Revising Constrained Variational Analysis for Treatment of Surface Complex Terrain

 
Poster PDF

Authors

Shuaiqi Tang — Pacific Northwest National Laboratory
Shaocheng Xie — Lawrence Livermore National Laboratory
Minghua Zhang — Stony Brook University

Category

ARM infrastructure

Description

Constrained Variational Analysis are currently designed for a cylinder atmospheric column in pressure coordinate. The lower surface of the atmospheric column is usually assumed to be flat with constant surface pressure within the column. For some field campaigns with complex terrain variability, such as the Cloud, Aerosol, and Complex Terrain Interactions (CACTI), it is not clear whether the flat-surface assumption still gives reasonable forcing, or how large the surface terrain variations will impact the derived forcing. We propose a revision to the constrained variational analysis to address the impact of surface terrain to the derived large-scale forcing. Specifically, we change the algorithm from the pressure coordinate into a terrain-following sigma coordinate. A set of sensitivity studies will be shown to quantify the impact of different grades of surface terrain to the large-scale forcing. This revision will help SCM/CRM/LES simulations and understanding of convective systems over complex terrains such as CACTI or propagating MCSs over the slope to the east of Rocky Mountains.