气候变暖对吉林省降雪量与新增雪深关系的影响

Impacts of climate change on the relationship between snowfall and newly-added snow depth in Jilin Province

降雪量和积雪深度的关系是降雪预报及水文气候模拟中的重要参数。本文利用吉林省50个站点1961—2021年的降水量、积雪深度、气温、风速和天气现象等气象观测资料,分析了降雪量和新增积雪深度的关系及主要气候影响因子。结果表明,在中等及以上强度的降雪过程中,吉林省新增积雪深度(D)与降雪量(S)的比值(深量比,Rds)平均为0.96 cm·mm^(-1);该比值存在空间差异,呈西部小东部大的分布特征,且存在明显的月际、年际和年代际变化特征,其中月际变化呈现不对称的抛物线型,12月和1月为大值时段;近60年来Rds呈减小趋势,变化速率为-0.01 cm·mm^(-1)·(10a)^(-1);降雪日Rds与气温呈明显反相关关系,其中在-12~0℃的温度区间,Rds随气温上升呈明显减小趋势。气候变暖、降水量增加和风速的减小是降雪过程中降雪量与新增雪深关系年代际变化的直接原因。揭示降雪量和新增雪深的关系对于认识东北亚中高纬度降雪积雪特征及其成因具有重要意义。

Snowfall is a common form of precipitation in mid-high latitudes during winter.Intense snowfall can lead to thick snow cover and trigger snow disasters,so it is one of the significant natural hazards in northern China and the Tibetan Plateau during the winter season.Past studies on snow density in snow-covered areas mainly focused on the overall snow cover condition over a certain period,but few focused on the newly-added snowfall.In this study,the observation data including precipitation,snow depth,temperature,wind speed,and weather phenomena from 50 meteorological stations in Jilin Province from 1961 to 2021 are utilized.After rigorous data verification and preliminary calculations,the sequence of newly-added snow depth of moderate to heavy snowfall events is obtained.Furthermore,the relationship between snowfall and newly-added snow depth is investigated,and then the causes of this relationship are analyzed.The results show that for the moderate to heavy snowfall events in Jilin Province,there is a correlation coefficient of 0.78 between snowfall(S)and newly-added snow depth(D),which has passed the significance testat 99.9%confidence level.The average ratio of newlyadded snow depth to snowfall(Rds)is 0.96 cm·mm^(-1).The Rds is small in western areas and large in eastern areas.In most stations of western areas,the multi-year average Rds ranges from 0.82 to 0.99 cm·mm^(-1).In most parts of Changchun City and Siping City,and the entire Liaoyuan City,the Rds is from 1.01 to 1.10 cm·mm^(-1).For the southern and most central-eastern areas of Jilin Province,the Rds is between 1.11 cm·mm^(-1) and 1.25 cm·mm^(-1).The Rds exhibits distinct monthly,annual and decadal variations.The monthly variations follow an asymmetric parabolic pattern,with December and January being the peak periods.The multi-year average Rds ranges from 1.22 to 1.24 cm·mm^(-1).The Rds is lower during November and February(from 1.07 to 1.10 cm·mm^(-1)),and is the lowest in October and April with an average of 0.89 cm·mm^(-1).Over the past 60 years,the Rds has decreased with a rate of -0.01 cm·mm^(-1)·(10a)^(-1),which has passed the significance test at the 95% confidence level.The Rds is relatively greater(1.16 cm·mm^(-1))in the 1970s and 1980s,slightly lower(from 1.13 to 1.14 cm·mm^(-1))in the 1960s and 2000s,and the lowest in the 1990s(1.09 cm·mm^(-1))and 2010s(1.05 cm·mm^(-1)).In the past 60 years,the Rds variation in December has contributed the greatest to the Rds variation in the whole snow season in Jilin Province.The monthly average difference of Rds between 1970s and 2010s(typical years)is larger than that between 1961—1990 and 1991—2020(standard climatic periods).Moreover,most months during the snow season have played an important role in the variations of the average Rds in typical years.The decrease of Rds in Jilin Province over the past 60 years has shown consistent spatial variation.The range and magnitude of the Rds decrease is larger in typical years than in the standard climatic periods.The Rds on snowfall days exhibits a clear negative correlation with temperature.Within the temperature range of -12℃ to 0℃,the Rds significantly decreases as temperature rises.Global warming,increased precipitation,and reduced wind speed are direct factors contributing to the interdecadal variations of the relationship between snowfall and newly-added snow depth.Understanding the relationship between snowfall and newly-added snow depth is important in comprehending the characteristics and formation mechanisms of snowfall and snow cover in midhigh latitudes of Northeast Asia.We hope the results may provide some valuable insights for predicting snow depth,snowfall parameterization,and snow disaster mitigation.