Extreme climate events over northern China during the last 50 years

Climate extremes for agriculture-pasture transitional zone, northern China, are analyzed onthe basis of daily mean temperature and precipitation observations for 31 stations in the period1956-2001. Analysis season for precipitation is May-September, i.e., the rainy season. Fortemperature is the hottest three months, i.e., June through August. Heavy rain events, defined asthose with daily precipitation equal to or larger than 50 mm, show no significant secular trend. Ajump-like change, however, is found occurring in about 1980. For the period 1980-1993, thefrequency of heavy rain events is significantly lower than the previous periods. Simultaneously, theoccurring time of heavy rains expanded, commencing about one month early and ending one month