Summary of Abstract Submission

Abstract Submission No. IO50-05-0032PresentationPoster

STUDY ON THE EFFECT OF 3D CLOUD DISTRIBUTION UNCERTAINTIES ON THE MODEL PREDICTION OF RADIATION FLUXES

Dr. Timmy Francis*1, Dr. John P. George1, Dr. E. N. Rajagopal1

1 National Centre for Medium Range Weather Forecasting (NCMRWF), India

ABSTRACT :

Clouds interact with radiation and modify the atmospheric and surface energy budget. Uncertainties in the representation of clouds in the model initial conditions and forecasts is still one of the major challenges for the weather and climate modelling community. This study assess the uncertainties in the three dimensional representation of clouds in model predictions and its impact on the solar and terrestrial radiation fluxes reaching different levels of the atmosphere. The 3D distributions of clouds predicted by the global (~25km; 70 Levels) Unified Model at NCMRWF (NCUM) with the lead time up to 10 days have been used for this study. The A-train satellite observations from CALIPSO and CloudSat over north Indian Ocean is used for the verification. Studying the effect of feeding observed cloud distribution to the model radiation flux calculations is computationally expensive to carry out via the global model simulations. Different feedback process also may affect the global model simulations. An alternate approach is to use the single column version of the global model. The Single Column Model (SCM) of the Unified Model, is used here to study the impact of the uncertainties in the predicted cloud distribution on the radiation flux computations. SCM has same number of vertical levels of NCUM with same physics. The surface and TOA radiation fluxes at solar (shortwave) and the terrestrial (longwave) wavelengths in the SCM simulations - run with the global model simulated as well as the satellite observed cloud distribution - over the north Indian Ocean will also be discussed.