How Much Variability in Upper Atmospheric Heating Rates Can Be Attributed to Ice Microphysics?

Abstract:

We investigate the radiative impacts of convectively detrained and in-situ formed ice crystals at uppermost altitudes with high-resolution ICON model runs in the Asian monsoon region. Radiatively, this area should be characterized by persistent longwave warming from thin and ubiquitous anvils and intermittent shortwave cooling from deep but infrequent convective systems. But how do different degrees of sophistication in the ice microphysics schemes modulate this picture? Three days coinciding with Flight 7 of the StratoClim field campaign are simulated (7-9 August 2017), using both one- and two-moment microphysics and lower and higher vertical resolutions (75 versus 120 levels). In-situ ice water content (IWC) values and specific humidity profiles are used for validation, as are the CloudSat 2C-ICE product and CERES measurements of outgoing longwave radiation. A trajectory module is implemented in ICON, and its output fields are used to force the detailed two-moment microphysics of the Chemical Lagrangian Model of the Stratosphere (ClaMs-ice). We compare the variability in longwave and shortwave heating rates between 14 and 17 km for these two setups with equivalent thermodynamics but differing ice microphysics.