The observed teleconnection between the equatorial Amazon and the Intra-Americas Seas
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Using observations of rainfall and SST analysis it is shown that there is a robust relationship with two-season lag between the austral summer (December–January–February [DJF]) Equatorial Amazon (EA) rainfall and the following boreal summer season (June–July–August [JJA]) Intra-Americas Seas (IAS) Sea Surface Temperature Anomalies (SSTA). It is observed that in wetter than normal austral summer seasons over EA, the SSTA in the IAS are cooler than normal in the following JJA season. This teleconnection also manifests in the ocean heat content of the IAS region. Our analysis indicates that the net surface heat flux into the ocean (particularly the surface longwave and the shortwave radiative fluxes) dictates the strongest influence on the JJA Caribbean SSTA, the core region of the IAS where the observed teleconnection with EA rainfall is strongest. This study also finds that this teleconnection is in fact a manifestation of the remote ENSO forcing on the Caribbean SSTA through its modulation of the EA rainfall anomalies. In a wet DJF year over EA, the Atlantic Inter-Tropical Convergence Zone (ITCZ) moves further southward than climatology. This causes the dry limb of the associated overturning circulation of the Atlantic ITCZ to reside over the Caribbean Sea region in the subsequent March–April–May and JJA seasons. As a result of this large-scale descent in the wet DJF year over EA, there is a net decrease in the heat flux into the ocean from increased emission of surface longwave radiation in the presence of anomalously dry atmosphere. In a dry DJF year over EA the Atlantic ITCZ is nearly co-located in the core region of the IAS, which is northward than the climatological location, resulting in the descending limb of the overturning location to be located further south of the Caribbean Sea leading to warmer SSTA.
KeywordsClimate Forecast System Reanalysis Ocean Heat Content Ensemble Empirical Mode Decomposition North Atlantic Subtropical High Atlantic ITCZ
This work was supported by NOAA grant NA07OAR4310221, CDC grant U01EH000421. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the acknowledged funding agencies.
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