厄尔尼诺/拉尼娜事件对陕西省榆林地区气候的影响

Effects of El Nino/La Nina Events on Climate of Yulin Area of Shaanxi Province

通过对陕西省榆林地区近56a来气象资料、历史资料的搜集和整理,研究了厄尔尼诺/拉尼娜(ElNino/Southern Oscillation,ENSO)事件对榆林地区气候与气象灾害的影响,分析了降水及气温变化的周期性。结果表明,1954年以来,榆林地区气候变暖变干趋势显著。1954年以来榆林地区年均温平均升高了0.025℃/a,年降水量递减率为1.740mm/a;厄尔尼诺年气温高出正常年份0.12℃,拉尼娜事件发生年年平均气温较正常年份平均气温没明显变化。厄尔尼诺事件年榆林地区降水呈现明显的减少趋势,比正常年份减少了8mm。拉尼娜事件年对榆林地区降水增加也有一定影响,平均增加3mm/a。榆林地区气温与降水量存在3a为主的短周期和20a为主的长周期。ENSO暖事件对榆林地区气候特别是气象灾害的影响比ENSO冷事件更为显著和强烈,厄尔尼诺年榆林地区易于发生高温干旱灾害。

Based on the meteorological and historical data in Yulin area of Shaanxi Province from 1961 to pres- ent, statistical analysis was conducted. The objectives of this study were： （1） Examine the relationship among precipitation, temperature, natural disaster events, and the ENSO（E1 Nino/Southern Oscillation） events. （2） Reveal the correlation between ENSO events and the climate of Yulin area. （3） Identify the peri- odicity of the precipitation and temperature changes. The results show that since 1954, the climate was war- ming significantly in Yulin area, with an annual temperature increasing rate of 0. 025 ~C per year. However, the annual total precipitation decreased at rate of 1. 740 mm per year. In E1 Nino years, the temperature was O. 12 ~C higher than that in normal years, and in La Nina years, the annual average temperature remained same to that in normal years. E1 Nino event lowered annual total precipitation approximately 8 mm than the normal years, while La Nina events did approximately 3 ram. The temperature and precipitation of the area changed at a short period of 3 years and a long period of 20 years. ENSO events was prone to cause high tem- perature and drought disasters, and ENSO warming events caused more meteorological disasters than ENSO cold events in the study area according to statistical analysis.