Regime dependence of cloud condensate variability observed at the Atmospheric Radiation Measurement Sites
Regime dependence of cloud condensate variability observed at the Atmospheric Radiation Measurement Sites
复制标题
在大气辐射测量站点观测到的云凝结水变化的规律依赖性
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
R. Forbes
中科院分区：
文献类型：
--
作者：
M. Ahlgrimm;R. Forbes
微物理过程和云-辐射相互作用发生在变率的空间尺度上，比全球天气预报和气候模型中明确表示的尺度要小。因此，为了准确预测过程速率，有必要将未解决的湿度和云凝结的非均质性参数化为参数。位于世界不同气候区域的大气辐射测量点的地面观测提供了云凝结的高时间分辨率观测来源。针对不同的地理区域、年份和季节，对不同的云凝析油提取产品进行了评估。反演的可靠性因云类型不同而不同，但对于基本上不受降水影响的云类别，可以跨站点和更长时间段进行比较。这些观测结果证实了以前记录的云量变化行为，但也揭示了一种系统的制度依赖性，这是现有的参数化方法所没有捕捉到的。在具有可比云类型和比例的场景中，以暖边界层云的分数标准差(FSD)衡量的凝析油变率在热带地区大于中高纬度地区，观测到的FSD从热带地区的1.2到北极的0.4不等。提出了一种基于网格箱平均总水量和云量的云-液-凝析油FSD的参数化方法，该方法能更好地捕捉不同地理位置、不同季节的FSD值的观测范围。卷云的FSD与液态云相比没有那么明显，与卫星观测得到的FSD值基本一致。
Microphysical processes and cloud–radiation interaction occur on spatial scales of variability smaller than those represented explicitly in global weather forecasting and climate models. It is therefore necessary to parametrize the unresolved heterogeneity of humidity and cloud condensate in order to predict process rates accurately. Ground‐based observations from the Atmospheric Radiation Measurement sites located in various climatic regions of the world provide a source of high‐temporal‐resolution observations of cloud condensate. A number of different retrieval products for cloud condensate are assessed for the different geographical regions, years and seasons. The retrieval reliability varies with cloud type, but for cloud categories largely unaffected by precipitation a comparison across sites and longer time periods is possible. These observations confirm previously documented variability behaviour as a function of cloud fraction, but also reveal a systematic regime dependence that is not captured by existing parametrizations. Condensate variability measured as a fractional standard deviation (FSD) in warm boundary‐layer clouds is greater in the Tropics than in mid and high latitudes for scenes with comparable cloud type and fraction, with the observed FSD varying from 1.2 in the Tropics to 0.4 in the Arctic. A parametrization of the FSD of cloud liquid condensate based on the grid‐box mean total water amount and cloud fraction is formulated and shown to capture the observed range of FSD values better across different geographical sites and different seasons. The regime dependence of FSD for cirrus cloud is less pronounced than that for liquid clouds and is found largely to agree with FSD values previously derived from satellite observations.
影响因子：
2.2
作者：
N. Gaussiat;R. Hogan;A. Illingworth
通讯作者：
N. Gaussiat;R. Hogan;A. Illingworth
影响因子：
8.9
作者：
J. Shonk;Robin J. Hogan
通讯作者：
J. Shonk;Robin J. Hogan
影响因子：
8.9
作者：
P. Hill;R. Hogan;J. Manners;J. Petch
通讯作者：
P. Hill;R. Hogan;J. Manners;J. Petch