The variation of Venus cloud investigated from SOIR onboard Venus Express and radiative transfer calculation

Abstract:

Venus is our nearest neighbor, and has a size very similar to the Earth’s. However, previous observations discovered an extremely dense (90 bar at the surface) and dry CO₂-rich atmosphere with H₂SO₄clouds floating at 47 – 70 km.The haze layer lies above the thick cloud surrounding the planet, ranging from the cloud top (70 km) up to as high as 90 km.

The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express (ESA) was designed to measure the Venusian atmospheric transmission at high altitudes (65 – 220 km) in the infrared wavelength range (2.2 – 4.3 µm) with a high spectral resolution. In Takagi et al. (2019), the optical properties of upper haze layer above 90 km have been investigated with SOIR observations. Vertical and latitudinal profiles of the extinction coefficient, optical thickness, and mixing ratio of aerosols are retrieved.

Anew cloud model was constructed based on the results of Takagi et al. (2019). In this presentation, I will show the results of a radiative transfer calculation (in the near-infrared region) that incorporates a new cloud model and discuss themeteorological some changes that contribute to cloud variation.Furthermore, I will introduce Venus observation plan using the 1.6 m Pirka telescope and Multi-Spectral Imager (MSI) [Watanabe et al., 2012] mounted on the Cassegrain focus of the telescope at the Nayoro Observatory of Hokkaido University.