北京潜在蒸散发量年内-年际的气候变化特征及成因辨识

论文基于北京站1951—2009 年的气象资料,采用Penman-Monteith 公式估算潜在蒸散发,并对其年际年内的变化特征进行辨析。结果表明:北京1951—2009 年年均潜在蒸散发量呈显著上升趋势;气象要素的敏感性从强到弱依次为:空气相对湿度、温度、太阳辐射和风速;论文提出实测变幅均值法,基于此方法考虑气象要素年内变化特征,估算温度、饱和差、风速和太阳辐射的贡献率分别为13%、58%、17%和11%;对气象因子的年际变化趋势进行分析,平均气温在0.05 显著水平下增加趋势显著,太阳辐射和空气相对湿度在0.05 显著水平下减少趋势显著,风速变化趋势没有通过显著性检验;综合考虑年际变化和敏感性的去趋势分析显示:温度增加和空气相对湿度减少是造成潜在蒸散发增加的主要原因,太阳辐射的减少使得其增加趋势有所减弱,但未改变其增加趋势。

The Inter-Intra Annual Climatic Pattern of Potential Evaporation in Beijing and Attribution

Based on the metrological data in Beijing station during 1951-2009, this paper firstly uses the Penman-Monteith formula to estimate the potential evaporation. Then the climatic character istics in inter-and intra-annual potential evaporation are analyzed. The results show that at 95% confidence level, the trend in annual potential evaporation during 1951-2009 increases significantly. The trends of relativity humidity and solar radiation decrease, temperature increases, and wind speed shows no trend in Beijing station. The sensitivity to potential evaporation (ET₀) from strong to weak is relativie humidity, temperature, solar radiation and wind speed. Considering the fluctuation variation pattern of climatic variables, the contribution of temperature, VDP, wind speed and solar radiation is 13%, 58%, 17% and 11% respectively. This suggests the fluctuation of climatic variables have great effect on the change pattern of ET₀, especially the wind speed. In order to detect how climatic variables affect ET₀, this paper uses the detrend method considering the inter-annual change pattern combined with sensitivity of climatic variables. The detrend analysis demonstrate that the increasing temperature and decreasing relativie humidity are the main cause for increasing potential evaporation. As to the decreasing shortwave radiation, the ET₀ slightly decreases, but no change in its increasing trend.