40a气候变化对扎龙湿地蒸散影响分析

Analysis of effects of climate change on evapotranspiration in Zhalong wetland in recent 40 years

利用扎龙湿地周边5气象站1961～2000年的气象数据，研究了湿地区域最高气温、最低气温、降雨量、2m高风速等气象因子的变化趋势，分析40a气候变化对湿地蒸散耗水产生的影响．气象因子趋势分析使用Mann—Kendall检验，芦苇沼泽蒸散耗水计算采用耦合上述气象因子的经验模型．结果表明，研究区域最高气温具有不显著的上升趋势（0．15℃／10a），最低气温呈现显著的上升趋势（O．74℃／10a），二者变化是非对称的；风速具有显著的下降趋势（-0．14m·s^-1／10a），而降雨量没有显著变化，芦苇蒸散量呈下降趋势（-22．9mm／10a）．最高气温、最低气温是影响蒸散量变化的主要因子，二者升温速度的差异决定蒸散量的变化趋势，气象因子的变化表征了近年来空气中悬浮物气溶胶的增加屏蔽了太阳辐射，进而引起净辐射的降低．

By using the meteorological data from 1961 to 2000, the change trends of four meteorological factors, the maximum temperature （θmax）, the minimum temperature （θmin）, wind speed at 2 meters （U2） and precipitation （P） were detected, and the effects of climate change on evapotranspiration （E） from reed swamp of Zhalong wetland were analyzed. The trend analyses are performed by univariate Mann-Kendall test, a well-performed experiential model is introduced for E calculating. The results show that significant increasing trend is found of θmin in recent 40 years in Zhalong wetland region, the climatic tendency is 0.74 ℃/10 a, however, no significant increasing trend is found of θmax, the climatic tendency is 0.15 ℃/10 a, the U2 shows significant degressive trend, and no evident change of P in the region studied is detected, the annual E on reed swamp shows degressive tendency, the decrease in recent 40 years is 92 mm. The trend analysis and sensitivity analysis of meteorological factors illuminate that θmax and θmin are two key factors which influence E markedly, the difference of the change speed between them results in the decrease of E, the records of θmax and θmin mean the augment of greenhouse gas and aerosol in the atmosphere, these substances serve as a screen to prevent the heat transferring to outer space and at the same time reduce extraterrestrial radiation, consequently, decrease net radiation, the most correlative variable to E.