Frequency, intensity and influences of tropical cyclones in the Northwest Pacific and China, 1977–2018

Abstract China is part of the western Pacific region, which is the source of the most frequent tropical cyclones in the world. These cause severe disasters each year, including huge economic losses and casualties. To better understand their frequency and intensity, remote sensing tropical cyclone data were obtained for the entire Northwest Pacific region for the period 1977–2018. MATLAB and ArcGIS were used to analyse the frequency and intensity of tropical cyclones and their landfall characteristics in various regions of China. The annual frequency of tropical cyclones in the Northwest Pacific showed a trend of fluctuating and decreasing. In particular, since 1994, the overall frequency decreased significantly but rebounded in recent years, while the intensity did not change significantly. It was found that cyclone intensity is lower when the frequency is higher, and vice versa. Some 85% of tropical cyclones occurred in summer and autumn, with the highest intensities in autumn, when the maximum average wind speed peaked at 37 m/s. The area with the most frequent tropical cyclones was 5–20° N, 125–155 °E. A total of 314 tropical cyclones made landfall in China, an annual average of about 7.5. Their frequency and intensity gradually decreased as they moved from coastal to inland areas. Both sea surface temperature and El Niño were significantly related to tropical cyclones. This study’s analyses of the distribution, intensity and landfall characteristics of Northwest Pacific tropical cyclones will help to predict the frequency of disasters and provide a basis for disaster prevention work.