Investigating the dependence of SCM simulated precipitation and clouds on the spatial scale of large‐scale forcing at SGP

Abstract

AbstractLarge‐scale forcing data, such as vertical velocity and advective tendencies, are required to drive single‐column models (SCMs), cloud‐resolving models, and large‐eddy simulations. Previous studies suggest that some errors of these model simulations could be attributed to the lack of spatial variability in the specified domain‐mean large‐scale forcing. This study investigates the spatial variability of the forcing and explores its impact on SCM simulated precipitation and clouds. A gridded large‐scale forcing data during the March 2000 Cloud Intensive Operational Period at the Atmospheric Radiation Measurement program's Southern Great Plains site is used for analysis and to drive the single‐column version of the Community Atmospheric Model Version 5 (SCAM5). When the gridded forcing data show large spatial variability, such as during a frontal passage, SCAM5 with the domain‐mean forcing is not able to capture the convective systems that are partly located in the domain or that only occupy part of the domain. This problem has been largely reduced by using the gridded forcing data, which allows running SCAM5 in each subcolumn and then averaging the results within the domain. This is because the subcolumns have a better chance to capture the timing of the frontal propagation and the small‐scale systems. Other potential uses of the gridded forcing data, such as understanding and testing scale‐aware parameterizations, are also discussed.