Interannual Sea Surface Temperature Variability and the Predictability of Tropical Intraseasonal Variability

Abstract

Abstract The objective of this study is to examine the relationship between interannual SST variability and the activity and predictability of tropical intraseasonal variability (TISV). A 10-yr simulation forced by climatological SSTs and a 10-member 10-yr (1979–88) ensemble of simulations forced by observed SSTs from the NASA Goddard Laboratory for the Atmospheres GCM coupled to a weakly interacting slab ocean mixed layer are analyzed. The climatological simulation provides a measure of the natural variability associated with TISV, while the observed SST simulations provide an indication of how externally imposed SST anomalies modify this variability. Analysis is conducted on both the eastward-propagating (winter mode) and northeastward-propagating (summer mode) forms of TISV. Indices of TISV are constructed from the amplitude time series of the leading EOFs of intraseasonally bandpassed model precipitation and 850-hPa zonal wind. Analysis of the TISV activity indices from the climatological SST simulati...