4:30 PM - 4:45 PM
[PPS04-05] Study on the variation of the Venusian polar atmospheric structure and gravity waves using radio occultation data
Keywords:Venus, cloud-level convection, atmospheric gravity wave, radio occultation
At 50-70km altitudes in the Venusian atmosphere, there is a thick cloud layer composed of H2SO4 and H2O liquid. Around the cloud base, the clouds absorb infrared radiation from the lower atmosphere and then the atmosphere is heated. On the other hand, the atmosphere near the cloud top is cooled by emitting infrared radiation to space. This drives convection in the lower cloud layer. Atmospheric gravity waves, with this convection being one of the excitation sources, propagate vertically and transport momentum between distant altitude regions. Thus, they play important roles in atmospheric dynamics.
In the previous studies, the latitudinal and local-time dependences of the convective layer thickness and the gravity wave activity were suggested. Unlike Earth, observations of Venus Express and Akatsuki radio occultation showed that the convective layer is thicker at higher latitudes (Tellmann et al. 2009; Ando et al. 2020). As the solar heating in the upper cloud layer decreases with latitude, convection will be enhanced at higher latitudes (Imamura et al. 2014). Similarly, convection is expected to be stronger on the night side than on the dayside. Also, the activity of gravity waves is enhanced in high latitudes (Tellmann et al. 2012; Ando et al. 2015).
In this study, we analyze the Venus Express radio occultation data to study the day-to-day changes in the structure of the convective layer and the amplitude of gravity waves in the polar atmosphere associated with a planetary-scale wave with period of ~3 Earth days, which was reported by Ando et al. (2017), and the relationship between them.
In the previous studies, the latitudinal and local-time dependences of the convective layer thickness and the gravity wave activity were suggested. Unlike Earth, observations of Venus Express and Akatsuki radio occultation showed that the convective layer is thicker at higher latitudes (Tellmann et al. 2009; Ando et al. 2020). As the solar heating in the upper cloud layer decreases with latitude, convection will be enhanced at higher latitudes (Imamura et al. 2014). Similarly, convection is expected to be stronger on the night side than on the dayside. Also, the activity of gravity waves is enhanced in high latitudes (Tellmann et al. 2012; Ando et al. 2015).
In this study, we analyze the Venus Express radio occultation data to study the day-to-day changes in the structure of the convective layer and the amplitude of gravity waves in the polar atmosphere associated with a planetary-scale wave with period of ~3 Earth days, which was reported by Ando et al. (2017), and the relationship between them.