Improvement of cloud microphysics in the aerosol‐climate model BCC_AGCM2.0.1_CUACE/Aero, evaluation against observations, and updated aerosol indirect effect
Improvement of cloud microphysics in the aerosol‐climate model BCC_AGCM2.0.1_CUACE/Aero, evaluation against observations, and updated aerosol indirect effect
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DOI：
10.1002/2014jd021886
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发表时间：
2014-07
期刊：
影响因子：
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通讯作者：
Zhili Wang;Hua Zhang;P. Lu
中科院分区：
文献类型：
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作者：
Zhili Wang;Hua Zhang;P. Lu
在气溶胶-气候模式BCC_AGCM2.0.1_CUACE/AERO中实施了一个预报云滴和冰晶质量浓度和数浓度的两矩云微物理方案。对气溶胶、云特性和气象场的模式结果进行了评估，并估计了人为气溶胶间接效应(AIE)。与原始模式相比，新模式模拟的气溶胶质量浓度和光学厚度比使用一阶矩大块云微物理方案更为真实。新模式得到的全球年平均柱状云雾滴密度为3.3×10 10 m−2，与卫星反演的4.0×10 10 m−2相当。新模型得到的全球云顶年平均云滴有效半径为8.1微米，小于观测得到的10.5微米。新模型的模拟液态水路径(LWP)明显低于原模型。特别是，在一些中纬度地区，新模式的年平均LWP降低了100g m−2以上，因此与卫星反演的结果更加一致。新模式对云辐射强迫和降水有不同程度的改善。全球大气顶部年平均辐射收支为−0.6W m−2，与原模式的1.8W m−2相差较大。在没有设定CDNC值下限的情况下，全球年平均人为AIE估计为−1.9Wm−2，而当设定CDNC值下限较高时，其值显著减小。
A two‐moment cloud microphysical scheme, to predict both the mass and number concentrations of cloud droplets and ice crystals, is implemented into the aerosol‐climate model BCC_AGCM2.0.1_CUACE/Aero. The model results for aerosols, cloud properties, and meteorological fields are evaluated, and the anthropogenic aerosol indirect effect (AIE) is estimated. The new model simulates more realistic aerosol mass concentrations and optical depth compared with the original version using a one‐moment bulk cloud microphysical scheme. The global annual mean column cloud droplet number concentration (CDNC) from the new model is 3.3 × 1010 m−2, which is comparable to the 4.0 × 1010 m−2 from satellite retrieval. The global annual mean cloud droplet effective radius at the cloud top from the new model is 8.1 µm, which is smaller than the 10.5 µm from observation. The simulated liquid water path (LWP) in the new model is significantly lower than that in the original model. In particular, the annual mean LWP is lower in the new model by more than 100 g m−2 in some midlatitude regions and hence much more consistent with satellite retrievals. Cloud radiative forcing and precipitation are improved to some extent in the new model. The global annual mean radiation budget at the top of the atmosphere is −0.6 W m−2, which is considerably different from the value of 1.8 W m−2 in the original model. The global annual mean anthropogenic AIE is estimated to be −1.9 W m−2 without imposing a lower bound of CDNC, whereas it is reduced significantly when a higher lower bound of CDNC is prescribed.