Venus's winds and temperatures during the MESSENGER's flyby: An approximation to a three‐dimensional instantaneous state of the atmosphere

Abstract

Even though many missions have explored the Venus atmospheric circulation, its instantaneous state is poorly characterized. In situ measurements vertically sampling the atmosphere exist for limited locations and dates, while remote sensing observations provide only global averages of winds at altitudes of the clouds: 47, 60, and 70 km. We present a three‐dimensional global view of Venus's atmospheric circulation from data obtained in June 2007 by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Venus Express spacecrafts, together with ground‐based observations. Winds and temperatures were measured for heights 47–110 km from multiwavelength images and spectra covering 40°N–80°S and local times 12 h–21 h. Dayside westward winds exhibit day‐to‐day changes, with maximum speeds ranging 97–143 m/s and peaking at variable altitudes within 75–90 km, while on the nightside these peak below cloud tops at ∼60 km. Our results support past reports of strong variability of the westward zonal superrotation in the transition region, and good agreement is found above the clouds with results from the Laboratoire de Météorologie Dynamique (LMD) Venus general circulation model.