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General circulation model (AFES-Venus) and data assimilation system (ALEDAS-V) for the Venus Atmosphere

Presentation #502.02 in the session Venus I (Oral Presentation)

Published onOct 23, 2023
General circulation model (AFES-Venus) and data assimilation system (ALEDAS-V) for the Venus Atmosphere

We have developed the Venusian general circulation model (GCM) named AFES-Venus (Atmospheric GCM for the Earth Simulator for Venus) [1, 2] and the data assimilation system based on the Local Ensemble Transform Kalman Filter (LETKF) named ALEDAS-V (AFES-LETKF data assimilation system for Venus) [3]. We will introduce important recent results of AFES-Venus and ALEDAS-V.

AFES-Venus reproduced the cold collar in the polar region [4], the planetary-scale streak structure observed by Akatsuki infrared (IR2) camera [5], a fully developed super-rotation [6], and spontaneous gravity waves radiated from the thermal tides [7]. Recently, by improving the profiles of static stability and solar heating, the thermal tides [8] and the planetary-scale short periods (Kelvin and Rossby) waves [9] consistent with observations are reproduced. We also checked how the super-rotation depends on the magnitude of horizontal hyper diffusion with medium and high resolutions [10].

ALEDAS-V improved the horizontal structures of thermal tides with the data assimilation of horizontal winds derived by cloud tracking of ultra-violet images from Venus Express [11] and Akatsuki [12]. Although the observed horizontal winds are limited to low latitudes on the day side, the zonal-mean zonal winds and temperature are also modified globally [12]. We have also conducted observing system simulation experiments (OSSEs) assuming Akatsuki Longwave Infrared Camera (LIR) observations [13].

References: [1] Sugimoto N. et al. (2014) JGR-Planets, 119, 1950–1968. [2] Sugimoto N. et al. (2014) GRL, 41, 7461–7467. [3] Sugimoto N. et al. (2017) Sci. Rep.. 7, 9321. [4] Ando H. et al. (2016) Nature Comm., 7, 10398. [5] Kashimura H. et al. (2019) Nature Comm., 10, 23. [6] Sugimoto N. et al. (2019) GRL, 46, 1776–1784. [7] Sugimoto N. et al. (2021) Nature Comm., 12, 3682. [8] Suzuki A. et al. (2022) JGR-Planets, 127, 7243. [9] Takagi M. et al. (2022) JGR-Planets, 127, 7164. [10] Sugimoto N. et al. (2023) Earth, Planets and Space, 75, 44. [11] Sugimoto N. et al. (2019) GRL, 46, 4573–4580. [12] Fujisawa Y. et al. (2022) Sci. Rep., 12, 14577. [13] Sugimoto N. et al. (2022) Geoscience Lett., 9, 44.

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