Empirical model of equatorial electrojet based on ground-based magnetometer data during solar minimum in fall

Abstract. Thermospheric drag is the major non-gravitational perturbation acting on Low Earth Orbit (LEO) satellites at altitudes up to 1000 km. The drag depends on the thermospheric density, which is a key parameter in the planning of LEO missions, e.g. their lifetime, collision avoidance, precise orbit determination, as well as orbit and re-entry prediction. In this study, we present an empirical model, named CH-Therm-2018, of the thermospheric mass density derived from 9-year (from August 2000 to July 2009) accelerometer measurements at altitude from 460 to 310 km, from the CHAllenging Minisatellite Payload (CHAMP) satellite. The CHAMP dataset is divided into two 5-year periods with 1-year overlap (from August 2000 to July 2005 and from August 2004 to July 2009), to represent the high-to-moderate and moderate-to-low solar activity conditions, respectively. The CH-Therm-2018 model is a function of seven key parameters, including the height, solar flux index, season (day of year), magnetic local time, geographic latitude and longitude, as well as magnetic activity represented by the solar wind merging electric field. Predictions of the CH-Therm-2018 model agree well with the CHAMP observations (disagreements within ±20 %), and show different features of thermospheric mass density during solar activities, e.g. the March-September equinox asymmetry and the longitudinal wave pattern. We compare the CH-Therm-2018 predictions with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended (NRLMSISE-00) model. The result shows that CH-Therm-2018 better predicts the density evolution during the last solar minimum (2008-2009) than the NRLMSISE-00 model. By comparing the Satellite Laser Ranging (SLR) observations of the ANDE-Pollux satellites during August-September 2009, we estimate 6-h scaling factors of thermospheric mass density and obtain a median value of 1.27 ± 0.60, indicating that our model, on average, slightly underestimates the thermospheric mass density at solar minimum.

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Data-driven Modeling of the Day-to-Day Variability of the Equatorial Electrojet Using Ground- and Space-based Magnetometer Data

10.1002/essoar.10508648.1 ◽

2021 ◽

Author(s):

Chuan-Ping Lien ◽

Tomoko Matsuo ◽

Astrid Maute ◽

Claudia Stolle

Keyword(s):

Equatorial Electrojet ◽

Data Driven ◽

Magnetometer Data ◽

Data Driven Modeling

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Electron density at F1-layer heights in the last solar minimum (2007–2009)

Solar-Terrestrial Physics ◽

10.12737/stp-41201806 ◽

2018 ◽

Vol 4 (1) ◽

pp. 61-63

Author(s):

Галина Кушнаренко ◽

Galina Kushnarenko ◽

Ольга Яковлева ◽

Olga Yakovleva ◽

Галина Кузнецова ◽

...

Keyword(s):

Characteristic Feature ◽

Electron Density ◽

Empirical Model ◽

Solar Minimum ◽

Ionospheric Physics ◽

Annual Variations ◽

Ionospheric Station ◽

Semi Empirical

We present the results of the analysis of annual variations in daily electron density (N) at heights 140–160 km for the last solar minimum (2007–2009) obtained from digisonde measurements at the ionospheric station Irkutsk (52 °N, 104 °E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermospheric characteristics are calculated to identify regularities of these variations. We have revealed that a characteristic feature of the annual N variations during the solar minimum is a change in their phase by 180° in a relatively narrow altitude interval (170–180 km). These results and the new SEM coefficients are original and important for atmospheric and ionospheric physics.

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Electron density at F1-layer heights in the last solar minimum (2007–2009)

Solnechno-Zemnaya Fizika ◽

10.12737/szf-41201806 ◽

2018 ◽

Vol 4 (1) ◽

pp. 72-75

Author(s):

Галина Кушнаренко ◽

Galina Kushnarenko ◽

Ольга Яковлева ◽

Olga Yakovleva ◽

Галина Кузнецова ◽

...

Keyword(s):

Characteristic Feature ◽

Electron Density ◽

Empirical Model ◽

Solar Minimum ◽

Ionospheric Physics ◽

Annual Variations ◽

Ionospheric Station ◽

Semi Empirical

We present the results of the analysis of annual variations in daily electron density (N) at heights 140–160 km for the last solar minimum (2007–2009) obtained from digisonde measurements at the ionospheric station Irkutsk (52 °N, 104 °E). New coefficients of the known semi-empirical model (SEM) describing the connection between N and thermospheric characteristics are calculated to identify regularities of these variations. We have revealed that a characteristic feature of the annual N variations during the solar minimum is a change in their phase by 180° in a relatively narrow altitude interval (170–180 km). These results and the new SEM coefficients are original and important for atmospheric and ionospheric physics.

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Statistical study of the DP2 enhancement at the dayside dip-equator compared to low latitudes

Annales Geophysicae ◽

10.5194/angeo-29-2225-2011 ◽

2011 ◽

Vol 29 (12) ◽

pp. 2225-2233 ◽

Cited By ~ 6

Author(s):

N. M. Mene ◽

A. T. Kobea ◽

O. K. Obrou ◽

K. Z. Zaka ◽

K. Boka ◽

...

