SF6气体的辐射强迫和全球增温潜能的研究

A Study of the Radiative Forcing and Global Warming Potentials of SF_6

IPCC(2007)指出,六氟化硫(SF6)作为臭氧消耗物质(ODSs)的部分替代物质,近年来排放量大大增加。它作为控制排放的人造长寿命温室气体之一已经被列入《京都议定书》。但是,目前在臭氧消耗物质替代品中,对SF6的辐射强迫和全球增温潜能的研究较少,而且所用的谱吸收资料陈旧。本文采用最新的分子吸收数据库HITRAN2004中的SF6的吸收截面数据,利用Shi(1981)的吸收系数重排法,建立了SF6的相关k分布的辐射计算方案,在此基础上研究了SF6在晴空大气下的辐射效率和全球增温潜能,并首次计算了SF6的全球温变潜能,与其全球增温潜能进行了比较。本文的研究表明:SF6的辐射效率为0.512W/m2,经过大气寿命调整之后的辐射效率为0.506W/m2,二者差别不大;根据IPCC(2007)给出的排放情景,到2100年,SF6在大气中的体积分数将达到35×10-12～70×10-12,引起的相应辐射强迫将在0.004～0.028W/m2之间变化;相对于二氧化碳的100年全球增温潜能为2.33×104,比IPCC(2007)的结果大2.2%;100年的持续排放的全球增温潜能为2.26×104,与其他长寿命人造温室气体一道,其对全球变暖的长期影响不容忽视。

IPCC （2007） points out that the emission of sulphur hexafluoride （SF6） has been increasing greatly in re- cent years as part of the replacements for the Ozone Depleting Substances （ODSs）. SF6 has been included in the Kyoto Protocol as one of the controlled man-made long-lifetime greenhouse gases. But there were few studies on its radiative forcing and global warming potentials and the absorption dataset used before also needs to be updated. In this work, the absorption cross sections of SF6 from the latest version of HITRAN2004 database are used. A radia- tion parameterization based on correlated k-distribution method for SF6 is developed, following the method of ab- sorption coefficient rearrangement by Shi （1981）, to calculate the radiative efficiency for clear sky and its global warming potentials. The global temperature potentials of SF6 are calculated here for the first time for the comparison with its global warming potentials. It is shown that the radiative efficiency of SF6 is 0. 512 W/m2 , which differs slightly from 0. 506 W/m2 with the consideration of lifetime adjustment. According to the emission scenarios in IPCC （2007）, the volume fraction of SF6 will be 35 × 10^-12 to 70× 10^ 12 in 2100, corresponding to the radiative forcing of 0. 004 to 0. 028 W/m2. For SF6, the 100-year global warming potential relative to CO2 is 2. 33 × 10^4 , which is 2. 2% larger than that in IPCC （2007）. The 100-year global temperature potential relative to CO2 for sus- tained emission is 2. 26× 10^4. The long-term influence of SF6 on global warming together with other man-made long- lifetime greenhouse gases should not be ignored. Key words SF6, radiative forcing, global warming potential, global temperature potential, correlated h-distribution