新疆塔城地区大-暴雪特征及其与大气环流和海温的关系

Snowstorm characteristics and its relationship with atmospheric circulation and sea surface temperature in Tacheng Region,Xinjiang

利用1961—2018年新疆塔城地区气象观测站逐日观测数据、海表温度和环流指数数据,分析塔城地区大-暴雪时空分布及其与大气环流、海温之间的相互联系,结果表明:(1)塔城地区大-暴雪事件在空间分布上具有明显的分散性和局地性特征,塔额盆地发生频数最高,北部山地最少;近58 a平均频数为1.44次·a^(-1),年均降雪量为17.9 mm,且分别以0.16次·(10a)^(-1)、2.35 mm·(10a)^(-1)的速率不显著增加,其中42.9%的站点表现为显著增加趋势;大-暴雪事件主要出现在11月、12月和3月,占总数的65.2%。(2)塔城地区大-暴雪年频数与同期NAO/AO呈显著负相关(相关系数为-0.35/-0.46),与AAO、SOI相关不明显。(3)塔城地区大-暴雪年频数与同期海表温度指数(AMO、NTA、TSA、TNA、Niño3.4、Niño4)呈显著正相关,相关系数在0.27~0.45;不同区域的月尺度海表温度对大-暴雪月频数的影响存在明显差异,前期SST的异常信号对大-暴雪事件的发生具有预示意义。(4)近58 a大西洋海表温度呈显著升高趋势,有利于沿西风带向东输送的水汽含量增加,同时海温变化通过海气耦合作用影响和驱动中高纬度大气环流发生改变或异变,对其下游塔城地区大-暴雪事件产生重要影响。

Based on the daily observation data of seven national meteorological stations in the Tacheng Region,sea surface temperature(SST)and atmospheric circulation indices during 1961-2018,and using some mathematical statistical methods,such as the least-squares method,wavelet and correlation analyses,the temporal and spatial distribution of snowstorm and its relationship with atmospheric circulation and SST were analyzed.The results showed obvious dispersive and local characteristics on spatial distribution of snowstorm events.There was high frequency area in the Tacheng-Emin Basin,and the least area was in northern mountain area.The mean snowstorm was frequency 1.44 times per year,the annual average snowfall of snowstorm was 17.9 mm,and the processes snowfall was 12.5 mm per time.The snowstorm frequency was insignificantly increasing at the rate of 0.16 times per ten years and snowfall wasinsignificantly increasing at the rate of 2.35 mm per 10 years,and 42.9% of the stations were significantly increasing.Snowstorms mainly occurred in November,December and March,accounting for 65.2%.The snowstorm’s annual frequency negatively correlated with North Atlantic Oscillation or Arctic Oscillation index,their correlation coefficient was -0.35 or -0.46.The snowstorm events responded to SST indices,such as Atlantic Multidecadal Oscillation,North Tropical Atlantic SST index,Tropical Southern Atlantic index,Tropical Northern Atlantic index,East Central Tropical Pacific SST,and Central Tropical Pacific SST,their correlation coefficients were from 0.27 to 0.45.But it was obviously different that monthly SST from different regions affected on monthly frequency of snowstorm.The abnormal signal of SST in the early stage can predict the change monthly snowstorm’s frequency.For the past 58 years,SST of the Atlantic Ocean were a significant warming,the Northern hemisphere and Asia Polar vortex area(intensity)indices were decreasing(weakening)significantly,the North Atlantic-European circulation W pattern index was increasing insignificantly.Owing to the Atlantic SST significant increasing,moisture content was increasing in the upper ocean,which traveled into the westerlies.Simultaneously,the atmospheric circulation was changed in the middle and high latitudes,and the abnormal SST might cause the abnormal change of the atmospheric circulation,which might influence to the snowstorm events in Teacheng Region.