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Comparison of equatorial wave activity in the tropical tropopause layer and stratosphere represented in reanalyses

Title
Comparison of equatorial wave activity in the tropical tropopause layer and stratosphere represented in reanalyses
Authors
Kim Y.-H.Kiladis G.N.Albers J.R.Dias J.Fujiwara M.Anstey J.A.Song I.-S.Wright C.J.Kawatani Y.Lott F.Yoo C.
Ewha Authors
유창현
SCOPUS Author ID
유창현scopus
Issue Date
2019
Journal Title
Atmospheric Chemistry and Physics
ISSN
1680-7316JCR Link
Citation
Atmospheric Chemistry and Physics vol. 19, no. 15, pp. 10027 - 10050
Publisher
Copernicus GmbH
Indexed
SCIE; SCOPUS WOS scopus
Document Type
Article
Abstract
Equatorial Kelvin and mixed Rossby-gravity (MRG) waves in the tropical tropopause layer and stratosphere represented in recent reanalyses for the period of 1981-2010 are compared in terms of spectral characteristics, spatial structures, long-term variations, and their forcing of the quasi-biennial oscillation (QBO). For both wave types, the spectral distributions are broadly similar among most of the reanalyses, while the peak amplitudes exhibit considerable spread. The longitudinal distributions and spatial patterns of wave perturbations show reasonable agreement between the reanalyses. A few exceptions to the similarity of the spectral shapes and spatial structures among them are also noted. While the interannual variations of wave activity appear to be coherent for both the Kelvin and MRG waves, there is substantial variability in long-term trends among the reanalyses. Most of the reanalyses which assimilate satellite data exhibit large increasing trends in wave variance (-15%-50% increase in 30 years at 100-10hPa), whereas one reanalysis (Japanese 55-year Reanalysis assimilating conventional observations only; JRA-55C) produced without satellite data does not. Several discontinuities are found around 1998 in the time series of the Kelvin and MRG wave variances, which manifest in different ways depending on the reanalysis, and are indicative of impacts of the transition of satellite measurements during that year. The equatorial wave forcing of the QBO, estimated by the Eliassen-Palm (EP) flux divergence, occurs in similar phase-speed ranges in the lower stratosphere among the reanalyses. However, the EP flux and its divergence are found to be dependent on the zonal-mean winds represented in reanalyses, exhibiting different magnitudes, altitudes, and phase-speed ranges of the Kelvin wave forcing between the reanalyses, especially at 20-10hPa. In addition, at around 20hPa, a wave signal which appears only in easterly mean winds with westward phase speeds is found and discussed. © Author(s) 2019.
DOI
10.5194/acp-19-10027-2019
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일반대학원 > 대기과학공학과 > Journal papers
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