Influence of spectral characteristics of the Earth's surface radiation on the greenhouse effect: Principles and mechanisms

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Enhanced greenhouse effects by anthropogenic emissions of greenhouse gases (GHGs) resulted in global warming since the Industrial Revolution. However, the influence of the spectral characteristics of the Earth's surface radiation on the greenhouse effect has not been completely explored. This work uses the surface temperature as the variable of model and investigates the response mechanism of the greenhouse effect. According to the GHGs' different selective spectral absorption of earth's infrared radiation (IR) band and the distribution characteristic of spectral radiant intensity with the temperature increases, some quantified analysis shows that the greenhouse effect is highly dependent on two factors: the radiation intensity enhancement (RIE) and the spectral absorption enhancement (SAE). RIE is determined by the spectral radiant intensity of earth's IR while SAE represents the GHGs' spectral absorption change under different wavelength. As the results show, RIE always enhances the greenhouse effect, while SAE, as a result of the spectral shift in the Earth's radiant energy, can enhance or weaken the greenhouse effect depending on the positive or negative total SAE integrated over the entire spectral region. The quantified data of this work also explain the reason why greenhouse effect has greater impact on extreme cold areas from the aspect of spectral characteristics: when the surface temperature drops below −20 °C, SAE of CO2 has an enhancing effect, so that both RIE and SAE exert positive influences with the temperature increase in the polar region for its extremely low surface temperature, which doubly enhances the global warming.