石河子地区年冻融指数的多尺度变化特征

Multiscale Variation of Annual Freezing and Thawing Indexes in Shihezi

基于石河子地区各气象站点1961─2013年的逐日平均气温数据,计算年冻融指数,并利用集合经验模态分解(EEMD)分析其多尺度变化特征。结果表明:在过去53 a,石河子地区冻结指数和融化指数的年际变化明显,其中冻结指数总体呈减少趋势,融化指数总体呈增加趋势,气候倾向率分别为-3.84℃·a-1和8.64℃·a-1。在年际变化上,冻结指数年际波动较大,其变幅为820~1 900.7℃;融化指数年际波动较小,变幅为3 518.8~4 577.9℃。在年代尺度上,冻结指数与气温呈明显的负相位,且两者的年际变化周期相同(3 a),年代尺度周期大致相当(10 a左右);融化指数与气温呈明显的正相位,且两者存在年际变化的同周期(3 a)。变化趋势特征表明,伴随着气温的增加,冻结指数呈非线性减少趋势,而融化指数呈非线性增加趋势。

Based on the average daily temperature data from 4 meteorological stations in Shihezi during the period of 1961 -2013 ,the variation of annual freezing and thawing indexes was investigated,and the muhiseale variation was analyzed using the ensemble empirical mode decomposition. The results showed that the freezing index was in a significant decrease trend with a rate of - 3.84 ℃·a-1 in recent 53 years, but the thawing index was in a signifi- cant increase trend with a rate of 8.64 ℃·a-1 The inter-annual fluctuation of the freezing index was high with an amplitude of 820.3 - 1 900.7 ℃. The fluctuation of annual thawing index was relatively low with a range of 3 518.8 -4 577.9 ℃. There was a significant negative phase between the freezing index and mean air tempera- ture ,their inter-annual periods were the same （3 years）, and their decadal periods were similar （about 10 years）. However, there was a positive phase between the thawing index and the mean air temperature, and their inter-annual periods were all for 3 years. Accompany with the nonlinear increase trend of temperature, the freezing index was in a nonlinear decrease trend, and the thawing index was in a nonlinear increase trend.