The Characteristics of Pekeris Modes Revealed by Long‐Term Reanalysis Data JAWARA Covering the Entire Middle Atmosphere

Abstract The characteristics of Pekeris modes as well as Lamb modes are investigated using the new reanalysis data set JAWARA, which spans over 19 years and covers the entire middle atmosphere. Pekeris modes are a class of global normal modes whose energy is trapped in two height regions that is, around the stratopause and the surface, while the energy of Lamb mode is trapped only at the surface. Statistically significant spectral peaks corresponding to both Pekeris and Lamb modes are detected for seven normal modes. The vertical structures closely match theoretical expectations for most modes. Notably, the geopotential height amplitudes of the Pekeris modes are comparable to or greater than those of the Lamb modes in the mesosphere and lower thermosphere, suggesting an important role for Pekeris modes in the dynamics of this region. On the other hand, the Lamb modes are dominant in the stratosphere.