GEOGRAPHICAL RESEARCH ›› 2010, Vol. 29 ›› Issue (12): 2271-2280.doi: 10.11821/yj2010120016

• Earth Surface Processes • Previous Articles     Next Articles

Variations of precipitation of different categories in the Bohai Rim area in recent 47 years

GUO Jun1, REN Guo-yu2, LI Ming-cai1   

  1. 1. Tianjin Climate Center, Tianjin 300074, China;
    2. Laboratory for Climate Studies, National Climate Center, CMA, Beijing 100080, China
  • Received:2009-11-03 Revised:2010-06-26 Online:2010-12-20 Published:2010-12-20

Abstract:

In line with the global climate change, the surface air temperature in the Bohai Rim area significantly increased for the 20th century. Accompanying the change of surface air temperature, heavy and very heavy precipitation has greatly changed, especially in recent years. Changes in patterns of extreme precipitation events and the possible mechanism for the changes have received more and more attention worldwide. The study aims to investigate the climatic characters and changing trend of rainfall days, rainfall amount and rainfall intensity in the Bohai Rim area by using daily precipitation data from 1961 to 2007. The results show that the number of annual and seasonal rainfall days (days with rainfall more than 0.1 mm) significantly decreases, and the decrease of rainfall days dominantly results from the significant decline in trace and light rainfall days, especially in autumn. In contrast, rainfall intensity shows a weak increase, mainly due to the increase in trace and light rainfall intensities. In comparison of the contribution of different categories of precipitation to annual total rainfall, it is found that there is a significant interannual variation in the contribution. Since the 1990s, annual rainfall has mainly come from light and moderate rainfall, whereas extreme heavy rainfall has contributed less to the annual rainfall due to the decrease in frequency and amount of extreme heavy rain. The results indicate that the decrease of trace and light rainfall days, which leads to the increase in frequency of events of continuous non-rain days, might have partly exacerbated the extent of drought in this area. However, the decline of annual rainfall as a result of the decrease of heavy rain or rainstorms, which is the dominant contribution to total rainfall, is the main factor for producing the severe meteorological drought after 1980.

Key words: rainfall days, rainfall intensity, climate change, the Bohai Rim