Thursday, 17 January 2002: 11:15 AM
Observations of Atlantic Convergence Zones by QuikSCAT and TRMM
Applying observations from spaceborne microwave scatterometers and radiometers, seasonal and interannual variations associated with Atlantic convergence zones are investigated. The spacebased measurements include surface wind vectors, sea surface temperature (SST), integrated water vapor, cloud liquid water, and precipitation rate. With the advantage of high spatial and temporal resolution of data, we reveal the existence of a second convergence zone in the southern Atlantic ocean during austral winter, which is the counterpart of the northern Atlantic ITCZ. This secondary convergence zone extends from the eastern tip of Amazon at about 7S to the middle of Atlantic ocean, with coherent structure of SST, surface wind divergence, rainfall, and sea level change. The preferred timing of this convergence zone is consistent with the seasonal march of the equatorial cold tongue. Relationship between the Amazon rainfall and the Atlantic convergence zones, as well as the remote link to the tropical Pacific on interannual time scale, will be discussed.