基于SPEI的中国东北地区1961-2014年干旱时空演变

利用中国东北地区84个气象站1961-2014年逐月气温、降水资料，采用标准化降水蒸散指数（SPEI）、气候倾向率及M-K统计检验方法，从不同时间尺度（年、季、月）探讨了东北地区干旱频率、干旱站次比和干旱强度的演变特征，研究了干旱指数与不同环流指数 （亚洲极涡面积指数I_APV、亚洲纬向环流指数I_AZC、东亚槽位置指数I_EAT、极地-欧亚遥相关型指数I_POL）的相关关系。结果表明：东北地区多年平均的干旱发生频率为26%～36%，不同等级干旱发生频次以重旱和特旱的增速最快。春、夏、秋三季干旱站次比和干旱强度都有所增强，其中秋旱变化最为显著，通过了0.95水平的显著性检验。从SPEI与各环流指数的相关来看，亚洲极涡面积指数与SPEI表现为全区一致的正相关关系，而其他3个指数与SPEI则表现出明显的反向变化。4个指数与SPEI的对应关系还存在明显的季节变化，其中亚洲极涡面积指数、亚洲纬向环流指数与SPEI在春、夏季的相关性更好，东亚槽位置指数、极地-欧亚遥相关型指数则是在秋、冬季与SPEI的相关性更显著。

Temporal and Spatial Distributions of Drought in Northeast China in 1961-2014 Based on Standardized Precipitation Evapotranspiration Index

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.