Bibliography
|
Notice:
|
Found 14 entries in the Bibliography.
Showing entries from 1 through 14
| 2020 |
|
A method to derive global O/N2 ratios from SSUSI/DMSP based on Re-AURIC algorithm Global thermospheric O/N2 column density ratios are obtained using the SSUSI/DMSP far-ultraviolet (FUV) dayglow data and the Re-AURIC simulation results. The Re-AURIC is derived from the AURIC algorithm after some old modules are updated. The calculation processes of O/N2 ratio are then established using the simulations of Re-AURIC to calibrate the ratios of the OI 135.6\ nm emission and N2 LBHS emission from SSUSI observations. The standard deviation (1σ) and correlation coefficient are 0.045 and 0.769 compared with the O/N2 ratios provided by the SSUSI EDR data. The statistical errors between the calculated ratios and the EDR references are generally less than 0.2 with 96.40\% at 2σ (95.44\%) and less than 0.1 with 60.51\% at about 1σ (68.26\%). Two global O/N2 ratio maps are obtained using this method to study its variations when the magnetic storm occurs. The significant O/N2 depletion can be seen in one O/N2 ratio map whose Kp index is 6. Also, the depletion is not uniform at different longitudes and the scales extend from high latitude to low latitude during magnetic storm. This proposed method provides us with a simple and useful tool to obtain the global O/N2 distribution and even the future modeling from the observations on satellites. Ding, GuangXing; Chen, Bo; Zhang, Xiaoxin; He, Fei; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 03/2020 YEAR: 2020 DOI: 10.1016/j.jastp.2020.105196 |
| 2015 |
|
Ionospheric effects of solar flares and their associated particle ejections in March 2012 Flares of March 4\textendash9, 2012 were accompanied by an intensification of solar electromagnetic and corpuscular radiations and five coronal mass ejections. Bursts of X-rays and increased solar cosmic ray fluxes caused an increase in ionospheric absorption manifesting itself in data from vertical sounding stations as enhancements of the lowest frequency of reflections up to 4\textendash6\ MHz at the daytime and as the disappearance of reflections in the ionograms of high latitude stations. Interplanetary coronal mass ejections (ICME) generated March 7\textendash8 moderate and March 8\textendash11 intense magnetic storms accompanied by ionospheric disturbances. At the peaks of both magnetic storms there were abrupt afternoon\textendashevening decreases in the ionospheric F2-layer critical frequency (foF2). During the March 7\textendash8 storm, the foF2 decrease concurred with the reversal of the interplanetary magnetic field azimuthal component (IMF By) which initiated restructuring of magnetospheric convection; during the March 8\textendash11 storm, with the abrupt weakening of the interplanetary magnetic field southward component (IMF Bz) which triggered a substorm. Zolotukhina, N.; Polekh, N.; Kurkin, V.; Romanova, E.; Published by: Advances in Space Research Published on: 06/2015 YEAR: 2015 DOI: 10.1016/j.asr.2015.03.004 Ionospheric disturbance; Magnetic storm; X-ray flare; Solar cosmic rays; Coronal mass ejection |
| 2013 |
|
Auroral Precipitation Model and its applications to ionospheric and magnetospheric studies Based on statistical treatment of DMSP F6 and F7 spacecraft observations, an interactive Auroral Precipitation Model (APM) parameterized by magnetic activity has been created (available athttp://apm.pgia.ru/). For a given level of magnetic activity the model yields a global distribution of electron precipitation and planetary patterns of both average electron energy and electron energy flux in different precipitation zones. Outputs of the model were used to determine the basic variables of the magnetosphere, such as boundary location and the area of the polar cap, magnetic flux transferred from the dayside magnetosphere into the tail, global precipitation power realized by different types of precipitation and others. The model predicts an increase in the polar cap area from about 6.3\texttimes106\ km2 to 2.0\texttimes107\ km2, in the magnetic flux from 390\ MWb to 1200\ MWb, and in the global precipitation power from 3.4\ GW to 188.0\ GW, when the magnetic activity changes from silence (null AL and Dst) to significant disturbance (AL=-1000\ nT, Dst=-200\ nT). The use of dayside auroral observations as an input for APM provides an opportunity for continuous monitoring of magnetospheric conditions. Two time intervals on Dec. 27, 2000, and Dec. 12, 2004, of dayside auroral observations with the meridian scanning photometer at Barentsburg (Spitsbergen) were selected to demonstrate derivation of magnetospheric variables with APM. It is shown that the values of the AL index derived from optical observation appear in a reasonable agreement with those published by WDC. Vorobjev, V.G.; Yagodkina, O.I.; Katkalov, Yu.V.; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 09/2013 YEAR: 2013 DOI: 10.1016/j.jastp.2013.05.007 AL and Dst indexes; Auroral Precipitation Model; Dayside aurorae; Magnetic storm |
