In disaster management, early warning systems are typically categorized into four levels, underscoring the critical need for scientifically determining threshold values. Currently, the meteorological, hydrological, and oceanic sectors in China have developed threshold standards primarily based on the intensity of individual hazards. However, most tropical cyclone (TC) disasters result from multiple hazards. Neglecting the cascading effects of these multiple hazards may lead to an underestimation of their overall impact. Moreover, emergency response capacities differ significantly across national, provincial, city, and county administrative levels due to variations in disaster management responsibilities and regional resilience. Therefore, it is advisable to establish customized early warning thresholds considering multiple hazards and administrative levels. To this end, it is essential to define early warning thresholds for all hazards based on quantitative intensity-frequency analysis. We collected long-term data on historical TC tracks, wind fields, precipitation, storm surge, and wave heights affecting China from 1949 to 2014. Eight hazard indexes were developed, which are maximum wind speed (Vm), pressure difference (ΔP), radius of maximum wind (Rm), forward speed (Vt), wind hazard index (Hw), precipitation hazard index (Hp), storm surge hazard index (Hss), and wave hazard index (Hs). We employed Generalized Pareto Distribution and Peaks Over Threshold methods for intensity-frequency analysis to quantify the thresholds for these indexes across national, provincial, city, and county levels. The results indicate that the thresholds for Vm, ΔP, Hw, and Hp generally increase from north to south, while those for Rm and Vt decrease. The established thresholds ensure a reasonable proportion for initiating early warnings at all levels, facilitating effective resource allocation and enhancing emergency response strategies. Ultimately, this study provides a comprehensive framework for establishing early warning thresholds that consider multiple hazards and their cascading effects, which can help improve the effectiveness of early warning systems for TCs.

Intensity-frequency analysis on multiple hazards considering cascading effects for comprehensive tropical cyclone early warnings

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发表日期：

2026年2月3日

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Jian Li,
Weihua Fang

摘要

In disaster management, early warning systems are typically categorized into four levels, underscoring the critical need for scientifically determining threshold values. Currently, the meteorological, hydrological, and oceanic sectors in China have developed threshold standards primarily based on the intensity of individual hazards. However, most tropical cyclone (TC) disasters result from multiple hazards. Neglecting the cascading effects of these multiple hazards may lead to an underestimation of their overall impact. Moreover, emergency response capacities differ significantly across national, provincial, city, and county administrative levels due to variations in disaster management responsibilities and regional resilience. Therefore, it is advisable to establish customized early warning thresholds considering multiple hazards and administrative levels. To this end, it is essential to define early warning thresholds for all hazards based on quantitative intensity-frequency analysis. We collected long-term data on historical TC tracks, wind fields, precipitation, storm surge, and wave heights affecting China from 1949 to 2014. Eight hazard indexes were developed, which are maximum wind speed (V_m), pressure difference (ΔP), radius of maximum wind (R_m), forward speed (V_t), wind hazard index (H_w), precipitation hazard index (H_p), storm surge hazard index (H_ss), and wave hazard index (H_s). We employed Generalized Pareto Distribution and Peaks Over Threshold methods for intensity-frequency analysis to quantify the thresholds for these indexes across national, provincial, city, and county levels. The results indicate that the thresholds for V_m, ΔP, H_w, and H_p generally increase from north to south, while those for R_m and V_t decrease. The established thresholds ensure a reasonable proportion for initiating early warnings at all levels, facilitating effective resource allocation and enhancing emergency response strategies. Ultimately, this study provides a comprehensive framework for establishing early warning thresholds that consider multiple hazards and their cascading effects, which can help improve the effectiveness of early warning systems for TCs.