Evaluation of Ncep Global Forecast System (gfs) Cloud Properties Using Satellite Retrievals

Our poor understanding of cloud vertical structure on a global scale leads to large uncertainties in weather and climate models. Many cloud and radiation processes in general circulation models (GCMs) are parameterized due to insufficient knowledge of underlying physical processes and the computational burden. Multi-layer clouds are crucial for climate studies due to its impact on both the Earth’s radiation budget as well as retrievals of cloud properties. Therefore, it is important to advance our knowledge of cloud vertical distribution and improve the representation of clouds in climate models. The proposed study will evaluate clouds generated by the National Center for Environmental Prediction (NCEP) Global Forecast System (GFS) model using different types of satellite products. Several model cloud parameters will be evaluated including cloud fraction (CF), cloud optical depth (COD), liquid water path (LWP), ice water path (IWP), and cloud effective radius (Re). Cloud vertical structure in the GFS model can be validated by bringing together different measurements such as those from passive and active sensors on satellite platforms and those from the ground pointed upwards. The main objectives of the study are to 1) evaluate model parameterizations of cloud properties such as cloud fraction, phase, optical thickness, etc.via both novel and conventional retrieval methodologies applied to passive satellite data, especially those from the A-Train’s Moderate Resolution Imaging Spectroradiometer (MODIS), the Atmospheric Infrared Sounder (AIRS) and other passive sensors; 2) diagnose cloud overlapping schemes in the GFS model by using active satellite retrievals from CloudSat and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) platform; 3) assess the quality and consistency between model outputs and ground measurements from the U.S. Department of Energy Atmospheric Radiation Measurement Climate research Facility (ACRF) site.