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Artykuły w czasopismach na temat „Equatorial plasma bubbles”

Autor: Grafiati

Data publikacji: 6 września 2023

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1

Li, G., B. Ning, L. Liu, W. Wan i J. Y. Liu. "Effect of magnetic activity on plasma bubbles over equatorial and low-latitude regions in East Asia". Annales Geophysicae 27, nr 1 (19.01.2009): 303–12. http://dx.doi.org/10.5194/angeo-27-303-2009.

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Abstract. The dependence of plasma bubble occurrence in the eveningside ionosphere, with magnetic activity during the period years 2001–2004, is studied here based on the TEC observations gathered by ground-based GPS receivers which are located in the equatorial and low-latitude regions in East Asia. The observed plasma bubbles consist of the plasma-bubble events in the equatorial (stations GUAM, PIMO and KAYT), and low-latitude regions (stations WUHN, DAEJ and SHAO). It is shown that most equatorial plasma-bubble events commence at 20:00 LT, and may last for >60 min. The magnetic activity appears to suppress the generation of equatorial plasma bubbles with a time delay of more than 3 h (4–9 h). While in the low-latitude regions, most plasma-bubble events commence at about 23:00 LT and last for <45 min. The best correlation between Kp and low-latitude plasma-bubble occurrence is found with an 8–9 h delay, a weak correlation exists for time delays of 6–7 h. This probably indicates that over 3 h delayed disturbance dynamo electric fields obviously inhibit the development of plasma bubbles in the pre-midnight sector.

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Narayanan, V. L., S. Gurubaran, K. Shiokawa i K. Emperumal. "Shrinking equatorial plasma bubbles". Journal of Geophysical Research: Space Physics 121, nr 7 (lipiec 2016): 6924–35. http://dx.doi.org/10.1002/2016ja022633.

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3

Bhattacharyya, Archana. "Equatorial Plasma Bubbles: A Review". Atmosphere 13, nr 10 (8.10.2022): 1637. http://dx.doi.org/10.3390/atmos13101637.

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The equatorial plasma bubble (EPB) phenomenon is an important component of space weather as the ionospheric irregularities that develop within EPBs can have major detrimental effects on the operation of satellite-based communication and navigation systems. Although the name suggests that EPBs occur in the equatorial ionosphere, the nature of the plasma instability that gives rise to EPBs is such that the bubbles may extend over a large part of the global ionosphere between geomagnetic latitudes of approximately ±15°. The scientific challenge continues to be to understand the day-to-day variability in the occurrence and characteristics of EPBs, such as their latitudinal extent and the development of irregularities within EPBs. In this paper, basic theoretical aspects of the plasma processes involved in the generation of EPBs, associated ionospheric irregularities, and observations of their characteristics using different techniques will be reviewed. Special focus will be given to observations of scintillations produced by the scattering of VHF and higher frequency radio waves while they propagate through ionospheric irregularities associated with EPBs, as these observations have revealed new information about the non-linear development of Rayleigh–Taylor instability in equatorial ionospheric plasma, which is the genesis of EPBs.

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4

Singh, Sardul, D. K. Bamgboye, J. P. McClure i F. S. Johnson. "Morphology of equatorial plasma bubbles". Journal of Geophysical Research: Space Physics 102, A9 (1.09.1997): 20019–29. http://dx.doi.org/10.1029/97ja01724.

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5

Pottelette, R., M. Malingre, J. J. Berthelier, E. Seran i M. Parrot. "Filamentary Alfvénic structures excited at the edges of equatorial plasma bubbles". Annales Geophysicae 25, nr 10 (6.11.2007): 2159–65. http://dx.doi.org/10.5194/angeo-25-2159-2007.

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Abstract. Recent observations performed by the French DEMETER satellite at altitudes of about 710 km suggest that the generation of equatorial plasma bubbles correlates with the presence of filamentary structures of field aligned currents carried by Alfvén waves. These localized structures are located at the bubble edges. We study the dynamics of the equatorial plasma bubbles, taking into account that their motion is dictated by gravity driven and displacement currents. Ion-polarization currents appear to be crucial for the accurate description of the evolution of plasma bubbles in the high altitude ionosphere. During their eastward/westward motion the bubbles intersect gravity driven currents flowing transversely with respect to the background magnetic field. The circulation of these currents is prohibited by large density depressions located at the bubble edges acting as perfect insulators. As a result, in these localized regions the transverse currents have to be locally closed by field aligned currents. Such a physical process generates kinetic Alfvén waves which appear to be stationary in the plasma bubble reference frame. Using a two-dimensional model and "in situ" wave measurements on board the DEMETER spacecraft, we give estimates for the magnitude of the field aligned currents and the associated Alfvén fields.

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6

Chapagain, Narayan P. "Dynamics Ionospheric Plasma Bubbles Measured by Optical Imaging System". Journal of Institute of Science and Technology 20, nr 1 (25.11.2015): 20–27. http://dx.doi.org/10.3126/jist.v20i1.13906.

