June 8, 2015
Journal Article

How Does Increasing Horizontal Resolution in a Global Climate Model Improve the Simulation of Aerosol-Cloud Interactions?

Abstract

The Community Atmosphere Model Version 5 is run at horizontal grid spacing of 2, 1, 0.5, and 0.25 degrees, with the meteorology nudged towards the Year Of Tropical Convection analysis, and cloud simulators and the collocated A-Train satellite observations are used to explore the resolution dependence of aerosol-cloud interactions. The higher-resolution model produces results that agree better with observations, showing an increase of susceptibility of cloud droplet size, indicating a stronger first aerosol indirect forcing (AIF), and a decrease of susceptibility of precipitation probability, suggesting a weaker second AIF. The resolution sensitivities of AIF are attributed to those of droplet nucleation and precipitation parameterizations. The annual average AIF in the northern hemisphere mid-latitudes (where most anthropogenic emissions occur) in the 0.25° model is reduced by about 1?W?m-2 (-30%) compared to the 2° model, leading to a 0.26?W?m-2 reduction (-15%) in the global annual average AIF.

Revised: August 7, 2020 | Published: June 8, 2015

Citation

Ma P., P.J. Rasch, M. Wang, H. Wang, S.J. Ghan, R.C. Easter, and W.I. Gustafson, et al. 2015. How Does Increasing Horizontal Resolution in a Global Climate Model Improve the Simulation of Aerosol-Cloud Interactions?. Geophysical Research Letters 42, no. 12:5058-5065. PNNL-SA-109623. doi:10.1002/2015GL064183