UTIG PhD student
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The Gulf of Mexico (GOM) is an integral component of tropical-to-extratropical heat transfer in the Western Hemisphere. Sea-surface temperature (SST) and sea-surface salinity (SSS) in the GOM strongly influence the moisture budget of North America. Oceanographically, the GOM is dynamically complex owing to the Loop Current, a surface current that transports 23 Sv (1 Sv = 106 m3s-1) of warm Caribbean waters through the Yucatan Strait into the GOM and ultimately flows out of the Florida Straits as a precursor to the Gulf Stream. The signature of the Loop Current is manifest as SST and SSS anomalies in the northern and western GOM through eddies. The brief length of the observational record however, limits us from knowledge of long-term (century-scale) variability in GOM oceanography. Understanding variability of GOM SSTs and SSS on these timescales is crucial in understanding North American hydroclimate variability and equally importantly, can give us key insights into Atlantic Ocean dynamics. Here, using a suite of well-dated sediment cores collected from the Garrison Basin, GOM, we reconstruct local SST and SSS variability during the late Holocene by employing planktic foraminiferal geochemistry. I will make a case in this talk that the reconstructed temperature and salinity variations at Garrison Basin are representative of large-scale climatic processes on centennial timescales. With a multiproxy analysis, we show that proxy data during the Little Ice Age (1450-1850 AD) display a spatially consistent pattern compared to low-frequency analysis of observational data. Our study provides strong evidence for a tight coupling between Atlantic Ocean dynamics and hydroclimate in the Western Hemisphere, during a time period where climatic background conditions were similar to the preindustrial era.