资源环境科技发展态势分析平台

Abstract. The studies on the sources of three concentric gravity waves (CGWs) excited by a moving Mesoscale Convective System (MCS) on the night of October 1 – 2, 2019 are investigated. These CGWs were observed using an OH all-sky imager whereas the MCS were observed by the Geostationary Operational Environmental Satellite (GOES). Using 2D spectral analysis, we observed that the CGWs have horizontal wavelength λ_H ∼30 – 55 km, phase speed c_H ∼70 – 90 m/s, and period τ ∼7 – 12 min. By backward ray tracing we found that two of the waves were excited from convective cores within the MCS. We also found that the epicenters of the CGWs were close to the tropopause positions of the ray traced paths as well as the nearby convective cores. Regarding the source, we verified that on this night the cold-point tropopause (CPT) was ∼-80 °C, which was ∼10 °C cooler than CPT on the days preceding and after the MCS, and also colder than usually observed. Since the tropopause height and temperature are fundamental parameters underlying the analysis of the overshooting extent, we developed our own methodology to establish a reference tropopause that would enable a quantitative estimate of this parameter. Since the MCS (CGWs source) was moving, the overshooting convective cores were tracked in space and time. Finally, we found that two out of the three CGWs were excited by the MCS whereas the source of the remaining one was found not to be directly associated with the MCS.