Changes in extreme events of temperature and precipitation over Xinjiang, northwest China, during 1960-2009

Based on daily surface air temperature (maximum, minimum and mean values) and precipitation records at 52 meteorological stations over Xinjiang, China, the spatial and temporal distributions of climate extremes are analyzed over the period 1960-2009. Twelve indices of extreme temperature and ten of extreme precipitation are studied. Temperature extremes show patterns consistent with a general warming trend, with most regions showing statistically significant changes for all the temperature-based indices. The regionally averaged occurrence of summer days, growing season length, tropical nights, warm spell duration indicator, warm nights and days have significantly increased by 2.14, 2.74, 1.71, 0.88, 6.23 and 3.59 days/decade, respectively. Over the same period, the occurrence of extreme ice days, frost days, cold spell duration indicator, cold nights and days show statistically significant decreasing trends at rates of 1.61, 3.69, 1.27, 6.57 and 2.6 days/decade, respectively. The diurnal temperature range (DTR) exhibits a decreasing trend of -0.26 degrees C/decade. With the exception of diurnal temperature range, the other temperature indices are strongly correlated with annual mean temperature. For precipitation indices, most precipitation indices show increasing trends in northern Xinjiang and exhibit decreasing trends in southern Xinjiang. Average maximum with 1-day and 5-day precipitation, very wet and extremely wet day precipitation, number of 10 and 20 mm precipitation days, consecutive wet days and averaged daily rainfall intensity show increasing trends whereas consecutive dry days decrease. In the meantime, annual total precipitation shows positive correlations with precipitation indices except consecutive dry days. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.