a desired landing point at the time of touchdown. A low-order model of the helicopter dynamics in autorotation is used to evaluate dynamic feasibility of the generated trajectories. By generating and evaluating trajectories to an array of candidate landing points, the set of reachable landing points in front of the aircraft is determined. Simulation results are presented in which the trajectory generator is coupled with a previously derived autorotation controller. Example cases and trade studies are conducted in a six degree-of-freedom simulation environment to demonstrate overall performance as well as robustness of the algorithm to variations in target landing point, helicopter gross weight, and winds. The robustness of the reachability determination portion of the algorithm is likewise evaluated through trade studies examining off-nominal flare entry conditions and the effects of winds.
16
Kustas, William P., Jerry L. Hatfield, and John H. Prueger. "The Soil Moisture–Atmosphere Coupling Experiment (SMACEX): Background, Hydrometeorological Conditions, and Preliminary Findings." Journal of Hydrometeorology 6, no. 6 (December 1, 2005): 791–804. http://dx.doi.org/10.1175/jhm456.1.
Full textAbstract:
Abstract The Soil Moisture–Atmosphere Coupling Experiment (SMACEX) was conducted in conjunction with the Soil Moisture Experiment 2002 (SMEX02) during June and July 2002 near Ames, Iowa—a corn and soybean production region. The primary objective of SMEX02 was the validation of microwave soil moisture retrieval algorithms for existing and new prototype satellite microwave sensor systems under rapidly changing crop biomass conditions. The SMACEX study was designed to provide direct measurement/remote sensing/modeling approaches for understanding the impact of spatial and temporal variability in vegetation cover, soil moisture, and other land surface states on turbulent flux exchange with the atmosphere. The unique dataset consisting of in situ and aircraft measurements of atmospheric, vegetation, and soil properties and fluxes allows for a detailed and rigorous analysis, and the validation of surface states and fluxes being diagnosed using remote sensing methods at various scales. Research results presented in this special issue have illuminated the potential of satellite remote sensing algorithms for soil moisture retrieval, land surface flux estimation, and the assimilation of surface states and diagnostically modeled fluxes into prognostic land surface models. Ground- and aircraft-based remote sensing of the land surface and atmospheric boundary layer properties are used to quantify heat fluxes at the tower footprint and regional scales. Tower- and aircraft-based heat and momentum fluxes are used to evaluate local and regional roughness. The spatial and temporal variations in water, energy, and carbon fluxes from the tower network and aircraft under changing vegetation cover and soil moisture conditions are evaluated. An overview of the experimental site, design, data, hydrometeorological conditions, and results is presented in this introduction, and serves as a preface to this special issue highlighting the SMACEX results.
17
Palmer, Diane, Elena Koumpli, Ian Cole, Ralph Gottschalg, and Thomas Betts. "A GIS-Based Method for Identification of Wide Area Rooftop Suitability for Minimum Size PV Systems Using LiDAR Data and Photogrammetry." Energies 11, no. 12 (December 15, 2018): 3506. http://dx.doi.org/10.3390/en11123506.
Full textAbstract:
Knowledge of roof geometry and physical features is essential for evaluation of the impact of multiple rooftop solar photovoltaic (PV) system installations on local electricity networks. The paper starts by listing current methods used and stating their strengths and weaknesses. No current method is capable of delivering accurate results with publicly available input data. Hence a different approach is developed, based on slope and aspect using aircraft-based Light Detection and Ranging (LiDAR) data, building footprint data, GIS (Geographical Information Systems) tools, and aerial photographs. It assesses each roof’s suitability for PV deployment. That is, the characteristics of each roof are examined for fitting of at least a minimum size solar power system. In this way the minimum potential solar yield for region or city may be obtained. Accuracy is determined by ground-truthing against a database of 886 household systems. This is the largest validation of a rooftop assessment method to date. The method is flexible with few prior assumptions. It can generate data for various PV scenarios and future analyses.
18
Gentner, D. R., T. B. Ford, A. Guha, K. Boulanger, J. Brioude, W. M. Angevine, J. A. de Gouw, et al. "Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley." Atmospheric Chemistry and Physics Discussions 13, no. 10 (October 31, 2013): 28225–78. http://dx.doi.org/10.5194/acpd-13-28225-2013.
