水汽浓度变化对温室效应影响的定量分析

Impacts of Water-vapor Concentration Variation on Greenhouse Effect:Quantitative Analysis

为了考察大气水汽浓度变化对温室效应的影响,以全球大气温度探空数据集RATPAC-A为基础,对流层采用固定相对湿度的假设,并根据平流层水汽的历史变化趋势,进行了定量研究。结果表明,对流层绝对湿度的增加,会造成其各处向上出射长波通量的减少,并在层顶处达到最大,且对流层顶水汽含量的变化,对于向上长波通量的影响最为显著;如果地表温度升高1 K,大气水汽浓度增加所导致的对流层顶向上长波通量的减小值为2.22 W/m2,对流层水汽含量变化与地表温升之间存在着强烈的正反馈关系,有能力使二氧化碳所造成的温室效应进一步增强50%;平流层水蒸汽体积浓度每上升1×10-6,将会使对流层顶的向下长波通量增加0.31 W/m2。

A quantitative analysis referring to impacts of the variation of water-vapor concentration in atmosphere on greenhouse effect was conducted based on RATPAC-A, the global atmosphere temperature radiosonde dataset, and the trend analysis of water vapor variation in stratosphere, with the assumption that relative humidity in troposphere is fixed. Findings of the quantitative analysis suggested that increases of troposphere absolute humidity would cause reduction of the upward outgoing long-wave flux in troposphere, which could reach the zenith at the tropopause; if ground surface temperature increases by 1 K, the reduction of upward long-wave flux would be 2.22 W/m2, indicating that there existed a strong positive feedback between concentration variation of water vapor in troposphere and the increase of ground surface temperature, thus enabling the greenhouse effect resulted from CO2 to be enhanced by 50%. On the other hand, in cases when water vapor concentration in stratosphere is raised by 1 ×10-6, an increase of downward long-wave flux at tropopause could accordingly attain 0,31 W/m2.