Unexpected Changes of Aerosol Burdens With Decreased Convection in the Context of Scale‐Aware Convection Schemes

Abstract

Atmospheric aerosols in global climate models (GCMs) can be removed by both large‐scale and convective precipitation. As the horizontal resolution of GCMs increases, it is expected that large‐scale precipitation increases and convective precipitation decreases if scale‐aware convection schemes are well developed. To explore its impact on aerosol burdens, this study develops a novel method and applies it to the National Center for Atmospheric Research Community Atmosphere Model version 5.3 to mimic the behavior of scale‐aware convective schemes. Surprisingly, it is found that aerosol burden increases globally as convective precipitation decreases and large‐scale precipitation increases, which can be attributed to the reduced light rain. In the light‐rain intensity category, the decreased frequency of convective precipitation is not offset by the increased frequency of large‐scale precipitation. Therefore, for aerosol simulations in high‐resolution GCMs using scale‐aware convection schemes, subgrid convection and large‐scale condensation should be coordinated to assure light rain stays the same.