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Deep plasma depletions during the nighttime period in the equatorial ionosphere (referred to as equatorial plasma bubbles –EPBs) can significantly affect communications and navigation systems. In this study, we present the image measurements of plasma bubble from Christmas Island (2.1°N, 157.4°W, dip latitude 2.8°N) in the central Pacific Ocean. These observations were made during September-October 1995 using a Utah State University (USU) CCD imaging system measured at ~280 km altitude. Well-defined magnetic field-aligned plasma depletions were observed for 18 nights, including strong post-midnight fossilized structures, enabling detailed measurements of their morphology and dynamics. We also estimate zonal velocity of the plasma bubbles from available images. The zonal drift velocity of the EPBs is a very important parameter for the understanding and modeling of the electrodynamics of the equatorial ionosphere and for the predictions of ionospheric irregularities. The eastward zonal drift velocities were around 90-100 m/s prior to local midnight, and decreases during the post-midnight period that persisted until dawn.Journal of Institute of Science and Technology, 2015, 20(1): 20-27

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7

Makela, J. J., B. M. Ledvina, M. C. Kelley i P. M. Kintner. "Analysis of the seasonal variations of equatorial plasma bubble occurrence observed from Haleakala, Hawaii". Annales Geophysicae 22, nr 9 (23.09.2004): 3109–21. http://dx.doi.org/10.5194/angeo-22-3109-2004.

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Abstract. Over 300 nights of airglow and GPS scintillation data collected between January 2002 and August 2003 (a period near solar maximum) from the Haleakala Volcano, Hawaii are analyzed to obtain the seasonal trends for the occurrence of equatorial plasma bubbles in the Pacific sector (203° E). A maximum probability for bubble development is seen in the data in April (45%) and September (83%). A broad maximum of occurrence is seen in the data from June to October (62%). Many of the bubbles observed from June through August occur later in the evening, and, as seen in the optical data, tend to be "fossilized". This suggests that the active growth region during these months is to the west of the observing location. These seasonal trends are consistent with previous data sets obtained both from other ground-based and satellite studies of the occurrence of equatorial bubbles in the Pacific sector. However, our data suggests a much greater probability of bubble occurrence than is seen in other data sets, with bubbles observed on over 40% of the nights studied.

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8

Huba, J. D., i G. Joyce. "Global modeling of equatorial plasma bubbles". Geophysical Research Letters 37, nr 17 (wrzesień 2010): n/a. http://dx.doi.org/10.1029/2010gl044281.

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9

Laakso, Harri, Thomas L. Aggson, Robert F. Pfaff i William B. Hanson. "Downdrafting plasma flow in equatorial bubbles". Journal of Geophysical Research 99, A6 (1994): 11507. http://dx.doi.org/10.1029/93ja03169.

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10

Nade, D. P., A. K. Sharma, S. S. Nikte, P. T. Patil, R. N. Ghodpage, M. V. Rokade, S. Gurubaran, A. Taori i Y. Sahai. "Zonal velocity of the equatorial plasma bubbles over Kolhapur, India". Annales Geophysicae 31, nr 11 (22.11.2013): 2077–84. http://dx.doi.org/10.5194/angeo-31-2077-2013.

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Abstract. This paper presents the observations of zonal drift velocities of equatorial ionospheric plasma bubbles and their comparison with model values. These velocities are determined by nightglow OI 630.0 nm images. The nightglow observations have been carried out from the low latitude station Kolhapur (16.8° N, 74.2° E; 10.6° N dip lat.) during clear moonless nights. Herein we have presented the drift velocities of equatorial plasma bubbles for the period of February–April 2011. Out of 80 nights, 39 showed the occurrence of equatorial plasma bubbles (49%). These 39 nights correspond to magnetically quiet days (ΣKp < 26). The average eastward zonal velocities (112 ± 10 m s−1) of equatorial plasma bubbles increased from evening sector to 21:00 IST (Indian Standard Time = Universal Time + 05:30:00 h), reach maximum about 165 ± 30 m s−1 and then decreases with time. The calculated velocities are in good agreement with that of recently reported values obtained with models with occasional differences; possible mechanisms of which are discussed.

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11

Kashchenko, Nikolay M., Sergey A. Ishanov i Sergey V. Matsievsky. "Simulation equatorial plasma bubbles started from plasma clouds". Computer Research and Modeling 11, nr 3 (czerwiec 2019): 463–76. http://dx.doi.org/10.20537/2076-7633-2019-11-3-463-476.

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12

Pimenta, A. A., P. R. Fagundes, Y. Sahai, J. A. Bittencourt i J. R. Abalde. "Equatorial F-region plasma depletion drifts: latitudinal and seasonal variations". Annales Geophysicae 21, nr 12 (31.12.2003): 2315–22. http://dx.doi.org/10.5194/angeo-21-2315-2003.

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Abstract. The equatorial ionospheric irregularities have been observed in the past few years by different techniques (e.g. ground-based radar, digisonde, GPS, optical instruments, in situ satellite and rocket instrumentation), and its time evolution and propagation characteristics can be used to study important aspects of ionospheric dynamics and thermosphere-ionosphere coupling. At present, one of the most powerful optical techniques to study the large-scale ionospheric irregularities is the all-sky imaging photometer system, which normally measures the strong F-region nightglow 630 nm emission from atomic oxygen. The monochromatic OI 630 nm emission images usually show quasi-north-south magnetic field-aligned intensity depletion bands, which are the bottomside optical signatures of large-scale F-region plasma irregularities (also called plasma bubbles). The zonal drift velocities of the plasma bubbles can be inferred from the space-time displacement of the dark structures (low intensity regions) seen on the images. In this study, images obtained with an all-sky imaging photometer, using the OI 630 nm nightglow emission, from Cachoeira Paulista (22.7° S, 45° W, 15.8° S dip latitude), Brazil, have been used to determine the nocturnal monthly and latitudinal variation characteristics of the zonal plasma bubble drift velocities in the low latitude (16.7° S to 28.7° S) region. The east and west walls of the plasma bubble show a different evolution with time. The method used here is based on the western wall of the bubble, which presents a more stable behavior. Also, the observed zonal plasma bubble drift velocities are compared with the thermospheric zonal neutral wind velocities obtained from the HWM-90 model (Hedin et al., 1991) to investigate the thermosphere-ionosphere coupling. Salient features from this study are presented and discussed.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric irregularities; instruments and techniques)