|
Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere\textendashIonosphere\textendashMesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) Volume Emission Rates (VER) derived from the TIMED/SABER 4.3\ μm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3\ μm VER is most sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3\ μm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known nighttime quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part I of this series gives a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3\ μm limb emission measurements. In this paper, Part II of the series, the development of the E-region electron density storm-time correction factor is described. The STORM-E storm-time correction factor is fit to a single geomagnetic index. There are four versions of the STORM-E model, which are currently independent of magnetic local time. Each version is fit to one of the following indices: HP, AE, Ap, or Dst. High-latitude Incoherent Scatter Radar (ISR) E-region electron density measurements are compared to STORM-E predictions for various geomagnetic storm periods during solar cycle 23. These comparisons show that STORM-E significantly improves the prediction of E-region electron density enhancements due to auroral particle precipitation, in comparison to the nominal IRI model or to the quiet-time baseline electron density concentrations measured by ISR. The STORM-E/ISR comparisons indicate that the STORM-E fits to the Ap-, AE-, and HP-indices are comparable in both absolute accuracy and relative dynamical response. Contrarily, the Dst-index does not appear to be a suitable input driver to parameterize the E-region electron density response to geomagnetic activity. Mertens, Christopher; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin; Russell, James; Published by: Advances in Space Research Published on: 02/2013 YEAR: 2013 DOI: 10.1016/j.asr.2012.09.014 AURORA; Auroral particle precipitation; E-region; Infrared remote sensing; Ionosphere; Magnetic storm; TIMED |
|
Empirical STORM-E model: I. Theoretical and observational basis Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3μm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3μm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3μm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3μm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented. Mertens, Christopher; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin; Russell, James; Published by: Advances in Space Research Published on: YEAR: 2013 DOI: https://doi.org/10.1016/j.asr.2012.09.009 Auroral particle precipitation; Ionosphere; E-region; Magnetic storm; Infrared remote sensing; SABER |
| 2012 |
|
Research on Retrieving Thermospheric O/N2 from FUV Remote Sensing Magnetic storms usually cause significant departures of thermospheric O and N2\ from their normal values. To study the effects on thermospheric neutral species caused by magnetic storms, a method to retrieve thermospheric O/N2\ based on the data obtained from global ultraviolet imager on board TIMED is presented. With the help of AURIC, the normalizations of observing angles and SZAs were preformed to the measurements and a relationship between 135.6/LBHs and O/N2\ was established. Finally, applying the proposed method to retrieve O/N2\ during a magnetic period(29, September\textemdash4, October, 2002), it was shown that magnetic storms could induce significant O/N2\ depletion, extending from the polar regions towards the equator. Peng, S.; Tang, Y.; Wang, J.; Zheng, X.; Published by: Spectroscopy and Spectral Analysis Published on: 05/2012 YEAR: 2012 DOI: 10.3964/j.issn.1000-0593(2012)05-1296-05 |
| 2010 |
|
