Frequency Spectrum Dynamic Characteristics of Atmospheric Gravity Waves during Various Types of Thunderstorms in Foshan

Taking advantage of the high-precision microbarograph data from Jan 2017 to Oct 2019 in Foshan, a statistical analysis of the frequency spectrum characteristics of the atmospheric gravity waves during various types of thunderstorms in Foshan was presented. Results showed that the thunderstorms were closely related to the occurrence and development of gravity waves. Long-period (90–270 min) and short-period (1–90 min) gravity waves presented different features during various types of thunderstorms. Long-period gravity waves exhibited large amplitudes (≥110 Pa) and wide periodic ranges. Most of strong storms resulted in long-period gravity waves with increased amplitudes and wide period ranges. An increased occurrence rate of long-period gravity waves with center amplitudes greater than 130 Pa was also observed. On the other hand, short-period gravity waves exhibited period ranges of about 10–90 min and center amplitudes of about 11–47 Pa. Strong storms could also spark short-period (10–90 min) gravity waves with a higher occurrence rate than that with weak storms. Furthermore, strong storms were more likely to initiate shorter periods (1–20 min) of gravity waves with larger amplitudes (≥50 Pa) than weak storms. The near-distance storms exerted a more positive impact on the long-period and short-period gravity waves compared with the far-distance storms. Before part of the storms occurred, long-period and short-period gravity waves showed precursor activities with an advancing time of about 114–168 min. Moreover, the center amplitudes of the long-period (90–270 min) and short-period (30–90 min) gravity waves were 84–106 Pa and 12–43 Pa, respectively. The near-distance storms exhibited a higher occurrence rate of the gravity waves’ precursor activities than that of the far-distance storms. Strong storms resulted in larger amplitudes of waves and higher occurrence rates of short-period (20–30 min) gravity waves’ precursor activities than weak storms. The precursor activity of the gravity waves may be meaningful in severe storm warnings.