Linkage among ice crystal microphysics, mesoscale dynamics, and cloud and precipitation structures revealed by collocated microwave radiometer and multifrequency radar observations
Linkage among ice crystal microphysics, mesoscale dynamics, and cloud and precipitation structures revealed by collocated microwave radiometer and multifrequency radar observations
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DOI：
10.5194/acp-2020-256
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发表时间：
2020-04
影响因子：
6.3
通讯作者：
J. Gong;Xiping Zeng;Dong L. Wu;S. Munchak;Xiaowen Li;S. Kneifel;D. Ori;L. Liao;D. Barahona
中科院分区：
文献类型：
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作者：
J. Gong;Xiping Zeng;Dong L. Wu;S. Munchak;Xiaowen Li;S. Kneifel;D. Ori;L. Liao;D. Barahona
抽象的。冰云和降雪在全球范围内无处不在，在地球辐射收支和降水过程中发挥着重要作用。冰粒的微物理性质(如大小、习性和取向)不仅受周围环境的动力和热力学条件的影响，而且与云的辐射效应和粒子的下落速度密切相关，从而对未来的气候预测以及地表降水的细节(如开始时间、位置、类型和强度)产生影响。我们以前的工作表明，来自被动微波传感器的高频(>；150 GHz)极化辐射差异(PD)是水平定向冰粒体积长宽比的一个很好的指示器，这种冰粒经常出现在砧状云和/或层状降水中。在目前的工作中，我们进一步研究了与不同局部放电信号相对应的冰相微物理相关的动力学和热力学机制以及云降水结构。为此，配置云卫星雷达(W波段)和全球降水测量双频降水雷达(GPM DPR，Ku-Ka波段)的观测以及欧洲中期天气预报中心(ECMWF)的大气背景资料根据PD的大小进行了分组，仅针对层状降水和/或砧状云场景。我们发现，水平定向的雪团或大的雪粒可能是166 GHz高PD信号的主要贡献者，而低PD可以归因于小的云冰、随机取向的雪团、边缘雪或过冷水。此外，高PD(低PD)场景与较强(较弱)的风切变和较高(较低)的环境湿度有关，这两者都有助于促进(禁止)冻结粒子的生长和对流系统的组织。结果表明，深对流线前缘和后缘的PD不对称性分别与顶云和层状降水层密切相关，表明PD作为层状对流降水旗帜的替代物和对流生命阶段的替代物具有潜在的应用价值。
Abstract. Ice clouds and falling snow are ubiquitous globally and play important roles in the Earth's radiation budget and precipitation processes. Ice particle microphysical properties (e.g., size, habit and orientation) are not only influenced by the ambient environment's dynamic and thermodynamic conditions, but are also intimately connected to the cloud radiative effects and particle fall speeds, which therefore have an impact on future climate projection as well as on the details of the surface precipitation (e.g., onset time, location, type and strength). Our previous work revealed that high-frequency (> 150 GHz) polarimetric radiance difference (PD) from passive microwave sensors is a good indicator of the bulk aspect ratio of horizontally oriented ice particles that often occur inside anvil clouds and/or stratiform precipitation. In this current work, we further investigate the dynamic and thermodynamic mechanisms and cloud–precipitation structures associated with ice-phase microphysics corresponding to different PD signals. In order to do so, collocated CloudSat radar (W-band) and Global Precipitation Measurement Dual-frequency Precipitation Radar (GPM DPR, Ku–Ka-bands) observations as well as European Centre for Medium-Range Weather Forecasts (ECMWF) atmosphere background profiles are grouped according to the magnitude of PD for only stratiform precipitation and/or anvil cloud scenes. We found that horizontally oriented snow aggregates or large snow particles are likely the major contributor to the high-PD signals at 166 GHz, while low-PD magnitudes can be attributed to small cloud ice, randomly oriented snow aggregates, riming snow or supercooled water. Further, high-PD (low-PD) scenes are found to be associated with stronger (weaker) wind shear and higher (lower) ambient humidity, both of which help promote (prohibit) the growth of frozen particles and the organization of convective systems. An ensemble of squall line cases is studied at the end to demonstrate that the PD asymmetry in the leading and trailing edges of the deep convection line is closely tied to the anvil cloud and stratiform precipitation layers, respectively, suggesting the potential usefulness of PD as a proxy of stratiform–convective precipitation flag, as well as a proxy of convection life stage.