基于SPI和SPEI指数的辽宁省大豆生长季干旱时空变化特征

Temporal and spatial characteristics of drought during soybean growing season in Liaoning province based on SPI and SPEI

选用1961—2020年辽宁省52个气象站的日降水量和日平均气温资料,计算大豆生长季和各发育阶段的标准化降水指数(SPI)和标准化降水蒸散指数(SPEI),选取5个代表站,应用M-K趋势检验方法分析大豆不同时间尺度的干旱时空变化。结果表明:大豆生长季SPI和SPEI均呈干旱化趋势,SPEI监测的干旱程度略大于SPI;大豆播种期—出苗期SPEI和SPI呈湿润化趋势,出苗期—开花期、开花期—结荚期和结荚期—成熟期均为干旱化趋势,其中开花期—结荚期最为显著。SPEI监测的干旱范围及高发区均大于SPI,且干旱程度更强,其中,辽宁西部的干旱程度最为严重。从大豆生长季和发育阶段进行干旱评估,SPEI适用性优于SPI。

Using daily precipitation and daily average temperature from 52 meteorological stations in Liaoning province from 1961 to 2020,the standard precipitation index(SPI)and the standard precipitation evaporation index(SPEI)were calculated at soybean growing season scale and at each developmental stage scale.Mann-Kendall test was used to examine the spatial and temporal variation characteristics of drought and drought frequency of soybean at different time scales.The study showed that both SPI and SPEI indices showed aridity trends during soybean growing season,with SPEI monitoring a slightly more severe drought than SPI.At all soybean developmental stages,SPEI and SPI indices showed wetting trends at the sowing-emergence stage,and aridity trends at the emergence-flowering,flowering-podding,and podding-maturity stages,with significant aridity trends at the flowering-podding stage.Spatially,the SPEI index monitored a larger range of drought and drought prone areas than those monitored by the SPI,and the degree of drought was stronger,with the most severe drought happening in the west of Liaoning.Therefore,the SPEI index is more applicable compared to the SPI index when evaluating drought of the soybean at growing season and each developmental stage.