雅鲁藏布江流域1978-2009年气候时空变化及未来趋势研究

利用1 km 分辨率DEM数据及ArcHydro Tools 提取了雅鲁藏布江流域边界, 明确给出了该流域具体的地理边界及空间范围. 依据雅鲁藏布江流域范围内及周边39个气象站点1978-2009年近32 a逐年气象数据, 综合运用GIS空间插值技术及气象统计分析方法, 对雅鲁藏布江流域气候(着眼于降水和气温指标)时空变化特征及未来变化趋势进行了研究. 结果表明: 1978-2009年间流域范围内多年平均降水大致趋势为由西至东逐步增加, 年平均降水量以7.935 mm·(10a)^-1的速度缓慢增加. 流域多年平均气温大致由河源至下游逐渐升高, 河谷腹地至流域边界处逐渐降低, 并出现了以拉萨、乃东为中心的局部高温带; 近32 a流域年平均气温增加2.2 ℃, 增加幅度达到0.489 ℃·(10a)^-1, 高于全球及全国同期增温速率. 近10 a间, 流域平均降水以 -139 mm·(10a)^-1的速度显著减少, 气温则以1.14 ℃·(10a)^-1的速度增加, 整个流域气候呈现暖干趋势. 利用R/S分析法预测得知, 流域年降水量可能出现短时间的减少波动, 但未来较长一段时间内, 流域降水及气温仍将保持增加趋势, 流域气候呈现暖湿化趋势.

Spatial and Temporal Climate Variations from 1978 to 2009 and Their Trend Projection over the Yarlung Zangbo River Basin

By means of 1-km spatial resolution DEM data and Archydro Tools,the geographic boundary and the area of the Yarlung Zangbo River basin were precisely extracted.Based on the annual mean climatic data from 39 meteorological stations during 1978—2009 within and around this basin,by means of synthetic usage of climatic statistics models and GIS spatial interpolation techniques,the spatial and temporal characteristics of climate variations were analyzed and the future trend of the climatic variations was projected.The study results suggest that: 1) From 1978 to 2009,precipitation within the watershed roughly increased from west to east,and the basin scale averaged precipitation increased slowly with a speed of 7.935 mm·(10a)-1.Annual mean temperature increased gradually from the river source area to downstream and from the basin boundary to hinterland,with an exception for a local high-temperature zone emerged over the Lhasa city and the Naidong area.In the 32 years from 1978 to 2009,annual mean temperature increased about 2.2 ℃ with an increasing rate of 0.489 ℃·(10a)-1(through 99% significance test),which was obviously higher than the reported global temperature increase rate and that for China as a whole.2) Over the past 10 years,the basin scale averaged precipitation notably reduced with a speed of-139 mm·(10a)-1,while air temperature increased with a speed of 1.14 ℃·(10a)-1,implying that the whole watershed tends to be much warm and dry in the recent decade.3) In addition,according to the R/S analyses,Hurst index of the 32 years predicts that air temperature and precipitation would increase in some phases in the future,and the climate over the basin would tend to be much warm and wet.