In the tropical Atlantic, we can find astrong air-sea coupled variability as we alsocan realize that the air-sea coupled ENSOdominates in the tropical Pacific. The configuration of the Atlantic coupled variability, however, is very much different from that in the Pacific. An equatorial symmetric cold tongue expands from the eastern boundary into the central basin in the Pacific. Whereas, in the Atlantic, an equatorial anti-symmetric pattern is seen in the SST and SLP fields.As many studies showed before, the tropical dipole mode is associated with a migration of the Atlantic ITCZ.
However, the dipole mode is not the only mode of SST variability in the tropical Atlantic. A scatter plot of zonal mean SST and SLP anomalies in 10-20degree latitudinal bands presents an apparent inter- hemispheric decorrelation in both SST and SLP fields.In the present study, we further examine this inter-hemispheric relation in the SST variability from different perspective.
For the present study, we construct 4 degree longitude by 4degree latitude monthly averaged marine meteorological data sets from quality controlled ship and buoy observations, compiled in Long Marine Reports of COADS. We will examine SST, SLP, vector and scalar surface wind, sensible and latent heat fluxes. A higher resolution data set of cloudiness is also included here. We also complement the COADS with the NCEP reanalysis because COADS observations in the South Atlantic may suffer large sampling errors due to few ship observations. For example, the NCEP provides dynamically-consistent SLP and wind velocity data. In contrast, grid point values of COADS are calculated from independent observations of SLP and wind velocity. We would like to take both advantages into our study.