Mesospheric Gravity Waves in the OH Airglow Layer Generated by Winter Convection during an East Asian Winter Storm

Abstract. Gravity waves (GWs) are small-scale disturbances that play an important role in transporting momentum and energy from the lower to the upper atmosphere. Because mesospheric GWs can be observed far from their sources, event-resolved studies linking them to their tropospheric sources remain limited, particularly for midlatitude wintertime. Here, we investigate GWs associated with wintertime convection over East Asia during the winter storm of 24 January 2024. The Atmospheric Infrared Sounder (AIRS) and the Atmospheric Waves Experiment (AWE) observed semi-concentric GW patterns with horizontal wavelengths of several hundred kilometers in the stratosphere at ~05 UT and in the mesosphere at ~12 UT, respectively. A convection-permitting simulation using the Weather Research and Forecasting (WRF) model reproduced GW structures up to an altitude of ~47 km that were similar to those observed by AIRS. The simulation linked their generation to convection within a cold front north of Hokkaido (~144° E, ~47° N). Backward ray tracing suggested source regions north of Hokkaido (136−149° E, 44−53° N) for the stratospheric and mesospheric GWs, consistent with regions of possible deep convection identified in the Himawari-9 observations. The agreement among the observations, WRF simulation, and ray tracing results supports the interpretation that primary GWs generated by wintertime convection could propagate into the upper mesosphere. Additionally, those primary GWs were possibly saturated above ~68 km, raising the possibility of secondary GW generation. These results highlight the difficulty of distinguishing primary and secondary GWs based solely on concentric mesospheric wave patterns, including under wintertime.