Analysis of spatiotemporal variation characteristics of local typhoons in the South China Sea

Locally generated typhoons in the South China Sea (SCS), referred to as “local typhoons”, are characterized by strong abruptness, complex trajectories, and high forecasting difficulty, posing significant challenges to regional disaster prevention and mitigation. Systematic statistical research is urgently needed to enhance understanding of their genesis and evolution patterns. For comparison, typhoons originating in the Northwest Pacific outside the SCS and entering the region are termed “non-local typhoons”. Current research on local typhoons remains fragmented, with insufficient systematic analysis of long-term data and inadequate comparison with non-local typhoons, limiting the in-depth understanding of their climatic characteristics. Based on the China Meteorological Administration (CMA) Northwest Pacific typhoon best-track dataset (1949—2024), this study systematically analyzes the frequency, intensity, trajectories, and genesis distribution of local typhoons in the SCS, with comparisons to non-local typhoons, to reveal their spatiotemporal variation patterns. Key findings include: 1) The annual average number of local typhoons is 5.86, showing a unimodal seasonal distribution with peak occurrence from June to October (accounting for 78.9% of the total), especially in September (21.7%), and exhibiting a significant decreasing trend (-0.05·a-1); 2) Local typhoons have an annual average minimum central pressure ranging from 965.0 to 999.5 hPa, also showing a significant decreasing trend, predominantly follow westward or northwestward trajectories, and mostly originate in the central and northern SCS; 3) Compared with non-local typhoons, local typhoons are generally weaker (only 13.7% reach typhoon intensity or above, versus 61.7% for non-local typhoons), but intensify more rapidly, with higher landfall proportions, greater abruptness, and stronger locality. This study provides critical data support for understanding the formation mechanisms and climatic patterns of local typhoons, while offering a reference for improving regional disaster early warning capabilities and risk management strategies.