One-parameter scaling and exponential-sum fitting for water vapor and CO2 infrared transmission functions
One-parameter scaling and exponential-sum fitting for water vapor and CO2 infrared transmission functions
复制标题
水蒸气和CO2红外传输函数的一参数缩放和指数和拟合
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
M. M. Yan
中科院分区：
文献类型：
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作者：
M. Chou;W. L. Ridgway;M. M. Yan
摘要利用单参数标度近似建立了一个中等尺度的水汽和CO2吸收带模型。红外光谱分为10个波段。普朗克加权漫透射率减少到一个函数，只依赖于缩放的吸收体的量和拟合的指数和。通过选择特定的吸收系数组进行指数和拟合，可以非常快速地计算通量和冷却速率。与宽带模型相比，准确性、速度和通用性都得到了增强。由于水汽线、连续谱、CO2和O3的吸收，参数化在通量方面引入了< 1.5 W m−2的误差，在对流层和平流层下部的冷却速率方面引入了<0.15°C day−1的误差。
Abstract A medium-sized band model for water vapor and CO2 absorption is developed using the one-parameter scaling approximation. The infrared spectrum is divided into 10 bands. The Planck-weighted diffuse transmittance is reduced to a function dependent only upon the scaled absorber amount and fit by an exponential sum. By selecting specific sets of absorption coefficients for exponential-sum fitting, computations of fluxes and cooling rate are made very fast. Compared to a broadband model, the accuracy, speed, and versatility are all enhanced. With absorption due to water vapor line, continuum, CO2 as well as O3 included, the parameterization introduces an error of < 1.5 W m−2 in fluxes and <0.15°C day−1 in the tropospheric and lower stratospheric cooling rates.