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Development of fine‐resolution analyses and expanded large‐scale forcing properties: 2. Scale awareness and application to single‐column model experiments
Author(s) -
Feng Sha,
Li Zhijin,
Liu Yangang,
Lin Wuyin,
Zhang Minghua,
Toto Tami,
Vogelmann Andrew M.,
Endo Satoshi
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2014jd022254
Subject(s) - mesoscale meteorology , scale (ratio) , grid , meteorology , data assimilation , forcing (mathematics) , environmental science , climatology , geology , physics , geodesy , quantum mechanics
Fine‐resolution three‐dimensional fields have been produced using the Community Gridpoint Statistical Interpolation (GSI) data assimilation system for the U.S. Department of Energy's Atmospheric Radiation Measurement Program (ARM) Southern Great Plains region. The GSI system is implemented in a multiscale data assimilation framework using the Weather Research and Forecasting model at a cloud‐resolving resolution of 2 km. From the fine‐resolution three‐dimensional fields, large‐scale forcing is derived explicitly at grid‐scale resolution; a subgrid‐scale dynamic component is derived separately, representing subgrid‐scale horizontal dynamic processes. Analyses show that the subgrid‐scale dynamic component is often a major component over the large‐scale forcing for grid scales larger than 200 km. The single‐column model (SCM) of the Community Atmospheric Model version 5 is used to examine the impact of the grid‐scale and subgrid‐scale dynamic components on simulated precipitation and cloud fields associated with a mesoscale convective system. It is found that grid‐scale size impacts simulated precipitation, resulting in an overestimation for grid scales of about 200 km but an underestimation for smaller grids. The subgrid‐scale dynamic component has an appreciable impact on the simulations, suggesting that grid‐scale and subgrid‐scale dynamic components should be considered in the interpretation of SCM simulations.