1971—2020年呼伦贝尔市积雪气候特征和未来趋势预估

Climatic Chracteristics of Snow Cover during 1971-2020 in Hulun Buir City and Future Trend Prediction

利用1971—2020年呼伦贝尔市16个国家气象站最长积雪日数和最大积雪深度资料,采用经验正交函数(EOF)分析、重标极差分析(R/S)和非周期循环分析,统计最长积雪日数和最大积雪深度时间序列的Hurst指数、分维数和非周期循环的平均循环长度,分析最长积雪日数和最大积雪深度变化趋势和记忆周期;同时采用MOD10A2积雪产品,研究2001—2018年呼伦贝尔市积雪覆盖率变化。结果表明:(1)近50年呼伦贝尔市最长积雪日数呈递减趋势,最大积雪深度呈递增趋势;(2)积雪深度>20、30cm的年平均积雪日数主要出现在1996—2014年,其中积雪深度>30cm年平均积雪日数>1d;(3)呼伦贝尔市积雪初日出现在10月中旬至11月上旬,积雪终日在4月结束,积雪初日出现最早时间和积雪终日结束最晚时间都在呼伦贝尔市的北部地区;(4)R/S分析和非周期循环研究表明,呼伦贝尔市最长积雪日数和最大积雪深度H指数分别为0.5899和0.889,即最长积雪日数未来减少和最大积雪深度未来增多趋势持续,持续时间分别为8和12 a;(5)呼伦贝尔市年平均积雪覆盖率为98.87%,呈波动增加趋势,空间分布呈自西北向西南和东南地区增加,10月和翌年3月增加显著,9、12月和翌年4月减少。

The longest snow cover days(LSCD)and maximum snow depth(MSD)data of 16 national stations in Hulun Buir were used to calculate the values of Hurst,fractal dimension and non-cycle average cycle length,as well as variation trends and memory cycles of snow cover,using EOF,R/S analysis and non-periodic cycle analysis.The snow cover percentage and frequency were studied using MOD10A2 from 2001 to 2018 in Hulun Buir.The results showed that:(1)In recent 50 years,LSCD in Hulun Buir showed a decreasing trend,while MSD increasing.(2)The days when snow depth was greater than 20 cm and 30 cm mainly occurred from 1996 to 2014.The annual average snow cover days with snow depth over 30 cm exceeded 1 day.(3)Initial snow cover date in Hulun Buir mainly occurred in mid-October to early November,while final snow cover date in April.The earliest initial snow cover date and the latest final snow cover date were all in the northern area of Hulun Buir.(4)R/S and non-periodic cycle analysis showed that the H index of LSCD and MSD in Hulun Buir city were0.5899 and 0.889 respectively,indicating the decreasing trend of LSCD and increasing trend of MSD in the future.The durations were 8 years and 12 years respectively.(5)The annual average of the snow cover percentage in Hulun Buir was 98.87%with a fluctuating increasing trend.The snow cover percentage increased from northwest to southwest and southeast.The snow cover percentage significantly increased in October and next March,while decreased in September,December and next April.