Variation of dry-wet climate and its correlation with El Nino-Southern Oscillation and Pacific decadal oscillation in North China during 1961-2020
To identify the dry and wet characteristics of meteorology under climate change conditions and their relationship with atmospheric circulation,based on the long-term daily data measured at 64 meteorological stations in North China during 1960-2020,Using standardized Precipitation Evapotranspiration Index(SPEI)sa dry-wet,the climate tendency rate and Mann-Kendall trend test are used to investigate the spatial-temporal characteristics of droughts and floods from 1961 to 2020 in the North China,the influences of El Nino Southern Oscillation(ENSO)and Pacific Decadal Oscillation(PDO)on the drought-flood threshold over North China during 1961-2020 are analyzed.The precipitation in North China had a periodic change of 10～20 years in the past 60 years,the overall annual SPEI of North China fluctuated stably and did not follow an obvious linear growth trend,and the drought situation was alleviating in North China.The frequencies of mild drought(flood)and moderate drought(flood)were relatively high,while the frequencies of severe drought(flood)and extreme drought(flood)were relatively low.The frequencies of flood at most stations in North China were greater than that of droughts.In terms of spatial distribution,a real differentiation between the frequency of drought and flood in North China was obvious.The high frequency area of flood was located in the eastern part of Shanxi,the cen-tral and southern part of Hebei,the northern part of Henan,and the western part of Shandong hills,the frequen-cy of drought was relatively high in Beijing-Tianjin region,north-central Hebei and western Shanxi.Drought and flood alternated in North China and were controlled by multiple periodic laws.The SPEI sequence fluctuated significantly on the scale of 4a,23 a and 34a in North China.The alternation of drought and flood in North China for about 20 years was the result of atmospheric circulation anomalies.Drought was frequent during EI Nino,and flood was frequent during La Nina.The drought events occurred frequently in the PDO positive phase,the flood events occurred frequently in the PDO negative phase.sea surface temperature anomaly had a significant negative correlation with SPEI in annual and summer time scales,PDO and SPEI in North China are significantly nega-tively correlated in summer and winter scales.
SPEIvariation of droughts and floodsEl Nino Southern OscillationPacific decadal oscillationNorth China
NETL
NSTL
万方数据
