北京冬季城市人为水汽排放的定量估算研究

Quantitative Estimation of Anthropogenic Water Vapor Emissions in Winter in Beijing

在北京城市气象环境的数值模拟中,人为热的设置是一个难点。人为热包括感热和潜热,人为潜热可以通过计算人为水汽排放获得。本文利用飞机观测资料对北京冬季人为水汽排放进行了定量估算。研究发现,在北京城区下风方向观测到相对周边区域更高的水汽摩尔分数,当观测到城市水汽过量信号时,水汽排放率的估计值在58~9539 kg/s,占城市大气边界层水汽总平流(背景+城市过量)的0.64%到13.12%。城市过量水汽排放的主要来源是天然气燃烧、水冷空调系统、城市交通等人为水汽的排放,中心城区和周边区域融雪率和蒸发率的差异可能也会有一定的贡献,但所占比例较小。

The setting of anthropogenic heat is a difficult point in the numerical simulation of Beijing's urban meteorological environment.Anthropogenic heat includes sensible heat and latent heat.Anthropogenic latent heat can be obtained by calculating anthropogenic water vapor emissions.This paper uses aircraft observation data to quantitatively estimate the anthropogenic water vapor emissions in Beijing in winter.Results reveal a higher water vapor mole fraction in the downwind direction of the Beijing urban area than in the surrounding area.When an excess signal of urban water vapor was observed,the estimated value of water vapor emission rate was between 58 and 9539 kg/s,accounting for 0.64% to 13.12% of the total water vapor advection in the urban atmospheric boundary layer(background+urban excess).The most important source of excessive urban water vapor emission is the emission of urban anthropogenic latent heat such as natural gas combustion,water-cooled air conditioning system and urban transportation.The difference in the snow melting rate and evaporation rate in the central city and surrounding areas may also have a certain contribution,but the proportion is small.