Full textAbstract:
Abstract. Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. Ground site measurements in Bakersfield and aircraft measurements of reactive gas-phase organic compounds were made in this region as part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions from these prominent sources that are relatively understudied compared to motor vehicles We also developed a statistical modeling method with the FLEXPART-WRF transport and meteorological model using ground-based data to assess the spatial distribution of emissions in the San Joaquin Valley. We present evidence for large sources of paraffinic hydrocarbons from petroleum extraction/processing operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes that have limited previous in situ measurements or characterization in emissions from petroleum operations. Observed dairy emissions were dominated by ethanol, methanol, and acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well-correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The good agreement of the observed petroleum operations source profile with the measured composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil suggests a fugitive emissions pathway during petroleum extraction, storage, or processing with negligible coincident methane emissions Aircraft observations of emission hotspots from operations at oil wells and dairies are consistent with the statistical source footprint determined via transport modeling and ground-based data. At Bakersfield, petroleum and dairy operations each comprised 22–23% of anthropogenic non-methane organic carbon and were each responsible for ~12% of potential precursors to ozone, but their direct impacts as potential SOA precursors were estimated to be minor. A comparison with the California Air Resources Board emission inventory supports the current relative emission rates of reactive organic gases from these sources in the region.
19
Rahoui, Amine, and Zinab Aalaoui. "Development of a innovative solution for energy recovery from the flow exhaust gas on bench test facility of turbofan aircraft engine through the use of innovative design methods: Definition of the process and the operating environment." MATEC Web of Conferences 286 (2019): 02003. http://dx.doi.org/10.1051/matecconf/201928602003.
Full textAbstract:
Civil aviation is driven nowadays by exceptional growth in the number of passengers. It should double or even triple by 2050 and thus, all industrials also plan to double the number of device delivery by mid-century. Responsible for about 2% of carbon dioxide on the planet, they must now deal with the environmental issues facing the sector. At this moment in the world, several lines of research focus on increasing the efficiency of aircraft engines, development of new engines, efficient technologies, sustainable sources of alternative fuels and improved management air traffic on the ground and in flight [1]. The present work deals with a research focused on the engine test when passing in review in repair facilities. This operation which consist in making engine running while the cycles to test its performance in a test bench are studied to define a technological solution to reduce CO2 carbon footprint of the aircraft engine in this phase of the cycle of life. The idea is to produce electrical energy during these tests. To achieve this, we will highlight the case of a type bench facility for a specific airplane engines. As a result high-performance analysis tools are implemented to define the most suitable technological solution that ensures maximum efficiency, meets the functional and regulatory requirements taking into account the force of integration with the existing and cost optimization. In this paper we present the summary of the working definition of the research process for the final term set in the operating environment integration relevance that provides bench test and level of innovation that provides the methods selected.
20
Gentner, D. R., T. B. Ford, A. Guha, K. Boulanger, J. Brioude, W. M. Angevine, J. A. de Gouw, et al. "Emissions of organic carbon and methane from petroleum and dairy operations in California's San Joaquin Valley." Atmospheric Chemistry and Physics 14, no. 10 (May 21, 2014): 4955–78. http://dx.doi.org/10.5194/acp-14-4955-2014.
Full textAbstract:
Abstract. Petroleum and dairy operations are prominent sources of gas-phase organic compounds in California's San Joaquin Valley. It is essential to understand the emissions and air quality impacts of these relatively understudied sources, especially for oil/gas operations in light of increasing US production. Ground site measurements in Bakersfield and regional aircraft measurements of reactive gas-phase organic compounds and methane were part of the CalNex (California Research at the Nexus of Air Quality and Climate Change) project to determine the sources contributing to regional gas-phase organic carbon emissions. Using a combination of near-source and downwind data, we assess the composition and magnitude of emissions, and provide average source profiles. To examine the spatial distribution of emissions in the San Joaquin Valley, we developed a statistical modeling method using ground-based data and the FLEXPART-WRF transport and meteorological model. We present evidence for large sources of paraffinic hydrocarbons from petroleum operations and oxygenated compounds from dairy (and other cattle) operations. In addition to the small straight-chain alkanes typically associated with petroleum operations, we observed a wide range of branched and cyclic alkanes, most of which have limited previous in situ measurements or characterization in petroleum operation emissions. Observed dairy emissions were dominated by ethanol, methanol, acetic acid, and methane. Dairy operations were responsible for the vast majority of methane emissions in the San Joaquin Valley; observations of methane were well correlated with non-vehicular ethanol, and multiple assessments of the spatial distribution of emissions in the San Joaquin Valley highlight the dominance of dairy operations for methane emissions. The petroleum operations source profile was developed using the composition of non-methane hydrocarbons in unrefined natural gas associated with crude oil. The observed source profile is consistent with fugitive emissions of condensate during storage or processing of associated gas following extraction and methane separation. Aircraft observations of concentration hotspots near oil wells and dairies are consistent with the statistical source footprint determined via our FLEXPART-WRF-based modeling method and ground-based data. We quantitatively compared our observations at Bakersfield to the California Air Resources Board emission inventory and find consistency for relative emission rates of reactive organic gases between the aforementioned sources and motor vehicles in the region. We estimate that petroleum and dairy operations each comprised 22% of anthropogenic non-methane organic carbon at Bakersfield and were each responsible for 8–13% of potential precursors to ozone. Yet, their direct impacts as potential secondary organic aerosol (SOA) precursors were estimated to be minor for the source profiles observed in the San Joaquin Valley.