Keyword(s):

Statistical Study ◽

Equatorial Electrojet ◽

Magnetic Effect ◽

Longitudinal Variation ◽

Enhancement Ratio ◽

Polar Cap ◽

Maximum Value ◽

Low Latitudes ◽

Magnetometer Data ◽

Dip Equator

Abstract. It has been largely investigated and established that the DP2 events are enhanced at dip-equator compared to low latitudes. Studies by several authors showed various enhancement ratio values of DP2 amplitude at the dayside dip-equator relative to those at low latitudes. In order to quantify this enhancement ratio, we carried out a statistical study on this phenomenon using the ground magnetometer data at locations ranging from polar cap to dip-equator over the African, Asian and American sector. Our result gave an enhancement ratio which shows a diurnal variation with a maximum value around 12:00 LT and is correlated with the regular variation of the geomagnetic H-component. The longitudinal variation of the enhancement ratio of the DP2 exhibits high values over the American sector compared to Asian sector and African sector which have lowest values. This longitudinal dependence is similar to that of the equatorial electrojet magnetic effect.

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Unusual behavior of quiet-time zonal and vertical plasma drift velocities over Jicamarca during the recent extended solar minimum of 2008

Annales Geophysicae ◽

10.5194/angeo-35-1219-2017 ◽

2017 ◽

Vol 35 (6) ◽

pp. 1219-1229 ◽

Cited By ~ 3

Author(s):

Ângela M. Santos ◽

Mangalathayil A. Abdu ◽

Jonas R. Souza ◽

Inez S. Batista ◽

José H. A. Sobral

Keyword(s):

Zonal Wind ◽

Solar Minimum ◽

Anomalous Behavior ◽

Quiet Time ◽

Unusual Behavior ◽

Plasma Drift ◽

Ionosphere Model ◽

Early Afternoon ◽

Minimum Solar Activity ◽

Magnetometer Data

Abstract. The influence of the recent deep and prolonged solar minimum on the daytime zonal and vertical plasma drift velocities during quiet time is investigated in this work. Analyzing the data obtained from incoherent scatter radar from Jicamarca (11.95° S, 76.87° W) we observe an anomalous behavior of the zonal plasma drift during June 2008 characterized by lower than usual daytime westward drift and its early afternoon reversal to eastward. As a case study the zonal drift observed on 24 June 2008 is modeled using a realistic low-latitude ionosphere simulated by the Sheffield University Plasmasphere-Ionosphere Model-INPE (SUPIM-INPE). The results show that an anomalously low zonal wind was mainly responsible for the observed anomalous behavior in the zonal drift. A comparative study of the vertical plasma drifts obtained from magnetometer data for some periods of maximum (2000–2002) and minimum solar activity (1998, 2008, 2010) phases reveal a considerable decrease on the E-region conductivity and the dynamo electric field during 2008. However, we believe that the contribution of these characteristics to the unusual behavior of the zonal plasma drift is significantly smaller than that arising from the anomalously low zonal wind. The SUPIM-INPE result of the critical frequency of the F layer (foF2) over Jicamarca suggested a lower radiation flux than that predicted by solar irradiance model (SOLAR2000) for June 2008.

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Peak time of equatorial electrojet from different longitude sectors during fall solar minimum

Journal of Physics Conference Series ◽

10.1088/1742-6596/852/1/012015 ◽

2017 ◽

Vol 852 ◽

pp. 012015 ◽

Cited By ~ 2

Author(s):

N S A Hamid ◽

H Liu ◽

T Uozumi ◽

A Yoshikawa ◽

N M N Annadurai

Keyword(s):

Solar Minimum ◽

Equatorial Electrojet ◽

Peak Time

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An empirical model of electron temperature in the Indian topside ionosphere for solar minimum based on SROSS C2 RPA data

Advances in Space Research ◽

10.1016/j.asr.2005.09.016 ◽

2006 ◽

Vol 37 (5) ◽

pp. 897-902 ◽

Cited By ~ 3

Author(s):

P.K. Bhuyan ◽

Minakshi Chamua

Keyword(s):

Electron Temperature ◽

Empirical Model ◽

Solar Minimum ◽

Topside Ionosphere

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Comparison of EEJ Longitudinal Variation from Satellite and Ground Measurements over Different Solar Activity Levels

Universe ◽

10.3390/universe7020023 ◽

2021 ◽

Vol 7 (2) ◽

pp. 23

Author(s):

Wan Nur Izzaty Ismail ◽

Nurul Shazana Abdul Hamid ◽

Mardina Abdullah ◽

Akimasa Yoshikawa ◽

Teiji Uozumi ◽

...

Keyword(s):

Solar Activity ◽

Local Time ◽

Equatorial Electrojet ◽

Activity Level ◽

South American ◽

Activity Levels ◽

Swarm Satellites ◽

Magnetometer Data ◽

Longitudinal Profiles ◽

Longitudinal Variability

The longitudinal variability and local time of equatorial electrojet (EEJ) current using simultaneous data recorded by ground and satellite magnetometers at different levels of solar activity were investigated. In this study, we used data from the CHAMP and Swarm satellites to obtain EEJ current measurements around the globe. The ground data were provided by the MAGDAS, INTERMAGNET, and IIG networks. The ground observation was carried out by analyzing magnetometer data in four different sectors: the South American, Indian, African, and Southeast Asian sectors. These ground data were normalized to the dip equator to overcome the latitudinal variation of each station. The analysis for both measurements was performed using quiet day data. Both the ground and satellite data were categorized according to solar activity level; low, moderate, and high. The results revealed that, during the low solar activity, there was a good agreement between the longitudinal profiles of the EEJ measured using the satellite and the ground data. In general, strong correlations were obtained in most of the sectors where ground data were available between 11 and 13 local time (LT). Besides that, our analysis revealed that the different times of maximum EEJ appearances were seasonally dependent only at certain longitude sectors.

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