石羊河下游物候季节的水热分配及变化特征

基于物候季节,分析了石羊河下游地区1971-2000年各季节的水热分配状况及多年变化特征。结果表明,石羊河下游物候季节的更迭与气候的季节性演变相吻合,稳定通过物候四季的温度界限分别为春季≥2.9℃,夏季≥19.0℃,秋季<19.0℃,冬季≤4.5℃。水热资源最丰富为物候的夏季,其≥0℃的积温和降水分别占全年的55.8%和62.5%。多年来,温度的四季变化和年际变化具有明显的增加趋势,增长幅度依次为冬季>全年>春季>夏季>秋季。年均温的升高以1986年为突变年,而冬季和春季气温的升高分别以1985年和1991为突变年;降水变化的趋势不明显,年降水的波动形态与夏季基本一致,春季则与夏季相反,有春湿夏干或春干夏湿的趋势。

Water & Heat Distribution and Climatic Changes of Phenological Seasons in the Lower Reaches of Shiyang River

Base on the phenological seasons,the water & heat distribution and the climatic changes of phenological seasons in the lower reaches of Shiyang river from the year of 1971 to 2000 are analyzed in this paper.The results show that the changes of phenological seasons in the lower reaches of Shiyang river are coincide with the seasonal evolution of climate.The temperatures of phenological seasons are ≥2.9℃in spring,≥19.0℃in summer,<19.0℃in autumn and ≤4.5℃in winter.Water & heat is plenty in summer of phenological seasons,in which ≥0℃accumulated temperature and rainfall occupy 55.8% and 62.5% in the whole year respectively.The seasonal and annual changes of temperature within several years show a obvious tendency of increase,and the increase rate is the biggest in winter,followed by the whole year,spring,summer,and the smallest is in autumn.There were jumps of annual mean temperature from low to high in 1986;also a jump of the mean temperature in winter and spring in 1985 and 1991.The variation tendency of precipitation is not obvious.The fluctuation of precipitation in summer is basically coincide with annual precipitation,while the fluctuation of rainfall in spring is contrary to that in summer,which shows a tendency of wet in spring while drought in summer or drought in spring while wet in summer.