Numerical Experiments on Interaction Between Tropical Pacific and Tropical Atlantic Through the Windstress “BRIDGE”

Abstract

AbstractInteraction between the tropical Pacific and the tropical Atlantic through the wind stress bridge was numerically studied with intermediate models of global tropical atmosphere and ocean. In a control experiment, the atmospheric model was run from 1958 to 1998 with observed monthly SST data taken from NCEP reanalysis to generate surface wind stress, and with which the oceanic model was run over the same period with the heat flux taken and/or calculated from NCEP reanalysis data to generate SST. In a parallel experiment, everything is the same as in the control run except that the SST used to force the atmospheric model was fixed to climatological mean in a basin (say, the tropical Pacific or the tropical Atlantic). The difference between the control and parallel experiments indicates how the SST anomaly (SSTA) in one basin influences the other through the wind stress bridge. The main results are as follows. In general, the warm SSTA in one basin locally produces westerly anomaly in the west and easterly anomaly in the east, and vice versa. For a warm SSTA in the tropical Pacific, the surface easterly anomaly in the east of the basin extends into the tropical Atlantic, inducing a cold SSTA there, and vice versa. For a warm SSTA in the tropical Atlantic, the surface westerly anomaly in the west of the basin extends into tropical Pacific, inducing a warm SSTA there.