Utilizing Observations and Coral Reconstructions to Analyze the Variability of Sea Surface Temperatures in the Intra-Americas Sea

Abstract

The Intra-Americas Sea (IAS) includes the Gulf of Mexico and Caribbean, regions relatively understudied in comparison to the larger Atlantic, considering their importance in moisture transport across the United States, Central and South America. The influence of the IAS on hydroclimate in these regions is substantial and has been connected to various processes including tropical storms, the springtime sea surface temperature anomaly dipole and the Atlantic warm pool. However, observational records are not long enough to fully understand variability in this region, particularly on decadal, multi-decadal, and longer timescales and can disagree on signals. A typical springtime dipole is noted by cooler sea surface temperatures in the Gulf of Mexico and warmer in the Caribbean and has been linked to precipitation anomalies in the eastern US and much of the Amazon region. In boreal summer, the Atlantic warm pool is a phenomenon marked by anomalously warm sea surface temperatures, critical for hurricane development. This study uses observations, coral-based reconstructions, and climate model data from the nineteenth to the twenty-first century to examine the variability of the springtime dipole in the IAS and how it impacts the Atlantic warm pool. Coral data was retrieved from CoralHydro2k with the addition of new records near Tobago, Cuba, and Flower Garden Banks. Each record found enhanced warming in the Caribbean compared to the GOM. The reduction of the Loop Current inhibits warm Caribbean SSTs from warming the GOM, a potential cause of this trend difference between regions. Power spectra analysis found significant periods in each region within the periodicities for El Ni\~no Southern Oscillation and Pacific Decadal Oscillation, in agreement with previous studies. During dipole years, in which the average was approximately 4 per decade, warmer sea surface temperature anomalies dominate the IAS in the following summer months through the end of the Atlantic hurricane season. Following a springtime dipole, the Atlantic warm pool increases in extent and intensity when compared to non-dipole years. Non-dipole years display the opposite pattern with cooler sea surface temperature anomalies dominating the IAS in the summer and hurricane season. Climate projections indicate an increase in intensity of weather events such as extreme precipitation, drought as well as enhanced Atlantic hurricane seasons, all of which are particularly impactful to coastal communities lacking adaptive and resilient infrastructure in the Intra-Americas Region. Through the use of observations, models and proxy data, a better understanding of the variability of sea surface temperatures in the IAS will help these regions prepare for a changing climate.