Exploring the effects of cloud-precipitation microphysics on simulations of moist climates on tidally-locked terrestrial exoplanets

Abstract:

Cloud processes behave as cogwheels in climate systems that link atmospheric processes across a wide range of spatial scales, from planetary-scale circulations to cloud microphysics. But cloud-precipitation microphysics is still not well understood today, and the representation in current global climate models has considered as one of the crudest aspects. Here we develop a moist general circulation model with real-gas radiative transfer and multiple scattering calculations to explore the effects of cloud-precipitation microphysics on moist climates on tidally-locked terrestrial exoplanets. In our model, autoconversion of cloud condensate to precipitation is parameterized as an exponential decay with a fixed autoconversion timescale. We investigate how this timescale affects the climatology and observation features, including the planetary albedo, nightside greenhouse effect, water vapor transit spectroscopy, and broadband thermal phase curve. Our work will help to evaluate the uncertainty in climate simulations on tidally-locked terrestrial planets due to representations of cloud-precipitation microphysics.