Sensitivity of the tropical easterly jet to the distribution and magnitude of latent heating in an aqua-planet model

Abstract

Sensitivity of the tropical easterly jet (TEJ) to the distribution and magnitude of tropical latent heating was examined using an aqua-planet configuration of the Community Atmosphere Model, version 3.1 (CAM-3.1), of the National Center for Atmospheric Research. A series of aqua-planet simulations show that the wind speeds associated with the TEJ are directly controlled by the magnitude and location of tropical heating. Specifically, heating in the off-equator and higher tropical latitudes can generate strong easterlies. In contrast, a single heat source in the equatorial region, even with high magnitude, does not force strong easterlies. However, heating in the higher tropical latitudes is not relevant to explain the structure of the TEJ, whereas equatorial heating is crucial for the realistic vertical and meridional structures of the TEJ. The location of peak zonal wind is influenced by the off-equatorial heating near the TEJ. In a realistic model configuration, it is shown that a zonally elongated precipitation band in the Pacific Ocean warm pool is important for the TEJ to extend eastwards into this region.