Microphysical controls on clouds, radiation, and tropical circulation
High-resolution, large-domain simulations finally allow us to link microphysical processes to cloud controlling factors such as updraft wind speed and mixing. We investigate how understanding of how the tropical climate changes with warming depends on the knowledge of microphysics and its representation in numerical models. A goal is to quantify how microphysical process assumptions influence heat budgets in the tropics, the response of clouds to warming, and their effect on tropical circulation.
To constrain microphysical sensitivities we link high-resolution simulations with satellite data and with EUREC4A measurements.
Contact person: Ann Kristin Naumann
On the organization of shallow convection and its link to precipitation
How shallow trade wind cumuli respond to warming is the primary source of spread in climate sensitivity estimates across climate models. Shallow cumuli fields exhibit patterns of various shape and structure, commonly denoted as mesoscale organization, and often associated with precipitation. To understand either might require understanding both. Therefore, we investigate the role of precipitation for the organization of shallow convection and vice versa. To do so, the project will take advantage of experimental activities in the tropical Atlantic (EUREC4A campaign) and high-resolution simulations.
Contact person: Jule Radtke
Understanding model differences in the distribution of upper-tropospheric humidity
The distribution of water vapour and cloud ice in the upper troposphere has a strong impact on the Earth’s radiation budget. However, conventional climate models differ substantially in these distributions, which is most likely a consequence of the parameterizations used to model the effect of processes like convection and cloud microphysics. So-called global convection-permitting models are the first global models that are able to explicitly resolve deep convection and hence forgo cumulus parameterizations. A first intercomparison project called DYAMOND compares 40-day simulations of nine different global convection-permitting models. Questions we are trying to answer based on these simulations are for example: Is the inter-model spread reduced now that convective circulations are explicitly resolved? To what extent are remaining inter-model differences caused by differences in the circulation and in the parameterization of microphysical processes? Are the models able to reproduce the distributions observed by satellite instruments?
Contact person: Theresa Lang