Analysis of the Causation of Drought in Both the Annual Flooding Seasons of Leizhou Peninsula
ZHENG Kai;ZHAO Bo;Dissemination Center for Pre-warning Information of Breaking Incidents of Guangdong Province/Center of Weather Modification of Guangdong Province;
With the rainfall data of observation stations in Xuwen and Zhanjiang and NCEP/NCAR reanalysis from April to October in 1960-2015 and following the principle of one time standard deviation,we determine the anomalously large(small) extremes of three variables of accumulated rainfall,total number of rain-free days and maximum number of consecutive rain-free days. Then,for the drought years chosen on the basis of that,we perform a composite analysis of anomalous distribution of 500 h Pa geopotential height,850 h Pa wind field and vertical integration of water vapor transport. The result is shown as follows. Between the two stations,the total number of rain-free days is quite consistent between the two flooding seasons while the maximum number of consecutive rain-free days is much different between them. The subtropical high anomalies for anomalously dry years in both seasons are much positive. The positive anomalies of the subtropical high play an enhancing role in the drought of Leizhou Peninsula in both seasons. Under the control of anticyclonic circulation and anti-cyclonic water vapor circulation,the drought in the Zhanjiang station during the annually first flooding season and the Xuwen station during the annually second flooding season is affected.Anomalously weaker monsoon circulation and water vapor transported along the monsoon route affect the drought of Zhanjiang station in the annually second flooding season while water vapor divergence affects the drought of Xuwen station in the annually first flooding season.
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