关键词: SPEI, 一路一带, 趋势分析, PCA分析, 小波分析

Abstract:

In order to understand the existing drought variation, to unveil the alternation between wet condition and dry condition, and to predict the future of drought in the countries and regions along “The Belt and Road Initiatives”, we analyzed the pattern of periodical variation and the trend of drought under multiple temporal scales. Specifically, we used 0.5°×0.5° SPEI (Standardized Precipitation Evaporation Indices) data with two temporal scales of 12-month and 3-month from 1901 to 2013 for analysis. Linear trend, principal component analysis (PCA), Mann-kenndall (M-K), and wavelet analysis are employed to analyze the multi-temporal scale data. The results showed that the SPEI and the drought area increase slowly at both annual and seasonal（except summer）scales over the past 113 years. However, 60% of the research area is slowly getting wetter. Also, 25.38% of the research area had significant SPEI increased, and only 12.02% of the research area had significant SPEI decreased. Both M-K and PCA indicated that the low latitude area between 15°-35°, including North Africa, Arabian Peninsula and Iranian Plateau, has the most frequent drought occurrence. M-K and PCA also show that Russia, Kazakhstan, the India Peninsula, Mongolia, and China have significant seasonal drought discrepancies. The wavelet spectral analysis revealed that the main periods of the annual and seasonal scale have both similar and different features: investigation with a long-time scale (annual) presents general trends yet fails the significance test of the wetting and drying alternation pattern. Such alternation only presents significant patterns with short-time scale. Finally, it appears that the variation pattern of drought is significant with annual drought period of 2-4 a.

Key words: SPEI, The Belt and Road Initiatives, trend analysis, PCA, wavelet analysis