P2.26
A Large-Eddy Smulation Study of Observed Stratocumulus Clods Under Weak Inversion during POST
Shouping Wang, NRL, Monterey, CA; and Q. Wang and A. Bucholtz
Physics of Stratocumulus Top (POST) is a field program designed to understand the physi-cal processes operating within the temperature inversion at the top of stratocumulus clouds. It was conduced in July-August 2008 off the west coast of California. The inversion that caps the stratocumulus has been frequently observed to be strong with more than 10K across the 100 m thickness. Observations made during POST showed, however, that the temperature inversion may be very weak. For example, the soundings on 8 August 2008 demonstrate that the tempera-ture jump across the inversion is only 3K and the water vapor is only 1 g kg-1. The maximum cloud water mixing ratio reaches to 0.7 g kg-1 with the cloud top at 690m and the cloud base at 200m. It is well known that the strength of the inversion has important impact on the cloud and tur-bulence structure due to its effects on the evaporation and turbulence mixing. This work is fo-cused on the processes in the entrainment zone. We apply COAMPS-LES to a nighttime cloud case observed on 8 August. Sounding taken during the flight is used for initial and large-scale conditions. The LES model is configured to cover a 5„e5„e3km domain with horizontal grid spac-ing being 30m and the vertical stretching grid between 15m to 5m. We use a simple longwave (LW) radiation scheme with the LW downward flux above the inversion as the boundary condi-tion. The model results are compared with the available observations. The analysis is focused on the turbulence mixing generated by the wind shear, the radiative cooling and the evaporation
Poster Session 2, Cloud Physics Poster Session II
Wednesday, 30 June 2010, 5:30 PM-8:30 PM, Exhibit Hall
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