Role of Latent Heating Vertical Distribution in the Formation of the Tropical Cold Trap

摘要

This study examines the role of latent heating (LH) vertical distribution in tropical tropopause layer (TTL) cooling and upper-tropospheric warming associated with equatorial wave responses using LH from the Tropical Rainfall Measurement Mission and temperature from radio occultation observations.We distinguish the effects of convective and stratiform LH in tropical convection on temperature in the upper troposphere and lower stratosphere. Cross-spectral analysis of time series of temperature and LH shows that stratiform LH exhibits higher coherence with temperature throughout most of the upper troposphere and lower stratosphere, especially in the equatorial Rossby wave response. Coherence between total LH and temperature tends to increase with the altitude of heating. Highest coherences occur almost exclusively at time scales of the Madden-Julian Oscillation, suggesting the importance of mesoscale convective activity in TTL cooling and subsequent dehydration processes. These results demonstrate that TTL and upper-tropospheric temperature perturbations depend on the vertical distribution of LH and that stratiform LH release has strong relationship with the formation of the horseshoe-shaped cold trap over the Maritime Continent andWest Pacific.