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13

Huang, Chao-Song. "Occurrence of Equatorial Plasma Bubbles during Intense Magnetic Storms". International Journal of Geophysics 2011 (2011): 1–10. http://dx.doi.org/10.1155/2011/401858.

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An important issue in low-latitude ionospheric space weather is how magnetic storms affect the generation of equatorial plasma bubbles. In this study, we present the measurements of the ion density and velocity in the evening equatorial ionosphere by the Defense Meteorological Satellite Program (DMSP) satellites during 22 intense magnetic storms. The DMSP measurements show that deep ion density depletions (plasma bubbles) are generated after the interplanetary magnetic field (IMF) turns southward. The time delay between the IMF southward turning and the first DMSP detection of plasma depletions decreases with the minimum value of the IMFBz, the maximum value of the interplanetary electric field (IEF)Ey, and the magnitude of the Dst index. The results of this study provide strong evidence that penetration electric field associated with southward IMF during the main phase of magnetic storms increases the generation of equatorial plasma bubbles in the evening sector.

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14

Ma, Guanyi, Klemens Hocke, Jinghua Li, Qingtao Wan, Weijun Lu i Weizheng Fu. "GNSS Ionosphere Sounding of Equatorial Plasma Bubbles". Atmosphere 10, nr 11 (2.11.2019): 676. http://dx.doi.org/10.3390/atmos10110676.

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Ground- and space-based Global Navigation Satellite System (GNSS) receivers can provide three-dimensional (3D) information about the occurrence of equatorial plasma bubbles (EPBs). For this study, we selected March 2014 data (during solar maximum of cycle 24) for the analysis. The timing and the latitudinal dependence of the EPBs occurrence rate are derived by means of the rate of the total electron content (TEC) index (ROTI) data from GNSS receivers in China, whereas vertical profiles of the scintillation index S4 are provided by COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate). The GNSS receivers of the low Earth orbit satellites give information about the occurrence of amplitude scintillations in limb sounding geometry where the focus is on magnetic latitudes from 20° S to 20° N. The occurrence rates of the observed EPB-induced scintillations are generally smaller than those of the EPB-induced ROTI variations. The timing and the latitude dependence of the EPBs occurrence rate agree between the ground-based and spaceborne GNSS data. We find that EPBs occur at 19:00 LT and they are mainly situated above the F2 peak layer which descended from 450 km at 20:00 LT to 300 km at 24:00 LT in the equatorial ionosphere. At the same time, the spaceborne GNSS data also show, for the first time, a high occurrence rate of post-sunset scintillations at 100 km altitude, indicating the coexistence of equatorial sporadic E with EPBs.

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15

Makela, J. J., S. L. Vadas, R. Muryanto, T. Duly i G. Crowley. "Periodic spacing between consecutive equatorial plasma bubbles". Geophysical Research Letters 37, nr 14 (lipiec 2010): n/a. http://dx.doi.org/10.1029/2010gl043968.

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16

Singh, Sardul, F. S. Johnson i R. A. Power. "Gravity wave seeding of equatorial plasma bubbles". Journal of Geophysical Research: Space Physics 102, A4 (1.04.1997): 7399–410. http://dx.doi.org/10.1029/96ja03998.

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17

Burke, W. J., C. Y. Huang, L. C. Gentile i L. Bauer. "Seasonal-longitudinal variability of equatorial plasma bubbles". Annales Geophysicae 22, nr 9 (23.09.2004): 3089–98. http://dx.doi.org/10.5194/angeo-22-3089-2004.

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Abstract. We compare seasonal and longitudinal distributions of more than 8300 equatorial plasma bubbles (EPBs) observed during a full solar cycle from 1989-2000 with predictions of two simple models. Both models are based on considerations of parameters that influence the linear growth rate, γRT, of the generalized Rayleigh-Taylor instability in the context of finite windows of opportunity available during the prereversal enhancement near sunset. These parameters are the strength of the equatorial magnetic field, Beq, and the angle, α, it makes with the dusk terminator line. The independence of α and Beq from the solar cycle phase justifies our comparisons. We have sorted data acquired during more than 75000 equatorial evening-sector passes of polar-orbiting Defense Meteorological Satellite Program (DMSP) satellites into 24 longitude and 12 one-month bins, each containing ~250 samples. We show that: (1) in 44 out of 48 month-longitude bins EPB rates are largest within 30 days of when α=0°; (2) unpredicted phase shifts and asymmetries appear in occurrence rates at the two times per year when α≈0°; (3) While EPB occurrence rates vary inversely with Beq, the relationships are very different in regions where Beq is increasing and decreasing with longitude. Results (2) and (3) indicate that systematic forces not considered by the two models can become important. Damping by interhemispheric winds appears to be responsible for phase shifts in maximum rates of EPB occurrence from days when α=0°. Low EPB occurrence rates found at eastern Pacific longitudes suggest that radiation belt electrons in the drift loss cone reduce γRT by enhancing E-layer Pedersen conductances. Finally, we analyze an EPB event observed during a magnetic storm at a time and place where α≈-27°, to illustrate how electric-field penetration from high latitudes can overwhelm the damping effects of weak gradients in Pedersen conductance near dusk.

