Spatio-temporal Variation Characteristics of Snowfall and Snowfall Ratio in Henan Province Based on Snowfall Identification
Based on the meteorological data of 119 national meteorological stations in Henan Prov-ince in the recent 52 years from 1968 to 2019,daily precipitation phase states are labeled by daily weather phenomena,and a localized regional snowfall identification method is constructed by the double tempera-ture threshold method fitted with exponential equation.After more accurate snowfall amount is obtained through snowfall identification,the spatio-temporal variation of snowfall and snowfall ratio(SR)in Henan Province in the 52 years is studied.The results show that the double temperature threshold method fitted with the exponential equation has a high accuracy in snowfall identification in Henan Province,and the correlation coefficients between the snowfall and the total snowfall estimated by the exponential equation in the five regions all exceed 0.96.During the recent 52 years,the average annual snowfall in Henan Province is 10-50 mm,and the maximum snowfall areas are distributed in the southeastern part of west-ern Henan and the southeastern part of southern Henan.The annual snowfall in Henan Province has de-creased at the rate of-0.87 mm per decade,and the regional annual snowfall decline rate has increased in northern Henan,central Henan,western Henan,eastern Henan and southern Henan by order.The monthly snowfall in the snowfall period has increased in April,November,March,December,February and January by order,among which the snowfall in November shows an increasing trend but the snowfall in December,February and March has a decreasing trend.In the 52 years,the SR value is between 0.13 and 0.44,showing the characteristics of high in the west and the north but low in the east and the south.Dur-ing the snowfall period,the SR of the whole province has decreased at a rate of-0.0092 per decade,while the regional SR decline rate has increased in the order of western Henan,northern Henan,central Henan,southern Henan and eastern Henan.In general,the decline rate of larger SR in the western and northern Henan regions is smaller,while the decline rate of smaller SR in the southern and eastern Henan regions is larger.From the distribution of stations,78％of the stations in the province show a downward trend in SR,and 22％of the stations show an upward trend.The stations with an upward trend of SR are located in the western and northern regions of Henan,and the stations with a downward trend of SR are in the east-ern,southern and central regions of Henan.
double temperature threshold methodsnowfall identificationsnowfall ratiospatio-temporal variation
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