A Study of Atmospheric Factor Affecting Tropical Cyclone Intensity Over the Mid-Latitude Region in East Asia Using the WRF Model: Focusing on the Jet Stream

Due to climate change, predicting the intensity of Tropical Cyclone (TC) has become increasingly challenging. Marine factors like Sea Surface Temperature (SST) have been well known so far as factors affecting the intensity of TC. However, there is still a tendency to prioritize SST in TC intensity forecasts. With the changing characteristics of TC due to climate change, there is an increasing need to consider not only SST but also other factors in a comprehensive manner for accurate TC intensity forecasts. Among the various factors that can affect TC intensity, we particularly focused on the jet stream. Generally, it is known that when the jet stream strengthens, the vertical wind shear increases, leading to a weakening of TC intensity. However, considering the secondary circulation structure of the jet stream, we hypothesized that the impact on TC intensity may not follow a linear decrease but could temporarily intensify before sharply declining. The temporary intensification of a TC due to the secondary circulation structure of the jet stream could lead to unexpected damage when the TC makes landfall in the East Asia. What we want to propagate is that most researchers are not taking into consideration the possibility that the intensity of TC may temporarily strengthen due to the jet stream. To prove our hypothesis, we used the WRF model. By adjusting the intensity of the jet stream in the model, we examined how the intensity of TC beyond the mid-latitudes changed. Our results suggest the importance of comprehensively considering not only SST but also other factors, such as jet stream in predicting TC intensity in the future climate.