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18

Sharma, A. K., D. P. Nade, S. S. Nikte, P. T. Patil, R. N. Ghodpage, R. S. Vhatkar, M. V. Rokade i S. Gurubaran. "Occurrence of equatorial plasma bubbles over Kolhapur". Advances in Space Research 54, nr 3 (sierpień 2014): 435–42. http://dx.doi.org/10.1016/j.asr.2013.07.018.

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19

Saito, S., i T. Maruyama. "Ionospheric height variations observed by ionosondes along magnetic meridian and plasma bubble onsets". Annales Geophysicae 24, nr 11 (21.11.2006): 2991–96. http://dx.doi.org/10.5194/angeo-24-2991-2006.

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Abstract. Since October 2004, a Frequency Modulated–Continuous Wave (FM–CW) ionosonde chain along the magnetic meridian has been operating in Southeast Asia, in Kototabang (0.2° S, 100.3° E), Indonesia, Chumphon (10.7° N, 99.4° E), Thailand, and Chiang Mai (18.8° N, 98.9° E), Thailand. Variations in the virtual height of the bottomside of the F-region (h'F) at 2.5 MHz were analyzed, in order to study the day-to-day variability of plasma bubble occurrence for the periods of October 2004 and March–April 2005. When plasma bubbles were generated, h'F was enhanced at the three stations. However, even when h'F at the equatorial station, Chumphon, was largely enhanced, plasma bubbles were not generated when a noticeable north-south asymmetry of h'F existed. This asymmetry could be attributed to the transequatorial thermospheric wind. Our results show that the strong transequatorial thermospheric wind can suppress the plasma bubble generation and is one of the important factors which controls the day-to-day variability of plasma bubble occurrences.

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20

De Michelis, Paola, Giuseppe Consolini, Roberta Tozzi, Alessio Pignalberi, Michael Pezzopane, Igino Coco, Fabio Giannattasio i Maria Federica Marcucci. "Ionospheric Turbulence and the Equatorial Plasma Density Irregularities: Scaling Features and RODI". Remote Sensing 13, nr 4 (18.02.2021): 759. http://dx.doi.org/10.3390/rs13040759.

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In the framework of space weather, the understanding of the physical mechanisms responsible for the generation of ionospheric irregularities is particularly relevant for their effects on global positioning and communication systems. Ionospheric equatorial plasma bubbles are one of the possible irregularities. In this work, using data from the ESA Swarm mission, we investigate the scaling features of electron density fluctuations characterizing equatorial plasma bubbles. Results strongly support a turbulence character of these structures and suggest the existence of a clear link between the observed scaling properties and the value of the Rate Of change of electron Density Index (RODI). This link is discussed, and RODI is proposed as a reliable proxy for the identification of plasma bubbles.

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21

Paulino, Igo, Ana Roberta Paulino, Ricardo Y. C. Cueva, Ebenezer Agyei-Yeboah, Ricardo Arlen Buriti, Hisao Takahashi, Cristiano Max Wrasse, Ângela M. Santos, Amauri Fragoso de Medeiros i Inez S. Batista. "Semimonthly oscillation observed in the start times of equatorial plasma bubbles". Annales Geophysicae 38, nr 2 (31.03.2020): 437–43. http://dx.doi.org/10.5194/angeo-38-437-2020.

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Abstract. Using airglow data from an all-sky imager deployed at São João do Cariri (7.4∘ S, 36.5∘ W), the start times of equatorial plasma bubbles was studied in order to investigate the day-to-day variability of this phenomenon. Data from a period over 10 years were analyzed from 2000 to 2010. Semimonthly oscillations were clearly observed in the start times of plasma bubbles from OI6300 airglow images during this period of observation, and four case studies (September 2003, September–October 2005, November 2005 and January 2008) were chosen to show in detail this kind of modulation. Since the airglow measurements are not continuous in time, more than one cycle of oscillation in the start times of plasma bubbles cannot be observed from these data. Thus, data from a digisonde at São Luís (2.6∘ S, 44.2∘ W) in November 2005 were used to corroborate the results. Technical/climate issues did not allow one to observe the semimonthly oscillations simultaneously by the two instruments, but from October to November 2005 there was a predominance of this oscillation in the start times of the irregularities over Brazil. Besides, statistical analysis for the data in the whole period of observation has shown that the lunar tide, which has semimonthly variability, is likely the main forcing for the semimonthly oscillation in the start times of equatorial plasma bubbles. The presence of this oscillation can contribute to the day-to-day variability of equatorial plasma bubbles.

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Kil, Hyosub. "The Morphology of Equatorial Plasma Bubbles - a review". Journal of Astronomy and Space Sciences 32, nr 1 (15.03.2015): 13–19. http://dx.doi.org/10.5140/jass.2015.32.1.13.

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Tang, Long, Osei-Poku Louis, Wu Chen i Mingli Chen. "A ROTI-Aided Equatorial Plasma Bubbles Detection Method". Remote Sensing 13, nr 21 (29.10.2021): 4356. http://dx.doi.org/10.3390/rs13214356.

