Quantifying the changing properties of climate extremes in Guangdong Province using individual and integrated climate indices.

ABSTRACT The temporal and spatial trends of four climate extreme indices for Guangdong Province of China were calculated based on observed daily precipitation, daily maximum, and daily minimum temperatures at 24 weather stations as well as the frequency of typhoon events during the period of 1957-2013. An integrated extreme climatic index ( IECI) was derived from four individual climate extreme indices (high temperature days ( H_td), low temperature days ( L_td), intensive precipitation days ( I_pd) and number of typhoon events ( TT)), considering their weights using an information theory model. A simple linear regression model was utilized to analyze the spatiotemporal trends of the climate extremes. The correlation analysis between the above extreme climatic indices and the socioeconomic losses [affected area of crops ( AAC), direct losses of the economy ( DLE), and affected population ( AP)] was calculated. The results indicate that H_td increased while L_td decreased significantly at the 5% significance level. By contrast, there were no significant long-term changes in I_pd and TT. The rate of change of IECI was 0.006 per decade and no long-term trend was detected in IECI. Spatially, a positive trend was observed in the Yuexi River Basin ( YXRB) for I_pd, while a negative trend was found in the East River Basin ( ERB). L_td followed an opposite spatial pattern to that of H_td. Extreme temperature days occurred more frequently in the Pearl River Delta ( PRD) than in other parts of Guangdong Province. Regions with positive IECI rates of change were mostly in the YXRB, the coastal area of the Yuedong River Basin ( YDRB) and the northern and southern part of the ERB. The correlation coefficients between IECI and AAC, DLE, and AP are 0.375, 0.424 and 0.603, respectively. In general, IECI correlated more strongly with the loss indices caused by extreme climatic events than did the four individual extreme climatic indices. [ABSTRACT FROM AUTHOR]