A scale and aerosol aware stochastic convective parameterization for weather and air quality modeling
A scale and aerosol aware stochastic convective parameterization for weather and air quality modeling
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DOI：
10.5194/acp-14-5233-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Freitas, S. R.
中科院分区：
文献类型：
--
作者：
Grell, G. A.;Freitas, S. R.
本文描述并评估了一种对流参数化方法，该方法可用于高分辨率非流体静力中尺度模式，以及具有非结构化变化网格分辨率的建模系统和对流感知模拟。该方案基于最初由Grell和Devenyi（2002）实现的随机方法。在20公里到5公里的分辨率范围内测试了两种方法。一种方法是基于相邻网格点的沉降扩散，另一种方法是基于Arakawa等人（2011）最近引入的方法。模型间比较的结果以及与观测的验证表明，沉降的扩展和Arakawa的方法都适用于最高分辨率的运行。由于其简单性和随着分辨率增加而自动平滑过渡的能力，Arakawa的方法可能是首选的。此外，与气溶胶的相互作用已经通过云凝结核（CCN）依赖的云水到雨的自动转化以及气溶胶依赖的云滴蒸发来实现。用这种新实施的气溶胶方法进行的初步试验显示，由于自动转换机制的改变，某些地区的预测降水减少，结果似乎是可信的。这种变化也导致云顶附近云水和冰的流失显著增加。一些地区也经历了降水的增加，这很可能是由加强的下沉气流造成的。
A convective parameterization is described and evaluated that may be used in high resolution non-hydrostatic mesoscale models as well as in modeling system with unstructured varying grid resolutions and for convection aware simulations. This scheme is based on a stochastic approach originally implemented by Grell and Devenyi (2002). Two approaches are tested on resolutions ranging from 20 km to 5 km. One approach is based on spreading subsidence to neighboring grid points, the other one on a recently introduced method by Arakawa et al. (2011). Results from model intercomparisons, as well as verification with observations indicate that both the spreading of the subsidence and Arakawa's approach work well for the highest resolution runs. Because of its simplicity and its capability for an automatic smooth transition as the resolution is increased, Arakawa's approach may be preferred. Additionally, interactions with aerosols have been implemented through a cloud condensation nuclei (CCN) dependent autoconversion of cloud water to rain as well as an aerosol dependent evaporation of cloud drops. Initial tests with this newly implemented aerosol approach show plausible results with a decrease in predicted precipitation in some areas, caused by the changed autoconversion mechanism. This change also causes a significant increase of cloud water and ice detrainment near the cloud tops. Some areas also experience an increase of precipitation, most likely caused by strengthened downdrafts.