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In this study, we present a Rate of Total Electron Content Index (ROTI)-aided equatorial plasma bubbles (EPBs) detection method based on a Global Navigation Satellite System (GNSS) ionospheric Total Electron Content (TEC). This technique seeks the EPBs occurrence time according to the ROTI values and then extracts the detrended ionospheric TEC series, which include EPBs signals using a low-order, partial polynomial fitting strategy. The EPBs over the Hong Kong area during the year of 2014 were detected using this technique. The results show that the temporal distribution and occurrence of EPBs over the Hong Kong area are consistent with that of previous reports, and most of the TEC depletion error is smaller than 1.5 TECU (average is 0.63 TECU), suggesting that the detection method is feasible and highly accurate. Furthermore, this technique can extract the TEC depletion series more effectively, especially for those with a long duration, compared to previous method.

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24

Sidorova, L. N. "Equatorial Plasma Bubbles: Occurrence Probability versus Local Time". Geomagnetism and Aeronomy 60, nr 5 (wrzesień 2020): 530–37. http://dx.doi.org/10.1134/s001679322005014x.

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Kepkar, Ankur, Christina Arras, Jens Wickert, Harald Schuh, Mahdi Alizadeh i Lung-Chih Tsai. "Occurrence climatology of equatorial plasma bubbles derived using FormoSat-3 ∕ COSMIC GPS radio occultation data". Annales Geophysicae 38, nr 3 (13.05.2020): 611–23. http://dx.doi.org/10.5194/angeo-38-611-2020.

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Abstract. The Global Positioning System – Radio Occultation (GPS-RO) observations from FormoSat-3 ∕ COSMIC are used to comprehend the global distribution of equatorial plasma bubbles which are characterized by depletion regions of plasma in the F region of the ionosphere. Plasma bubbles that cause intense scintillation of the radio signals are identified based on the S4 index derived from the 1 Hz raw signal-to-noise ratio measurements between 2007 and 2017. The analyses revealed that bubbles influenced by background plasma density occurred along the geomagnetic equator and had an occurrence peak around the dip equator during high solar activity. The peak shifted between the African and American sectors, depending on different solar conditions. Plasma bubbles usually developed around 19:00 local time (LT), with maximum occurrence around 21:00 LT during solar maximum and ∼22:00 LT during solar minimum. The occurrence of bubbles showed a strong dependence on longitudes, seasons, and solar cycle with the peak occurrence rate in the African sector around the March equinox during high solar activity, which is consistent with previous studies. The GPS-RO technique allows an extended analysis of the altitudinal distribution of global equatorial plasma bubbles obtained from high vertical resolution profiles, thus making it a convenient tool which could be further used with other techniques to provide a comprehensive view of such ionospheric irregularities.

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De Michelis, Paola, Giuseppe Consolini, Tommaso Alberti, Roberta Tozzi, Fabio Giannattasio, Igino Coco, Michael Pezzopane i Alessio Pignalberi. "Magnetic Field and Electron Density Scaling Properties in the Equatorial Plasma Bubbles". Remote Sensing 14, nr 4 (14.02.2022): 918. http://dx.doi.org/10.3390/rs14040918.

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The ionospheric plasma density irregularities are known to play a role in the propagation of electromagnetic signals and to be one of the most important sources of disturbance for the Global Navigation Satellite System, being responsible for degradation and, sometimes, interruptions of the signals received by the system. In the equatorial ionospheric F region, these plasma density irregularities, known as plasma bubbles, find the suitable conditions for their development during post-sunset hours. In recent years, important features of plasma bubbles such as their dependence on latitude, longitude, and solar and geomagnetic activities have been inferred indirectly using their magnetic signatures. Here, we study the scaling properties of both the electron density and the magnetic field inside the plasma bubbles using measurements on board the Swarm A satellite from 1 April 2014 to 31 January 2016. We show that the spectral features of plasma irregularities cannot be directly inferred from their magnetic signatures. A relation more complex than the linear one is necessary to properly describe the role played by the evolution of plasma bubbles with local time and by the development of turbulent phenomena.

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dos Santos Prol, Fabricio, Manuel Hernández-Pajares, Marcio Tadeu de Assis Honorato Muella i Paulo de Oliveira Camargo. "Tomographic Imaging of Ionospheric Plasma Bubbles Based on GNSS and Radio Occultation Measurements". Remote Sensing 10, nr 10 (23.09.2018): 1529. http://dx.doi.org/10.3390/rs10101529.

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Total electron content measurements given by the global navigation satellite system (GNSS) have successfully presented results to capture the signatures of equatorial plasma bubbles. In contrast, the correct reproduction of plasma depletions at electron density level is still a relevant challenge for ionospheric tomographic imaging. In this regard, this work shows the first results of a new tomographic reconstruction technique based on GNSS and radio-occultation data to map the vertical and horizontal distributions of ionospheric plasma bubbles in one of the most challenging conditions of the equatorial region. Twenty-three days from 2013 and 2014 with clear evidence of plasma bubble structures propagating through the Brazilian region were analyzed and compared with simultaneous observations of all-sky images in the 630.0 nm emission line of the atomic oxygen. The mean rate of success of the tomographic method was 37.1%, being more efficient near the magnetic equator, where the dimensions of the structures are larger. Despite some shortcomings of the reconstruction technique, mainly associated with ionospheric scintillations and the weak geometry of the ground-based GNSS receivers, both vertical and horizontal distributions were mapped over more than 30° in latitude, and have been detected in instances where the meteorological conditions disrupted the possibility of analyzing the OI 630 nm emissions. Therefore, the results revealed the proposed tomographic reconstruction as an efficient tool for mapping characteristics of the plasma bubble structures, which may have a special interest in Space Weather, Spatial Geodesy, and Telecommunications.

