Climatic Characteristics of Intense Snowfall in China with Its Variation

Based on daily ground snowfall observations of national meteorological stations, climatic zonation is carried out according to the snowfall variability with the REOF method to the north of 25°N in China. The main climatic characteristics and variation of intense snowfall events in different climate zones are analyzed, including the spacial distribution difference, the changing characteristics of intense snowfall and the number of snow days of the month, ten-day, spatial changes and temporal evolutions in the trend of intense snowfall, the number of snow days and intensity, and the climate change trends of the 1961—2008 and 1981—2008 (considering climate warming) are calculated, respectively.It shows that the east of Tibet Plateau, Xinjiang and the north of Northeast China have the highest amount and frequency of intense snowfall. The maximum intense snow intensity centers in Yunnan. The percentage of intense snow days to total snowfall days is generally low in North China, followed by the north of Northeast China and Xinjiang, and the largest percentage occurs in the Huang-Huai River Areas. In the north of Northeast China, North China, Northwest China and the east of Tibet Plateau, the high-frequency periods of intense snow events are generally in spring and early winter. It comes to mid-winter in Xinjiang, and to late winter in the Huang-Huai River Areas. In the north of Northeast China, Xinjiang and the east of Tibet Plateau, the intense snowfall and snow days obviously increased over the last 48 years. With climate warming, the intense snowfall and snow days increase, and meanwhile the intense snow intensity strengthens in most regions of China.Due to the snowfall measurement error, the estimation results of the mean intense snowfall and snow intensity in the north of China may be low, in the spring, the mean wind speed is strong, and the intense snowfall and snow intensity estimation is lower. Because the wind speed near the ground is in decreasing trend, the analysis of climate change on intense snowfall and snow intensity may be that the increasing trend is overestimated, while the decreasing trend is underestimated. The snowfall measurement error change caused by the average wind speed decreasing mainly affects the analysis of intense snowfall events of climate change, while has few impacts on the research of climatic characteristics.