Continuous monitoring of typhoon-induced gravity waves via multisource optical satellites

Atmospheric gravity waves are defined as periodic fluctuations generated by the interplay of gravity and buoyancy in air masses within a stably stratified atmosphere when vertically perturbed. In this paper, the MERSI-LL instrument of the FY-3E satellite is employed for the first time to observe gravity waves. In combination with data from multiple optical satellites of the JPSS series, gravity waves triggered by Super Typhoons Freddy and Bolaven in 2023 are continuously observed, addressing the data gap in gravity wave observations from polar-orbiting satellites in observing gravity waves. In order to enhance the clarity of the gravity wave stripes, image processing techniques, such as the Sobel operator and adaptive histogram equalization, were applied to the images taken at different times. The findings demonstrate that the observational capability of the FY-3E satellite’s MERSI-LL instrument during dawn and dusk periods is comparable to that of the DNB band in the JPSS satellites, enabling clear detection of gravity waves induced in the troposphere by typhoons. A comparative analysis of the observation data of Typhoon Freddy and Typhoon Bolaven reveals that typhoon-generated gravity waves show significant vertical stratification, with the wavelengths of the gravity waves in the troposphere typically in the range of 5 to 8 kilometers, while those in the mesosphere can reach tens of kilometers. The utilization of multi-source optical satellite data facilitates the effective observation of typhoon-generated gravity waves, thereby providing novel data support for the forecasting of typhoon intensity and track.