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28

Krall, J., J. D. Huba, S. L. Ossakow, G. Joyce, J. J. Makela, E. S. Miller i M. C. Kelley. "Modeling of equatorial plasma bubbles triggered by non-equatorial traveling ionospheric disturbances". Geophysical Research Letters 38, nr 8 (19.04.2011): n/a. http://dx.doi.org/10.1029/2011gl046890.

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McNamara, L. F., R. G. Caton, R. T. Parris, T. R. Pedersen, D. C. Thompson, K. C. Wiens i K. M. Groves. "Signatures of equatorial plasma bubbles in VHF satellite scintillations and equatorial ionograms". Radio Science 48, nr 2 (marzec 2013): 89–101. http://dx.doi.org/10.1002/rds.20025.

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Alam Kherani, E., M. A. Abdu, E. R. de Paula, D. C. Fritts, J. H. A. Sobral i F. C. de Meneses. "The impact of gravity waves rising from convection in the lower atmosphere on the generation and nonlinear evolution of equatorial bubble". Annales Geophysicae 27, nr 4 (7.04.2009): 1657–68. http://dx.doi.org/10.5194/angeo-27-1657-2009.

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Abstract. The nonlinear evolution of equatorial F-region plasma bubbles under varying ambient ionospheric conditions and gravity wave seeding perturbations in the bottomside F-layer is studied. To do so, the gravity wave propagation from the convective source region in the lower atmosphere to the thermosphere is simulated using a model of gravity wave propagation in a compressible atmosphere. The wind perturbation associated with this gravity wave is taken as a seeding perturbation in the bottomside F-region to excite collisional-interchange instability. A nonlinear model of collisional-interchange instability (CII) is implemented to study the influences of gravity wave seeding on plasma bubble formation and development. Based on observations during the SpreadFEx campaign, two events are selected for detailed studies. Results of these simulations suggest that gravity waves can play a key role in plasma bubble seeding, but that they are also neither necessary nor certain to do so. Large gravity wave perturbations can result in deep plasma bubbles when ionospheric conditions are not conducive by themselves; conversely weaker gravity wave perturbations can trigger significant bubble events when ionospheric conditions are more favorable. But weak gravity wave perturbations in less favorable environments cannot, by themselves, lead to strong plasma bubble responses.

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Fritts, D. C., M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buriti, B. R. Clemesha i in. "Overview and summary of the Spread F Experiment (SpreadFEx)". Annales Geophysicae 27, nr 5 (11.05.2009): 2141–55. http://dx.doi.org/10.5194/angeo-27-2141-2009.

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Abstract. We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12, and the GUVI instrument aboard the TIMED satellite. Initial results of our SpreadFEx analyses are described separately by Fritts et al. (2009). Further analyses of these data provide additional evidence of 1) gravity wave (GW) activity near the mesopause apparently linked to deep convection predominantly to the west of our measurement sites, 2) small-scale GWs largely confined to lower altitudes, 3) larger-scale GWs apparently penetrating to much higher altitudes, 4) substantial GW amplitudes implied by digisonde electron densities, and 5) apparent influences of these perturbations in the lower F-region on the formation of equatorial spread F, RTI, and plasma bubbles extending to much higher altitudes. Other efforts with SpreadFEx data have also yielded 6) the occurrence, locations, and scales of deep convection, 7) the spatial and temporal evolutions of plasma bubbles, 8) 2-D (height-resolved) structures in electron density fluctuations and equatorial spread F at lower altitudes and plasma bubbles above, and 9) the occurrence of substantial tidal perturbations to the large-scale wind and temperature fields extending to bottomside F-layer and higher altitudes. Collectively, our various SpreadFEx analyses suggest direct links between deep tropical convection and large GW perturbations at large spatial scales at the bottomside F-layer and their likely contributions to the excitation of RTI and plasma bubbles extending to much higher altitudes.

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Kil, Hyosub. "The Occurrence Climatology of Equatorial Plasma Bubbles: A Review". Journal of Astronomy and Space Sciences 39, nr 2 (czerwiec 2022): 23–33. http://dx.doi.org/10.5140/jass.2022.39.2.23.

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Electron density irregularities in the equatorial ionosphere at night are understood in terms of plasma bubbles, which are produced by the transport of low-density plasma from the bottomside of the F region to the topside. Equatorial plasma bubbles (EPBs) have been detected by various techniques on the ground and from space. One of the distinguishing characteristics of EPBs identified from long-term observations is the systematic seasonal and longitudinal variation of the EPB activity. Several hypotheses have been developed to explain the systematic EPB behavior, and now we have good knowledge about the key factors that determine the behavior. However, gaps in our understanding of the EPB climatology still remain primarily because we do not yet have the capability to observe seed perturbations and their growth simultaneously and globally. This paper reviews the occurrence climatology of EPBs identified from observations and the current understanding of its driving mechanisms.

