Acta Geographica Sinica ›› 2010, Vol. 65 ›› Issue (7): 863-872.doi: 10.11821/xb201007010

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Changes in Pan Evaporation and Its Cause over Guangdong

FAN Lingli1,2, GUO Pinwen1, GUAN Yong3, LIANG Minyan3   

  1. 1. College of Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China;
    2. College of Oceanography and Meteorology, Guangdong Ocean University, Zhanjiang 524088, Guangdong, China;
    3. Jiangmen Meteorological Office, Jiangmen 529030, Guangdong, China
  • Received:2010-03-03 Revised:2010-04-15 Online:2010-07-20 Published:2010-07-20
  • Supported by:

    Natural Science Foundation of Guangdong Ocean University, No.0812070

Abstract:

The observation data of 20 cm caliber evaporation pan and related meteorological elements were collected from 86 weather stations of Guangdong for 1961-2008. Statistical analysis shows that the pan evaporation in Guangdong as a whole has continuously decreased at a rate of 54.67 mm per decade, although the annual mean temperature has increased at a rate of 0.21 oC per decade. The regions with a significant drop in pan evaporation are the Pearl River Delta, as well as southwestern and eastern coastal regions of Guangdong. Only a small part of regions with a rise in pan evaporation is located in the central region of Guangdong. Through analysis of variations of the dynamic term and energy term in Penman equation, separately, it is found that the drop of pan evaporation is mainly attributed to decreases in the energy term, and that the dynamic term in the southwestern and eastern coastal regions of Guangdong is mainly attributed to decreases in the energy term in the Pearl River delta. The rise of pan evaporation is mainly due to the fact that the increase in the dynamic term is greater than the decrease in the energy term. Further investigation into tendencies of meteorological impacting factors and the correlation analysis between pan evaporation and the influencing factors show that the sunshine duration and wind peed are remarkable.

Key words: Guangdong, pan evaporation, Penman equation, energy term, aerodynamic term