RESUMEN
Climate change is increasing the intensity of extreme climate events. Significant impacts of extreme climate events on human society and ecosystem have occurred in many places of the world, for example, Southwest China (SWC). In this study, the daily temperature and precipitation data from 438 meteorological stations are used to analyze the variation characteristics of extreme climate events in the SWC from 1961 to 2017. The annual extreme warm events show a significant increasing trend at 99% confidence level at most stations, and a few stations with a decreasing trend are mainly located in the southern Sichuan Province, the northern Yunnan Province and the western Guizhou Province. Meanwhile, the annual extreme cold events show a significant decreasing trend at 99% confidence level at most stations, and a few stations with an increasing trend are mainly distributed in the Sichuan Basin. Both the annual extreme heavy precipitation indexes and rainstorm indexes show nonsignificant increasing trends, but they differ greatly in the spatial distribution. These indexes in the western Tibet, Chongqing and most parts of Guizhou show significant increasing trends at 95% confidence level, while those in the central Sichuan and southeastern Yunnan show significant decreasing trends. The percentage of extreme heavy precipitation shows a significant increasing trend at 99% confidence level, especially in the northeastern Sichuan, the central-eastern Guizhou and the central Yunnan. Overall, under the background of global warming, the extreme warm events in SWC increase significantly from 1961 to 2017, and the extreme cold events decrease significantly. The variation trends of extreme precipitation events differ greatly in different regions, and the percentage of extreme heavy precipitation increases significantly.
RESUMEN
Based on 99 clear sky Terra satellite images of Chengdu City in 2005-2010, and by using a novel automatic extraction method of suburb temperature, i. e., each city-circle temperature jump, this paper studied the spatiotemporal variation characteristics of the urban heat island (UHI) effect in the City in 2005-2010, and analyzed the causes of the variation characteristics. In the study period, the central area of the largest and strongest UHI was in the Jinhua Town located in the southwest of Chengdu. The UHI effect had no significant spatial variation, but the range and intensity of the UHI effect tented to be decreased. The intra-annual UHI intensity and area within the ring roads showed a three-peak distribution pattern, with the peak values appeared in April, July, and October, and the intensity reached the maximum in July. The UHI intensity in Chengdu was attenuated by the decrease of air temperature and the increase of precipitation and urban vegetation cover.
