寒旱区草地不对称增温现象对蒸散发的影响分析

Asymmetric warming of grassland and its effect on evapotranspiration in cold and arid region

选取1981—2020年海拉尔河流域及周边地区气象站点观测资料,结合水文数据,利用适用于植被稀疏下垫面的BTOP(Block-wise use of TOPMODEL)分布式水文模型估算区域蒸散发量,进而在不对称增温现象影响下,分析其对蒸散发的影响特征。结果表明:①流域内1981—2020年不对称增温现象显著,主要表现为因夜间温度升幅较大为主的昼夜不对称增温及地表温度升幅较大为主的地气不对称增温;②影响蒸散发的主要气象因子依次为相对湿度、风速、地气温差、地表温度和昼夜温差,且相对湿度、昼夜温差及地气温差与蒸散发量变化趋势相反,其中相对湿度及风速影响强度年际变化平稳,温度因子影响强度则逐年增强;③不对称增温对于流域蒸散发量的影响逐年增强,地表增温速率的增强是造成地气不对称增温的主要原因,在此影响下,区域蒸散发呈现减小趋势,故在探究蒸散发量变化原因时,温差变化不可忽视。

In this study,observations from meteorological stations in and around the Hailar River basin from 1981 to 2020 were selected and combined with hydrological data to estimate regional evapotranspiration using the BTOP distributed hydrological model applicable to sparsely vegetated substrates,and then to analyze its influence characteristics on evapotranspiration under the influence of asymmetric warming phenomena.The results show that the asymmetric warming phenomenon in the basin from 1981 to 2020 is significant,mainly due to the diurnal asymmetric warming dominated by a larger increase in nighttime temperature and the asymmetric warming of ground air dominated by a larger increase in surface temperature.The main meteorological factors affecting evapotranspiration were relative humidity,wind speed,ground temperature difference and diurnal temperature difference,and relative humidity,diurnal temperature difference and ground temperature difference had the opposite trend of evapotranspiration,among which relative humidity and wind speed had a stable interannual variation,while temperature factor had an increasing intensity year by year.And the influence of asymmetric warming on basin evapotranspiration increases year by year,and the enhancement of surface warming rate is the main reason for the asymmetric warming of ground gas,under which the regional evapotranspiration shows a decreasing trend,so the temperature difference change cannot be ignored when exploring the reasons for the change of evapotranspiration.