Influence of the Subtropical High over Western Pacific on the Difference between Precipitation and Evaporation in North China

The influence of the subtropical high over western Pacific(STH) on the difference between precipitation and evaporation(DPE) in North China are analyzed by the wavelet cross-correlation and cross wavelet transform as well as anomalous circulation analysis methods.The results show that the surface water resource lack is weakening in the middle and south part of North China after 2000,but continuing at the area of around Beijing in the northeast part of North China.There are significant correlation oscillations of interannual and interdecadal scales between the DPE in North China and the location of ridge line and northern limit of STH,and the coherence of interdecadal correlation between the DPE and the STH ridge line is higher then the coherence of interdecadal correlation between the DPE and the STH northern limit.The significance of interdecadal correlation is exhibited at a stage and the interannual correlations are localized in the period from 1955 to 2007.It is found that the main reason of the increasing of DPE in the middle and south part of North China since 2000 is the northward advancing of the STH ridge line and northern limit and the strengthening of the southeast current in the anticyclonic circulation leading to the water vapor transported to North China and the increase of rainfall.The continual decreasing of DPE in the northeast part of North China is due to the weakening of East Asia monsoon that prevent water vapor transported to North China and the obvious increasing of temperature in Mongolia Plateau which bring on the evaporation increasing.