广西春旱特征及其成因

Characteristics and causes of spring drought in Guangxi

【目的】为广西预防和减轻春旱灾害提供基础理论依据。【方法】采用1961-2016年共56年广西90个国家气象观测站春季各月逐旬总雨量资料,计算广西逐年春旱分布情况;采用NCEP/NCAR全球2.5°×2.5°的平均大气环流资料,分析春旱的气候成因。【结果】广西春旱频率自东北向西南增大,和春季雨量分布大致相反;广西春旱的变化具有阶段性特征,重旱有增加的趋势;大气环流系统是春旱形成的主要因素,云贵高原余脉的背风坡地形使桂西春旱加剧。【结论】广西春旱发生频率的地域差异较大,主要是自东北向西南增大。近10多年处在春旱偏重时期,呈上升趋势。桂东春季受华南静止锋南北摆动影响,又处在副高西北侧,春旱频率低。桂西和广西沿海地区因地形阻挡,加上热低压的影响,干热天数多,因此春旱频率高。

【Objective】To provide the basic theoretical basis for prevent and reduce the spring drought disasters in Guangxi.【Method】Applying technique reference for a period of ten days precipitation data in March to May from 90 meteorological stations in Guangxi during 1961- 2015, the distribution and variation characteristics of spring droughts in Guangxi are analyzed by statistical and analytical methods and the Climatic Causes also be discussed. 【Results】The results show that：（1） The same as the spring rainfall distribution,Spring droughts event have increased in frequency from northeast to southwest area.（2） There are some stage characteristics about the change of spring drought. The severe droughts have Increasing trend.（3） The atmospheric circulation system is the main factors of drought formation. The leeward slope of Yunnan Guizhou Plateau Terrain Mountains makes the spring drought in west of Guangxi intensified.【Conclusion】The frequency of spring drought has large regional difference, mainly increased in frequency from northeast to southwest area.