Recorded presentation14.2
The Intra-Americas Sea springtime temperature dipole as fingerprint of remote influences
Ernesto Muņoz, NOAA/AOML, Miami, FL; and C. Wang and D. B. Enfield
The influence of teleconnections on the Intra-Americas Sea (IAS; Gulf of Mexico and Caribbean Sea) has been mostly analyzed from the perspective of the El Nino Southern Oscillation (ENSO) on the Caribbean Sea (the latter being an extension of the tropical North Atlantic). This emphasis has overlooked: 1) the influence of other teleconnections on the IAS and 2) which teleconnections affect the Gulf of Mexico climate variability. In this study we analyze the different fingerprints that major teleconnection patterns have on the IAS during boreal spring. Indices of teleconnection patterns are regressed and correlated to observations of oceanic temperature and atmospheric data from reanalyses and observational data sets. We find that the Pacific teleconnection patterns that influence the IAS SSTs do so affecting the Gulf of Mexico in an opposite manner to the Caribbean Sea. For example, during a warm ENSO event the Caribbean warms but the Gulf of Mexico cools concurrently. A similar behavior is observed for the Pacific Decadal Oscillation (PDO) and the Pacific North American pattern (PNA) influences on the IAS. The North Atlantic Oscillation (NAO) is related to a lesser degree than the Pacific teleconnection patterns. By calculating an index that represents the IAS SST anomaly dipole we find that the dipole forms mostly in response to changes in the air-sea heat fluxes. In the Gulf of Mexico the dominant mechanisms are the air-sea differences in humidity and temperature. The changes in shortwave radiation also contribute to the dipole of net air-sea heat flux. The changes in shortwave radiation arise, in part, by the cloudiness triggered by the air-sea differences in humidity, and also by the changes in the convection cell that connects the Amazon basin to the IAS. Weaker Amazon convection (e.g., in the event of a warm ENSO event) reduces the subsidence over the IAS and henceforth the IAS cloudiness increases (and the shortwave radiation decreases). This study contributes to a greater understanding of how the Intra-Americas Sea is influenced by different Pacific and Atlantic teleconnections.
Session 14, Coupled ocean-atmosphere interactions and their contribution to climate variability on all time scales: Part 3
Thursday, 15 January 2009, 1:30 PM-3:00 PM, Room 128AB
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