| dc.description.abstract | This study used a high-frequency Doppler system to observe traveling ionospheric disturbances caused by Typhoon Chanthu during September 10-14, 2021, and the front on March 6-7, 2022. The disturbances were analyzed using Fast Fourier Transform (FFT), cross-correlation analysis, and Arithmetic Optimization Algorithm (AOA) analysis to investigate their correlation with the events. The results revealed that on September 11, 2021, at 0600 LT, as the typhoon approached Taiwan, disturbances with a 15-minute periodicity, 140 km wavelength, and a horizontal propagation velocity of 155-158 m/s were observed. The disturbances exhibited a deviation angle of 6.9-9 ° from the typhoon′s eye position, suggesting a connection with the typhoon. The vertical propagation velocity of the disturbances was upward, ranging from 170-194 m/s, using group and phase velocity calculation for validation, it indicates the speed of 110-165 m/s in the upward direction. The data from both methods show similar values. Furthermore, on March 6, 2022, at 2000 LT, the front caused significant Doppler frequency shift disturbances. These disturbances had a horizontal propagation velocity of 180-181 m/s, with a deviation angle of 26 ° from the center of the front. The vertical propagation velocity was downward at 143 m/s, opposite to the vertical propagation of the typhoon. In conclusion, the findings established a correlation between the disturbance signals and the respective events. | en_US |