中国降雪气候学特征

利用逐日地面降雪观测资料,分析中国25oN以北范围内降雪量、降雪日数、雪带分布和各强度降雪的气候学特征,得到以下结论:①雪季长度与年降雪日数在东部呈纬向分布,大兴安岭北部最长(>210 d),长江以南最短(常年无雪或偶尔降雪);在西部青海省南部和西藏自治区北部最长(>300 d),滇、川、藏交界处及新疆自治区北部较长,南疆较短(<60 d)。年降雪量东南部最少,东北和西北北部较多(>30 mm),青海和西藏降雪量最多(>60 mm)。平均降雪强度江淮一带最大。②根据雪季降雪频次划分中国的雪带,东北大部、内蒙自治区东部、新疆北部、青藏高原大部、秦岭等地区为常年多雪带;长江以南的滇南、四川盆地、江浙沿海等地区为永久无雪带;其余地区为常年降雪带和偶尔降雪带。③不同区域各级降雪日数占总降雪日数的比例都是暴雪日数最少,大雪日数其次,小雪日数最多;但中雪降雪量占总降雪量的比例在东北北部、华北、西北、新疆、东南、青藏高原东部等区域仅高于小雪降雪量,而在黄-淮地区仅次于暴雪降雪量。④降雪年内分配在东北北部、西北、新疆、青藏高原东部等地区都呈双峰型,最多雪时节在早冬和晚冬、早春,隆冬时节并不是降雪最多时间,黄-淮和东南地区呈单峰型,东南地区峰值更陡。⑤总降雪日数和除暴雪外的各等级降雪日数与地理位置关系较明显,在中国东部主要随着纬度升高增加,在中国西部随海拔高度增加而增加;随着纬度升高,东部和西部的总降雪强度都减小,西部的小雪强度也减小。

Climatology of Snow in China

Climatic characteristics of snowfall,snow days,snow belt north of 25°N in China is analyzed using the daily snow observation data.The following results have been obtained in the analysis.1) Snow season length and snow days have the feature of latitudinal distribution in the east,with the Da Hinggan Mountains recording the longest(>210 d) snow season,and no snow or only occasional snow all year round in the south of the Yangtze River.In the west,Qinghai Province has the longest(>300 d) snow season,followed by the junction areas of Yunnan,Sichuan and the Tibet.Snow season length in northern Xinjiang is close to the north of Northeast China.The least snowfall occurs in the southeast,and Northeast and northern Northwest record the higher snowfall more(>30 mm),and Qinghai and Tibet are characterized by the highest snowfall(>60 mm).Maximum snowfall intensity is in the Yangtze-Huaihe region.2) Snow belts are divided based on snowfall frequency: the Northeast and eastern Inner Mongolia,Northern Xinjiang,the Qinghai-Tibet Plateau,and the Qinling Mountains are snow-frequent belts.Southern Yunnan,Sichuan Basin,coastal areas of Jiangsu and Zhejiang and other areas are permanent snow-free belts.The other areas are snow-ordinary belts and snow-occasional belts.3) The percentage of snowstorm days to total snow days is generally low in all of the regions.The highest percentage is seen for light snow days to total snow days.In view of the ratio of snowfall of all categories to total snowfall,the proportion of snowstorm witnesses the lowest value,followed by heavy snow,and light snow has the highest value in the north of Northeast,North,Northwest,Xinjiang and eastern Tibet Plateau.However,Southeast China is characterized by lowest value of the ratios for light snow,and the highest value for snowstorm.4) The double-peak distribution of snowfall within the year is seen in northern Northeast,Northwest,Xinjiang and eastern Tibet Plateau,and the Yellow-Huai River basins and Southeast have a single-peak distribution of snowfall.5) The total snow days,heavy snow days,medium snow days and light snow days generally increase with increasing latitude in the East of China,meanwhile with increasing altitude in the West;with increasing latitude,the total snowfall intensity has a decreasing trend in both the East and the West,also the small snow intensity in the West.