21
Mandlburger, Gottfried, Martin Pfennigbauer, Roland Schwarz, Sebastian Flöry, and Lukas Nussbaumer. "Concept and Performance Evaluation of a Novel UAV-Borne Topo-Bathymetric LiDAR Sensor." Remote Sensing 12, no. 6 (March 19, 2020): 986. http://dx.doi.org/10.3390/rs12060986.
Full textAbstract:
We present the sensor concept and first performance and accuracy assessment results of a novel lightweight topo-bathymetric laser scanner designed for integration on Unmanned Aerial Vehicles (UAVs), light aircraft, and helicopters. The instrument is particularly well suited for capturing river bathymetry in high spatial resolution as a consequence of (i) the low nominal flying altitude of 50–150 m above ground level resulting in a laser footprint diameter on the ground of typically 10–30 cm and (ii) the high pulse repetition rate of up to 200 kHz yielding a point density on the ground of approximately 20–50 points/m2. The instrument features online waveform processing and additionally stores the full waveform within the entire range gate for waveform analysis in post-processing. The sensor was tested in a real-world environment by acquiring data from two freshwater ponds and a 500 m section of the pre-Alpine Pielach River (Lower Austria). The captured underwater points featured a maximum penetration of two times the Secchi depth. On dry land, the 3D point clouds exhibited (i) a measurement noise in the range of 1–3 mm; (ii) a fitting precision of redundantly captured flight strips of 1 cm; and (iii) an absolute accuracy of 2–3 cm compared to terrestrially surveyed checkerboard targets. A comparison of the refraction corrected LiDAR point cloud with independent underwater checkpoints exhibited a maximum deviation of 7.8 cm and revealed a systematic depth-dependent error when using a refraction coefficient of n = 1.36 for time-of-flight correction. The bias is attributed to multi-path effects in the turbid water column (Secchi depth: 1.1 m) caused by forward scattering of the laser signal at suspended particles. Due to the high spatial resolution, good depth performance, and accuracy, the sensor shows a high potential for applications in hydrology, fluvial morphology, and hydraulic engineering, including flood simulation, sediment transport modeling, and habitat mapping.
22
Paris, J. D., A. Stohl, P. Ciais, P. Nédélec, B. D. Belan, M. Yu Arshinov, and M. Ramonet. "Source-receptor relationships for airborne measurements of CO<sub>2</sub>, CO and O<sub>3</sub> above Siberia: a cluster-based approach." Atmospheric Chemistry and Physics 10, no. 4 (February 15, 2010): 1671–87. http://dx.doi.org/10.5194/acp-10-1671-2010.
Full textAbstract:
Abstract. We analysed results of three intensive aircraft campaigns above Siberia (April and September 2006, August 2007) with a total of ~70 h of continuous CO2, CO and O3 measurements. The flight route consists of consecutive ascents and descents between Novosibirsk (55° N, 82° E) and Yakutsk (62° N, 129° E). We performed retroplume calculations with the Lagrangian particle dispersion model FLEXPART for many short segments along the flight tracks. To reduce the extremely rich information on source regions provided by the model calculation into a small number of distinct cases, we performed a statistical clustering – to our knowledge for the first time – into potential source regions of the footprint emission sensitivities obtained from the model calculations. This technique not only worked well to separate source region influences but also resulted in clearly distinct tracer concentrations for the various clusters obtained. High CO and O3 concentrations were found associated with agricultural fire plumes originating from Kazakhstan in September 2006. A statistical analysis indicates that summer uptake of CO2 is largely explained (~50% of variance) by air mass exposure to uptake by Siberian and sub-arctic ecosystems. This resulted in an average 5 to 10 ppm difference with overlaying air masses. Stratosphere-troposphere exchange is found to strongly influence the observed O3 mixing ratios in spring, but not in summer. European emissions contributed to high O3 concentrations above Siberia in April 2006 and August 2007, while emissions from North Eastern China also contributed to higher O3 mixing ratios in summer, but tend to lower mixing ratios in spring, when the airmass aerosol burden is important. In the lower troposphere, large-scale deposition processes in the boreal and sub-arctic boundary layer is a large O3 sink, resulting in a ~20 ppb difference with overlaying air masses. Lagrangian footprint clustering is very promising and could also be advantageously applied to the interpretation of ground based measurements including calculation of tracers' sources and sinks.
