Effect of Vortex Initialization and Relocation Method in Anticipating Tropical Cyclone Track and Intensity over the Bay of Bengal
Effect of Vortex Initialization and Relocation Method in Anticipating Tropical Cyclone Track and Intensity over the Bay of Bengal
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DOI：
10.1007/s00024-021-02815-x
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发表时间：
2021-07
影响因子：
2
通讯作者：
R. Nadimpalli;K. Osuri;U. Mohanty;A. Das;D. Niyogi
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文献类型：
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作者：
R. Nadimpalli;K. Osuri;U. Mohanty;A. Das;D. Niyogi
本研究评估了两种不同的涡旋初始化（VI）和重新定位方法，以改进孟加拉湾（BoB）热带气旋（TC）的预测，使用三重嵌套（27/9/3公里）的国家的最先进的飓风天气研究和预报（HWRF）模式。第一种VI方法，“冷启动”，从全球分析中获得初始TC涡旋。第二个，“循环开始”，收到的初始涡从6小时的预测前一个预测周期的同一模式。在这两种策略中，印度气象局都根据印度气象局确定的位置、强度和结构对涡旋进行了修正。总共有32个预测案例（来自5个气旋）在鲍勃被认为是。与冷启动实验相比，循环启动实验产生了更好的初始结构和不对称性。平均统计数据表明，循环初始化可以提高24小时轨道预测（提高29%），而冷初始化可以更好地提高72小时预测（提高~ 28%）。在循环启动实验中，强度持续提高高达68%。循环初始化的次数取决于TC持续时间。平均而言，循环初始化在第一次冷启动后的9个循环中改善了初始漩涡的表现（强度和大小），并表现出25%的技能提高;超过9个循环，技能提高仅为12%。对非常强气旋风暴（VSCS）Phailin（迅速增强）和VSCS Lehar（迅速减弱）的诊断分析表明，循环初始化真实地代表了等效位温、高层云凝结和水分入侵，这提高了模式的性能。这项研究带来了好处的（循环）VI提高TC的预测能力在BoB盆地。
This study assessed two different vortex initialization (VI) and relocation methods for improved prediction of tropical cyclones (TCs) over the Bay of Bengal (BoB) using the triply nested (27/9/3 km) state-of-the-art Hurricane Weather Research and Forecasting (HWRF) model. The first VI method, “cold-start,” obtained the initial TC vortex from the global analysis. The second one, “cyclic-start,” received the initial vortex from the 6-h forecast of the previous forecast cycle of the same model. In both the strategies, the vortex was corrected to the position, strength, and structure defined by the India Meteorological Department. A total of 32 forecast cases (from five cyclones) over the BoB were considered. The cyclic-start experiments yielded better initial structure and asymmetry as compared to the cold-start experiments. The average statistics indicated that the cyclic initialization improved the 24-h track prediction (by 29%), while the cold initialization was better for the 72-h prediction (by ~ 28%). The intensity was consistently improved in the cyclic-start experiment by up to 68%. The number of cyclic initializations depended on the TC duration. On average, the cyclic initialization improved the representation (strength and size) of the initial vortex up to nine cycles after the first cold start and exhibited an improved skill of 25%; beyond nine cycles, the skill improvement was only 12%. Diagnostic analyses of very severe cyclonic storm (VSCS) Phailin (rapidly intensified) and VSCS Lehar (rapidly weakening) revealed that the cyclic initialization realistically represented equivalent potential temperature, upper-level cloud condensate, and moisture intrusion, which improved the model performance. This study brought out the benefit of the (cyclic) VI for improved TC prediction capabilities in the BoB basin.