N2O增加对大气环境影响的模拟及其与甲烷和平流层水汽影响的比较

本文利用美国国家大气环境中心(NCAR)的二维化学、辐射和动力相互作用的模式(SOCRATES),模拟了大气中N₂O增加对O₃和温度的影响,并从化学、辐射和动力过程讨论了影响原因,此外还与大气甲烷和平流层水汽增加对大气环境的影响进行了对比.分析表明:大气中N₂O浓度增加以后,将通过化学过程引起30 km以上O₃损耗,30~40 km损耗较多;30 km以上降温明显,下平流层中低纬度地区以及对流层O₃增加并有微弱升温;30~40 km附近,北半球中高纬地区O₃减少以及降温幅度都大于南半球.对流层升温主要是N₂O和O₃增加所致,而平流层温度变化主要受O₃控制.北半球中高纬地区动力过程对温度变化的反馈较其它地区明显,这种反馈对平流层中高层北半球中高纬地区温度和O₃的变化都有明显影响.大气中甲烷增加引起的O₃损耗在45 km以上,45 km以下O₃增加.平流层水汽增加会引起40 km以上O₃减少,20~40 km大部分地区O₃增加.N₂O增加造成的O₃损耗正好位于臭氧层附近,其排放对未来O₃层恢复至关重要.N₂O增加引起下平流层15~25 km中低纬度地区有弱的升温,这与其它温室气体增加对该地区温度的影响不同,CO₂,CH₄和H₂O等增加后下平流层通常是降温.

Simulation of influence of N2O’s increase on atmospheric environment and comparison with the influences of methane and stratospheric water vapor

A sensitivity experiment, with the increasing N₂O volume mixing ratio, was carried out to study the influence of an increase of N₂O on O₃ and temperature using the 2D interactive chemical radiative dynamical (SCORATES) model of the National Center for Atmospheric Research, and the reasons for O₃ and temperature change were analyzed from chemistry, radiation and dynamical processes. Moreover, the differences in influences on the atmospheric environment of methane and water vapor increase as well as N₂O increases were compared. The results show that when N₂O concentration increases, the chemical process results in O₃ depletion over 30 km, and the high value appear between 30 and 40 km. The cooling is obvious over 30 km, the O₃ increase and slight warming appear at middle-lower latitudes in the lower stratosphere and troposphere. The extents of ozone decrease and cooling over 30~40 km are larger at middle-high latitudes in the North Hemisphere than in the South Hemisphere. The tropospheric warming is mainly caused by the increases of N₂O and O₃, while the temperature change in the stratosphere is mainly dominated by O₃. The dynamical feedback to temperature change is more distinct at middle-high latitudes in the Northern Hemisphere than in other regions and significantly affects temperature and ozone in the middle-high stratosphere at middle-high latitudes in the Northern Hemisphere. Whereas the O₃ depletion caused by methane increase appears above 45 km, and the O₃ increases below 45 km. The stratospheric water vapor increase can result in the O₃ depletion above 40 km, and the O₃ increases in the most of between 20 and 40 km. The O₃ depletion caused by N₂O increase appears right near the O₃ layer, and its emission is very important to the future O₃ layer recovery. The slight warming caused by N₂O increase appears from 15 to 25 km at middle and low latitudes, however the increase in CO₂, CH₄, and stratospheric water vapor can respectively lead to cooling there.