Stochastic Aspects of Physical and Radar Meteorology

该研究旨在对云物理学，降水物理学，雷达气象学和云辐射传输进行基本了解。 为此，研究人员与研究生合作，计划进行理论研究，进行数值实验，分析来自各种传感器的数据，并提出新的实验。 具体目标如下。雨的物理学：所有的雨滴都以极限速度落下吗？ 将对视频测速仪和多普勒雷达的数据进行理论研究和分析，重点是雨滴下落速度的波动和与终端速度的偏差。 这项研究将对廓线仪、多普勒雷达和多普勒仪的反演产生影响。雷达气象学：这项研究将根据新的理论分析寻找相干后向散射数据。 将进行短脉冲雷达数据分析和探索性信号处理。 这项研究将影响最近发现的雨滴表面张力波动的雷达偏振。 还将研究雷达回波的非瑞利信号统计和异构目标的同相/正交特征。云物理学：云冰是“草率”的吗？将对过冷水滴的冻结和由此产生的“疤痕”冰进行研究，并对冰中缺陷数密度与过冷度的关系进行理论研究。 研究云滴的扩散增长，重点是准定常近似和混合相云滴中的相关弛豫时间。通过云层的辐射传输：将研究由地表引起的光学性质的变化和云层中高光谱特征的可能性。知识价值：上述问题以前没有得到充分解决。此外，对云和降水波动的基础研究可能会深入了解降水介质的结构、云的基本过程、雷达信号分析和解释以及异质材料中的光衰减。更广泛的影响：这项研究也可能对云物理和降水的发展产生广泛的影响。 它将改善降雨空间结构的表征，以便更好地利用天气雷达进行降雨估计，并改善云的辐射特性。此外，由于过冷水是一种亚稳液体，因此相关的不可逆相变在材料科学中具有广泛的意义。 因此，研究由此产生的缺陷布满冰可能有助于固体物理学以及物理气象学。

The research seeks fundamental understanding in cloud physics, precipitation physics, radar meteorology, and radiative transfer through clouds. To that end, the researcher, in collaboration with graduate students, plans to conduct theoretical investigations, perform numerical experiments, analyze data from a variety of sensors, and suggest novel experiments. The specific objectives are following.1. Physics of rain: do all raindrops fall at terminal speed? Theoretical investigation and analysis of data from video disdrometers and Doppler radars will be conducted, with emphasis on fluctuations of raindrop fall velocities and deviations from a terminal speed. This study will have implications for retrieval by profilers, Doppler radars and disdrometers.2. Radar meteorology: the research will search for coherent backscatter data based on new theoretical analyses. Data analysis from short pulse radars, and exploratory signal processing will be conducted. This study will have implications of recently discovered fluctuations in raindrop surface tension in radar polarimetry. Non-Rayleigh signal statistics of radar echoes and in-phase/quadrature signatures of heterogeneous targets will also be investigated.3. Cloud physics: Is cloud ice "sloppy"? Study of freezing of supercooled water droplets and the resulting "scarred" ice and theoretical investigation of defect number density in ice versus the degree of supercooling will be carried out. Investigation of diffusional growth of cloud droplets with emphasis on the quasi-steady approximation and associated relaxation times in mixed-phase clouds will be conducted.4. Radiative transfer through clouds: surfactant-caused change in optical properties and the possibility of hyperspectral signatures in cloud albedo will be investigated.Intellectual merits:The questions above have not been fully addressed previously. Furthermore, fundamental studies of fluctuations in clouds and precipitation are likely to yield insights into the structure of precipitation media, fundamental processes in clouds, radar signal analysis and interpretation, and light attenuation in heterogeneous materials.Broader impacts:This research is also likely to have broad impacts on cloud physics and development of precipitation. It will improve characterization of rainfall spatial structure for better rainfall estimation with weather radar, and radiative properties of clouds. In addition, insofar as supercooled water is a metastable liquid, the associated irreversible phase transition is of wide interest in material science. Hence, study of the resulting defect riddled ice is likely to contribute to solid state physics as well as to physical meteorology.