1960~2023年新疆塔城地区汛期极端降水指数时空变化特征及其对大气环流因子的响应

Temporal and Spatial Variation Characteristics and Its Response to Atmospheric Circulation Factors of Extreme Precipitation Index in Flood Season in Tacheng Area of Xinjiang from 1960 to 2023

摘要: 利用近64年(1960~2023年)新疆塔城地区7个气象观测站汛期(5~9月)降水资料，采用世界气象组织推荐的11个极端降水指数，分别讨论了其时空变化特征，探讨了其对大气环流因子的响应，结果表明：① 近64a塔城地区汛期极端降水指数除CDD和CDW呈不显著减少趋势外，其余各极端降水指数均呈不显著增多趋势。② 7站各极端降水指数变化趋势差异较大，其中RX1day、R50仅托里以1.16 mm/10a、0.29 d/10a的速率显著增多，R20仅额敏以0.22 d/10a的速率显著增多，CDD仅裕民、乌苏以−0.17 d/10a、−0.20 d/10a的速率显著减少。③ 三个区域中RX1day、R50盆地和南部不显著增多，中部不显著减少，RX5day、R95P、PRCPFOT三个区域均不显著增多，R10、R20、R99P盆地及中部不显著增多，南部不显著减少，SDII盆地不显著增多，南部及中部不显著减少，CDD盆地及南部不显著减少，中部不显著增多，CWD中部及南部不显著增多，盆地不显著减少。④ 对塔城地区RX5day、SDII、R20、R50、PRCPFOT影响较大的大气环流因子是欧亚纬向环流、西太平洋副高北界位置指数、印度副高面积指数、西太平洋副高面积指数、东太平洋副高面积指数、北美副高面积指数、印缅槽强度指数、北非–大西洋–北美副高面积指数，当上述大气环流因子出现且指数较大(正值)时，则有利于塔城地区汛期上述极端降水指数增多，反之，则减少。⑤ 对单站RX1day、RX5day、SDII、R20、R50、CDD、CWD、R95P影响较大的大气环流因子是北美副高面积指数、西太平洋副高面积指数、印度副高面积指数、东太平洋副高面积指数、北非–大西洋–北美副高面积指数、印缅槽强度指数、印度副高北界位置指数、西太平洋副高北界位置指数、西太平洋副高西伸脊点、北非副高脊线位置指数、北非–北大西洋–北美副高脊线位置指数，当上述大气环流因子出现指数较大(正值)时，则有利于单站极端降水指数增多，反之，则减少。⑥ 对盆地和南部RX1day、RX5day、SDII、R50、R95P、R99P影响较大的大气环流因子是印缅槽强度指数、北非–大西洋–北美副高面积指数、印度副高面积指数、西太平洋副高面积指数、东太平洋副高面积指数、北美副高面积指数、印度副高北界位置指数，当上述大气环流因子出现指数较大(正值)时，则有利于盆地或南部汛期上述极端降水指数增多，反之，则减少。

Abstract: Based on the precipitation data of seven meteorological observation stations in flood season (May to September) in recent 64 years (1960~2023), the temporal and spatial variation characteristics of 11 extreme precipitation indexes recommended by the World Meteorological Organization were discussed, and the corresponding atmospheric circulation factors were analyzed. The results showed that ① the extreme precipitation indexes in flood season in Tacheng area in recent 64 years showed no significant decreasing trend, except CDD and CDW. ② The trends in extreme precipitation indices vary considerably across the seven stations; RX1day and R50 increase significantly only in the Tuoli at a rate of 1.16 mm/10a, 0.29 d/10a; R20 increases significantly only in the Emin at a rate of 0.22 d/10a; CDD decreases significantly only in the Yumin and Wusu at rates −0.17 d/10a, −0.20 d/10a respectively. ③ Among the three regions RX1day and R50 show non-significant increases in the basin and southern region, and non-significant decreases in the central region. RX5day, R95P, and PRCPTOT show non-significant increases in all three regions. R10, R20, and R99P show non-significant increases in the basin and central region, and non-significant decreases in the southern region. SDII shows a non-significant increase in the basin and non-significant decreases in the southern and central regions. CDD shows non-significant decreases in the basin and southern region, and a non-significant increase in the central region. CWD shows non-significant increases in the central and southern regions, and a non-significant decrease in the basin. ④ The atmospheric circulation factors that have great influence on RX5day, SDII, R20, R50 and PRCPFOT in Tacheng area are Eurasian zonal circulation, northern boundary position index of western Pacific subtropical high, Indian subtropical high area index, western Pacific subtropical high area index, eastern Pacific subtropical high area index, North America subtropical high area index, Indo-Myanmar trough intensity index and North Africa-Atlantic-North America subtropical high area index. When the above atmospheric circulation factors appear and the index is large. ⑤ The atmospheric circulation factors that have great influence on RXDAY, RXDAY, SDII, R20, R50, CDD, CWD and R95P of single station are North American subtropical high area index, western Pacific subtropical high area index, Indian subtropical high area index, eastern Pacific subtropical high area index, North Africa-Atlantic-North America subtropical high area index, Indo-Myanmar trough intensity index, northern boundary position index of Indian subtropical high and western Pacific subtropical high. The western extension ridge point of the western Pacific subtropical high, the position index of the north African subtropical high ridge line and the position index of the north African-North Atlantic-North American subtropical high ridge line, when the above atmospheric circulation factors appear and the index is large (positive), are beneficial to the increase of the single-station extreme precipitation index, and vice versa. ⑥ The atmospheric circulation factors that have a considerable influence on RX1day, RX5day, SDII, R50, R95P, and R99P in the basin and southern region include the Indian-Burmese Trough Intensity Index, North Africa-Atlantic-North American Subtropical High Area Index, Indian Subtropical High Area Index, Western Pacific Subtropical High Area Index, Eastern Pacific Subtropical High Area Index, North American Subtropical High Area Index, and the Northern Boundary Position Index of the Indian Subtropical High. When these atmospheric circulation factors exhibit higher index values (positive anomalies), they are conducive to an increase in the basin or southern region during the flood season. Conversely, lower index values (negative anomalies) are associated with a decrease in these indices.