On the influence of bulk-parameterization schemes of cloud microphysics on the predicted water-cycle-relevant quantities — A case study

Abstract

Two different bulk-parameterization schemes of cloud microphysics alternatively used in a meso-ß-scale meteorological model are compared to elucidate their influence on the predicted atmospheric water cycle. The different parameters (e.g., ice crystal types, density of ice) and parameterizations (e.g., terminal velocity, riming, accretion) used by the schemes cause differences in the mixing ratios of the predicted water substances and in the release and consumption of heat resulting in appreciable differences in the vertical motions. The first scheme leads to a larger and more stratiform cloud coverage than the second one which provides broken cloud fields. Consequently, the latter scheme predicts a more shower-like precipitation with locally greater intensities while the first scheme provides a homogeneous precipitation horizontally larger extended with lower intensity. Moreover, the domain-averaged maximal precipitation occurs in the afternoon for the second scheme and in the evening for the first scheme. Altogether, the differences in predicted cloud coverage, insolation, vertical motions, precipitation and soil wetness caused by the different microphysical parameterizations applied, strongly affect the partitioning of energy between sensible and latent heat at the Earth's surface and hence, the amount of water locally re-provided to the atmosphere.

Keywords

• bulk-parameterization
• ice crystal types
• vertical motions
• soil wetness
• atmosphere
• bulk-parametrisierung
• eiskristalltyp
• vertikalbewegungen
• bodenfeuchte
• atmosphäre