The Study of Zonal Circulation of Venus’s Atmosphere by Data Analysis of Radio Occultation Measurements Made by Venera-15 and -16 Satellites

The vertical profiles of temperature and pressure obtained from radio occultation measurements made by satellites Venera-15 and -16 from October 1983 to September 1984 are used for the analysis of wind speed in Venus’s atmosphere. The altitude and latitude dependences of zonal wind speed in the middle atmosphere of the planet’s northern and southern hemispheres are identified at altitudes from 50 to 80 km over the latitude interval of 60°–85°. Zonal speeds were determined assuming cyclostrophic atmosphere balance. The existence of jet flows, whose maximal speed is ~100 m/s and axis is placed at an altitude near 60 km within the latitude zone of 73°–75° N, is confirmed in the northern polar atmosphere of the planet. The results of wind speed measurements in the southern hemisphere clearly show that the jet flows exist at an altitude around 62 km at latitudes from 70° to 72° S, and their zonal speed reaches a maximum of ~115 m/s. It is found that these jets at high latitudes are stipulated by negative latitudinal temperature gradients at altitudes below the jet flow axes in Venus’s polar atmosphere.