Comparison of Cloud Fraction and Radiation Fluxes Among the Surface Observation (ACRF SGP CF) and Two Climate Models: the GFDL AM2 and the NCAR CAM3 Forecast Data

Xiquan Dong University of North Dakota
Baike Xi University of North Dakota
Stephen Klein Lawrence Livermore National Laboratory

Category: Radiation

One year (from January 3 to December 31, 2000) of observational data from the U.S. Department of Energy ARM Climate Research Facility Southern Great Plains Central Facility will be statistically compared with the outputs of National Center for Atmospheric Research Community Atmosphere Model (CAM3) and Geophysical Fluid Dy-namics Laboratory Atmospheric Climate Model (AM2) forecasts during the same period. In this study, we will focus on comparing the following parameters: cloud fraction and downwelling and upwelling shortwave (SW), longwave (LW) fluxes, and radiation budgets under the conditions of all skies, clear sky, cloudy skies. The total cloud fraction can be derived from the paired upward-looking narrow field-of-view radar/lidar measurements, and is simply the percentage of returns that are cloudy within a specified sampling period, and the total cloud fraction of the AM2 is selected by using random overlap technique from cloud area fraction in the atmosphere layer, which is cloud vertical distribution in the 35 layers, and the CAM3 model’s total is directly provided by its output. The SW and LW fluxes are measured by up- and down-looking standard precision spectral pyranometers and precision infrared radiometers and provided by both models.

This poster will be displayed at ARM Science Team Meeting.