JMSJ Highlights
Editor's Highlight : Sekido et al. (2024)
Sekido, H., K. Sato, H. Okui, D. Koshin, and T. Hirooka, 2024: A study of zonal wavenumber 1 Rossby-gravity wave using long-term reanalysis data for the whole neutral atmosphere.
J. Meteor. Soc. Japan
,
102
.
https://doi.org/10.2151/jmsj.2024-029
Early Online Release
Graphical Abstract
Editor in charge: Takatoshi Sakazaki
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I highlight this paper that provided the first, comprehensive analysis of normal mode Rossby Gravity wave with zonal wavenumber 1 in the whole atmosphere. (Editor in charge: Takatoshi Sakazaki).
- The analysis of long-term reanalysis dataset made it possible to clearly extract the RG1 component whose period is ~1.3 days, with little contamination from diurnal tides.
- The RG1 has horizontal and vertical structures that are basically consistent with the normal mode theory, while a marked seasonality is observed: the amplitude is largest in the winter hemisphere for the stratosphere and the lower mesosphere.
- Both the climatology of the geopotential height amplitude and the time evolution of the amplitude of a distinct case suggest that some part of RG1 may be excited in the middle atmosphere.
Abstract
The dynamical characteristics of the zonal wavenumber 1 (s = 1) Rossby-gravity (RG) wave are examined using recently available reanalysis data for the whole neutral atmosphere over 16 years. An isolated peak is detected in the two-dimensional zonal wavenumber-frequency spectra that likely corresponds to the theoretically-expected s = 1 RG mode at heights of z = 30, 50, 65, and 80 km. The wave period of the spectral peak is approximately 1.3 days, which is close to one day. The s = 1 RG wave is successfully extracted using a band-pass filter after removing the diurnal tide with quite large amplitudes. The s = 1 RG wave exhibits a characteristic seasonal variation: the geopotential height amplitudes are largest in the winter hemisphere in the stratosphere and lower mesosphere while enhancement is observed in both the winter and summer hemispheres in the upper mesosphere. Phase structures are examined in detail for a strong case. The horizontal phase structure at each height is consistent with the normal mode theory. The vertical phase structure is approximately barotropic from the lower stratosphere to the upper mesosphere at 30°N and 30°S where the amplitudes are large.