23
Przysowa, Radoslaw, Bartosz Gawron, Tomasz Białecki, Anna Łęgowik, Jerzy Merkisz, and Remigiusz Jasiński. "Performance and Emissions of a Microturbine and Turbofan Powered by Alternative Fuels." Aerospace 8, no. 2 (January 21, 2021): 25. http://dx.doi.org/10.3390/aerospace8020025.
Full textAbstract:
Alternative fuels containing biocomponents produced in various technologies are introduced in aviation to reduce its carbon footprint but there is little data describing their impact on the performance and emissions of engines. The purpose of the work is to compare the performance and gas emissions produced from two different jet engines—the GTM-140 microturbine and the full-size DGEN380 turbofan, powered by blends of Jet A-1 and one of two biocomponents: (1) Alcohol-to-Jet (ATJ) and (2) Hydroprocessed Esters and Fatty Acids (HEFA) produced from used cooking oil (UCO) in various concentrations. The acquired data will be used to develop an engine emissivity model to predict gas emissions. Blends of the mineral fuel with synthetic components were prepared in various concentrations, and their physicochemical parameters were examined in the laboratory. Measurements of emissions from both engines were carried out in selected operating points using the Semtech DS gaseous analyzer and the EEPS spectrometer. The impact of tested blends on engine operating parameters is limited, and their use does not carry the risk of a significant decrease in aircraft performance or increase in fuel consumption. Increasing the content of biocomponents causes a noticeable rise in the emission of CO and slight increase for some other gasses (HC and NOx), which should not, however, worsen the working conditions of the ground personnel. This implies that there are no contraindications against using tested blends for fuelling gas-turbine engines.
24
Vaughan, Adam R., James D. Lee, Marvin D. Shaw, Pawel K. Misztal, Stefan Metzger, Massimo Vieno, Brian Davison, et al. "VOC emission rates over London and South East England obtained by airborne eddy covariance." Faraday Discussions 200 (2017): 599–620. http://dx.doi.org/10.1039/c7fd00002b.
Full textAbstract:
Volatile organic compounds (VOCs) originate from a variety of sources, and play an intrinsic role in influencing air quality. Some VOCs, including benzene, are carcinogens and so directly affect human health, while others, such as isoprene, are very reactive in the atmosphere and play an important role in the formation of secondary pollutants such as ozone and particles. Here we report spatially-resolved measurements of the surface-to-atmosphere fluxes of VOCs across London and SE England made in 2013 and 2014. High-frequency 3-D wind velocities and VOC volume mixing ratios (made by proton transfer reaction – mass spectrometry) were obtained from a low-flying aircraft and used to calculate fluxes using the technique of eddy covariance. A footprint model was then used to quantify the flux contribution from the ground surface at spatial resolution of 100 m, averaged to 1 km. Measured fluxes of benzene over Greater London showed positive agreement with the UK’s National Atmospheric Emissions Inventory, with the highest fluxes originating from central London. Comparison of MTBE and toluene fluxes suggest that petroleum evaporation is an important emission source of toluene in central London. Outside London, increased isoprene emissions were observed over wooded areas, at rates greater than those predicted by a UK regional application of the European Monitoring and Evaluation Programme model (EMEP4UK). This work demonstrates the applicability of the airborne eddy covariance method to the determination of anthropogenic and biogenic VOC fluxes and the possibility of validating emission inventories through measurements.
25
Metzger, S., W. Junkermann, M. Mauder, K. Butterbach-Bahl, B. Trancón y Widemann, F. Neidl, K. Schäfer, et al. "Spatial resolution and regionalization of airborne flux measurements using environmental response functions." Biogeosciences Discussions 9, no. 11 (November 14, 2012): 15937–6003. http://dx.doi.org/10.5194/bgd-9-15937-2012.
