近60年秦岭山地旱涝变化规律

随着极端气候变化，山地灾害频发。基于秦岭山地32个气象站点的实测数据，以标准化降水蒸散指数(SPEI)为旱涝量化指标，研究了过去60年秦岭山地旱涝时空变化特征、频率、周期等变化规律，结果表明：(1)1960—2019年，秦岭山地年SPEI指数以0.124/10a的速度下降，其中，90.23%的面积呈显著下降趋势，1.96%的面积呈显著上升趋势，并在1990年发生干旱突变；秦岭北坡的干旱化趋势大于南坡，且高海拔地区干旱化更为明显。(2)突变前秦岭山地湿润比例平均值为36.94%,突变后下降为18.19%;干旱比例由突变前的17.64%急剧上升到突变后的38.19%;突变前30年秦岭山地极端干旱事件、严重干旱事件极少发生，发生频率几乎为0;突变后30年严重干旱和极端干旱事件发生频率增加，秦岭南北坡极端湿润和严重湿润事件近乎销声匿迹。(3)整体上，太阳黑子与秦岭山地旱涝变化以显著负相关关系为主；ENSO事件对秦岭山地的旱涝变化影响较大，在La Nina年易发生洪涝事件，在El Ni1o年易发生干旱事件；在不同时域范围内，海表温度距平(SSTA)对秦岭山地旱涝变化的影响不同：1990年以前，S...

Changes of drought and flood in the Qinling Mountains in the last 60 years

With the global environmental change, extreme climate events occur frequently and meteorological disasters become more and more serious, and mountain disasters are frequent. Based on the long-term monitoring data from 32 meteorological stations in the Qinling Mountains, we conducted a study using the standardized precipitation evapotranspiration index (SPEI) as a quantitative indicator of drought and flooding. We haved studied the spatial and temporal characteristics, frequency, and periodicity of drought and flood in the Qinling Mountains over the past 60 years. The results showed that:(1) from 1960 to 2019, the annual SPEI index in the Qinling Mountains decreased at a rate of 0.124/10 a. Of which, 90.23% of the area showed a significant decreasing trend and 1.96% showed a significant increasing trend, and aridity mutation occurred in 1990. The aridity trend of the northern slopes of the Qinling Mountains was greater than that of the southern slopes, and the aridity was more obvious at high altitudes. (2) The average wetness ratio of the Qinling Mountains was 36.94% before the mutation, and decreased to 18.19% after the mutation. The aridity ratio increased sharply from 17.64% before the mutation to 38.19% after the mutation. The frequency of extreme drought events and severe drought events in the Qinling Mountains in the 30 years before the mutation was almost zero; the frequency of severe drought and extreme drought events increased in the 30 years after the mutation, and the extreme wetness and severe wetness events on the north and south slopes of the Qinling Mountains nearly disappeared. (3) On the whole, there is a negative correlation between sunspots and drought and flood changes in the Qinling Mountains. ENSO events had a greater impact on drought and flood changes in the Qinling Mountains, and were prone to flood events in La Nina years and drought events in El Niño years. The impact of SSTA (Sea surface temperature anomaly) on drought and flood changes in the Qinling Mountains is different in different time domains:before 1990, there was a significantly negative correlation between SPEI and SSTA; After 1990, there was a strongly cohesive resonance cycle of 5-6 a between SPEI and SSTA, and SPEI lags SSTA by about 1/4 cycle. These findings would be of important reference value for the prevention of droughts and floods on the southern and northern slopes of the Qinling Mountains, and the development of forestry and agriculture in the Qinling Mountains.