Atmospheric circulation associated with the arrival of sargassum in the Caribbean Sea.

The arrival of sargassum in a massive way generates adverse environmental, social and economic impacts. Little is known about its origin and trajectory, as well as the atmospheric and oceanic conditions under which it arrives at the Mexican coasts of the Caribbean. This poster presents a diagnosis of the seasonal, annual and interannual variability of atmospheric circulations in the Atlantic and Caribbean Sea, identifying the atmospheric conditions under which sargassum arrived on the Mexican coasts. 30 years of surface wind data from CFSR (Climate Forecast System Reanalysis) of NCAR on the Atlantic and Caribbean were analyzed, dividing the area into six areas, for each one its seasonal, annual and interannual variability was estimated, as well as its extreme values from 1989 to 2018, focusing the study on both the Caribbean Sea and the Atlantic coast of Brazil.

Once the mean, extreme winds (10th and 90th percentiles) and their correlation with the NAO (North Atlantic Oscillation) were diagnosed interannually, particular years of the recent period were analyzed: from 2010 to 2019 incorporating the wind convergence as a physical process associated with the accumulation of sargassum, surface pressure and sea surface temperature (SST) and also correlating it with the NAO index.

The results show that the atmospheric conditions for transporting sargassum along the Mexican coasts of the Caribbean are more favorable in summer than in winter, besides it, the higher extremes (90th percentile) in the Caribbean favor the transport of sargassum both in winter and in summer. However, "connectivity" with other regions (Central Atlantic) makes summer more favorable, but winter is potentially viable. The atmospheric conditions of recent extreme years are discussed: 2013 (without the arrival of sargassum), medium: 2015 and extreme 2018 (with abundant sargassum) for both summer and winter.