Abstract
Absorption coefficient of water vapor proposed to be responsible for an increase in temperature in the troposphere layer with altitude less than 10 km is systematically presented in this work. Since global warming plays an important role in affecting the human life, a confirmative and detailed study of global warming is essentially need. Solar irradiation within short wavelength range can be extinguished from absorption and scattering by the atmosphere, and absorbed and reflected by the Earth's surface. Radiative within high wavelength range from the Earth's surface can be absorbed by atmospheric water vapor, carbon dioxide and other gases. The difference in solar irradiation and energy escaped to the space from the atmosphere results in the atmosphere acting as the glass of a greenhouse and increase atmospheric temperature. Extending the previous work [1] for predicting absorption coefficient of carbon dioxide through the troposphere, this work further determines absorption coefficients of water vapor in different wavelength bands centered at 71, 6.3, 2.7, 1.87 and 1.38 μm across the temperature, pressure and concentration-dependent troposphere layer. Solving one-dimensional unsteady heat conduction-radiation equation with the COMSOL computer code, the predicted temperature together with water vapor density for different optical path lengths can be used to interpret in details absorption coefficient or the ratio between band intensity and effective band width by using the exponential wide band model. The results show that absorption coefficients are strongly affected by water vapor concentration. For example, absorption coefficients in the band centered at 71 μm increases from 0.3 to 1.2 m−1 at the tropopause and 0.6 to 3.1 m−1 at the Earth's surface as mole fraction of water vapor increases from 0.005 to 0.02. The predicted absorption coefficients agree with experimental and theoretical results in the literature. A more detailed and realistic temperature profile through the troposphere with optical path length of 104 m is presented.
Highlights
Global warming is considered to be a consequence of the greenhouse effects of water vapor and other gases such as carbon dioxide and methane, and so on
With the predicted temperature which can increase and decrease, whereas water vapor density exponentially increases in the direction toward the Earth’s surface, the conclusions drawn are the following: 1. Absorption coefficients as functions of concentration, temperature, optical path length, and correlated parameters of water vapor in different wavelength bands required for predicting temperature across the troposphere layer are rigorously and quantitatively investigated
Absorption coefficient representing the ratio between band intensity and effective band width increases in the direction toward the Earth’s surface
Summary
Global warming is considered to be a consequence of the greenhouse effects of water vapor and other gases such as carbon dioxide and methane, and so on. Increases in water vapor can be responsible for lower atmospheric and Earth’s surface temperatures [3] Their impacts have been studied using different computer simulations of global warming induced by different emission gases, from simple zerodimensional model [4], one-dimensional model [4, 5, 6] to complex 3-dimensional, short period [7] to long periods [8], heat conduction to convection and radiation [5, 6], coupled with complicated ocean-atmosphere models [9]. The total band absorption A was first measured extensively for different pressures and absorber concentration of carbon dioxide and water vapor at an atmospheric temperature by Howard et al [15, 21]. Reflectivity rE 1⁄4 1-ε, where ε is emissivity of the Earth’s surface
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