Comparison of model predicted cloud cover profiles with observations from ground and satellite

Abstract

Cloud cover profiles predicted by a large-scale atmospheric model are directly compared with observations for three meteorologically different situations, i. e. a frontal system, a case of deep convection, and a case with low-level stratus. Observed profiles of cloud cover are inferred from measurements with a ground-based network of infrared radiometers and from satellite observations on a 100 kilometer scale. The corresponding model quantity is derived from the model cloud fraction profile assuming random-maximum overlap. A regional model at 50 km resolution and with 31 layers is operated in parallel with two different cloud schemes, i. e. the condensation scheme from the ECHAM4-model and a version of the prognostic cloud scheme from the ECMWF-model. Qualitative comparison shows that in either of the three cases there is room for substantial improvement. The results obtained with both cloud schemes tend to be closer to each other than to the observations, implying that the model components other than the cloud schemes are of relevance in reproducing an observed cloud cover profile.

Keywords

• cloud cover profiles
• frontal system
• deep convection
• low-level stratus
• wolkenbedeckung