Two Types of Sea Surface Temperature Anomaly Related to Persistent Drought Events in Guangdong Province
Two Types of Sea Surface Temperature Anomaly Related to Persistent Drought Events in Guangdong Province
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发表时间：
2009
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通讯作者：
Liang Jian-yin
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作者：
Liang Jian-yin
利用广东省45年(1961-2005)降水观测资料、ERSST全球海表温度(SST)和NCEP/NCAR大气变量,诊断了广东省跨季节持续性干旱事件与海表温度(SST)外强迫的关系,并探讨了这种关系的机制。东太平洋(即拉尼~a型)和赤道中太平洋正海温异常(即非拉尼~a型)。1970年代后期之前,广东持续干旱事件基本保持拉尼~a型。1970年代后期以后,除拉尼~a型外,赤道中太平洋型持续干旱事件出现海温正异常的概率明显表明在全球气候变暖的背景下,广东持续干旱事件的成因更加复杂。21世纪近几年广东持续干旱事件的频繁发生与非拉尼娜现象概率的增加有关。拉尼娜现象和赤道中太平洋正海温异常都与广东持续干旱事件动态联系在一起。不同类型海温异常影响广东干旱事件的物理过程是不同的。尽管对于同一类型的海温异常来说，这些过程都是不同季节的物理过程。但所有这些过程最终都会改变并削弱降雨所需的动力条件和水汽，从而导致局部干旱。
Relationships between spanning-seasonal persistent drought events in Guangdong Province and external forcing of sea surface temperature(SST) are diagnosed,and the mechanisms for the relationships are discussed using the 45-year(1961-2005) observational data of precipitation in Guangdong Province,ERSST global sea surface temperature(SST) and NCEP/NCAR atmospheric variables.The results show that there are two types of SST anomaly related to persistent drought events in Guangdong which are negative SST anomaly in equatorial eastern Pacific(namely La Nin~a pattern) and positive SST anomaly in equatorial mid-Pacific(namely non-La Nin~a pattern).The persistent drought events in Guangdong basically remained with La Nin~a pattern before the anaphase of 1970′s decade.And after the anaphase of 1970′s decade,besides the La Nin~a pattern,the probability of positive SST anomaly in pattern persistent drought events of equatorial mid-Pacific obviously increased.It is shown that the causes of persistent drought events in Guangdong are more complex under the background of global climate warming.The frequent occurrence of persistent drought events in Guangdong in the recent years of 21 centuries is related to the increasing of the probability of non-La Nin~a pattern.Both of La Nin~a and positive SST anomaly in equatorial mid-Pacific link with the persistent drought events in Guangdong dynamically.The physical processes of different types of SST anomaly impacting drought events in Guangdong are different from each other.So are the physical processes in different seasons even though for the same type of SST anomalies.However,all the processes change and weaken ultimately the dynamical conditions and water vapour required by raining,and then result in the local drought consequently.