Comparison of the Hill–Siscoe polar cap potential theory with the Weimer and AMIE models The magnetic storm on November 2004 was characterized by a high solar wind pressure and thus offers a unique opportunity to test the Hill–Siscoe formula (H–S) for the polar cap potential (PCP). To estimate the polar cap potential, we use the Weimer Statistical Convection Model (WCM), and the Assimilative Mapping of Ionospheric Electrodynamics Model (AMIE), based on ingestion of a number of data sets. H–S is in excellent agreement with WCM, and with AMIE during times when DMSP is used in the latter. The implication is that the AMIE conductivity model yields conductivities that are too high by a factor of 2–3. Both H–S and WCM display saturation effects, although WCM is more severe. The two methods track well until an IEF of about 20mV/m occurs, where H–S continues to increase while WCM levels off. Even at high electric field values, the pressure increases the denominator of the H–S formula by 60\%, keeping the potential lower than its saturation value. There are several H–S points above 250kV, even up to 400kV, that are not found in WCM and occur right after a rapid transition from Bz north to south. For Bz north, we find evidence for a saturation effect on the PCP at large IEF, little effect as a function of solar wind velocity, and an increase of the PCP with increasing pressure. This seems to rule out viscous interaction but may involve geometric changes in the high-altitude polar cusp that affect recombination there for Bz north. Kelley, Michael; Crowley, Geoffrey; Weimer, Daniel; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2010 DOI: https://doi.org/10.1016/j.jastp.2009.02.011 Magnetic storm; Polar cap potential; Hill–Siscoe formula; solar wind |
| 2009 |
|
This paper presents an investigation of geomagnetic storm effects in the equatorial and middle-low latitude F-region in the West Pacific sector during the intense geomagnetic storm on 13\textendash17 April, 2006. The event, preceded by a minor storm, started at 2130 UT on April 13 while interplanetary magnetic field (IMF)\ Bzcomponent was ready to turn southward. From 14\textendash17 the ionosphere was characterized by a large scale enhancement in critical frequency, foF2 (4\~6\ MHz) and total electron content (TEC) (\~30TECU, 1TECU=1\texttimes1016el/m2) followed by a long-duration negative phase observed through the simultaneous ionospheric sounding measurements from 14 stations and GPS network along the meridian 120\textdegreeE. A periodic wave structure, known as traveling ionospheric disturbances (TIDs) was observed in the morning sector during the initial phase of the storm which should be associated with the impulsive magnetospheric energy injection to the auroral. In the afternoon and nighttime, the positive phase should be caused by the combination of equatorward winds and disturbed electric fields verified through the equatorial F-layer peak height variation and modeled upward drift of Fejer and Scherliess [1997. Empirical models of storm time equatorial electric fields. Journal of Geophysical Research 102, 24,047\textendash24,056]. It is shown that the large positive storm effect was more pronounced in the Southern Hemisphere during the morning-noon sector on April 15 and negative phase reached to lower magnetic latitudes in the Northern Hemisphere which may be related to the asymmetry of the thermospheric condition during the storm. Zhao, Biqiang; Wan, Weixing; Liu, Libo; Igarashi, K.; Yumoto, K.; Ning, Baiqi; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: Jan-01-2009 YEAR: 2009 DOI: 10.1016/j.jastp.2008.09.029 |
|
Ionospheric response to the geomagnetic storm on 13–17 April 2006 in the West Pacific region This paper presents an investigation of geomagnetic storm effects in the equatorial and middle-low latitude F-region in the West Pacific sector during the intense geomagnetic storm on 13–17 April, 2006. The event, preceded by a minor storm, started at 2130 UT on April 13 while interplanetary magnetic field (IMF) Bz component was ready to turn southward. From 14–17 the ionosphere was characterized by a large scale enhancement in critical frequency, foF2 (4∼6MHz) and total electron content (TEC) (∼30TECU, 1TECU=1×1016el/m2) followed by a long-duration negative phase observed through the simultaneous ionospheric sounding measurements from 14 stations and GPS network along the meridian 120°E. A periodic wave structure, known as traveling ionospheric disturbances (TIDs) was observed in the morning sector during the initial phase of the storm which should be associated with the impulsive magnetospheric energy injection to the auroral. In the afternoon and nighttime, the positive phase should be caused by the combination of equatorward winds and disturbed electric fields verified through the equatorial F-layer