Full textAbstract:
Abstract. The goal of this study is to characterize the sensible (H) and latent (LE) heat exchange for different land covers in the heterogeneous steppe landscape of the Xilin River Catchment, Inner Mongolia, China. Eddy-covariance flux measurements at 50–100 m above ground were conducted in July 2009 using a weight-shift microlight aircraft. Wavelet decomposition of the turbulence data enables a spatial discretization of 90 m of the flux measurements. For a total of 8446 flux observations during 12 flights, MODIS land surface temperature (LST) and enhanced vegetation index (EVI) in each flux footprint are determined. Boosted regression trees are then used to infer an environmental response function (ERF) between all flux observations (H, LE) and biophysical- (LST, EVI) and meteorological drivers. Numerical tests show that ERF predictions covering the entire Xilin River Catchment (&approx; 3670 km2) are accurate to ≤ 18%. The predictions are then summarized for each land cover type, providing individual estimates of source strength (36 W m−2 < H < 364 W m−2, 46 W m−2 < LE < 425 W m−2) and spatial variability (11 W m−2 < σH < 169 W m−2, 14 W m−2 < σLE < 152 W m−2) to a precision of ≤ 5%. Lastly, ERF predictions of land cover specific Bowen ratios are compared between subsequent flights at different locations in the Xilin River Catchment. Agreement of the land cover specific Bowen ratios to within 12 ± 9% emphasizes the robustness of the presented approach. This study indicates the potential of ERFs for (i) extending airborne flux measurements to the catchment scale, (ii) assessing the spatial representativeness of long-term tower flux measurements, and (iii) designing, constraining and evaluating flux algorithms for remote sensing and numerical modelling applications.
26
Metzger, S., W. Junkermann, M. Mauder, K. Butterbach-Bahl, B. Trancón y Widemann, F. Neidl, K. Schäfer, et al. "Spatially explicit regionalization of airborne flux measurements using environmental response functions." Biogeosciences 10, no. 4 (April 3, 2013): 2193–217. http://dx.doi.org/10.5194/bg-10-2193-2013.
Full textAbstract:
Abstract. The goal of this study is to characterize the sensible (H) and latent (LE) heat exchange for different land covers in the heterogeneous steppe landscape of the Xilin River catchment, Inner Mongolia, China. Eddy-covariance flux measurements at 50–100 m above ground were conducted in July 2009 using a weight-shift microlight aircraft. Wavelet decomposition of the turbulence data enables a spatial discretization of 90 m of the flux measurements. For a total of 8446 flux observations during 12 flights, MODIS land surface temperature (LST) and enhanced vegetation index (EVI) in each flux footprint are determined. Boosted regression trees are then used to infer an environmental response function (ERF) between all flux observations (H, LE) and biophysical (LST, EVI) and meteorological drivers. Numerical tests show that ERF predictions covering the entire Xilin River catchment (&approx;3670 km2) are accurate to ≤18% (1 σ). The predictions are then summarized for each land cover type, providing individual estimates of source strength (36 W m−2 < H < 364 W m−2, 46 W m−2 < LE < 425 W m−2) and spatial variability (11 W m−2 < σH < 169 W m−2, 14 W m−2 < σLE < 152 W m−2) to a precision of ≤5%. Lastly, ERF predictions of land cover specific Bowen ratios are compared between subsequent flights at different locations in the Xilin River catchment. Agreement of the land cover specific Bowen ratios to within 12 &pm; 9% emphasizes the robustness of the presented approach. This study indicates the potential of ERFs for (i) extending airborne flux measurements to the catchment scale, (ii) assessing the spatial representativeness of long-term tower flux measurements, and (iii) designing, constraining and evaluating flux algorithms for remote sensing and numerical modelling applications.
27
Lampert, Astrid, Falk Pätzold, Magnus O. Asmussen, Lennart Lobitz, Thomas Krüger, Thomas Rausch, Torsten Sachs, et al. "Studying boundary layer methane isotopy and vertical mixing processes at a rewetted peatland site using an unmanned aircraft system." Atmospheric Measurement Techniques 13, no. 4 (April 17, 2020): 1937–52. http://dx.doi.org/10.5194/amt-13-1937-2020.
