Abstract: Influenced by human activities and changes of global climate, drought disaster is becoming more and more serious in Northeast China. In this paper, the monthly precipitation and temperature data of 84 weather stations from 1961 to 2014 in Northeast China were used and the standardized precipitation evapotranspiration index (SPEI) was applied. Based on multiple time scale SPEI data of each station in 1961-2014, the annual, seasonal and monthly drought occurrence frequency, coverage (the ratio that number of drought occurrence stations occupies the total weather stations) and intensity were analyzed, and the correlation between SPEI and Asia Polar Vortex Area Index (I_APV), Asian Zonal Circulation Index (I_AZC), East Asian Trough Position Index (I_EAT) and Polar-Eurasia Pattern (I_POL) were revealed. The results indicated that annual average drought frequency was between 26% and 36%, and there was an obviously growing trend in different grades of drought frequency, especially for heavy and severe drought. The annual drought frequency was above 26% in most of Northeast China, while autumn was the most prone to drought of four seasons. In recent 54 years both the coverage and intensity of drought in autumn presented an obvious increasing trend with a significance level of 0.05. There are different correlations between SPEI and circulation indexes. It is found that correlation of SPEI and I_APV, SPEI and I_AZC are better in summer half year, but SPEI and I_EAT, SPEI and I_POL are vice versa. We also found I_APV and SPEI had positive correlation, but the other three indexes and SPEI show opposite changes in Northeast China.

Key words: standardized precipitation evapotranspiration index, Northeast China, drought evolution, circulation indexes