Further FGGE Forecasts for Amazon Basin Rainfall

Julio Buchmann Dept. de Meteorologia-Instituto do Geociencias, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

Search for other papers by Julio Buchmann in
Current site
Google Scholar
PubMed
Close
,
Jan Paegle Dept. of Meteorology, University of Utah, Salt Lake City, Utah

Search for other papers by Jan Paegle in
Current site
Google Scholar
PubMed
Close
,
Lawrence Buja Dept. of Meteorology, University of Utah, Salt Lake City, Utah

Search for other papers by Lawrence Buja in
Current site
Google Scholar
PubMed
Close
, and
R. E. Dickinson National Center for Atmospheric Research, Boulder, Colorado

Search for other papers by R. E. Dickinson in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

A series of experiments using real-data general circulation model integrations is performed to study the impact of remote tropical Pacific heating modifications upon the rainfall over the Amazon Basin. In one set of experiments, a heating term is added to the thermodynamic equation in the western tropical Pacific Ocean, and in the second set, the sea surface temperatures are cooled in the eastern Pacific Ocean. The rainfall of northern sections of South America decreases in the first set of experiments and increases in the second set of experiments. Examination of the circulation changes for the second set of experiments suggests that the remote links occur through equatorially trapped flow modifications, perhaps related to the east-west Walker cells, rather than through midlatitude teleconnections via Hadley cells. The time evolution of these patterns suggests them to be clearly relevant for medium range weather prediction in the tropics.

Abstract

A series of experiments using real-data general circulation model integrations is performed to study the impact of remote tropical Pacific heating modifications upon the rainfall over the Amazon Basin. In one set of experiments, a heating term is added to the thermodynamic equation in the western tropical Pacific Ocean, and in the second set, the sea surface temperatures are cooled in the eastern Pacific Ocean. The rainfall of northern sections of South America decreases in the first set of experiments and increases in the second set of experiments. Examination of the circulation changes for the second set of experiments suggests that the remote links occur through equatorially trapped flow modifications, perhaps related to the east-west Walker cells, rather than through midlatitude teleconnections via Hadley cells. The time evolution of these patterns suggests them to be clearly relevant for medium range weather prediction in the tropics.

Save