Full textAbstract:
Abstract. The combination of two well-established methods, of quadrocopter-borne air sampling and methane isotopic analyses, is applied to determine the source process of methane at different altitudes and to study mixing processes. A proof-of-concept study was performed to demonstrate the capabilities of quadrocopter air sampling for subsequently analysing the methane isotopic composition δ13C in the laboratory. The advantage of the system compared to classical sampling on the ground and at tall towers is the flexibility concerning sampling location, and in particular the flexible choice of sampling altitude, allowing the study of the layering and mixing of air masses with potentially different spatial origin of air masses and methane. Boundary layer mixing processes and the methane isotopic composition were studied at Polder Zarnekow in Mecklenburg–West Pomerania in the north-east of Germany, which has become a strong source of biogenically produced methane after rewetting the drained and degraded peatland. Methane fluxes are measured continuously at the site. They show high emissions from May to September, and a strong diurnal variability. For two case studies on 23 May and 5 September 2018, vertical profiles of temperature and humidity were recorded up to an altitude of 650 and 1000 m, respectively, during the morning transition. Air samples were taken at different altitudes and analysed in the laboratory for methane isotopic composition. The values showed a different isotopic composition in the vertical distribution during stable conditions in the morning (delta values of −51.5 ‰ below the temperature inversion at an altitude of 150 m on 23 May 2018 and at an altitude of 50 m on 5 September 2018, delta values of −50.1 ‰ above). After the onset of turbulent mixing, the isotopic composition was the same throughout the vertical column with a mean delta value of −49.9 ± 0.45 ‰. The systematically more negative delta values occurred only as long as the nocturnal temperature inversion was present. During the September study, water samples were analysed as well for methane concentration and isotopic composition in order to provide a link between surface and atmosphere. The water samples reveal high variability on horizontal scales of a few tens of metres for this particular case. The airborne sampling system and consecutive analysis chain were shown to provide reliable and reproducible results for two samples obtained simultaneously. The method presents a powerful tool for distinguishing the source process of methane at different altitudes. The isotopic composition showed clearly depleted delta values directly above a biological methane source when vertical mixing was hampered by a temperature inversion, and different delta values above, where the air masses originate from a different footprint area. The vertical distribution of methane isotopic composition can serve as tracer for mixing processes of methane within the atmospheric boundary layer.
28
Schobesberger, Siegfried, Emma L. D'Ambro, Lejish Vettikkat, Ben H. Lee, Qiaoyun Peng, David M. Bell, John E. Shilling, et al. "Airborne flux measurements of ammonia over the southern Great Plains using chemical ionization mass spectrometry." Atmospheric Measurement Techniques 16, no. 2 (January 19, 2023): 247–71. http://dx.doi.org/10.5194/amt-16-247-2023.
Full textAbstract:
Abstract. Ammonia (NH3) is an abundant trace gas in the atmosphere and an important player in atmospheric chemistry, aerosol formation and the atmosphere–surface exchange of nitrogen. The accurate determination of NH3 emission rates remains a challenge, partly due to the propensity of NH3 to interact with instrument surfaces, leading to high detection limits and slow response times. In this paper, we present a new method for quantifying ambient NH3, using chemical ionization mass spectrometry (CIMS) with deuterated benzene cations as reagents. The setup aimed at limiting sample–surface interactions and achieved a 1σ precision of 10–20 pptv and an immediate 1/e response rate of < 0.4 s, which compares favorably to the existing state of the art. The sensitivity exhibited an inverse humidity dependence, in particular in relatively dry conditions. Background of up to 10 % of the total signal required consideration as well, as it responded on the order of a few minutes. To showcase the method's capabilities, we quantified NH3 mixing ratios from measurements obtained during deployment on a Gulfstream I aircraft during the HI-SCALE (Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems) field campaign in rural Oklahoma during May 2016. Typical mixing ratios were 1–10 parts per billion by volume (ppbv) for the boundary layer and 0.1–1 ppbv in the lower free troposphere. Sharp plumes of up to tens of ppbv of NH3 were encountered as well. We identified two of their sources as a large fertilizer plant and a cattle farm, and our mixing ratio measurements yielded upper bounds of 350 ± 50 and 0.6 kg NH3 h−1 for their respective momentary source rates. The fast response of the CIMS also allowed us to derive vertical NH3 fluxes within the turbulent boundary layer via eddy covariance, for which we chiefly used the continuous wavelet transform technique. As expected for a region dominated by agriculture, we observed predominantly upward fluxes, implying net NH3 emissions from the surface. The corresponding analysis focused on the most suitable flight, which contained two straight-and-level legs at ∼ 300 m above ground. We derived NH3 fluxes between 1 and 11 mol km−2 h−1 for these legs, at an effective spatial resolution of 1–2 km. The analysis demonstrated how flux measurements benefit from suitably arranged flight tracks with sufficiently long straight-and-level legs, and it explores the detrimental effect of measurement discontinuities. Following flux footprint estimations, comparison to the NH3 area emissions inventory provided by the U.S. Environmental Protection Agency indicated overall agreement but also the absence of some sources, for instance the identified cattle farm. Our study concludes that high-precision CIMS measurements are a powerful tool for in situ measurements of ambient NH3 mixing ratios, and even allow for the airborne mapping of the air–surface exchange of NH3.
