The Variation of Snow Cover and Its Relationship to Air Temperature and Precipitation in Liaoning Province during 1961-2007

Based on the observational data of first snow cover date,last snow cover date and snow cover duration,together with temperature and precipitation data,from 52 base stations of Liaoning province from 1961 to 2007,the variation characteristics of snow cover and the relationship between snow cover and climate are analyzed.The analyses show that the average first snow cover date was about on November 19,the average last snow cover date was on March 23,and the snow cover duration lasted for 125 days on average in Liaoning province.In the 47 years,the first snow cover date had no significant change,but the last snow cover date was put forward about 13 days,mainly in the southern coastal areas of the province,while snow cover duration was shortened about 13 days,mainly in the central,the most part of the east and some areas of the north of Liaoning province.In the 47 years,the first snow cover date had an abrupt change in 1998,the last snow cover date had two abrupt changes in 1974 and 1992,and the snow cover duration had no significant abrupt change.The first snow cover date,last snow cover date and snow cover duration had a cycle variation.The first snow cover date related well with meteorological factors in November and was controlled by the starting date of 0℃,and the last snow cover date related better with meteorological factors in April than that in other months,and strongly correlated with the ending date of 10℃.The first snow cover date and last snow cover date were more sensitive to temperature than to precipitation,and as to temperature,they were more tightly depended on the average surface temperature rather than on average air temperature.The lower the temperature was and the more the precipitation was,the longer the duration of snow cover.Temperature is more important for maintaining snow cover.