Japan Geoscience Union Meeting 2025

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[E] Oral

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

Mon. May 26, 2025 1:45 PM - 3:15 PM 303 (International Conference Hall, Makuhari Messe)

convener:Keisuke Hosokawa(Department of Communication Engineering and Informatics, University of Electro-Communications), Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University), Yuichi Otsuka(Institute for Space-Earth Environmental Research, Nagoya University), Loren Chang(Department of Space Science and Engineering, National Central University), Chairperson:Bernd Kaifler(German Aerospace Center), Huixin Liu(Earth and Planetary Science Division, Kyushu University SERC, Kyushu University)

2:00 PM - 2:15 PM

[PEM12-32] Causes of the abnormally strong easterly phase of the mesopause SAO during the March equinox of 2023 revealed by a new reanalysis data covering the entire middle atmosphere

*Kaoru Sato1, Dai Koshin2, Jose Suclupe3, Jorge L Chau3, Lourivaldo M Lima4, Guozhu Li5, S. Vijaya Bhaskara Rao6, M. Venkat Ratnam7, Rodolfo Rodriguez8, Danny Scipion9 (1.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 2.NSF National Center for Atmospheric Research, USA, 3.Leibniz-Institute of Atmospheric Physics at the University of Rostock, Germany, 4.Universidade Estadual da Paraiba, Brazil, 5.Beijing National Observatory of Space Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, China, 6.Department of Physics, Sri Venkateswara University, India, 7.National Atmospheric Research Laboratory, India, 8.Universidad de Piura, Peru, 9.Radio Observatorio de Jicamarca, Instituto Geofisico del Peru, Peru)

Keywords:equatorial mesopause semiannual oscillation , wave-mean flow interaction, residual mean circulation , extreme event, a new reanalysis JAWARA

During the March equinox of 2023, a strong easterly wind of about 80 m/s appeared at an altitude of about 82 km in the equatorial upper mesosphere, which is regarded as an enhancement of the mesopause semi-annual oscillation. In this study, a new reanalysis data available up to 110 km was used to investigate its momentum budget. The strong easterly acceleration was due to a similar contribution from resolved waves and parameterized gravity waves, but largely counteracted by an upward advection of westerly momentum. The significant anomaly in the mean winds was not restricted to the 82 km height, but also included strong westerly winds (about 50 m/s) at 65 km and easterly winds (about 40 m/s) at 42 km. The stratospheric quasi-biennial oscillation was westerly. The mean wind intensification at each height is explained by the acceleration due to upward propagating waves, which do not suffer from critical filtering below.