29
Xueref-Remy, Irène, Elsa Dieudonné, Cyrille Vuillemin, Morgan Lopez, Christine Lac, Martina Schmidt, Marc Delmotte, et al. "Diurnal, synoptic and seasonal variability of atmospheric CO<sub>2</sub> in the Paris megacity area." Atmospheric Chemistry and Physics 18, no. 5 (March 7, 2018): 3335–62. http://dx.doi.org/10.5194/acp-18-3335-2018.
Full textAbstract:
Abstract. Most of the global fossil fuel CO2 emissions arise from urbanized and industrialized areas. Bottom-up inventories quantify them but with large uncertainties. In 2010–2011, the first atmospheric in situ CO2 measurement network for Paris, the capital of France, began operating with the aim of monitoring the regional atmospheric impact of the emissions coming from this megacity. Five stations sampled air along a northeast–southwest axis that corresponds to the direction of the dominant winds. Two stations are classified as rural (Traînou – TRN; Montgé-en-Goële – MON), two are peri-urban (Gonesse – GON; Gif-sur-Yvette – GIF) and one is urban (EIF, located on top of the Eiffel Tower). In this study, we analyze the diurnal, synoptic and seasonal variability of the in situ CO2 measurements over nearly 1 year (8 August 2010–13 July 2011). We compare these datasets with remote CO2 measurements made at Mace Head (MHD) on the Atlantic coast of Ireland and support our analysis with atmospheric boundary layer height (ABLH) observations made in the center of Paris and with both modeled and observed meteorological fields. The average hourly CO2 diurnal cycles observed at the regional stations are mostly driven by the CO2 biospheric cycle, the ABLH cycle and the proximity to urban CO2 emissions. Differences of several µmol mol−1 (ppm) can be observed from one regional site to the other. The more the site is surrounded by urban sources (mostly residential and commercial heating, and traffic), the more the CO2 concentration is elevated, as is the associated variability which reflects the variability of the urban sources. Furthermore, two sites with inlets high above ground level (EIF and TRN) show a phase shift of the CO2 diurnal cycle of a few hours compared to lower sites due to a strong coupling with the boundary layer diurnal cycle. As a consequence, the existence of a CO2 vertical gradient above Paris can be inferred, whose amplitude depends on the time of the day and on the season, ranging from a few tenths of ppm during daytime to several ppm during nighttime. The CO2 seasonal cycle inferred from monthly means at our regional sites is driven by the biospheric and anthropogenic CO2 flux seasonal cycles, the ABLH seasonal cycle and also synoptic variations. Enhancements of several ppm are observed at peri-urban stations compared to rural ones, mostly from the influence of urban emissions that are in the footprint of the peri-urban station. The seasonal cycle observed at the urban station (EIF) is specific and very sensitive to the ABLH cycle. At both the diurnal and the seasonal scales, noticeable differences of several ppm are observed between the measurements made at regional rural stations and the remote measurements made at MHD, that are shown not to define background concentrations appropriately for quantifying the regional (∼ 100 km) atmospheric impact of urban CO2 emissions. For wind speeds less than 3 m s−1, the accumulation of local CO2 emissions in the urban atmosphere forms a dome of several tens of ppm at the peri-urban stations, mostly under the influence of relatively local emissions including those from the Charles de Gaulle (CDG) Airport facility and from aircraft in flight. When wind speed increases, ventilation transforms the CO2 dome into a plume. Higher CO2 background concentrations of several ppm are advected from the remote Benelux–Ruhr and London regions, impacting concentrations at the five stations of the network even at wind speeds higher than 9 m s−1. For wind speeds ranging between 3 and 8 m s−1, the impact of Paris emissions can be detected in the peri-urban stations when they are downwind of the city, while the rural stations often seem disconnected from the city emission plume. As a conclusion, our study highlights a high sensitivity of the stations to wind speed and direction, to their distance from the city, but also to the ABLH cycle depending on their elevation. We learn some lessons regarding the design of an urban CO2 network: (1) careful attention should be paid to properly setting regional (∼ 100 km) background sites that will be representative of the different wind sectors; (2) the downwind stations should be positioned as symmetrically as possible in relation to the city center, at the peri-urban/rural border; (3) the stations should be installed at ventilated sites (away from strong local sources) and the air inlet set up above the building or biospheric canopy layer, whichever is the highest; and (4) high-resolution wind information should be available with the CO2 measurements.
