Evaluation of the model representation of the evolution of convective systems using satellite observations of outgoing longwave radiation

Abstract

We introduce a technique for assessing the diurnal development of convective storm systems based on outgoing longwave radiation fields. Using the size distribution of the storms measured from a series of images, we generate an array in the length scale-time domain based on the standard score statistic. It demonstrates succinctly the size evolution of storms as well as the dissipation kinematics. It also provides evidence related to the temperature evolution of the cloud tops. We apply this approach to a test case comparing observations made by the Geostationary Earth Radiation Budget instrument to output from the Met Office Unified Model run at two resolutions. The 12 km resolution model produces peak convective activity on all length scales significantly earlier in the day than shown by the observations and no evidence for storms growing in size. The 4 km resolution model shows realistic timing and growth evolution, although the dissipation mechanism still differs from the observed data. Copyright © 2010 by the American Geophysical Union.