Basic Features of Climate Change in North China during 1961-2010

The spatial and temporal variations of some important near-surface climate parameters and extreme climate events in North China during 1961-2010 are analyzed by using 94 meteorological stations' data in the study area. Results show that the annual mean surface air temperature in North China increased at the rate of 0.36 degrees C per decade, higher than the national average in the same period. Increasing was particularly significant since the mid-1980s, with maximum increase in the middle and northeastern parts of Inner Mongolia. Increasing rate of the annual mean minimum temperature is much higher than that of the maximum temperature, which results in the decrease of the annual mean diurnal temperature range. Noticeable decrease is also observed in the frequency of cold wave. Annual precipitation shows a slight decreasing trend, with more pronounced decrease in southern Shanxi and eastern Hebei provinces, which is mainly represented as decreasing in contribution rates of rainstorm and heavy storm in flood-season (May to September). During 1961-2010, North China is characterized by a noticeable reduction in annual extreme precipitation, and an increase in high-temperature days over most parts, as well as more frequent droughts. There are remarkable reductions in annual sunshine duration and mean wind speed, associated with the most significant reduction of mean wind speed in midwestern and eastern parts of Inner Mongolia. Meanwhile, North China has experienced a noticeable decrease/increase in annual mean sanddust/haze days during the study period. However, there is no significant trend in fog days, except a pronounced decrease since the 1990s.