Extreme event changes of air temperature in Ningxia in recent 50 years

With the sustained global climatic warming,extreme weather and climate events occurred frequently and the number of meteorological disasters is growing.Deeply understanding the characteristics of the extreme climate could provide a reference basis for disaster forecast and prevention.So in this paper,the spatial and temporal variability of extreme events of temperature in recent 50 years was analyzed using the methods of regression analysis,inverse distance weighted and rescaled range analysis and ten indices of extreme temperature.With the analysis,the extremely temperature variation in the future was predicted.The thresholds of the extreme high temperature days and the extreme low temperature days were determined for different stations.The results are as follows: all-day warm days,warm days,warm nights,growing season length and summer days have significantly increased by 0.76,0.48,0.67,0.35 and 0.29 d/a,respectively;over the same period,all-day cold days,cold days,cold nights and consecutive frost days have significantly decreased by-0.40,-0.25,-0.66 and-0.30 d/a,respectively;the annual temperature range exhibits a decreasing trend(-0.02℃/a);in spite of the above-mentioned main trend in most parts,the differences in spatial distribution still exist significantly;except for the annual temperature range,other indices correlate with annual mean temperature very well;cold extremes and annual temperature range would keep decreasing while warm extremes would continue rising;the damage and effect caused by meteorological disasters would become more and more extensive in Ningxia.