Constructing a Multifrequency Passive Microwave Hail Retrieval and Climatology in the GPM Domain
Constructing a Multifrequency Passive Microwave Hail Retrieval and Climatology in the GPM Domain
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DOI：
10.1175/jamc-d-19-0042.1
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发表时间：
2019-08
影响因子：
3
通讯作者：
S. Bang;D. Cecil
中科院分区：
文献类型：
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作者：
S. Bang;D. Cecil
大冰雹是造成世界各地农业和基础设施损失的主要因素。被动微波辐射计测量对冰雹散射的敏感性导致开发了严重冰雹的替代物，其中大多数使用低地球轨道气象卫星上37 GHz和更高频率的微波通道的亮温阈值。利用来自热带降雨测量任务的16年以上的资料，我们将热带降雨测量任务的亮温降水特征与美国的地面冰雹报告配对，根据与微波数据拟合的概率曲线，对来自10、19、37和85 GHz通道的被动微波数据进行冰雹反演。然后，我们将这种冰雹反演应用于全球降水测量域(69°S到69°N)的特征，建立了一个几乎全球被动的基于微波的冰雹气候学。将GPM卫星的范围扩展到更高纬度，需要过滤掉我们认为覆盖在冰雪表面的特征。我们还通过对流层顶高度将亮度温度降低归一化，以努力解释热带和高纬度之间风暴深度的差异。我们的结果显示，冰雹频率最高的地区是阿根廷北部地区，通过巴拉圭、乌拉圭和巴西南部；美国中部；以及萨赫勒以南的非洲狭长地带。较小的热点包括巴基斯坦、东印度和孟加拉国。这些结果与之前许多基于卫星的研究之间的一个显著区别是，尽管中部非洲在我们的气候学中仍然活跃，但在提取冰雹频率方面无法与上述地区相匹敌。
Large hail is a primary contributor to damages and loss around the world, in both agriculture and infrastructure. The sensitivity of passive microwave radiometer measurements to scattering by hail led to the development of proxies for severe hail, most of which use brightness temperature thresholds from 37-GHz and higher-frequency microwave channels on board weather satellites in low-Earth orbit. Using 16+ years of data from the Tropical Rainfall Measuring Mission (TRMM; 36°S–36°N), we pair TRMM brightness temperature–derived precipitation features with surface hail reports in the United States to train a hail retrieval on passive microwave data from the 10-, 19-, 37-, and 85-GHz channels based on probability curves fit to the microwave data. We then apply this hail retrieval to features in the Global Precipitation Measurement (GPM) domain (from 69°S to 69°N) to develop a nearly global passive microwave–based climatology of hail. The extended domain of the GPM satellite into higher latitudes requires filtering out features that we believe are over icy and snowy surface regimes. We also normalize brightness temperature depression by tropopause height in an effort to account for differences in storm depth between the tropics and higher latitudes. Our results show the highest hail frequencies in the region of northern Argentina through Paraguay, Uruguay, and southern Brazil; the central United States; and a swath of Africa just south of the Sahel. Smaller hot spots include Pakistan, eastern India, and Bangladesh. A notable difference between these results and many prior satellite-based studies is that central Africa, while still active in our climatology, does not rival the aforementioned regions in retrieved hailstorm frequency.