Data assimilation of advanced precipitation radar to meso-scale numerical simulation and its application for rainfall and flood prediction

利用COBRA、400 MHz WPR和地面降水观测设备，在2004年（台风季、梅雨季）和2006年（台风季、梅雨季、秋冬季）观测到对流雨和层状云等多种降水过程。所收集的资料已被用于云微物理过程的研究和发展，包括雨滴谱分布（DSD）的分析，DSD的垂直廓线，评估COBRA的偏振参数，并开发了400 MHz WPR的DSD融化层以上的算法。研究了COBRA多参数多普勒雷达极化参数（水平回波ZH、垂直回波ZV、微分反射率ZDR和微分相移KDP）的有效性。然后通过比较观测参数和非参数化估计的参数，证明了线性去极化比（LDR）的有效性 关于我们 测量仪观察在此基础上，建立了一种考虑偏振参数的降水率估算方法，并对该方法进行了评价，将扩展卡尔曼滤波、集合卡尔曼滤波和四维变分方法应用于原有的静力学数值模拟模式，以发展偏振参数同化方法用于云分辨数值模拟。结果表明，集合卡尔曼滤波是最好的同化方法，台风内部的中尺度过程是研究台风生长和移动的新视角。因此，对COBRA数据进行了分析和数值模拟。然后通过对COBRA数据的分析，发现对流单体对眼壁组织的影响导致了眼壁的破坏。同时对CReSS模拟的风场进行了风眼壁组织破坏分析。特别是涡度和水平风辐散，这些结果已被报道，并将用于2007 - 2009年第二阶段的科研资助（A）。少

Many kinds of precipitation processes including convective rain and stratiform rain was observed by COBRA, 400MHz WPR and ground based rainfall observation devices in 2004 (baiu season, typhoon season) and in 2006 (baiu season, typhoon season, fall and winter season). The collected data have been used for investigation and development of cloud microphysical processes including analysis of rain drops size distribution (DSD), vertical profile of DSD, evaluation of polarimetric parameter of COBRA, and development of algorithms for DSD above melting layer by 400MHz WPR. Effectiveness of polarimetric parameters of multi parameter Doppler radar “COBRA" including horizontal radar echo (ZH), vertical radar echo (ZV), differential reflectivity (ZDR) and specific differential phase shift (KDP) has been investigated. Then effectiveness of linear depolarisation ratio (LDR) was shown by comparison of observed parameters and parameters estimated parametrically non-from DSD that was obtained by disdr … More ometer observation. Moreover, a rainfall rate estimation method has been built and evaluated by considering the polarimetric parameters.Extended Karman filter, ensemble Karman filter and four dimensional variation method have been applied to original hydrostatic numerical simulation model in order to develop assimilation methods for polarimetric parameters to cloud resolving numerical simulation. Then, it is found that ensemble Karman filter was the best way to assimilation.Meso scale processes inside typhoons were new point of view to investigate the growth and movement of typhoon. Therefore, analysis of COBRA data and numerical simulation were conducted. Then, eye wall corruption by impact of convective cell to eye wall organization was found by the analysis of COBRA data. Wind field simulated by CReSS was also analyzed for corruption of eye wall organization. Especially vorticity and divergence of horizontal wind was focused.These results were reported and will be used in the second stage that is grant-in-aid for scientific research (A) from 2007 to 2009. Less