Acta Geographica Sinica ›› 2004, Vol. 59 ›› Issue (2): 230-238.doi: 10.11821/xb200402009

Previous Articles     Next Articles

Extreme Climate Events in Northern China over the Last 50 Years

GONG Daoyi, HAN Hui   

  1. Laboratory of Environmental Change and Natural Disaster, Institute of Resources Science, Beijing Normal University, Beijing 100875, China
  • Received:2003-07-08 Revised:2003-10-20 Online:2004-03-25 Published:2004-03-25
  • Supported by:

    Huo Yingdong Education Foundation, No.81014

Abstract:

Climate in the agri-pasture transition zone, northern China is analyzed on the basis of daily mean temperature and precipitation observations for 31 stations during 1956-2001. Analysis season for precipitation is May-September, and for temperature is the hottest three months, i.e., June through August. Heavy rain events, defined as those with daily precipitation equal to or larger than 50 mm, show no significant secular trend. A jump-like change, however, is found occurring in about 1980. For the period 1980-1993, the frequency of heavy rain events is significantly lower than the previous periods. Simultaneously, the occurring time of heavy rains expanded, commencing about one month early and ending one month later. Long dry spells are defined as those with longer than 10 days without rainfall. The frequency of long dry spells displays a significant (at 99% confidence level) trend at the value of +8.3%/10a. That may be one of the major causes for the frequent droughts emerging over northern China during the last decades. The frequency of hot days is increasing, while the low temperatures are significantly decreasing.

Key words: agriculture-pasture transition zone, climate extremes, trends