An accurate approximation to the diffusivity factor

作者：Zhao, Jian-Qi^*; Shi, Guang-Yu

来源：Infrared Physics & Technology, 2013, 56: 21-24.

DOI：10.1016/j.infrared.2012.09.003

• Diffusivity factor
• Infrared calculation
• Exponential integral
• Bridging technique

A new analytical approximation for diffusivity factor has been developed to deal with the angular integration of the diffuse transmission function for infrared radiation. The method is based on the bridging function theory which connects the exact results at both of the transparent and opaque limits. It is shown that the new scheme is much more accurate than any previously proposed schemes. By implemented into a one-dimensional radiative model, it is found that the new diffusivity factor can produce very accurate results in flux and cooling rate in the main spectral ranges for CO2, O-3, and H2O. Also, the new proposed diffusivity factor is efficient in computing.
Therefore, the new scheme is a proper choice to replace the constant diffusivity factor of 1.66 currently used in radiative transfer models.

• 出版日期2013-1
• 单位中国科学院大气物理研究所