Venus’ upper atmosphere revealed by a GCM: I. Structure and variability of the circulation

A numerical simulation of the upper atmosphere Venus is carried out with an improved version Institut Pierre-Simon Laplace (IPSL) full-physics General Circulation Model (GCM). This reveals organization atmospheric circulation at altitude above 80 km in unprecedented detail. Converging flow towards antisolar point results supersonic wind speeds and generates a shock-like feature past terminator altitudes 110 km. greatly decreases nightside thermospheric speeds, favoring variability on hourly timescale thermosphere. ?5-day period Kelvin wave originating cloud deck found to substantially impact Venusian circulation. As impacts nightside, poleward meridional enhanced. Consequently, recombined molecular oxygen periodically ejected high latitudes, explaining characteristics various observations nightglow 1.27?m. An analysis simulated 1.27?m shows that it not necessarily good tracer dynamics, since contributions from chemical processes vertical transport often prevail over horizontal transport. Moreover, dayside atomic abundances also vary as momentarily enhances abundances, EUV dayglow. Despite nitrogen chemistry being currently included IPSL GCM, apparent maximum NO shifted morning might be explained by structure winds.