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The objective of this work was to analyze and compare results from two generations of global climate models (GCMs) simulations for the city of Recife-PE: CMIP3 and CMIP5. Differences and similarities in historical and future climate simulations are presented for four GCMs using CMIP3 scenarios A1B and A2 and for seven CMIP5 scenarios RCP4.5 and RCP8.5. The scale reduction technique applied to GCMs scenarios is statistical downscaling, employing the same set of large-scale atmospheric variables as predictors for both sets of scenarios, differing only in the type of reanalysis data used to characterize surface variables precipitation, maximum and minimum temperatures. For CMIP3 scenarios the simulated historical climate is 1961-1990 and CMIP5 is 1979-2000, and the validation period is ten years, 1991-2000 for CMIP3 and 2001-2010 for CMIP5. However, for both the future period analyzed is 2021-2050 and 2051-2080. Validation metrics indicated superior results from the historical simulations of CMIP5 over those of CMIP3 for precipitation and minimum and similar temperatures for maximum temperatures. For the future, both CMIP3 and CMIP5 scenarios indicate reduced precipitation and increased temperatures. The potencial evapotranspiration was calculated, projected to increase in scenarios A1B and A2 of CMIP3 and with behavior similar to that observed historically in scenarios RCP4.5 and 8.5.

The main economic activities of the Brazilian Northeast (NEB) are affected by the region's highly variable climate, requiring research into seasonal climate forecasting. In a work we show the results obtained after analysing the relationship between the main modes of NEB rainfall variability and lagged oceanic and atmospheric variable fields, that is, preceding rainfall. Consistent relationships were found between sea surface temperature (SST) in the Equatorial Pacific, Equatorial Atlantic and South Atlantic with NEB rainfall. Rossby wave patterns over the North Pacific that propagate from west to east to the Intertropical Convergence Zone (ITCZ), Walker Cell and Upper Bolivia have also been identified. In this research, the main objective was to identify the physical basis for the construction of linear regression models capable of predicting seasonal summer rainfall in the NEB, from the relationships between predictor-predictor. The adjusted regression model performed well between simulations and observations based on validation metrics and can be reliably indicated for operational climate forecasting systems.

The objective of this study was to identify heat islands and to evaluate the degree of thermal comfort / discomfort in selected urban areas. Landsat 5 and 8 satellite images were use in the thermal bands and, as a complement, observed data from meteorological stations present in the chosen cities. In order to evaluate heat islands and the degree of thermal comfort / discomfort, the surface temperature was obtain and the Kawamura Discomfort Index (IDK) was use. By means of surface temperature images, it was possible to identify the heat islands in these areas. For IDK, in spite of this index, in general, to present the situation of comfort, for some areas were observe situations of discomfort and heat stress due to the heat, mainly in the year of 2016, considered one of the hottest of this century. The use of observed data was necessary in order to corroborate with the information of the satellites.