长江流域近50 a≥0℃积温变化特征及农业适应对策

Changes in ≥0 ℃ Accumulated Temperature and Agricultural Adaptative Strategies in the Yangtze River Basin in Recent 50 Years

利用1961—2010年长江流域659个气象观测站日平均气温资料,运用线性倾向估计和GIS空间分析等方法,对近50 a长江流域≥0℃积温及其持续天数和起止日期的时空分布特征进行分析。结果表明,近50 a来长江流域年平均气温呈现缓慢上升趋势,倾向率达0.18℃·d·(10 a)-1,这一变化幅度低于中国同期的增温速率。长江全流域≥0℃积温平均值为5 496.77℃·d,倾向率为69.92℃·d·(10 a)-1,其中中游≥0℃积温的50 a均值最高,上游最低。持续天数多年平均值为342.25 d,倾向率为2.51 d·(10 a)-1。其中,中游的持续天数多年均值最高,达350.55 d。而倾向率则以下游为最高,达3.73 d·(10 a)-1。50 a间长江流域的≥0℃初日提前,≥0℃终日推后,持续天数的逐年稳步增加主要与流域≥0℃初日明显提前有关。积温年代际变化呈现明显的V字型特征,从20世纪90年代起积温明显增加。而初终日间天数则随年代际呈现持续增加趋势,其中以1970—1990年代间的增幅为最大。空间分布呈现由西北向东南逐渐增加的趋势。存在2个明显的高值区,一个位于西部的四川盆地,另一个位于流域的东南部,包括湖南省南部和江西省东南部地区。干流通天河流域则是流域内积温最低的区域。各积温等值线均随年代际缓慢西移,6 000℃·d等值线除西移外,在1990年代出现明显的北移特征。与1960年代相比,2000年代除四川小部分地区外,流域内其他地区均呈现积温增加的态势。随着热量资源的增加,需要针对流域内的作物品种、轮作方式等做出调整,避免热量资源的大量浪费以及热量资源增加对农作物生长发育造成的危害。

Analysis was done of the data of daily mean temperature of the recent 50 years ( 1961-2010) from the 659 me?teorological stations in the Yangtze River Basin using the linear trend estimation method and GIS spatial analysis method for≥0 ℃ accumulated temperature, duration of the days≥0℃ and temporal?spatial distribution of the beginning and ending of the period. Results show that in the past 50 years, the annual mean temperature in the basin is rising slowly with a tend?ency rate reaching to 0?18 ℃·d·(10 a)-1 and amplitude of the change is lower than the warming rate of the country during the same period. The annual mean≥0℃ accumulated temperature was 5 496?77℃·d with a tendency rate being 69?92℃·d·( 10 a)-1 in the Yangtze River Basin, of which the middle reaches were the highest in annual mean≥0 ℃accumulated temperature and the upper reaches were the lowest. The mean duration was 342?25 d with a trend rate being 2?51 d·( 10 a)-1 . The middle reaches were also the highest in duration, being 350?55 d and the lower reaches were in the tendency rate, being 3?73 d·( 10 a)-1 . The beginning date of the duration was advanced and the ending date post?poned. The duration was steadily increasing year by year, which was mainly attributed to the advancement of the beginning date. The decadal variation of accumulated temperature displayed V shaped curve, which began to increase significantly in the 1990s, while the number of days between the beginning and ending of the≥0℃ accumulated temperature period in?creased steadily with the decades. The increase was more significant in the 1970s-1990s. Spatial analysis shows that an in? creasing tendency went gradually from northwest to southeast. However, there were two distinct high value areas, one in the west Sichuan Basin, and the other in the southeast of the river basin, including south Hunan and southeast Jiangxi and one low value area that the Tongtian River Basin. The contours of accumulated temperatures moved westward slowly with decades passing by. Besides moving westward, the contour of 6 000 ℃·d, has also been moving northward significantly since the 1990s. Compared with the 1960s, accumulated temperature increased in the whole Yangtze River Basin, except for a small region in Sichuan Province in 2000s. In response to the increase in accumulated temperature, it is necessary to take some measures, like use of new crop varieties and crop rotation systems that are more suitable to warm weather, so as to a?void waste of the heat resources and prevent damage of increased heat resources to crop growth in the Yangtze River Basin.