广东省1956─2010年旱期降水特征

Characteristics of Rainfall during Drought Seasons in Guangdong Province from 1956 to 2010

旱灾是影响广东经济社会发展的主要自然灾害之一.利用1956─2010 年广东省125 个雨量站降雨资料,采用降雨量等值线图、累积距平、小波分析等方法分析广东省春旱、秋旱期降雨的多时间尺度变化及空间分布特征,以期为广东省干旱灾害的监测、预报提供依据.结果表明,（1）春旱期和秋旱期降雨空间分布表征总体相反,春旱降雨南少北多,高值区位于粤北清远,低值区位于粤西湛江雷州半岛地区;秋旱降雨南多北少,高值区位于珠江三角洲的江门,低值区位于粤北的韶关;但阳江、汕尾等地在春旱、秋旱期内均表现为降雨高值区.（2）1956-1986 年及2002-2010 年春旱、秋旱期降雨变化相似,在1956-1960 年、1971-1985 年间波动增加,1961-1970 年、2002-2010 年间减少;1986-2001 年间春、秋旱期降雨变化总体相反,1986-1992 年间春旱期降雨微弱增加,秋旱期降雨减少,1993-2001 年间春旱期降雨波动减少,秋旱期降雨波动增加;且春旱期降雨变化较秋旱期降雨更为显著：春旱期降雨量年代距平百分比变化范围为-10.96%-18.60%,而秋旱期降雨量的年代距平百分比变化范围为-8.51%-8.17%.（3）春、秋旱期降雨均以2-4 a 左右时间尺度的年际变化为主要周期,其中春旱降雨的主周期为4.5、2.5 a;秋旱降雨的主周期为2.9 a.南岭阻隔及局部地形变化是造成降雨空间分布差异的主要原因,北大西洋涛动对春旱期降雨的周期性变化存在一定影响,厄尔尼诺对春旱、秋旱期降雨的周期性变化也有一定的影响.

Drought is one of the major natural disasters which can influence the economic development of Guangdong province. Based on the data of 125 rainfall gauges from 1956 to 2010 in Guangdong province, three methods, i.e. isohyet maps, cumulative anomalies, and wavelet analysis were employed to analyze the multi-scale temporal variations and spatial distribution of rainfall during spring and autumn drought seasons, in order to support drought monitoring and forecasting. The results indicate that: (1) generally, the spatial distributions of rainfall during spring and autumn are opposite. During spring, rainfall declines from the north to the south, with the high center around Qingyuan in northern Guangdong and the low center in Zhanjiang which is located in the Leizhou Peninsula in western Guangdong. However, it is contrary except for a few places during the autumn. The high center in autumn appears in Jiangmen in the Pearl River Delta. The low center is located in Shaoguan in northern Guangdong. Yangjiang and Shanwei are both high rainfall areas in spring drought and autumn drought seasons. (2) the variations of rainfall during spring and autumn are quite similar in the years from 1956 to 1986 and from 2002 to 2010, which are more variable during 1956-1960 and 1970-1985 and less variable during 1961-1970 and 2002-2010. In contrast, rainfall varies in the opposite way during different seasons from 1986 to 2001. During 1986-1992, there is a slight increasing trend of spring rainfall and a declining trend of autumn rainfall. On the contrary, there is a declining trend of spring rainfall and an increasing trend of autumn rainfall during 1993-2001. Moreover, the percentage of rainfall anomaly in every decade during spring changes from -10.96% to 18.60%. But the percentage during autumn only changes from -10.83% to 8.17%, which indicates that rainfall in spring varies more than that in autumn. And (3) rainfall in spring varies mainly on scale of 4.5-year and 2.5-year, and 2.9-year during autumn. The barrier of Nan Ling to cold air from the north and the local terrain variations are the main factors inducing spatial variations of rainfall in different drought seasons. NAO has some effects on the periodic change of rainfall in spring drought seasons and ENSO can cause periodic variations of rainfall in both spring and autumn drought seasons.