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Sidorova, L. N. "Latitudinal distribution of the equatorial plasma bubbles: Altitude variability". INTERNATIONAL JOURNAL OF ELECTRONICS AND APPLIED RESEARCH 8, nr 1 (22.12.2021): 1–14. http://dx.doi.org/10.33665/ijear.2021.v08i01.001.

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Magdaleno, Sergio, Miguel Herraiz, David Altadill i Benito A. de la Morena. "Climatology characterization of equatorial plasma bubbles using GPS data". Journal of Space Weather and Space Climate 7 (2017): A3. http://dx.doi.org/10.1051/swsc/2016039.

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35

Sidorova, L. N. "Equatorial plasma bubbles at altitudes of the topside ionosphere". Geomagnetism and Aeronomy 48, nr 1 (luty 2008): 56–65. http://dx.doi.org/10.1134/s0016793208010076.

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Sidorova, L. N., i S. V. Filippov. "Wind Preparation of the Generation of Equatorial Plasma “Bubbles”". Geomagnetism and Aeronomy 59, nr 3 (maj 2019): 312–17. http://dx.doi.org/10.1134/s0016793219030137.

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37

Abiriga, Faustine, Emirant B. Amabayo, Edward Jurua i Pierre J. Cilliers. "Statistical characterization of equatorial plasma bubbles over East Africa". Journal of Atmospheric and Solar-Terrestrial Physics 200 (kwiecień 2020): 105197. http://dx.doi.org/10.1016/j.jastp.2020.105197.

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Park, Jaeheung, Kyoung Wook Min, Vitaly P. Kim, Hyosub Kil, Shin-Yi Su, Chi Kuang Chao i Jae-Jin Lee. "Equatorial plasma bubbles with enhanced ion and electron temperatures". Journal of Geophysical Research: Space Physics 113, A9 (wrzesień 2008): n/a. http://dx.doi.org/10.1029/2008ja013067.

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Yokoyama, Tatsuhiro, Hidekatsu Jin, Hiroyuki Shinagawa i Huixin Liu. "Seeding of Equatorial Plasma Bubbles by Vertical Neutral Wind". Geophysical Research Letters 46, nr 13 (lipiec 2019): 7088–95. http://dx.doi.org/10.1029/2019gl083629.

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Pautet, P. D., M. J. Taylor, N. P. Chapagain, H. Takahashi, A. F. Medeiros, F. T. São Sabbas i D. C. Fritts. "Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx)". Annales Geophysicae 27, nr 6 (8.06.2009): 2371–81. http://dx.doi.org/10.5194/angeo-27-2371-2009.

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Abstract. From September to November 2005, the NASA Living with a Star program supported the Spread-F Experiment campaign (SpreadFEx) in Brazil to study the effects of convectively generated gravity waves on the ionosphere and their role in seeding Rayleigh-Taylor instabilities, and associated equatorial plasma bubbles. Several US and Brazilian institutes deployed a broad range of instruments (all-sky imagers, digisondes, photometers, meteor/VHF radars, GPS receivers) covering a large area of Brazil. The campaign was divided in two observational phases centered on the September and October new moon periods. During these periods, an Utah State University (USU) all-sky CCD imager operated at São João d'Aliança (14.8° S, 47.6° W), near Brasilia, and a Brazilian all-sky CCD imager located at Cariri (7.4° S, 36° W), observed simultaneously the evolution of the ionospheric bubbles in the OI (630 nm) emission and the mesospheric gravity wave field. The two sites had approximately the same magnetic latitude (9–10° S) but were separated in longitude by ~1500 km. Plasma bubbles were observed on every clear night (17 from Brasilia and 19 from Cariri, with 8 coincident nights). These joint datasets provided important information for characterizing the ionospheric depletions during the campaign and to perform a novel longitudinal investigation of their variability. Measurements of the drift velocities at both sites are in good agreement with previous studies, however, the overlapping fields of view revealed significant differences in the occurrence and structure of the plasma bubbles, providing new evidence for localized generation. This paper summarizes the observed bubble characteristics important for related investigations of their seeding mechanisms associated with gravity wave activity.

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Paznukhov, V. V., C. S. Carrano, P. H. Doherty, K. M. Groves, R. G. Caton, C. E. Valladares, G. K. Seemala i in. "Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum". Annales Geophysicae 30, nr 4 (16.04.2012): 675–82. http://dx.doi.org/10.5194/angeo-30-675-2012.

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Abstract. We report on the longitudinal, local time and seasonal occurrence of equatorial plasma bubbles (EPBs) and L band (GPS) scintillations over equatorial Africa. The measurements were made in 2010, as a first step toward establishing the climatology of ionospheric irregularities over Africa. The scintillation intensity is obtained by measuring the standard deviation of normalized GPS signal power. The EPBs are detected using an automated technique, where spectral analysis is used to extract and identify EPB events from the GPS TEC measurements. Overall, the observed seasonal climatology of the EPBs as well as GPS scintillations in equatorial Africa is adequately explained by geometric arguments, i.e., by the alignment of the solar terminator and local geomagnetic field, or STBA hypothesis (Tsunoda, 1985, 2010a). While plasma bubbles and scintillations are primarily observed during equinoctial periods, there are longitudinal differences in their seasonal occurrence statistics. The Atlantic sector has the most intense, longest lasting, and highest scintillation occurrence rate in-season. There is also a pronounced increase in the EPB occurrence rate during the June solstice moving west to east. In Africa, the seasonal occurrence shifts towards boreal summer solstice, with fewer occurrences and shorter durations in equinox seasons. Our results also suggest that the occurrence of plasma bubbles and GPS scintillations over Africa are well correlated, with scintillation intensity depending on depletion depth. A question remains about the possible physical mechanisms responsible for the difference in the occurrence phenomenology of EPBs and GPS scintillations between different regions in equatorial Africa.

