青藏高原季节性降水的时空变化特征及其与海表温度的联系

Temporal and Spatial variation characteristics of seasonal precipitation over the Tibetan Plateau and its relationship with sea surface temperature

传统的动力学研究关注高原如何通过动力和热力作用影响亚洲气候和全球大气环流。然而对高原本身降水量变化及其危害缺乏系统评估,因此文章基于国家气象信息中心提供的日降水量、NOAA的海温资料(Sea Surface Temperature,SST)以及NCEP/NCAR的逐月位势高度场和风场的再分析资料,采用经验正交函数分析方法(Empirical Orthogonal Function,EOF)、回归分析、相关分析等方法探究了青藏高原降水的时空分布特征及其相关的海温和大气环流,从而对未来的防灾减灾以及生态环境保护提供意见和建议。结果表明:(1)高原降水量夏多冬少,春夏秋三季降水均由显著的年际变化;(2)春季在El Niño(La Niña)年、太平洋年代际振荡(Pacific Decadal Oscillation,PDO)处于正(负)位相或热带印度洋全区一致海温模态(Basin-Wide SSTA Variation In The Tropical Indian Ocean,IOBW)为正(负)位时,对应高原降水量以34°N为界南少北多(南多北少);(3)夏季当印度洋偶极子(Indian Ocean Dipole,IOD)为暖(冷)位相或Niño 1+2区海温偏高(低)时,有利(不利)于降水量呈现以30°N为分界线北多南少(南多北少)的分布;(4)春季高原低层850 hPa位势高度场呈现南正北负(北正南负),高层200 hPa贝湖反气旋(气旋)延伸至高原东北部,而东南部受低(高)压控制,导致以唐古拉山为界降水量北多南少(南多北少);(5)夏季低层高原西南侧为弱高(低)压,东北部为弱低(高)压,高层高原西南侧位于尼泊尔低压顶前,东北部处于华北高压底后,使得巴颜喀拉山以南降水量偏低(高),以北降水量偏高(低)。

Traditional dynamics studies have focused on how plateaus affect the Asian climate and global atmospheric circulation through dynamics and thermal interactions,but there is a lack of systematic assessment of precipitation changes and their hazards on the plateau itself.Therefore,based on the daily precipitation provided by the National Meteorological Information Center,the Sea Surface Temperature(SST)data of NOAA,and the monthly geopotential height field and wind field reanalysis data of NCEP/NCAR,this paper adopts the empirical orthogonal function(EOF),regression analysis,correlation analysis and other methods to explore the temporal and spatial distribution characteristics of precipitation and the related SST and atmospheric circulation on the Tibetan Plateau(TP),so as to provide opinions and suggestions for future disaster prevention,mitigation and ecological environment protection.The results show that:(1)The precipitation on the plateau is more in summer and less in winter,and the precipitation in spring,summer and autumn varies significantly from year to year.(2)In spring of the year El Niño(La Niña),when the Pacific Decadal Oscillation(PDO)is in the positive(or negative)phase or the consitent SST mode in the tropical Indian Ocean is positive(or negative),the corresponding plateau precipitation is bounded by 34°N and less south and more north(or more south and less north).(3)In summer,when the Indian Ocean Dipole(IOD)is in the warm(or cold)phase or the SST in the Niño 1+2 zone is high(or low),it is beneficial(or unfavorable)for precipitation,showing a districution of 30°N as the dividing line,more north and less south(or more south and less north).(4)In spring,the 850hPa geopotential height field in the lower layer of the plateau shows positive in the south and negative in the north(or positive in the north and negative in the south),and the Lake Baikal anticyclone(or cyclone)of the 200hPa geopotential height extends to the northeast of the TP,while the southeast is controlled by low(or high)pressure,resulting in more precipitation in the north and less in the south(or more in the south and less in the north)bounded by the Tanggula Mountains.(5)In summer,the southwest side of the plateau at low level is of weakly high(or low)pressure,while the northeast is of weakly low(or high)pressure;and the southwest side of the high-rise plateau is located in the front of the top of the Nepal low pressure,and the northeast is behind the bottom of the North China high pressure.As a result,the precipitation in the south of BayanKela Mountain is low(or high)and high(or low)in the north.