基于SPEI指数的秦岭南北地区干旱时空变化特征

基于秦岭南北地区47个气象站点1960-2016年实测气象资料，利用标准化降水蒸散指数（SPEI）定量分析了秦岭南北地区不同时间尺度干旱发生频率和强度的时空演变特征，并试图揭示该区域干旱发生的原因。结果表明：SPEI值能够较好的反映秦岭南北地区的干旱特征及干湿演变状况。从时间变化上看，近57 a来秦岭南北地区呈干旱化趋势，以20世纪90年干旱化趋势最为显著，干旱化趋势最显著的区域为秦岭以北地区，但近22 a秦岭南北地区开始出现湿润化趋势；从季节来看，四季大部分区域呈干旱化趋势，秋季干旱化趋势最显著且开始最早，春季次之，冬、夏干旱化趋势相对不显著。从空间来看，秦岭南北地区在年、季、月尺度上均有干旱发生且各地区分布极不均匀；其中秦岭以北地区干旱发生频率较高，其他子区域干旱发生频率的空间分布特征较为复杂。干旱发生强度呈现出中西部强，四周弱的特点，干旱发生强度最强的地方为陕西石泉，为14.7%，最弱的地方为四川阎中，为23.6%。

Spatial and temporal variations of drought in northern and southern regions of Qinling Mountains based on standardized precipitation evapotranspiration index

Drought disaster is one of the significant natural disasters in the northern and southern regions of the Qinling Mountains,and it affects people's daily life and social production to different degrees.In this paper,based on the observed meteorological data from 47 meteorological stations in the northern and southern regions of the Qinling Mountains from 1960 to 2016,and using standardized precipitation evapotranspiration index (SPEI) at different scales as one month,three months and twelve months,combined with M-K method and ArcGIS spatial visualized analysis,we analyzed the spatio-temporal evolution characteristics of the frequency and intensity of drought at different time scales in the Qinling Mountains,and revealed the drought causes.The results showed that the SPEI value effectively reflected the drought characteristics,and the evolution of the dry and wet of the northern and southern regions of the Qinling Mountains.As the time scale got increased,the amplitude of the SPEI was decreased and drought frequency was decreased.From the standpoint of time,there was an obviously growing trend in frequency of drought in recent 57 years,especially in the 1990s,the most significant area of drought is the northern of Qinling Mountains,but in the latest 22 years,it began with the trend of humidification in both the northern and southern regions of Qinling Mountains.From the seasonal perspective,most parts of the region tend to be droughty in all seasons,the trend of drought was the most significant in autumn,followed by spring,winter and summer drought.From the standpoint of space,drought occurred in both the northern and southern regions with a significant difference in different regions.The frequency of drought occurrence in the northern of Qinling Mountains is high,and the spatial distribution of drought frequency in other sub-regions is more complicated.It is mainly due to the non-uniform distribution of temperature and precipitation,coupled with the influence of the Qinling Mountains.The drought intensity distribution showed higher values in the mid-west region,and lower values around the Mountains.The maximum drought intensity value of 14.7% was recorded in Shiquan,Shaanxi Province,and the minimum,23.6%,occurred in Yanzhong,Sichuan Province.The intensity of drought in the rest of the region is between 17%-22%.The changes in temperature and precipitation have a significant impact on the drought in the northern and southern regions of the Qinling Mountains,the El Nino phenomenon is closely related to drought and the influence of special geographical location.