TY - JOUR
T1 - Effects of Electric Field and Neutral Wind on the Asymmetry of Equatorial Ionization Anomaly
AU - Khadka, Sovit M.
AU - Valladares, Cesar E.
AU - Sheehan, Robert
AU - Gerrard, Andrew
N1 - Funding Information:
We would like to thank Director Patricia H. Doherty and Research Scientist Rezy Pradipta of the Institute for Scientific Research, Boston College, for their helpful comments and suggestions on the paper. One of the authors, C. E. Valladares, was partially supported by National Science Foundation (NSF) grants AGS-1552161, AGS-1563025, and AGS-1724133. He was also supported by Office of Naval Research contract N-00014-17-1-2157. Moreover, A. J. Gerrard acknowledges the support of the Geophysical Institute of Peru in maintaining the SOFDI instrument. The LISN is a project led by The University of Texas at Dallas in collaboration with the Geophysical Institute of Peru and other institutions that provide information in benefit of the scientific community. We thank all organizations and persons that are supporting and operating receivers in LISN. The TEC values presented in this publication are stored in the LISN Web page (http://lisn.igp.gob.pe).
Publisher Copyright:
©2018. American Geophysical Union. All Rights Reserved.
PY - 2018/5
Y1 - 2018/5
N2 - The zonal electric field and the meridional neutral wind are the principal drivers that define the geometry and characteristics of the equatorial ionization anomaly (EIA). Here we present the response of the EIA to the variability of the zonal electric field based on measurements of the equatorial electrojet (EEJ) currents and trans-equatorial neutral winds for the generation and control of the asymmetries of the EIA crests of total electron content (TEC) in the western side of the South American continent. The EEJ strengths are determined using a pair of magnetometers. The 24-hr trans-equatorial neutral wind profile is measured using the Second-Generation, Optimized, Fabry-Perot Doppler Imager (SOFDI) located near the geomagnetic equator. The EIA is evaluated using TEC data measured by Global Positioning System (GPS) receivers from the Low-Latitude Ionospheric Sensor Network and several other networks in South America. A physics-based numerical model, Low-Latitude Ionospheric Sector, and SOFDI data are used to study the effects of daytime meridional neutral winds on the consequent evolution of an asymmetry in equatorial TEC anomalies during the afternoon and onward for the first time. We find that the configuration parameters such as strength, shape, amplitude, and latitudinal width of the EIAs are affected by the eastward electric field associated with the EEJ under undisturbed conditions. The asymmetries of EIA crests are observed more frequently during solstices and the September equinox than in the March equinox season. Importantly, this study indicates that the meridional neutral wind plays a very significant role in the development of the EIA asymmetry by transporting the plasma up the field lines. This result suggests that a precise observation of the latitudinal TEC profile at low latitudes can be used to derive the meridional wind.
AB - The zonal electric field and the meridional neutral wind are the principal drivers that define the geometry and characteristics of the equatorial ionization anomaly (EIA). Here we present the response of the EIA to the variability of the zonal electric field based on measurements of the equatorial electrojet (EEJ) currents and trans-equatorial neutral winds for the generation and control of the asymmetries of the EIA crests of total electron content (TEC) in the western side of the South American continent. The EEJ strengths are determined using a pair of magnetometers. The 24-hr trans-equatorial neutral wind profile is measured using the Second-Generation, Optimized, Fabry-Perot Doppler Imager (SOFDI) located near the geomagnetic equator. The EIA is evaluated using TEC data measured by Global Positioning System (GPS) receivers from the Low-Latitude Ionospheric Sensor Network and several other networks in South America. A physics-based numerical model, Low-Latitude Ionospheric Sector, and SOFDI data are used to study the effects of daytime meridional neutral winds on the consequent evolution of an asymmetry in equatorial TEC anomalies during the afternoon and onward for the first time. We find that the configuration parameters such as strength, shape, amplitude, and latitudinal width of the EIAs are affected by the eastward electric field associated with the EEJ under undisturbed conditions. The asymmetries of EIA crests are observed more frequently during solstices and the September equinox than in the March equinox season. Importantly, this study indicates that the meridional neutral wind plays a very significant role in the development of the EIA asymmetry by transporting the plasma up the field lines. This result suggests that a precise observation of the latitudinal TEC profile at low latitudes can be used to derive the meridional wind.
KW - asymmetry on EIAs crests
KW - equatorial ionosphere
KW - ionospheric and thermospheric dynamics
KW - variability of trans-equatorial neutral wind and EEJ
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U2 - 10.1029/2017RS006428
DO - 10.1029/2017RS006428
M3 - Article
AN - SCOPUS:85047660068
SN - 0048-6604
VL - 53
SP - 683
EP - 697
JO - Radio Science
JF - Radio Science
IS - 5
ER -