SA031-0018
The effect of F-layer zonal neutral wind on the monthly and longitudinal variability of equatorial ionosphere irregularity and drift velocity

Tuesday, 15 December 2020
Poster
Melessew Nigussie, Bahir Dar University, Bahir Dar, Ethiopia, Mark B. Moldwin, University of Michigan Ann Arbor, Department of Climate and Space Sciences and Engineering, Ann Arbor, MI, United States, Sandro M. Radicella, Telecommunications/ICT for Development Laboratory, Abdus Salam International Center for Theoretical Physic, Trieste, Italy, Endawoke Yizengaw, The Aerospace Corporation, Space Science Application Laboratory, El Segundo, CA, United States, Shasha Zou, University of Michigan, Climate and Space Sciences and Engineering, Ann Arbor, MI, United States and Bruno Nava, The Abdus Salam International Centre for Theoretical Physics, Telecommunications/ICT for Development Laboratory, Trieste, Italy
Abstract:
The effect of eastward zonal wind speed (EZWS) on vertical drift velocity (ExB drift) that mainly controls the equatorial ionospheric irregularities has been explained theoretically and through numerical models. However, its effect on the seasonal and longitudinal variations of ExB and the accompanying irregularities has not yet been investigated experimentally due to lack of F-layer wind speed measurements. Observations of EZWS from GOCE and ion density and ExB from C/NOFS satellites for years 2011 and 2012 during quite times are used in this study. Monthly and longitudinal variations of the irregularity occurrence, ExB, and EZWS show similar patterns. We find at most 50.85% of longitudinal variation of ExB can 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 of ExB. In Atlantic, Africa, and Indian sectors, from 42.63% to 79.80% of the monthly variations of the ExB can be explained by the monthly variations of EZWS only. It is found also that EZWS and ExB may 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 downward ExB which suggests that other factors dominate the ExB drift rather than the EZWS during these periods.
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