Diurnal Variation of Tropical Ice Cloud Microphysics: Evidence from Global Precipitation Measurement Microwave Imager Polarimetric Measurements
Diurnal Variation of Tropical Ice Cloud Microphysics: Evidence from Global Precipitation Measurement Microwave Imager Polarimetric Measurements
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DOI：
10.1002/2017gl075519
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发表时间：
2017-12
影响因子：
5.2
通讯作者：
J. Gong;Xiping Zeng;Dong L. Wu;Xiaowen Li
中科院分区：
文献类型：
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作者：
J. Gong;Xiping Zeng;Dong L. Wu;Xiaowen Li
热带冰云的日变化在出现频率和总质量方面得到了较好的观测和研究，但从冰微物理参数的角度进行观测和研究的却很少。在评估冰云对全球辐射和水文收支的作用时，它占了很大一部分的不确定性。由于岁差轨道设计的优势和在对冰粒微物理特性特别敏感的高频微波波段进行成对偏振观测，利用全球降水测量微波成像仪（GPM-GMI）的166 GHz通道对3年的偏振差分（PD）测量结果进行了汇编，以揭示热带陆地上的强日周期（30°S-30°N），峰值振幅变化高达38%。由于PD信号主要由冰晶的大小、形状和方向决定，因此GMI观测到的日周期可以用来推断冰晶性质的变化。此外，PD变化被发现导致约2小时的日变化的冰云出现频率和总冰质量，这强烈意味着了解冰微物理是至关重要的预测，推断，和模拟冰云演变和降水过程。
The diurnal variation of tropical ice clouds has been well observed and examined in terms of the occurring frequency and total mass but rarely from the viewpoint of ice microphysical parameters. It accounts for a large portion of uncertainties in evaluating ice clouds' role on global radiation and hydrological budgets. Owing to the advantage of precession orbit design and paired polarized observations at a high‐frequency microwave band that is particularly sensitive to ice particle microphysical properties, 3 years of polarimetric difference (PD) measurements using the 166 GHz channel of Global Precipitation Measurement Microwave Imager (GPM‐GMI) are compiled to reveal a strong diurnal cycle over tropical land (30°S–30°N) with peak amplitude varying up to 38%. Since the PD signal is dominantly determined by ice crystal size, shape, and orientation, the diurnal cycle observed by GMI can be used to infer changes in ice crystal properties. Moreover, PD change is found to lead the diurnal changes of ice cloud occurring frequency and total ice mass by about 2 h, which strongly implies that understanding ice microphysics is critical to predict, infer, and model ice cloud evolution and precipitation processes.