Fast-J2: Accurate simulation of stratospheric photolysis in global chemical models
Fast-J2: Accurate simulation of stratospheric photolysis in global chemical models
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DOI：
10.1023/a:1014980619462
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发表时间：
2002-03-01
影响因子：
2
通讯作者：
Prather, MJ
中科院分区：
文献类型：
--
作者：
Bian, HS;Prather, MJ
模拟平流层中的光化学需要在极端波长范围和大气条件下求解辐射传输方程，从中间层中O-2的舒曼-龙格带传输到对流层云和气溶胶的多重散射。条件的复杂性和范围使得3-D化学传输模型中的光解计算在计算上昂贵。本文提出了一种计算平流层光解速率（J值）和太阳通量沉积的快速、精确的数值方法Fast-J2。Fast-J2为177至291 nm波长开发了一种优化的超宽11-bin正交，与已经为对流层开发的7-bin正交（291-850 nm）Fast-J相结合。291 nm以下，瑞利散射的影响被实现为伪吸收，而291 nm以上则使用Fast-J的完整多次散射代码。Fast-J2计算整个平流层这18个波长箱的平均紫外-可见光辐射场，因此可以很容易地实现新的物种和新的横截面。与标准的高分辨率多重散射光解模型相比，Fast-J2在太阳天顶角、高度（0-60 km）、纬度和季节的广泛范围内的最坏情况误差不超过5%，其中速率在光化学中很重要。
Modeling photochemistry in the stratosphere requires solution of the equation of radiative transfer over an extreme range of wavelengths and atmospheric conditions, from transmission through the Schumann-Runge bands of O-2 in the mesosphere, to multiple scattering from tropospheric clouds and aerosols. The complexity and range of conditions makes photolysis calculations in 3-D chemical transport models computationally expensive. This study pesents a fast and accurate numerical method, Fast-J2, for calculating photolysis rates (J-values) and the deposition of solar flux in stratosphere. Fast-J2 develops an optimized, super-wide 11-bin quadrature for wavelengths from 177 to 291 nm that concatenates with the 7-bin quadrature (291-850 nm) already developed for the troposphere as Fast-J. Below 291 nm the effects of Rayleigh scattering are implemented as a pseudo-absorption, and above 291 nm the full multiple-scattering code of Fast-J is used. Fast-J2 calculates the mean ultraviolet-visible radiation field for these 18 wavelength bins throughout the stratosphere, and thus new species and new cross sections can be readily implemented. In comparison with a standard, high-resolution, multiple-scattering photolysis model, worst-case errors in Fast-J2 do not exceed 5% over a wide range of solar zenith angles, altitudes (0-60 km), latitudes, and seasons where the rates are important in photochemistry.