基于GPM DPR探测的西北太平洋台风降水及微物理特征研究

Precipitation and its microphysical characteristics has been a hot topic in the field of meteorology. Due to the limitations of traditional observation methods, the studies on the precipitation and the microphysical processes of hydrometers are relatively rare for tropical cyclones (TCs) over the Northwest pacific as yet. On the basis of the precipitation and microphysical parameters detected by dual-frequency precipitation radar (DPR) abroad Global Precipitation Measurement (GPM) , associated with the rainfall observed from national gauge stations and the cloud information detected from Advanced Himawari Imager (AHI) aboard Himawari-8, merged datasets of surface rainfall from DPR and gauges, merged datasets of cloud, precipitation profile and microphysical parameters, and the correspondent monthly gridded merged datasets are established. Using these datasets, the detection ability of DPR in characterizing rainfall for TCs and non-tropical cyclones are evaluated from multi-temporal and spatial scales; the microphysical characteristics (the normalized intercept, Nw; the mass-weighted mean diameter, Dm; et al.) are investigated for TC clouds at different phases at different intensities over different underlying surfaces; the statistical relationship between cloud brightness temperature and the precipitation microphysical structures and so on are also investigated for TCs. This study will help to provide the observational evidence for the application of GPM DPR products to numerical weather and hydrological models; improve our understanding of the changes of precipitation microphysics during the developing and dissipating stages of TCs, and provide observational evidence of the optimal microphysical parameterization schemes of hydrometers in numerical models.

降水及微物理特征是气象领域的热点问题，常规观测不能满足对西北太平洋台风降水及微物理特征的深入研究。本项目利用最新的全球降水观测计划（GPM）双频测雨雷达（DPR）观测的降水及反演的微物理参量，结合国家站雨量计观测的降水、葵花8先进葵花成像仪探测的云顶亮温信息，建立GPM DPR与雨量计降水的资料集、轨道级的台风云、降水及微物理融合资料集及相应的逐月格点融合资料。在此基础上，探讨GPM DPR对多时间尺度不同等级台风和非台风降水的探测能力；揭示不同下垫面、不同发展阶段、不同相态的台风降水的微物理结构（归一化截距参数Nw和质量权重平均直径Dm等）的分布特性；及云顶亮温与降水微物理结构特征等的统计关系，本项目将为GPM DPR观测产品在数值和水文模式中应用提供观测依据、加强对台风降水发生发展过程微物理特征的认识，同时为数值模式中水成物微物理参数化方案提供观测依据。

降水及微物理特征是气象领域的热点问题，常规观测不能满足对西北太平洋台风降水及微物理特征的深入研究。2014年2月，新一代的全球卫星降水观测计划（Global Precipitation Measurement，简称GPM）主星的发射升空，其上搭载了全球首部星载双频降水测量雷达（Dual-frequency Precipitation Radar, 简称DPR），开启了GPM监测台风降水微物理的新时代。通过三年的研究，我们定量揭示了GPM降水产品对西北太平洋台风和非台风降水的探测能力，证实了GPM降水产品较TRMM降水产品与地基观测相比，在表征不同等级降水强度、频次以及降水日变化上更加可靠，可为水文和气候模式预报、和基于卫星的台风观测研究提供基础产品支撑。基于GPM DPR观测的三维降水微物理参数信息，研究了2014~2017年西北太平洋台风降水近地表微物理特征及其垂直结构特征，以及不同降水效率与近地表微物理过程的联系，首次从观测事实角度揭示随着台风系统内降水效率的增加，近地表降水粒子以碰并过程为主（暖雨过程为主），反之破碎过程的比例显著增加；通过对2014~2018年西北太平洋台风云墙、内外雨带的降水微物理特征研究发现，台风云墙内存在浓度较高且平均直径较小的水成物粒子，而外雨带存在浓度较低的大尺度水成物粒子；另外微波亮温（冰粒子信息）与近地表微物理过程的存在密切联系，微波亮温较高且回波顶高度较低时，近地表水成物粒子以碰并过程为主，反之以破碎过程为主，且这种现象在外雨带更为显著。上述研究不仅提高了对台风降水微物理特征的认知，还为极轨卫星微波产品同化提高数值模式台风强度路径预报提供了参考。