Advanced Two-Moment Bulk Microphysics for Global Models. Part II: Global Model Solutions and Aerosol-Cloud Interactions
Advanced Two-Moment Bulk Microphysics for Global Models. Part II: Global Model Solutions and Aerosol-Cloud Interactions
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DOI：
10.1175/jcli-d-14-00103.1
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发表时间：
2015-02-01
影响因子：
4.9
通讯作者：
Caldwell, P. M.
中科院分区：
文献类型：
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作者：
Gettelman, A.;Morrison, H.;Caldwell, P. M.
在社区大气模式第5版(CAM5)中实施了一个改进的微物理方案。新方案的特点是预报降水。微物理和模型其余部分之间的耦合被修改，使其更加灵活。单柱试验表明，新的微物理可以模拟一个受约束的层积雨情况。在时间步长内减少云凝结(宏观物理)可以改善单列结果。混合相情况的模拟对冰核非常敏感。新的微物理改变了单列和全球模拟的处理速度，即使在低水平分辨率(200公里)下也是如此。因此，预报降水可能很重要，即使在降水平流不重要的低分辨率模拟中也是如此。随着液态水路径的增加，吸积占主导地位，这与云分辨模式模拟和观测估计一致。具有预测降水的新的微物理增加了吸积与自动转化的比率。过程速率的变化似乎显著地减少了气溶胶云相互作用和人为气溶胶的间接辐射效应，在使用工业化前(1850)和现在(2000)气溶胶排放的模拟之间，降温最高可达33%(取决于分步)至低于1W m(-2)。
A modified microphysics scheme is implemented in the Community Atmosphere Model, version 5 (CAM5). The new scheme features prognostic precipitation. The coupling between the microphysics and the rest of the model is modified to make it more flexible. Single-column tests show the new microphysics can simulate a constrained drizzling stratocumulus case. Substepping the cloud condensation (macrophysics) within a time step improves single-column results. Simulations of mixed-phase cases are strongly sensitive to ice nucleation. The new microphysics alters process rates in both single-column and global simulations, even at low (200 km) horizontal resolution. Thus, prognostic precipitation can be important, even in low-resolution simulations where advection of precipitation is not important. Accretion dominates as liquid water path increases in agreement with cloud-resolving model simulations and estimates from observations. The new microphysics with prognostic precipitation increases the ratio of accretion over autoconversion. The change in process rates appears to significantly reduce aerosol cloud interactions and indirect radiative effects of anthropogenic aerosols by up to 33% (depending on substepping) to below 1 W m(-2) of cooling between simulations with preindustrial (1850) and present-day (2000) aerosol emissions.