The Modification of a Thermally Induced Mesoscale Circulation By Deep Moist Convection

Thursday, 18 December 2014: 10:20 AM
Malte Rieck1, Cathy Hohenegger1 and Pierre Gentine2, (1)Max Planck Institute for Meteorology, Hamburg, Germany, (2)Columbia University, New York, NY, United States
Land-atmosphere interactions play a crucial role in earth system modelling through their mutual control on the energy budget and its partition. Land surfaces are generally heterogeneous, can create mesoscale circulations and alter the development of clouds and precipitation. This can be a source of uncertainties for current climate and Numerical Weather Prediction (NWP) models, where convection is partially parameterized. Results of our simulations will help to identify the interaction between land-surface heterogeneities, moist convection and mesoscale circulations in NWP models.

In this study we simulate the diurnal cycle of mid-latitude summertime convection with a focus on the propagation of a thermally induced mesoscale circulation. High resolution large-eddy simulation with an interactive land-surface model is used to address the problem. Sensitivity studies show that moist convection significantly strengthens thermally induced mesoscale circulations. We identify three convective stages that influence mesoscale circulations within the diurnal cycle.