Investigating the effects of fractionation on HDO cycle and D/H on Venus

HDO is an isotopic form of water that can provide clues about the history and evolution of water on terrestrial planets. By comparing the D/H ratio derived from the abundance ratio of HDO and H2O on Venus with that of other planets or comets that have similar origins, we can estimate how much water Venus stored and lost during its formation and evolution. The Venus Plobal Climate Model (VPCM) developed by several laboratories (LMD, LATMOS) of Institute Pierre-Simon Laplace (IPSL, in Paris area) can simulate the chemical and dynamical processes of the Venusian atmosphere. However, HDO has so far not been included in the VPCM before. In this work, we first implement HDO in the gas and liquid phases as two additional tracers of the model to investigate their spatial and temporal distributions. As an isotope of water, HDO participates to all the chemical and physical processes in which water is involved. Furthermore, we have analyzed the influence of fractionation of HDO during condensation, and photolysis processes on the resulting D/H.