1971~2020年藏东南极端降水指数的时空变化特征

基于1971~2020年藏东南4个气象站逐日降水量资料，选取最大1日降水量（RX1day）、最大5日降水量（RX5day）、降水强度（SDII）、中雨日数（R10mm）、大雨日数（R20mm）、连续干燥日数（CDD）、连续湿润日数（CWD）、强降水量（R95pTOT）、极强降水量（R99pTOT）和年总降水量（PRCPTOT）共10个极端降水指数，采用线性趋势、Mann-Kendall非参数检验、R/S趋势分析、Morlet小波等方法，分析了藏东南极端降水指数的时空变化特征及其与大气环流指数、太阳黑子、海温指数之间的关系。结果表明:1971~2020年藏东南各极端降水指数变化幅度不大；RX1day、R20mm、CWD、R95pTOP、PRCPTOP呈下降趋势，尤其是近30 a（1991~2020年）PRCPTOP减幅显著，达?38.43 mm·10a?1；其他指数趋于增加，以CDD增幅最大（1.31 d·10a?1）。年代际变化尺度上，极端降水指数在20世纪90年代为正距平，21世纪前10年为负距平。极端降水指数的Hurst指数大多表现为较强或强持续性，未来将保持近50 a以来的变化趋势，仅CDD在2002年发生了气候突变。极端降水指数大多存在显著的3~4 a振荡周期。除CDD、CWD外，其他极端降水指数之间具有显著的正相关关系；而各极端降水指数均与年降水量、汛期降水量存在显著的相关性。多个极端降水指数与大气环流指数的相关性不显著，只有RX1day、RX5day、R95pTOT与亚洲极涡面积指数有显著的负相关，RX5day还与西太平洋副高强度指数有显著的正相关。绝大多数极端降水指数与太阳黑子的相关性不显著，仅有CWD与之有显著的正相关。RX5day、PRCPTOT和CDD与赤道太平洋次表层海温指数存在显著的相关关系。RX5day与印度洋暖池面积和强度指数存在显著的正相关，CWD与西太平洋暖池面积指数为显著的负相关。 

Spatio-temporal Change of Extreme Precipitation Index of Southeastern Tibet from 1971 to 2020

Based on the daily precipitation data of 4 meteorological stations in southeastern Tibet from 1971 to 2020, ten extreme precipitation indices were selected. By using the Mann-Kendall non-parametric test, R/S analysis, Morlet wavelet analysis, the temporal and spatial characteristics of extreme precipitation index in southeastern Tibet were analyzed. The results show that the extreme precipitation indices had little change in southeastern Tibet from 1971 to 2020. The RX1day, R20mm, CWD, R95pTOT and PRCPTOT appeared a decreasing trend, especially the PRCPTOT decreased significantly with a rate of ?38.43 mm·10a?1 in the past 30 years (1991~2020). Other indices tended to increase, with the CDD showed the highest value (1.31d·10a?1). In terms of decadal variations, the extreme precipitation indices were positive in the 1990s and negative in the first decade of the 21st century. The Hurst index of the extreme precipitation indices showed strong or stronger persistence, which would maintain the trend of nearly 50 years in the future. Only the CDD had an abrupt change in 2002. There were significant periods of 3 to 4 years for most extreme precipitation indices. Except for CDD and CWD, the other extreme precipitation indices had significant positive correlations with each other, and all extreme precipitation indices appeared significant correlations with annual precipitation and total precipitation during the flood season. It is also found that most of the EPI were insignificant correlated with the atmospheric circulation indices, and only RX1day, RX5day, R95pTOT had significant negative correlations with the Asian polar vortex area index, meanwhile there was the significant positive correlativity between RX5day and Western Pacific subtropical high intensity index. Only CWD was significantly positive correlated with sunspot. RX5day, PRCPTOT, CDD also had a significant correlation with the equatorial Pacific sub-surface SST index. RX5day was positively correlated with Indian Ocean warm pool area and intensity index, and CWD was negative correlated with the Western Pacific warm pool area index.