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Blanch, Estefania, David Altadill, Jose Miguel Juan, Adriano Camps, José Barbosa, Guillermo González-Casado, Jaume Riba, Jaume Sanz, Gregori Vazquez i Raúl Orús-Pérez. "Improved characterization and modeling of equatorial plasma depletions". Journal of Space Weather and Space Climate 8 (2018): A38. http://dx.doi.org/10.1051/swsc/2018026.

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This manuscript presents a method to identify the occurrence of Equatorial Plasma Bubbles (EPBs) with data gathered from receivers of Global Navigation Satellite System (GNSS). This method adapts a previously existing technique to detect Medium Scale Travelling Ionospheric Disturbances (MSTIDs), which focus on the 2nd time derivatives of total electron content estimated from GNSS signals (2DTEC). Results from this tool made possible to develop a comprehensive analysis of the characteristics of EPBs. Analyses of the probability of occurrence, effective time duration, depth of the depletion and total disturbance of the EPBs show their dependence on local time and season of the year at global scale within the latitude belt from 35°N to 35°S for the descending phase of solar cycle 23 and ascending phase of solar cycle 24, 2002–2014. These results made possible to build an EPBs model, bounded with the Solar Flux index, that simulates the probability of the number of EPBs and their characteristics expected for a representative day at given season and local time (LT). The model results provided insight into different important aspects: the maximum occurrence of bubbles take place near the equatorial anomaly crests, asymmetry between hemispheres and preferred longitudes with enhanced EPBs activity. Model output comparisons with independent observations confirmed its soundness.

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Takahashi, H., M. J. Taylor, P. D. Pautet, A. F. Medeiros, D. Gobbi, C. M. Wrasse, J. Fechine i in. "Simultaneous observation of ionospheric plasma bubbles and mesospheric gravity waves during the SpreadFEx Campaign". Annales Geophysicae 27, nr 4 (2.04.2009): 1477–87. http://dx.doi.org/10.5194/angeo-27-1477-2009.

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Abstract. During the Spread F Experiment campaign, under NASA Living with a Star (LWS) program, carried out in the South American Magnetic Equator region from 22 September to 8 November 2005, two airglow CCD imagers, located at Cariri (7.4° S, 36.5° W, geomag. 11° S) and near Brasilia (14.8° S, 47.6° W, geomag. 10° S) were operated simultaneously and measured the equatorial ionospheric bubbles and their time evolution by monitoring the airglow OI 6300 intensity depletions. Simultaneous observation of the mesospheric OH wave structures made it possible to investigate the relationship between the bubble formation in the ionosphere and the gravity wave activity at around 90 km. On the evening of 30 September 2005, comb-like OI 6300 depletions with a distance of ~130 km between the adjacent ones were observed. During the same period, a mesospheric gravity wave with a horizontal wavelength of ~130 km was observed. From the 17 nights of observation during the campaign period, there was a good correlation between the OI 6300 depletion distances and the gravity wave horizontal wavelengths in the mesosphere with a statistically significant level, suggesting a direct contribution of the mesospheric gravity wave to plasma bubble seeding in the equatorial ionosphere.

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Sidorova, L. N. "Equatorial Plasma Bubbles: The Influence of the Meridional Thermospheric Winds". Geomagnetism and Aeronomy 62, nr 3 (czerwiec 2022): 246–54. http://dx.doi.org/10.1134/s0016793222030161.

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Sidorova, L. N. "Equatorial Plasma Bubbles: Variability of the Latitudinal Distribution with Altitude". Geomagnetism and Aeronomy 61, nr 4 (lipiec 2021): 508–19. http://dx.doi.org/10.1134/s0016793221040162.

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Taori, A., J. J. Makela i M. Taylor. "Mesospheric wave signatures and equatorial plasma bubbles: A case study". Journal of Geophysical Research: Space Physics 115, A6 (czerwiec 2010): n/a. http://dx.doi.org/10.1029/2009ja015088.

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Chen, Pei-Ren. "Equatorial plasma bubbles/range spread F irregularities and the QBO". Geophysical Research Letters 20, nr 21 (5.11.1993): 2351–54. http://dx.doi.org/10.1029/92gl01935.

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Sidorova, L. N., i S. V. Filippov. "Equatorial Plasma Bubbles: Variation of the Longitudinal Distribution with Altitude". Geomagnetism and Aeronomy 60, nr 1 (styczeń 2020): 28–37. http://dx.doi.org/10.1134/s0016793219060100.

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Keskinen, M. J., S. L. Ossakow, Santimay Basu i P. J. Sultan. "Magnetic-flux-tube-integrated evolution of equatorial ionospheric plasma bubbles". Journal of Geophysical Research: Space Physics 103, A3 (1.03.1998): 3957–67. http://dx.doi.org/10.1029/97ja02192.

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Retterer, J. M., i L. C. Gentile. "Modeling the climatology of equatorial plasma bubbles observed by DMSP". Radio Science 44, nr 1 (luty 2009): n/a. http://dx.doi.org/10.1029/2008rs004057.

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