The Role of Shallow Convection in Tropical Climate via Impacts of the Model Spatial Resolution

Thursday, 18 December 2014
Hien Xuan Bui and Chia Chou, Research Center for Environmental Changes Academia Sinica, Taipei, Taiwan
We examine the role of shallow convection in tropical climate, using different spatial resolutions as sensitivity studies. After examining the vertical structure and spatial distribution of tropical convection, we found that a coarser resolution produces less partition of shallow convection, while a finer resolution tends to produce greater one in convective regions. We further examine the influence of shallow convection strength on precipitation by comparing the western and eastern Pacific ITCZ. In the western Pacific ITCZ, where is dominated by deep convection, the variation of precipitation among the spatial-resolution experiments is mainly due to the contribution of thermodynamic processes. The warmer climate found in coarser resolutions enhances precipitation frequency and intensity, and then the corresponding precipitation amount. In the eastern Pacific ITCZ, which has more shallow convection, shallow convection becomes the dominant factor to determine the variation of precipitation. More partition of shallow convection found in finer resolutions tends to enhance precipitation frequency and intensity, and the total precipitation amount. This provides potential evidence that shallow convection first affects the occurrence and intensity of precipitation, and then the total amount of precipitation in the region.