Wednesday, 1 May 2002: 2:15 PM
Tropical tropospheric temperature variations caused by ENSO and their influence on the remote tropical climate
The warming of the entire tropical troposphere to an El Nino is well established, if not well understood. This observation allows for a useful simplification of the tropical El Nino - Southern Oscillation (ENSO) teleconnection problem, through assuming that ENSO controls the interannual variability of tropical tropospheric temperatures. We examine the potential impact of this warming to tropical climate away from the ENSO region by examining the vertical adjustment of a single column model to imposed tropospheric temperature variations. The column model is set to predict the ENSO impact over P larger than E, P less than E, and no convection regions over a hypothetical mixed layer ocean. In both regions, model precipitation and sea surface temperature (SST) responds significantly to the forcing; in general, precipitation decreases and SST increases to warmer tropospheric temperatures. However, the amplitude and phase of precipitation and SST response depends on how fast the mixed layer ocean adjusts to the forcing. We analyze the model response to understand the underlying mechanisms behind the precipitation and SST variations. We show observational evidence that suggests our model results are applicable to SST and precipitation variability over the global tropics. In particular, our mechanism offers a simple explanation why the southeastern tropical Atlantic and southeastern tropical Indian ocean SST variability is not linked to ENSO. We discuss the implications of our results to ENSO teleconnections over the global tropics.
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