Journal cover Journal topic
Annales Geophysicae Sun, Earth, planets, and planetary systems An interactive open-access journal of the European Geosciences Union
Ann. Geophys., 29, 157-165, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
14 Jan 2011
Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations
S. V. Thampi1, N. Balan1, C. Lin2, H. Liu1, and M. Yamamoto1 1Research Institute for Sustainable Humanosphere (RISH), Kyoto University, 611-0011, Japan
2Department of Earth Science, National Cheng Kung University, Tainan, Taiwan
Abstract. In this paper, we present model simulations of the Mid-latitude Summer Nighttime Anomaly (MSNA) in the Northern Hemisphere, which is characterized by noon-time dip and evening maximum in the diurnal variation of the ionospheric density. The simulations are carried out using SUPIM (Sheffield University Plasmasphere Ionosphere Model) for solar minimum at 135° E longitude where MSNA is most pronounced in the Northern Hemisphere. The simulations are used to understand the relative importance of electric fields, and zonal and meridional winds in the formation of MSNA. The wind velocities measured by the Middle and Upper atmosphere radar (MU radar) and those obtained from the horizontal wind model (HWM93) are used. The results show that the formation of MSNA is closely related to the diurnal variation of the neutral winds with little contribution from the changes in the electric fields. The observed features of MSNA are better reproduced when MU radar winds are used as model input rather than HWM winds.

Citation: Thampi, S. V., Balan, N., Lin, C., Liu, H., and Yamamoto, M.: Mid-latitude Summer Nighttime Anomaly (MSNA) – observations and model simulations, Ann. Geophys., 29, 157-165,, 2011.
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