论文部分内容阅读
利用彭曼公式计算了 80年代以来黄河上游流域蒸散量 ,分析了该地区蒸散量、日照时数、气温、空气饱和差等气候因子的变化趋势 ,着重研究了诸因子对蒸散量的影响。研究发现 ,黄河上游流域蒸散量呈逐年增大趋势 ,并以每年 3.2 5mm的速度递增 ;而作为主要影响因子的日照时数则以每年 3.6小时的速度增加 ;气温同样表现出逐年升高的趋势 ,其气候倾向率为 0 .4℃ /1 0 a;空气饱和差也以每年 0 .0 2 h Pa的速度递增。因此 ,可以认为 ,黄河上游流域日照时数、气温及饱和差的增加 ,加剧了草地蒸散量的增大 ,而蒸散量的增大和降水量的减少则直接影响到了黄河上游流量的减少和草地荒漠化的蔓延。
The Penman formula was used to calculate the evapotranspiration of the upper reaches of the Yellow River since the 1980s. The trends of evapotranspiration, sunshine duration, air temperature and air saturation in the region were analyzed. The effects of various factors on evapotranspiration were studied. The study found that the evapotranspiration in the upper reaches of the Yellow River has been increasing year by year and increasing at an annual rate of 3.2 mm, while the sunshine duration as the main factor increased by 3.6 hours per year. The temperature also showed an upward trend year by year , With a climatic propensity of 0 .4 ° C / 1 0 a. The air saturation difference also increases at a rate of 0 · 0 2 h Pa per year. Therefore, it can be considered that the increase of sunshine hours, temperature and saturation difference in the upper reaches of the Yellow River aggravate the increase of grassland evapotranspiration. However, the increase of evapotranspiration and decrease of precipitation have a direct impact on the reduction of the flow in the upper reaches of the Yellow River and desertification The spread.