The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

A single-column radiative-convective model (RCM) is a useful tool to investigate the physical processes that determine the tropical tropopause layer (TTL) temperature structures. Previous studies on the TTL using the RCMs, however, omitted the cloud radiative effects. In this study, we examine the impact of cloud radiative effects on the simulated TTL temperatures using an RCM. We derive the cloud radiative effects based on satellite observations, which show heating rates in the troposphere but cooling rates in the stratosphere. We find that the cloud radiative effect warms the TTL by as much as 2 K but cools the lower stratosphere by as much as -1.5 K, resulting in a thicker TTL. With (without) considering cloud radiative effects, we obtain a convection top of approximate to 167 hPa (approximate to 150 hPa) with a temperature of approximate to 213 K (approximate to 209 K), and a cold point at approximate to 87 hPa (approximate to 94 hPa) with a temperature of approximate to 204 K (approximate to 204 K). Therefore, the cloud radiative effects widen the TTL by both lowering the convection-top height and enhancing the cold-point height. We also examine the impact of TTL cirrus radiative effects on the RCM-simulated temperatures. We find that the TTL cirrus warms the TTL with a maximum temperature increase of approximate to 1.3 K near 110 hPa.