peak height variation and modeled upward drift of Fejer and Scherliess [1997. Empirical models of storm time equatorial electric fields. Journal of Geophysical Research 102, 24,047–24,056]. It is shown that the large positive storm effect was more pronounced in the Southern Hemisphere during the morning-noon sector on April 15 and negative phase reached to lower magnetic latitudes in the Northern Hemisphere which may be related to the asymmetry of the thermospheric condition during the storm. Zhao, Biqiang; Wan, Weixing; Liu, Libo; Igarashi, K.; Yumoto, K.; Ning, Baiqi; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: YEAR: 2009 DOI: https://doi.org/10.1016/j.jastp.2008.09.029 |
| 2008 |
|
Ionosphere disturbances observed throughout Southeast Asia of the superstorm of 20--22 November 2003 Ionospheric disturbances in the Southeast Asian region during the super magnetic storm of 20–22 November 2003 were investigated through an ionosonde chain and a GPS network assisted by the space-borne instruments. At early stage of the storm in the postsunset sector, large enhancements in the critical frequency of F2 layer and total electron content were observed at northern crest region of the equatorial ionization anomaly (EIA), which might be produced by both the storm meridional wind superimposed with traveling atmospheric disturbances and prompt penetration electric field (PPE). During the main phase of the storm when interplanetary magnetic field started a 12-h southward turning, equatorial ionosphere was elevated to a very high level which should be most probably caused by a long-duration PPE event. Meanwhile, at mid-low latitudes, ionosphere witnessed an initial simultaneous decrease then followed by drastic increases, which is very different from the past observations in this region (Reddy and Nishida, 1992). Combined analysis of the data from the ionosonde and other space-based measurement shows that for the present case the penetration efficiency of the interplanetary electric field (IEF) to the equatorial ionosphere was larger at night than in the daytime, which agrees with the results of Fejer et al. (2007) showing the ratios of PPE and IEF changes were highly variable with the local time. During the recovery phase, EIA was severely inhibited owing to a wind convergence and possibly because of the westward disturbance dynamo electric field. Zhao, B; Wan, W; Tschu, K; Igarashi, K; Kikuchi, T; Nozaki, K; Watari, S; Li, G; Paxton, LJ; Liu, L; , others; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2008 DOI: 10.1029/2008JA013054 |
| 2005 |
|
Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations Undulations on the equatorward edge of the diffuse proton aurora have been identified by using TIMED/GUVI auroral images in the far ultraviolet wavelengths. While undulations have been previously reported on the duskside (Lui et al., 1982), GUVI observations show the undulation also occurs in the dayside, nightside, and morningside. The GUVI proton auroral images provide direct optical evidence that the undulations occur in the proton aurora. It is also the first detection of the undulation in the dayside indicating strong convection shear in the region. The undulation in the nightside, a wavy structure in the whole diffuse proton aurora, is significantly different from those in the duskside and dayside. While almost all of the undulation events are observed during magnetic storms (Dst \< -60 nT), one exceptional case shows undulation in the dayside with Dst = 30 nT. However, the case is associated with a large solar wind speed (650 km/s) and a high dynamic pressure (14 nPa). Coincident DMSP SSIES observations suggest that both large ion drift velocity (\>1000 m/s) and strong velocity shear (\>0.1 s-1) within the diffuse aurora oval are necessary conditions for the undulation to occur. The SSIES data also indicate the areas with large ion drift velocity and shear move to higher latitudes in the MLT sectors toward midnight. This may explain why the undulation is rarely detected in the nightside. Zhang, Y.; Paxton, L.; Morrison, D.; T. Y. Lui, A.; Kil, H.; Wolven, B.; Meng, C.-I.; Christensen, A.; Published by: Journal of Geophysical Research Published on: 09/2005 YEAR: 2005 DOI: 10.1029/2004JA010668 auroral undulation; K-H instability; Magnetic storm; plasma convection |
|
