动力降尺度在次季节热带气旋预报中的附加价值
Added value of dynamical downscaling in sub-seasonal tropical cyclone forecast
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中文总结 AI 辅助
该研究针对GloSea6次季节TC预报的缺陷，发现动力降尺度可直接改进TC特征、间接优化关键环境场，显著提升次季节TC预报精度。
中文摘要 AI 辅助
改进热带气旋（TC）的次季节预报仍是气候模型面临的重大挑战。本研究使用韩国气象厅（KMA）运行的业务级季节至次季节预报模型——全球季节预报系统6（GloSea6），评估了1993年至2016年6-9月（JJAS）西北太平洋（WNP）次季节预报中热带气旋的特征。研究发现，GloSea6对所有月份的TC频率、路径（尤其中纬度地区）、寿命和强度均存在低估，其中8月的误差最为显著。为解决这些缺陷，研究人员针对GloSea6 TC预报技能最低的时段——2016年8月，检验了对GloSea6应用动力降尺度是否能改进次季节TC预报。结果显示，动力降尺度的应用展现出附加价值，直接改进了TC的频率、结构、强度和寿命的模拟，尽管存在轻微高估；此外，对印度季风和环球遥相关型（CGT）的模拟改进，二者均对西北太平洋副热带高压（WNPSH）有强烈影响，有助于更准确地预报WNPSH的变率，进而更好地预测中纬度和东亚地区的TC活动。因此，动力降尺度不仅能直接改进TC特征，还能间接优化对TC活动至关重要的环境场（如WNPSH、印度季风和CGT），可显著推进次季节TC预报。
英文摘要
Improving the sub-seasonal forecast of tropical cyclones (TCs) remains a significant challenge for climate models. This study evaluated the characteristics of tropical cyclones (TCs) in sub-seasonal forecasts using the Global Seasonal Forecast System 6 (GloSea6), an operational seasonal-to-sub-seasonal forecasting model operated by the Korea Meteorological Administration (KMA) during June-September (JJAS) from 1993 to 2016 over the western North Pacific (WNP). GloSea6 was found to underestimate TC frequency, tracks, particularly in mid-latitudes, lifetime, and intensity across all months, with the most significant errors occurring in August. To address these deficiencies, we examined whether applying dynamical downscaling to GloSea6 during August 2016, a period characterized by the lowest TC forecast skill in GloSea6, could improve sub-seasonal TC forecasts. The application of dynamical downscaling demonstrated added value by directly improving the simulation of TCs in terms of frequency, structure, intensity, and lifetime, although slight overestimations were observed. Furthermore, improved reproductions of the Indian monsoon and circumglobal teleconnection (CGT), both of which strongly influence the western North Pacific subtropical high (WNPSH), contributed to more accurate forecasts of WNPSH variability and, consequently, better predictions of TC activity in the mid-latitudes and East Asia. Therefore, dynamical downscaling can significantly advance sub-seasonal TC forecasts by not only directly improving TC characteristics but also indirectly enhancing the environmental fields (e.g., WNPSH, Indian monsoon, and CGT) that are critical to TC activity.
发表机构
- Ulsan National Institute of Science and Technology（蔚山科学技术院）
- Yonsei University（延世大学）
- National Institute of Meteorological Sciences（韩国气象科学研究院）
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