Venus wind map at cloud top level with the MTR/THEMIS visible spectrometer. I. Instrumental performance and first results

TL;DR

This study demonstrates the use of the MTR/THEMIS spectrometer to measure Venus' cloud top winds via Doppler shifts in visible light, providing initial results despite limited observation time.

Contribution

First application of the MTR/THEMIS spectrometer for Venus wind mapping at cloud top level, assessing instrumental performance and initial wind speed measurements.

Findings

Instrumental velocity sensitivity of 31 m/s per pixel.

Zonal wind speed at Venus' equator measured at 151 +/- 16 m/s.

Successful Doppler velocity measurement with limited observation time.

Abstract

Solar light gets scattered at cloud top level in Venus' atmosphere, in the visible range, which corresponds to the altitude of 67 km. We present Doppler velocity measurements performed with the high resolution spectrometer MTR of the Solar telescope THEMIS (Teide Observatory, Canary Island) on the sodium D2 solar line (5890 \AA). Observations lasted only 49 min because of cloudy weather. However, we could assess the instrumental velocity sensitivity, 31 m/s per pixel of 1 arcsec, and give a value of the amplitude of zonal wind at equator at 151 +/- 16 m/s.