Nightside detached auroras due to precipitating protons/ions during intense magnetic storms Nightside detached auroras (NDA) during intense magnetic storms are studied by using FUV image data from Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED)/Global Ultraviolet Imager (GUVI), Imager for Magnetopause-to-Aurora Global Exploration (IMAGE)/FUV, and particle data from DMSP/SSJ/4 instruments. We found that NDA are caused by proton/ion precipitation only. Thin arc-shaped NDA are very likely due to soft (\<1 keV) proton/ion precipitation. Thick or patch-shaped NDA are caused by energetic (\~10 keV) proton/ion precipitation. All the cases indicate that the NDA were observed when\ Dst\ was less -130 nT. More specifically, the NDA occurred during recovery or the lowest\ Dst\ period for each intense storm. The magnetic latitudes of the NDA are between 45\textdegree and 55\textdegree (Lshell: 2.0\textendash3.0). We found that the latitude location of the NDA is quasi-linearly correlated with\ Dst. The magnetic local time (MLT) of the NDA ranges from 1930 to 0300. All the facts indicate that the source of the NDA is the trapped protons/ions in the ring current. Precipitation of the trapped protons/ions is caused by an interaction between the perpendicularly heated ring current particles and the cold/dense plasma at the plasmapause. Zhang, Y; Paxton, LJ; Morrison, D; Wolven, B; Kil, H; Wing, S; Published by: Journal of Geophysical Research: Space Physics (1978\textendash2012) Published on: YEAR: 2005 DOI: 10.1029/2004JA010498 detached aurora; proton precipitation; ring current; Magnetic storm |
|
The GPS-derived total electron content (TEC), ion drift measurements from the ROCSAT-1 spacecraft at around 600 km altitude, and far-ultraviolet airglow measured by the Global Ultraviolet Imager (GUVI) carried on board the NASA TIMED satellite are utilized for studying large disturbances of the low-latitude ionosphere during the October–November 2003 superstorm period. Two chains of GPS receivers, one in the American sector (∼70°W) and the other in the Asian/Australian sector (∼120°E), are used to simultaneously observe the daytime equatorial ionization anomaly (EIA) during the entire storm period. It is found from the GPS-TEC measurements that the EIA expanded to very high latitudes with large increases of TEC right after the storm started. The large expansion of the EIA was associated with strong upward E × B drifts measured from the Ionospheric Plasma and Electrodynamics Instrument (IPEI) on board the ROCSAT-1, providing evidence of a penetration electric field and a strong plasma fountain effect. Suppression of the EIA was observed during the storm recovery, associated with downward E × B drifts that were observed by the ROCSAT-1. Significant negative storm effects in the southern hemisphere were also observed in the GPS-TEC during the first day of the recovery phase. The areas of negative storm effects are in good agreement with reductions in the [O]/[N2] density ratio inferred from the ratio of OI (135.6 nm) to LBH emissions measured from GUVI. An enhancement of the EIA was observed on the day, 1 November, that the storm was about to fully recover. Lin, C.; Richmond, A.; . Y. Liu, J; Yeh, H.; Paxton, L.; Lu, G.; Tsai, H.; Su, S.-Y.; Published by: Journal of Geophysical Research: Space Physics Published on: YEAR: 2005 DOI: https://doi.org/10.1029/2004JA010900 |
| 2004 |
|
O/N 2 changes during 1--4 October 2002 storms: IMAGE SI-13 and TIMED/GUVI observations Thermospheric O/N2 column density ratios referenced at a N2 column density of 1017 cm-2 are obtained using the IMAGE SI-13 and TIMED/GUVI far-ultraviolet (FUV) dayglow data, AURIC simulation results, and MSIS86 model. Each of the magnetic storms occurring during a 4-day period (1\textendash4 October 2002) caused significant O/N2 depletion that was detected by both of the IMAGE SI-13 and GUVI instruments. The depletion extended down to latitudes of 10\textdegree and -5\textdegree in the Northern and Southern Hemispheres, respectively. Simultaneous measurements show an excellent agreement between the SI-13 and GUVI O/N2 on both global and local scales. The IMAGE SI-13 O/N2 data provide direct optical evidence that the O/N2 depletion corotates with the Earth. The GUVI O/N2 indicate the depletion in both of the hemispheres is not symmetric owing to the seasonal effect and differences in heating and convection induced winds. Both the IMAGE SI-13 and GUVI O/N2 maps also provide a good opportunity for future modeling efforts. Zhang, Y.; Paxton, L.; Morrison, D.; Wolven, B.; Kil, H.; Meng, C.-I.; Mende, S.; Immel, T.; Published by: Journal of Geophysical Research Published on: 10/2004 YEAR: 2004 DOI: 10.1029/2004JA010441 |
1