The Fidelity of NCEP CFS Seasonal Hindcasts over Nordeste

Abstract

The fidelity of the interannual variability of precipitation over Nordeste is examined using the suite of the NCEP Climate Forecast System (CFS) seasonal hindcasts. These are coupled ocean?land?atmosphere multiseasonal integrations. It is shown that the Nordeste rainfall variability in the season of February?April has relatively low skill in the CFS seasonal hindcasts. Although Nordeste is a comparatively small region in the northeast of Brazil, the analysis indicates that the model has a large-scale error in the tropical Atlantic Ocean. The CFS exhibits a widespread El Niño?Southern Oscillation (ENSO) forcing over the tropical Atlantic Ocean. As a consequence of this remote ENSO forcing, the CFS builds an erroneous meridional SST gradient in the tropical Atlantic that is known from observations to be a critical forcing for the rainfall variability over Nordeste.