Impact of four‐stream radiative transfer algorithm on aerosol direct radiative effect and forcing
Impact of four‐stream radiative transfer algorithm on aerosol direct radiative effect and forcing
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DOI：
10.1002/joc.4289
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发表时间：
2015-11
期刊：
影响因子：
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通讯作者：
Hua Zhang;Zhili Wang;Feng Zhang;Xianwen Jing
中科院分区：
文献类型：
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作者：
Hua Zhang;Zhili Wang;Feng Zhang;Xianwen Jing
气溶胶直接辐射效应（DRE）和强迫（DRF）的估算存在较大的不确定性。在这项工作中，使用气溶胶气候模式与双流和四流辐射方案，我们表明，辐射传输算法的不确定性。双流算法明显低估了气溶胶短波DRES和加热率。对于目前的条件，四流算法被发现在大气顶部（TOA）将全球年平均气溶胶短波DRES提高了8%（14%），在大气中提高了15%（18%），在全天空（晴空）情况下，在地面提高了12%（15%）。两流和四流算法之间气溶胶短波DRE的区域平均相对差异随着纬度的增加而增加，在南半球高纬度地区，TOA超过25%，地面超过30%。除北极、青藏高原、阿拉伯半岛和撒哈拉沙漠外，四流算法的DRE差异在TOA处为负值，在大气中为正值，在地表为负值，最大值超过4.0 W m−2。由于四流算法，气溶胶短波加热速率的增加通常超过10%，甚至可能超过100%。我们的结果还表明，双流算法低估了人为气溶胶造成的DRF。在北方半球的中纬度地区出现了显著的低估，最大值接近晴空情况下的0.6 W m−2。这项研究表明，多流辐射传输算法是必要的，以减少全球气候模式估计的气溶胶DRE和DRF的不确定性。
Large uncertainties remain in the estimation of aerosol direct radiative effect (DRE) and forcing (DRF). In this work, using an aerosol‐climate model with two‐ and four‐stream radiation schemes, we show that the radiative transfer algorithms contribute to the uncertainties. Aerosol shortwave DREs and heating rate are underestimated significantly by the two‐stream algorithm. For present‐day conditions, the four‐stream algorithms are found to enhance global annual mean aerosol shortwave DREs by more than 8% (14%) at the top of the atmosphere (TOA), 15% (18%) in the atmosphere, and 12% (15%) at the surface for all‐sky (clear‐sky) case. The regional‐averaged relative differences in aerosol shortwave DREs between the two‐ and four‐stream algorithms increase as latitude increases, exceeding 25% at the TOA and 30% at the surface in the high latitudes of the Southern Hemisphere. The DRE differences due to the four‐stream algorithms are negative, except for the Arctic, Tibetan Plateau, Arabia, and Sahara, at the TOA, are positive in the atmosphere, and are negative at the surface, with the maximum exceeding 4.0 W m−2. Increases in aerosol shortwave heating rates due to the four‐stream algorithms are generally more than 10% and may even exceed 100%. Our results also show that the two‐stream algorithm underestimates the DRFs due to anthropogenic aerosols. Significant underestimation appears in the middle latitudes of the Northern Hemisphere, with the maximum being close to the quantity of 0.6 W m−2 for clear‐sky case. This study indicates that a multi‐stream radiative transfer algorithm is necessary to reduce the uncertainties of aerosol DREs and DRFs estimated by global climate models.