JCMT-Venus: Monitoring HDO Absorption in Venus’ Mesosphere

Abstract In the JCMT-Venus project, we conducted three multi-week disc-integrated observations of Venus’ atmosphere using the JCMT ‘Ū‘ū receiver. This paper focuses on the HDO 2(2,0)-3(1,3) transition line at 266.1611 GHz, employed as a proxy for water abundance under the assumption of a constant D/H ratio. Based on the HDO line depth, we observed significant and rapid short-term variations, and have tentatively identified potential long-term effects. Water vapor abundance values were retrieved daily, and their variations will be displayed and discussed in our forthcoming publications.