The Variation of Extreme Temperature and Precipitation in Shandong Province during 1961-2008

We drew on data of daily average temperature,average maximum temperature,average minimum temperature and precipitation from 78 meteorological stations during 1961-2008 of Shandong Province,analyzed the variation of extreme temperature and precipitation events.The results showed that although extreme cold days decreased by 0.23 d/a on average,after the average temperature steadily passed 10 ℃ in spring,it would still appear 1-2 days of frost,wheat and fruit trees would still suffer frozen injury every year in the central Shandong and the inland of Shandong Peninsula.Although the number of annual extreme hot days has an increasing trend obviously in Shandong and increased by 0.19 days a year.After 2000,aimed at the days of daily maximum temperature ≥ 35 ℃,the mean value and standard deviation of daily maximum temperature in summer decreased comparing with the normal year in West Shandong,and decreased by 1-3 days.In recent 50 years,the extreme precipitation trend increased,but not statistically significant.The number of light rain days has a decreasing trend and decreased by 0.17 days every year,in contrast,the frequency of downpour has an increasing trend.

Changes in Daily Climate Extremes of Observed Temperature and Precipitation in China

Daily precipitation for 1960-2011 and maximum/minimum temperature extremes for 1960-2008 recorded at 549 stations in China are utilized to investigate climate extreme variations.A set of indices is derived and analyzed with a main focus on the trends and variabilities of daily extreme occurrences.Results show significant increases in daily extreme warm temperatures and decreases in daily extreme cold temperatures,defined as the number of days in which daily maximum temperature （Tmax） and daily minimum temperature （Tmin） are greater than the 90th percentile and less than thel0th percentile,respectively.Generally,the trend magnitudes are larger in indices derived from Tmin than those from Tmax.Trends of percentile-based precipitation indices show distinct spatial patterns with increases in heavy precipitation events,defined as the top 95th percentile of daily precipitation,in westem and northeastern China and in the low reaches of the Yangtze River basin region,and slight decreases in other areas.Light precipitation,defined as the tail of the 5th percentile of daily precipitation,however,decreases in most areas.The annual maximum consecutive dry days （CDD） show an increasing trend in southem China and the middle-low reach of the Yellow River basin,while the annual maximum consecutive wet days （CWD） displays a downtrend over most regions except western China.These indices vary significantly with regions and seasons.Overall,occurrences of extreme events in China are more frequent,particularly the night time extreme temperature,and landmasses in China become warmer and wetter.

Inhomogeneous trends in the onset date of extreme hot days in China over the last five decades

Using a homogenized daily maximum temperature(T_(max))dataset across China,this study characterized the spatiotemporal variation of the onset date of extreme hot days in a year(i.e.,FirstEHD)during 1960-2018.Inhomogeneous trends of FirstEHD over China during 1960-2018 can be found,with the advanced trend of FirstEHD over most parts in China,while a number of stations in North-Central China(NC)show the delayed trend of FirstEHD.Moreover,there exist interdecadal changes of FirstEHD trend,with a remarkable difference in the trend magnitude before and after the 1990s over South China(SC),and the sign of trend can even reverse from negative to positive after the 1990s in Xinjiang(XJ)and Yangtze River Basin(YR),and from positive to negative in NC.The overall trends of FirstEHD over NC,YR,and XJ during 1960-2018 are dominated by the trends before the 1990s,while they are dominated by the sharp advance after the 1990s over SC.It is further found that the trend of FirstEHD can generally be explained by the long-term trend in T_(max) over most parts of China,but the contribution from T_(max) variabilities is also non-negligible and can even account for more than 75% of the overall trend over NC.The possible factors responsible for the decadal changes in FirstEHD trends are also discussed.

华北农牧交错带极端高温时空分布特征

利用华北农牧交错带及其附近32个气象站点1961-2012年的逐日最高地面气温资料,采用去趋势波动分析法确定了极端高温事件的阈值,分析了华北农牧交错带极端高温日数和极端高温日平均最高气温的时空动态变化特征。结果表明:52a来,华北农牧交错带极端高温主要集中于5-8月,年均极端高温日数为1 d,极端高温日平均最高气温为36.9℃,两者分别从20世纪80和90年代由负距平转为正距平,均存在25~30 a的显著振荡周期;极端高温在空间分布上具有海拔依赖性,极端高温日数有显著的代际变化特征,并以20世纪90年代为界呈现两种不同的分布形态,极端高温日平均最高气温分布相对稳定;21世纪最初的12 a,华北农牧交错带各站点极端高温日数、极端高温日平均最高气温均呈增大的趋势。