The impacts of cloud snow radiation on Pacific Ocean heat content and meridional overturning circulation in coupled GCM simulations

Abstract:

The radiative effect of cloud snow interaction is one of physical processes influencing model performances. According to sensitivity experiments in a coupled general circulation model, the presence of cloud snow radiation has been found to alternate the vertical distribution of atmospheric radiation, moist and dynamic processes in the atmosphere over cloudy regions in the Pacific. Its imprints on upper oceans via vertical mixing are observed as well where cooler sea surface temperature (SST) and subsurface ocean temperature are attributable to stronger surface wind stress. To complement previous works, this study focuses on the model behavior in terms of ocean heat content and meridional overturning circulation with and without the cloud snow radiative effect. Consistent with SST and subsurface ocean temperature, the presence of cloud snow radiation generates pronouncedly less ocean heat content in the top of 300 m between the Intertropical Convergence Zone and South Pacific Convergence Zone and more ocean heat content in the Pacific storm tracks, which reduces biases relative to observations. In addition, the presence of snow cloud radiation induces Pacific meridional overturning circulation anomalies in upper 700 m between 10^oN and 20^oS where more southward mass is transported south of the equator and more northward mass is transported north of the equator. The divergence of mass transport is likely to be linked to less ocean heat content in the subtropical Pacific. This study illustrates the importance of cloud snow radiation to energy redistribution in oceans in the modeling climate system.