Problems to be solved
Current climate models contain important deficiencies in the representation of cloud systems. Well known symptoms, when comparing model simulation of the present climate with observations, is the lack of stratocumulus over the ocean, of incorrect diurnal cycle of cumulus and precipitating deep convection over continents, and lack of sensitivity of deep convection development to the moisture profile. Clouds remain one of the largest sources of uncertainty in climate change predictions.
Scientific objectives and approach
The strategy to address these issues is based on the use of the hierarchy of models and observations to integrate cloud studies across the full range of scales. Numerical models range from General Circulation Models (GCM) through Single Column models (SCM) to Cloud Resolving Models (CRM) and Large Eddy Simulations (LES). Observations, which will be used, vary from global satellite measurements to local observations of individual clouds through lidar and millimetric radar. A comprehensive 4-D database will be established using several LES models and CRMs of specific cases. These cases relate to the critical problems noted above associated with the prediction of clouds in regional and global climate and Numerical Weather Prediction (NWP) models. The LES/CRM datasets will be used to investigate deficiencies in climate and NWP models using 9 different SCMs as a test bed. Specific issues to be addressed will be the general failure of regional and global models to predict stratocumulus amounts, the diurnal triggering of boundary layer convection and deep precipitating convection over land, and the lack of sensitivity of deep convection development on moisture profile in these models. Once reasons for deficiencies have been identified, physically based corrections will be introduced in SCMs and GCMs. The project will aim to improve climate and NWP models ability to represent both the mean structure (horizontally and vertically) and time variability of cloud water and amount for the critical cases defined above. Six different European climate models will participate.
The results will help narrowing the uncertainties in global and regional climate models and climate predictions. The results will also be important for weather prediction and may contribute to better forecast of severe precipitation events and flooding.
Call for proposalData not available
Funding SchemeCSC - Cost-sharing contracts
3730 AE De Bilt
RG12 2SZ Bracknell - Berkshire
3584 CC Utrecht