1971-2017年羌塘国家级自然保护区持续干旱日数的时空变化特征

为全面分析羌塘国家级自然保护区的干旱变化特征,有效应对干旱风险和生态环境保护。本文采用利用5个气象站点1971－2016 年逐日降水量资料,以持续干旱日数(CDD)为干旱评价指标,采用线性回归、Mann-Kendall非参数检验和R/S分析等方法,分析了自然保护区CDD的时空变化特征。结果表明：多年平均下,自然保护区各站CDD为78～162 d,总体呈自西向东递减分布；CDD偏多概率为51.1%。近47年保护区CDD呈减少趋势,平均每10年减少3.4 d；20世纪90年代以来,CDD趋于增加。70年代CDD明显偏多,为近40年最多的10年；80年代至21世纪前10年基本正常。CDD异常特多年份出现过2次,均发生20世纪90年代；未出现异常特少年份。在时间转折上,保护区CDD的突变点出现在1980年, 从一个相对偏多期跃变为一个相对偏少期。根据R/S分析,保护区CDD的Hurst指数大于0.5,说明未来仍将趋于减少。

Spatial-temporal Change of Consecutive Dry Days in Changtang National Nature Reserve of Tibet During 1971-2017

The paper aims to comprehensively analyze the drought characteristics of Chang Tang national nature reserve region of Tibet during 1971-2017 and effectively response to drought risk and ecological environmental protection. The authors obtained the spatial-temporal drought distribution characteristics of Chang Tang national nature reserve region by using daily precipitation data of 5 meteorological stations from 1971 to 2017 with drought evaluation indicator as the Consecutive Dry Days (CDD) and statistical methods like linear regression, Mann-Kendall test and rescaled range analysis (R/S analysis) et al. The results shows that: On a multi-year average, the CDD ofSeachSstation were 78-162 days in nature reserve region, and the distribution was decreasing from eastern to western, as well as the probability of more CDD was 51.1%. The CDD exhibited decreasing trend with a rate of 3.4 d/10a in nature reserve region during the recent 47 years, and it increasing trend since the 1990s. On the decadal scale, the CDD was more in the 1970s and normal during 1980s to 2100s, in addition the CDD was the highest in the 1970s during the past 47 years. Also, the CDD were more anomalous years in the 1990s with a frequency of 2 times, whereas less anomalous years not occurred. According to the Mann-Kendall test, the abrupt change of CDD occurred in 1980, indicating a change from the more period to the less one. The results of R/S analysis showed that changes of CDD had the persistence with a Hurst index of larger than 0.5 in nature reserve, which indicates that it will assume continuous decrease in future.