scholarly journals A study of local time and longitudinal variability of the amplitude of the equatorial electrojet observed in POGO satellite data

1999 ◽  
Vol 51 (5) ◽  
pp. 373-381 ◽  
Author(s):  
H. R. Kim ◽  
Scott D. King
Keyword(s):  
Local Time ◽  
Satellite Data ◽  
Equatorial Electrojet ◽  
Longitudinal Variability

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

Universe ◽  
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.

scholarly journals Ozone and temperature decadal solar-cycle responses, and their relation to diurnal variations in the stratosphere, mesosphere, and lower thermosphere, based on measurements from SABER on TIMED

2019 ◽  
Vol 37 (4) ◽  
pp. 471-485 ◽  
Author(s):  
Frank T. Huang ◽  
Hans G. Mayr
Keyword(s):  
Solar Cycle ◽  
Local Time ◽  
Satellite Data ◽  
Diurnal Cycle ◽  
Lower Thermosphere ◽  
Diurnal Variations ◽  
Local Times ◽  
Data Set ◽  
Orbital Drift ◽  
Almost All

Abstract. There is evidence that the ozone and temperature responses to the solar cycle of ∼11 years depend on the local times of measurements. Here we present relevant results based on SABER data over a full diurnal cycle, which were not previously available. In this area, almost all satellite data used are measured at only one or two fixed local times, which can differ among various satellites. Consequently, estimates of responses can be different depending on the specific data set. Furthermore, over years, due to orbital drift, the local times of the measurements of some satellites have also drifted. In contrast, SABER makes measurements at various local times, providing the opportunity to estimate diurnal variations over 24 h. We can then also estimate responses to the solar cycle over both a diurnal cycle and at the fixed local times of specific satellite data for comparison. Responses derived in this study, based on zonal means of SABER measurements, agree favorably with previous studies based on data from the HALOE instrument, which only measured data at sunrise and sunset, thereby supporting the analysis of both studies. We find that for ozone above ∼40 km, zonal means reflecting specific local times (e.g., 6, 12, 18, 24 LST – local solar time) lead to different values of responses, and to different responses based on zonal means that are also averages over the 24 h local time period, as in 3-D models. For temperature, the effects of diurnal variations on the responses are not negligible even at ∼30 km and above. We also considered the consequences of local time variations due to orbital drifts of certain operational satellites, and, for both ozone and temperature, their effects can be significant above ∼30 km. Previous studies based on other satellite data do not describe the treatment, if any, of local times. Some studies also analyzed data merged from different sources, with measurements made at different local times. Generally, the results of these studies do not agree very well among themselves. Although responses are a function of diurnal variations, this is not to say that they are the major reason for the differences, as there are likely other data-related issues. The effects due to satellite orbital drift may explain some unexpected variations in the responses, especially above 40 km.

scholarly journals Longitudinal variation of equatorial electrojet and the occurrence of its counter electrojet

2017 ◽  
Vol 35 (3) ◽  
pp. 535-545 ◽  
Author(s):  
A. Babatunde Rabiu ◽  
Olanike Olufunmilayo Folarin ◽  
Teiji Uozumi ◽  
Nurul Shazana Abdul Hamid ◽  
Akimasa Yoshikawa
Keyword(s):  
Addis Ababa ◽  
Equatorial Electrojet ◽  
Seasonal Distribution ◽  
Horizontal Component ◽  
South American ◽  
The South ◽  
Counter Electrojet ◽  
Western Africa ◽  
Meridional Winds ◽  
Longitudinal Variability

Abstract. We examined the longitudinal variability of the equatorial electrojet (EEJ) and the occurrence of its counter electrojet (CEJ) using the available records of the horizontal component H of the geomagnetic field simultaneously recorded in the year 2009 (mean annual sunspot number Rz  =  3.1) along the magnetic equator in the South American, African, and Philippine sectors. Our results indicate that the EEJ undergoes variability from one longitudinal representative station to another, with the strongest EEJ of about 192.5 nT at the South American axis at Huancayo and a minimum peak of 40.7 nT at Ilorin in western Africa. Obtained longitudinal inequality in the EEJ was explicable in terms of the effects of local winds, dynamics of migratory tides, propagating diurnal tide, and meridional winds. The African stations of Ilorin and Addis Ababa registered the greatest % of CEJ occurrence. Huancayo in South America, with the strongest electrojet strength, was found to have the least occurrence of the CEJ. It is suggested that activities that support strong EEJ inhibits the occurrence of the CEJ. Percentage of occurrence of the CEJ varied with seasons across the longitudes. The order of seasonal variation of morning occurrence does not tally with the evening occurrence order at any station. A semiannual equinoctial maximum in percentage of morning occurrence of the CEJ was obtained at Huancayo and Addis Ababa. Only Addis Ababa recorded equal equinoctial maxima in percentage of evening occurrence of the CEJ. The seasonal distribution of the occurrences of the CEJ at different time regimes implies a seasonal variability of causative mechanisms responsible for the occurrence of the CEJ.

