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Regional climate projections are developed four Central America and the Caribbean, based on a multiparameter ensemble formed by four configurations with different convective cumulus schemes with the regional model RegCM4 at 25 km grid spacing, driven by the HadGEM2‐ES global model under the RCP4.5 and RCP8.5 scenarios. The precipitation change projections indicate drier conditions compared to present in the near future (2020–2049) and far future (2070–2099) time slices. These drier conditions are statistically significant at the 90% confidence level over the eastern Caribbean, central Atlantic Ocean, and the western Pacific Ocean and are more pronounced in the far future time slice. For temperature, the warmer conditions are statistically significant at the 95% confidence level over the study region. The drier and warmer signals are greater in extension and magnitude in the RCP8.5 than for RCP4.5. Projected changes in precipitation and temperature extreme indices show a reduction of consecutive wet days and an increment of consecutive dry days, with a reduction of cold days and nights and an increase of warm days and nights. Lower precipitation along with increased intensity of extreme events are projected over the Greatest Antilles region. [ABSTRACT FROM AUTHOR]

The climate features over Central America and the Caribbean are simulated with the regional climate model RegCM4 to analyze the performance of the model in reproducing precipitation and temperature patterns over the region. Results from RegCM4 and the driving global climate model (GCM) HadGEM2-ES (HadG) are compared against gridded observations for a period from January 1980 to December 2004 using a perturbed physics ensemble formed by four configurations of the RegCM4 using different combinations of four convection schemes run over land and ocean areas: Kain Fritsch (Kf), Emanuel (Em), Grell (Ge), and Tiedtke (Tk). The added value of RegCM4 relative to the GCM simulation is also estimated, with focus over four subregions, using several metrics calculated on the RegCM4 as well as the GCM grids. The RegCM4 downscaling, expressed by the ensemble mean ENS, adds significant details to the HadG simulation of the temperature field patterns, showing smaller biases of up to ± 1.6 °C at the RCM resolution. Regarding the spatial patterns of precipitation, the HadG has overall higher correlation values with observations than ENS. However, the regional model provides more detailed spatial distributions, decreasing the bias by more than 1 mm/day over some of the islands. It also captures extreme precipitation events that are underestimated in the HadG simulation, even after upscaling to the GCM resolution grid. Concerning the performance of the different RegCM4 convection scheme combinations, KfEm and EmEm show the highest skill values for precipitation, while for temperature TkEm and GeEm are the best performing. This highlights that no individual scheme outperforms the others in all respects, while the application of the averaged ensemble technique provides the best results. [ABSTRACT FROM AUTHOR]

A sensitivity study of the performance of the RegCM4 regional climate model driven by the ERA Interim reanalysis is conducted for the Central America and Caribbean region. A set of numerical experiments are completed using four configurations of the model, with a horizontal grid spacing of 25 km for a period of 6 years (1998-2003), using three of the convective parameterization schemes implemented in the model, the Emanuel scheme, the Grell over land-Emanuel over ocean scheme and two configurations of the Tiedtke scheme. The objective of the study is to investigate the ability of each configuration to reproduce different characteristics of the temperature, circulation and precipitation fields for the dry and rainy seasons. All schemes simulate the general temperature and precipitation patterns over land reasonably well, with relatively high correlations compared to observation datasets, though in specific regions there are positive or negative biases, greater in the rainy season. We also focus on some circulation features relevant for the region, such as the Caribbean low level jet and sea breeze circulations over islands, which are simulated by the model with varied performance across the different configurations. We find that no model configuration assessed is best performing for all the analysis criteria selected, but the Tiedtke configurations, which include the capability of tuning in particular the exchanges between cloud and environment air, provide the most balanced range of biases across variables, with no outstanding systematic bias emerging. [ABSTRACT FROM AUTHOR]