Extreme Events Detection and 21st Century Projections in The Intra-America Region

The Intra-America Region (IAR) comprises the Caribbean, the Gulf of Mexico, northern South America, and Central America.  The climate of the region is driven by complex atmospheric processes and it is very sensitive to a regional warming. A recently (1982-2012) IAR warming was detected in the region using high resolution blended satellite remote sensing products, where the annual average Sea Surface Temperatures (SSTs) indicate a continuous regional warming with a rate of increase of 0.4^oC per decade. Furthermore, a warmer region leads to a warmer atmosphere and a higher relative humidity driving the heat index (HI) climatology and trends. Since the 1990s the HI time variation points out a suddenly and accelerated heat index increases at an annual rate of 0.08^oC per year with high potential to intensify heat waves. The heat waves frequency indicates noticeable changes since the 80s. During this last period of time, the heat waves amplitude decreases while the frequency is increasing. On the other hand, the rainfall intensity in the region is driven by a unique convergence of multiple ageostrophic atmospheric processes, such as El Niño event, surface wind divergence, and the Saharan dust (SD). The rainfall reduction is quantified by mean of the standardized precipitation index (SPI), which is a measurement of drought events. Long term SPI averaged over the Caribbean region and for the early rainfall season (April-July) point out a permanent decreasing trend with a rate of -0.014 per year. Positive Multivariate ENSO Index (MEI) indicates that El Niño event from May to July cause negative SPI, while SD concentration shows good agreement with the SPI tendency, following an inverse relationship.

Q second main goal of this work is to project these recently observed trends into the 21^st Century.  The fifth phase of the Coupled Model Intercomparison Project (CMPI5) provides a series of numerical experiments under the IPCC scenarios. Six General Circulation Models were selected, covering the years 2006 to 2100, to project heat waves and drought events for the IAR. The air temperature and heat index averaged across the IAR, indicates a very fast increasing rate of change (0.16^oC and 0.3^oC per decade, respectively), enhancing the probability of higher heat strokes in the future. Furthermore, water content in the atmosphere will decrease at a negative rate of -0.06% per decade (relative humidity), decreasing the rainfall production of the region and hence a drought intensification.