Cloud radiative effect on tropical troposphere to stratosphere transport represented in a largescale model

[1] GFDL AM2 model simulations are analyzed to assess the simulated radiative effect of tropical tropopause layer (TTL) cirrus on tropical troposphere-to-stratosphere transport (TST). The strongest upward motion in the model’s TTL is generally driven by dynamics instead of radiation, occurring in those TTL cloudy regions that overlap with optically thick clouds in the upper troposphere (UT). However, the occurrence frequency of such strong ascent is about one order of magnitude smaller than that of moderate ascent related to the radiative effect of TTL cirrus. The mean upward velocity of moderate ascent in the cloudy regions ( 2.5— 3.5 hPa/day) is one order of magnitude larger than that induced by TTL clear-sky radiative heating ( 0.18 hPa/day). This supports the hypothesis that cirrus radiative heating contributes substantially to the average tropical TST rates. The implication for future model-satellite comparisons is discussed. Citation: Huang, X., and H. Su (2008), Cloud radiative effect on tropical troposphere to stratosphere transport represented in a large-scale model, Geophys. Res. Lett., 35, L21806, doi:10.1029/2008GL035673.