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Abstract The effect of eastward zonal wind speed (EZWS) on vertical drift velocity (E × Bdrift) that mainly controls the equatorial ionospheric irregularities has been explained theoretically and through numerical models. However, its effect on the seasonal and longitudinal variations ofE × Band the accompanying irregularities has not yet been investigated experimentally due to lack ofF‐layer wind speed measurements. Observations of EZWS from GOCE and ion density andE × Bfrom C/NOFS satellites for years 2011 and 2012 during quite times are used in this study. Monthly and longitudinal variations of the irregularity occurrence,E × B, and EZWS show similar patterns. We find that at most 50.85% of longitudinal variations ofE × Bcan be explained by the longitudinal variability of EZWS only. When the EZWS exceeds 150 m/s, the longitudinal variation of EZWS, geomagnetic field strength, and Pedersen conductivity explain 56.40–69.20% of the longitudinal variation ofE × B. In Atlantic, Africa, and Indian sectors, from 42.63% to 79.80% of the monthly variations of theE × Bcan be explained by the monthly variations of EZWS only. It is found also that EZWS andE × Bmay be linearly correlated during fall equinox and December solstice. The peak occurrence of irregularity in the Atlantic sector during November and December is due to the combined effect of large wind speed, solar terminator‐geomagnetic field alignment, and small geomagnetic field strength and Pedersen conductivity. Moreover, during June solstices, small EZWS corresponds to vertically downwardE × B, which suggests that other factors dominate theE × Bdrift rather than the EZWS during these periods.
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A height-dependent climatological model of the equatorial ionospheric zonal plasma drifts (EZDrifts): Description and application to an analysis of the longitudinal variations of the zonal drifts
We introduce the implementation of a global climatological model of the equatorial ionospheric F-region zonal drifts (EZDrifts) that is made available to the public. The model uses the analytic description of the zonal plasma drifts presented by Haerendel et al. (1992) [ J Geophys Res 97(A2) : 1209–1223] and is driven by climatological models of the ionosphere and thermosphere under a realistic geomagnetic field configuration. EZDrifts is an expansion of the model of the zonal drifts first presented by Shidler & Rodrigues (2021) [ Prog Earth Planet Sci 8 : 26] which was only valid for the Jicamarca longitude sector and two specific solar flux conditions. EZDrifts now uses vertical equatorial plasma drifts from Scherliess & Fejer (1999) [ J Geophys Res 104(A4) : 6829–6842] model which allows it to provide zonal drifts for any day of the year, longitude, and solar flux condition. We show that the model can reproduce the main results of the Shidler & Rodrigues (2021) [ Prog Earth Planet Sci 8 : 26] model for the Peruvian sector. We also illustrate an application of EZDrifts by presenting and discussing longitudinal variabilities produced by the model. We show that the model predicts longitudinal variations in the reversal times of the drifts that are in good agreement with observations made by C/NOFS. EZDrifts also predicts longitudinal variations in the magnitude of the drifts that can be identified in the June solstice observations made by C/NOFS. We also point out data-model differences observed during Equinox and December solstice. Finally, we explain that the longitudinal variations in the zonal plasma drifts are caused by longitudinal variations in the latitude of the magnetic equator and, consequently, in the wind dynamo contributing to the resulting drifts. EZDrifts is distributed to the community through a public repository and can be used in applications requiring an estimate of the overall behavior of the equatorial zonal drifts.
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- Award ID(s):
- 1916055
- PAR ID:
- 10435278
- Date Published:
- Journal Name:
- Journal of Space Weather and Space Climate
- Volume:
- 13
- ISSN:
- 2115-7251
- Page Range / eLocation ID:
- 8
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1051/swsc/2023006
