Comparison of a large‐scale inertia‐gravity wave as seen in the ECMWF analyses and from radiosondes

Abstract

The location, characteristics and evolution of a large‐scale inertia‐gravity wave that occurred in the lower stratosphere over the North of the British Isles on February 6, 1997, are studied. Numerous high‐resolution radiosondes were available at that time and in that region as part of the FASTEX database. They reveal an intense, large‐scale inertia‐gravity wave (IGW), propagating upwards above the tropopause. Maps of the divergence of the horizontal wind, on isentropic surfaces, were obtained from the ECMWF analyses, and showed a clear pattern of alternating bands of convergence and divergence, at the lower stratospheric heights, in the same geographical region and starting at the same time. The comparison of the characteristics of this IGW in the analyses and in the observations suggests that the ECMWF analyses can be used for qualitative indications regarding the locations most favorable to large‐scale IGW generation and the corresponding orientation of the waves.