Investigation of S3-2 satellite data for local time variation of energetic electron precipitation

1994 ◽  
Vol 99 (A3) ◽  
pp. 3845 ◽  
Author(s):  
S. Robbe ◽  
W. R. Sheldon ◽  
J. R. Benbrook ◽  
E. A. Bering ◽  
A. L. Vampola
Keyword(s):  
Local Time ◽  
Satellite Data ◽  
Time Variation ◽  
Energetic Electron ◽  
Electron Precipitation

Ground magnetic effects of the equatorial electrojet simulated by the TIE-GCM driven by TIMED satellite data

2014 ◽  
Vol 119 (4) ◽  
pp. 3150-3161 ◽  
Author(s):  
Yosuke Yamazaki ◽  
Arthur D. Richmond ◽  
Astrid Maute ◽  
Qian Wu ◽  
David A. Ortland ◽  
...  
Keyword(s):  
Satellite Data ◽  
Equatorial Electrojet ◽  
Magnetic Effects ◽  
Ground Magnetic

Local time and longitude dependence of the equatorial electrojet magnetic effects

2003 ◽  
Vol 65 (14-15) ◽  
pp. 1265-1282 ◽  
Author(s):  
V Doumouya ◽  
Y Cohen ◽  
B.R Arora ◽  
K Yumoto
Keyword(s):  
Local Time ◽  
Equatorial Electrojet ◽  
Magnetic Effects

scholarly journals Ozone and temperature decadal solar-cycle responses, and their relation to diurnal variations in the stratosphere, mesosphere, and lower thermosphere, based on measurements from SABER on TIMED

2019 ◽  
Author(s):  
Frank T. Huang ◽  
Hans Mayr
Keyword(s):  
Solar Cycle ◽  
Local Time ◽  
Satellite Data ◽  
Diurnal Cycle ◽  
Lower Thermosphere ◽  
3D Models ◽  
Diurnal Variations ◽  
Local Times ◽  
Data Set ◽  
Orbital Drift

Abstract. There is evidence that the ozone and temperature responses to the solar cycle of ~ 11 years depend on the local times of measurements. Here we present relevant results based on SABER data over a full diurnal cycle, not available previously. In this area, almost all satellite data used are made at only one or two fixed local times, which can be different among various satellites. Consequently, estimates of responses can be different depending on the specific data set. Also, over years, due to orbital drift, the local times of measurements of some satellites have also drifted. In contrast, SABER makes measurements at various local times, providing the opportunity to estimate diurnal variations over 24 hrs. We can then also estimate responses to the solar cycle over both a diurnal cycle and at the fixed local times of specific satellite data for comparison. Our results of responses, based on zonal means of SABER measurements, agree favorably with previous studies based on data from the HALOE instrument, which measured data only at sunrise and sunset, thereby supporting the analysis of both studies. We find that for ozone above ~ 40 km, zonal means reflecting specific local times (e.g., 6, 12, 18, 24 hrs) lead to different values of responses, and to different responses based on zonal means that are also averages over the 24 hours of local time, as in 3D models. For temperature, effects of diurnal variations on the responses are not negligible even at ~ 30 km and above. We also have considered the consequences of local-time variations due to orbital drifts of certain operational satellites, and for both ozone and temperature, their effects can be significant above ~ 30 km. Previous studies based other satellite data do not describe their treatment, if any, of local times. Some studies also analyzed data merged from different sources, with measurements made at different local times. Generally, the results of these studies do not agree so well among themselves. Although responses are a function of diurnal variations, this is not to say that they are the major reason for the differences, as there are likely other data-related issues. The effects due to satellite orbital drift may explain some unexpected variations in the responses, especially above 40 km.

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