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| A Relocation-based Initialization Scheme to Improve Track-forecasting of Tropical Cyclones简 | |
| 作者姓名： | GAO Feng Peter P. CHILDS Xiang-Yu HUANG Neil A. JACOBS Jinzhong MIN |
| 基金项目： | jointly supported by National Center for Atmospheric Research(NCAR)and Panasonic Avionics Corporation;National Natural Science Foundation of China(NSFC)under Grant No.40975068;the National Basic Research Program of China(973 Program)under Grand No.2013CB430102;Jiangsu province colleges and universities natural science major basic research projects |
| 摘 要： | A relocation procedure to initialize tropical cyclones was developed to improve the representation of the initial conditions and the track forecast for Panasonic Weather Solutions Tropical Operational Forecasts. This scheme separates the vortex perturbation and environment field from the first guess, then relocates the initial vortex perturbations to Lhe observed position by merging them with the environment field. The relationships of wind vector components with stream function and velocity potential are used for separating the vortex disturbance from first guess. For the separation of scalars, a low-pass Barnes filter is employed. The irregular-shaped relocation area corresponding to the specific initial conditions is determined by mapping the edge of the vortex radius in 36 directions.Then, the non-vortex perturbations in the relocation area are removed by a two-pass Barnes filter to retain the vortex perturbations, while the variable fields outside the perimeter of the modified vortex are kept ide.ntical to the original first guess. The potential impacts of this scheme on track forecasts were examined for three hurricane cases in the 2011-12 hurricane season. The experimental results demonstrate that the initialization scheme is able to effectively separate the vortex field from the environment field and maintain a relatively balanced and accurate relocated first guess. As the initial track error is reduced, the following track forecasts are considerably improved. The 72-h average track forecast error was redu,~ed by 32.6% for the cold-start cases, and by 38.4% when using the full-cycling data assimilation because of the accumulatedL improvements from the initialization scheme. |
| 关 键 词： | 热带气旋 轨道预报 初始化 基础 定位过程 环境领域 轨道预测 旋涡干扰 |
A relocation-based initialization scheme to improve track-forecasting of tropical cyclones |
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| GAO Feng,Peter P. CHILDS,Xiang-Yu HUANG,Neil A. JACOBS,Jinzhong MIN.A relocation-based initialization scheme to improve track-forecasting of tropical cyclones[J].Advances in Atmospheric Sciences,2014,31(1):27-36. | |
| Authors: | Feng Gao Peter P Childs Xiang-Yu Huang Neil A Jacobs Jinzhong Min |
| Institution: | 1. Nanjing University of Information Science & Technology, Nanjing, 210044, China 2. National Center for Atmospheric Research, Boulder, Colorado, 80307, USA 3. Panasonic Avionics Corporation Morrisville, North Carolina, USA 4. Key Laboratory of Meteorological Disaster of the Ministry of Education, Nanjing, 210044, China |
| Abstract: | A relocation procedure to initialize tropical cyclones was developed to improve the representation of the initial conditions and the track forecast for Panasonic Weather Solutions Tropical Operational Forecasts. This scheme separates the vortex perturbation and environment field from the first guess, then relocates the initial vortex perturbations to the observed position by merging them with the environment field. The relationships of wind vector components with stream function and velocity potential are used for separating the vortex disturbance from first guess. For the separation of scalars, a low-pass Barnes filter is employed. The irregular-shaped relocation area corresponding to the specific initial conditions is determined by mapping the edge of the vortex radius in 36 directions. Then, the non-vortex perturbations in the relocation area are removed by a two-pass Barnes filter to retain the vortex perturbations, while the variable fields outside the perimeter of the modified vortex are kept identical to the original first guess. The potential impacts of this scheme on track forecasts were examined for three hurricane cases in the 2011–12 hurricane season. The experimental results demonstrate that the initialization scheme is able to effectively separate the vortex field from the environment field and maintain a relatively balanced and accurate relocated first guess. As the initial track error is reduced, the following track forecasts are considerably improved. The 72-h average track forecast error was reduced by 32.6% for the cold-start cases, and by 38.4% when using the full-cycling data assimilation because of the accumulated improvements from the initialization scheme. |
| Keywords: | tropical cyclone vortex relocation data assimilation Barnes filtering |
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