两种逐线积分辐射模式大气吸收的比较研究

A Comparison Between the Two Line-by-Line Integration Algorithms

由于缺乏完整的和精确的实验室测量结果,目前无法判断各种逐线积分方案的最终精度。因此,逐线积分模式精度的比较基本上只能在模式之间进行。比较了作者研制的快速高效逐线积分大气吸收计算方法(简记为ZS2000),与国际上用得较多的LBLRTM(LineByLineRadiativeTransferModel)。得出:二者在长波区间向上和向下辐射通量的相对差别对整层大气均小于3.1%,大气冷却率的绝对差别对整层大气均小于0.13K·d-1,处于ICRCCM(IntercomparisonofRadiationCodesUsedinClimateModels)所得到的差别范围之内。经分析发现,这些差别主要是由于ZS2000在10～530cm-1区间计算的水汽吸收系数与LBLRTM的不同造成的。ZS2000和LBLRTM在近红外区间计算上的一致性较高,二者净辐射通量和大气加热率的最大相对差别均小于2%。由此,可以得出:逐线积分模式ZS2000在长波和近红外区间可以满足各种较为精确的辐射传输计算的需要。

There is no criterion to judge which one is the most accurate among different line-by-line (LBL) integration algorithms for lack of exact measurement data from laboratory currently. Therefore, the evaluation to the accuracy of LBL algorithm can only be made in the comparison among different models. A fast and efficient LBL algorithm for atmospheric absorption called ZS2000 developed by the authors is compared with LBLRTM in detail, which is one of the LBL integration models recognized officially in the world. It is shown that the relative differences of up and down radiative fluxes and the absolute differences of atmospheric cooling rates between them in the longwave region are less than 3.1% and 0.13 K·d -1 for the whole atmosphere, respectively. These differences are within the scope from ICRCCM (Intercomparison of Radiation Codes Used in Climate Models). It is found in the analysis that these differences are mainly caused by the smaller water vapor absorption coefficients in the region of 10~530 cm -1 obtained by ZS2000 than those calculated by LBLRTM. Especially in the infrared region, both of them are consistent with each other in radiative flux and heating rate with a high accuracy of relative difference within 2%. Therefore, it is concluded that ZS2000 can satisfy all kinds of need in accuracy in radiative transfer calculations for the longwave and infrared regions.