30
Schumann, Johann, Chetan Kulkarni, Michael Lowry, Anupa Bajwa, Christopher Teubert, and Jason Watkins. "Prognostics for Autonomous Electric-Propulsion Aircraft." International Journal of Prognostics and Health Management 12, no. 3 (March 30, 2021). http://dx.doi.org/10.36001/ijphm.2021.v12i3.2940.
Full textAbstract:
An autonomous unmanned aerial system (UAS) needs, during the flight, accurate information about the current failure state of the aircraft and its capabilities in order to safely perform its mission and properly react to contingencies. The flight battery of an electric-propulsion aircraft is its most relevant resource. Model-based prognostics algorithms are used to obtain good estimates of its current state of charge and remaining capacity. However, these algorithms can have a large computational footprint. We present Prognostics-as-a-Service, a hybrid approach combining on-board computation with server-based prognostics on the ground.In this paper, we focus on the role, battery prognostics plays for the safe operation of a highly autonomous aircraft: prognostics for (1) continuous on-board safety monitoring, (2) for UAS operations, and (3) for contingency planning. We present the NASA Autonomous Operating System (AOS) and discuss how the autonomous components closely work together with on-board and server-based ground prognostics systems. We will illustrate the system with case studies on small NASA unmanned aircraft.
31
Mascaro, Giuseppe, Ara Ko, and Enrique R. Vivoni. "Closing the Loop of Satellite Soil Moisture Estimation via Scale Invariance of Hydrologic Simulations." Scientific Reports 9, no. 1 (November 6, 2019). http://dx.doi.org/10.1038/s41598-019-52650-3.
Full textAbstract:
Abstract Surface soil moisture plays a crucial role on the terrestrial water, energy, and carbon cycles. Characterizing its variability in space and time is critical to increase our capability to forecast extreme weather events, manage water resources, and optimize agricultural practices. Global estimates of surface soil moisture are provided by satellite sensors, but at coarse spatial resolutions. Here, we show that the resolution of satellite soil moisture products can be increased to scales representative of ground measurements by reproducing the scale invariance properties of soil moisture derived from hydrologic simulations at hyperresolutions of less than 100 m. Specifically, we find that surface soil moisture is scale invariant over regimes extending from a satellite footprint to 100 m. We use this evidence to calibrate a statistical downscaling algorithm that reproduces the scale invariance properties of soil moisture and test the approach against 1-km aircraft remote sensing products and through comparisons of downscaled satellite products to ground observations. We demonstrate that hyperresolution hydrologic models can close the loop of satellite soil moisture downscaling for local applications such as agricultural irrigation, flood event prediction, and drought and fire management.
32
Fehr, R., D. Zeegers Paget, O. C. L. Mekel, and N. Bos. "Towards quantifying CO2 emissions from EPH conference travel." European Journal of Public Health 29, Supplement_4 (November 1, 2019). http://dx.doi.org/10.1093/eurpub/ckz185.482.
Full textAbstract:
Abstract Background Aviation is accountable for significant emissions of carbon dioxide (CO2). Factors determining emissions include, e.g., trip distance, aircraft fuel efficiency, cabin class, atmospheric conditions, and stopovers. Approaches to estimate the carbon footprint are available, e.g., as carbon emissions calculators, offered by carbon offset providers. Goal: To estimate the amount of CO2 emissions associated with EPH conference air travel, for fostering awareness among EPH conference attendees. Methods Based on EPH attendees’ empirical distribution of countries of origin for the 2017 Stockholm and 2018 Ljubljana conference, rough estimates of travel distances, CO2 emissions, and potential carbon offset costs were produced. In the absence of attendees’ detailed travel information, simplifying assumptions had to be made, e.g. on air vs. ground travel, place of departure, and stopovers. In approach A, using two different offset calculators, we look at a given “sample” country which provided a large fraction of foreign participants in both 2017 and 2018, then try to extrapolate to participants at large. In approach B, we use a rough approximation of total distance travelled by all participants, and an average emission value per distance unit. Results In approach A, expectedly, the emission estimates provided by the two different calculators and the associated price tags for offsetting were rather similar, whereas the overall approach B created lower estimates of CO2 emissions. In summary, the conference air travel was estimated to emit 650-930 tons CO2, with the cost for setoff being roughly € 20.000. In a typical case, the conference air travel CO2 emission of a person (foreign to the conference country) was estimated as being 580 kg. For comparison: to bring climate change to a halt, the total annual CO2 emission per person needs to be below 600 kg. Discussion While estimates should be improved, a major task lies in promoting CO2 emission reduction and mitigation.