Solar-locked and geographical atmospheric structures inferred from a Venus general circulation model with radiative transfer

• Published in: Icarus (New York, N.Y. 1962) Vol. 321; pp. 232 - 250
• Main Authors: Yamamoto, Masaru, Ikeda, Kohei, Takahashi, Masaaki, Horinouchi, Takeshi
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15-03-2019
• Subjects: Atmosphere; Meteorology; Venus; Venus; Atmosphere; Meteorology
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2018.11.015

•Solar-locked and geographical atmospheric structures on Venus are investigated.•The present study evaluates differences between zonal and dayside averages.•Indirect circulation is formed at high latitudes by thermal tide and baroclinic waves.•Stationary modification of middle-atmospheric structure is forced by topography.•Solar-locked wind fields are compared with the Akatsuki UV cloud tracked ones.
Solar-locked and geographical atmospheric structures of daily averaged wind and temperature on Venus were investigated using an atmospheric general circulation model with Venusian topography and a two-stream radiative code and were compared with wind fields obtained from the Akatsuki ultraviolet imager. The horizontal wind fields simulated around the subsolar region are similar to the observed ones at the cloud top. Mid-latitude jets of ∼120 m s–1 and an equatorial fast flow of ∼90 m s–1 are formed around the cloud top. A poleward flow of >8 m s–1 is formed above the cloud layer, where solar heating is strong. Around the cloud top, a poleward flow of ∼1 m s–1 is confined within the equatorward flank of the jet core, whereas an indirect circulation is formed in the jet core by the eddy heat fluxes owing to the thermal tide and baroclinic waves. In solar-fixed coordinates, the subsolar-to-antisolar circulation is predominant around the cloud top. Thus, differences are significant between the zonal and dayside averages of the meridional wind and its related fluxes within the cloud layer. This suggests the zonal mean meridional wind of the Hadley circulation, eddy momentum, and heat fluxes from the one-side hemisphere must be estimated carefully. In the experiment including topography, a near-surface subrotation is formed in latitudinal zones over high land and mountains, a weakly stable layer is formed at 10–20 km at low latitudes, and the zonal wind is weakened at the cloud top over the Aphrodite Terra. Regional stationary modification of the atmospheric structure due to topographical waves appears in the cloud layer.