Three-dimensional analysis of air temperature of the Hualien M6.9 earthquake based on the tidal forces

The Hualien M6.9 earthquake on September 18, 2022 was calculated based on the additional tectonic stress caused by celestial tidal-generating forces (ATSCTF) model. The period of celestial tidal-generating forces was the time background of the air temperature calculation, and the air temperature variation of three-dimensional layered before and after the Hualien earthquake was studied combined with the air temperature data from the National Center for Environmental Prediction (NCEP) of United States. According to the changes of ATSCTF, the Hualien earthquake occurred within the Period B among the three periods: Period A, Period B, and Period C. The air temperature stratification changes during these three periods were calculated separately, and the results showed that on September 12 in Period B, a temperature increase phenomenon began to occur near the epicenter of the Hualien earthquake. On September 13, the air temperature increase anomaly was significant, and the amplitude and area of the temperature enhancement anomaly increased. On September 14th and 15th, the anomaly gradually weakened and disappeared, and the change of the air temperature anomaly followed the seismic thermal anomaly law caused by tectonic movement: the air temperature closer to the land’s surface had a greater anomaly amplitude and a wider anomaly range; as the altitude increases, the air temperature gradually decreases, and the range of anomalies gradually reduces until it disappears. Meanwhile, there were also high temperature anomalies on September 4 and 5 in the Period A, as well as October 1 to October 4 in the Period C. However, the amplitude and area of the warming anomalies in the upper atmosphere were larger than those near the land surface, which did not conform to the seismic thermal anomaly law caused by tectonic movements and did not belong to the seismic thermal anomalies. In addition, the solar geomagnetic KP index in the study area was relatively low during Period B, indicating that it was in a calm period of solar geomagnetic.