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和地面雨量观测设备，分别在2004年(百牛季、台风季)和2006年(百牛季、台风季、秋冬季)观测到多种降水过程，包括对流雨和层状雨。收集的资料已用于研究和发展云微物理过程，包括雨滴尺寸分布(DSD)的分析、DSD的垂直廓线、COBRA偏振参数的估计以及400 MHz WPR对融化层以上DSD的算法开发。研究了水平雷达回波(ZH)、垂直雷达回波(ZV)、差分反射率(ZDR)和比差分相移(KDP)等多参数多普勒雷达“COBRA”极化参数的有效性。然后，通过比较观测参数和DISDR…得到的非参数估计的线性去极化比参数，验证了线性去极化比的有效性更多的仪表观测。将扩展卡曼滤波、集合卡尔曼滤波和四维变分方法应用到原始静力数值模拟模式中，发展了极化参数同化方法应用于云分辨数值模拟。结果表明，集合卡尔曼滤波法同化效果最好。台风内部中尺度过程是研究台风生长和移动的新视角。为此，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，发现对流细胞对眼壁组织的影响导致了眼壁的破坏。利用CRESS模拟的风场对眼壁组织的腐败进行了分析。特别是水平风的涡度和辐散。这些结果被报道并将用于第二阶段，即2007-2009年的科学研究资助(A)阶段。较少

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