近57年来El Nino/La Nina事件对鄂尔多斯高原东缘气候的影响

Effects of El Nino /La Nina Events on Climate of Eastern Edge of the Erdos Plateau in Recent 57 years

根据1955年～2011年期间发生的El Nino／LaNina事件和鄂尔多斯高原东缘3个站点（兴县，绥德和榆林）的气象资料，利用统计分析的方法研究了1955年以来该区的降水量、温度、旱涝灾害与El Nino／LaNina事件之间的关系，揭示了El Nino／LaNina事件对鄂尔多斯高原东缘气候的影响.结果表明，鄂尔多斯高原东缘近57年降水量呈减少趋势而气温呈升高的趋势；厄尔尼诺年降水量比正常年平均降水量少87.6mm，年平均气温比正常年高0.2℃；拉尼娜年降水量比正常年均降水量少22.3mm，年平均气温比正常年低0.1℃，且其年降水量递减率和增温率略高于全国.厄尔尼诺事件对鄂尔多斯高原东缘降水量减少的影响和气温上升的影响要大于拉尼娜事件对鄂尔多斯高原东缘的影响.由小波分析可知，鄂尔多斯高原东缘降水变化在30a尺度内存在2a、8a、20a、27a的变化周期，而气温变化在30a尺度内存在3a、5a,7a、29a的变化周期.El Nino／LaNina事件对该区的旱涝灾害影响显著，旱灾年份出现厄尔尼诺的概率为63％，出现拉尼娜的概率为25％，厄尔尼诺年易于发生旱灾.

Based on the statistics of the El Nino/La Nina events and the meteorological data of three sites （ Xingxian, Suide and Yulin） in eastern edge of the Erdos Plateau from 1955 to 2011, using the method of statistical analysis the relationship among precipitation, temperature, droughts and floods and El Nino/La Nina events are studied since 1955, and the effects of El Nino/La Nina events on the climate of eastern edge of the Erdos Plateau are showed. The results show that precipitation was decreased, and the temperature was elevated in the eastern edge of Erdos Plateau since 1955. El Nino annual precipitation is 87. 6 mm less than that of the normal average annual. The annual average temperature is 0.2℃ higher than that of normal year; while La Nina annual precipitation is less than the normal average annual precipitation by 22.3 mm. The annual average temperature is 0.1℃ lower than that of normal year. Its annual precipitation lapse rate and warming rate is slightly higher than that of the national. The impact of El Nino events on reducing rainfall and rising temperature is greater than that of La Nina events in the eastern edge of the Erdos Plateau. By the wavelet analysis, the cycle of precipitation changes are 2a, 8a, 20a, 27a in 30a-scale, while the cycle of temperature changes are 3a, 5a, 7a, 29a in 30a- scale in the eastern edge of Erdos Plateau. El Nino/La Nina events have a significant effect on floods in this area. The probability of El Nino is 63% in the El Nino events are prone to drought. droughts and drought year and the probability of La Nina is 25%,