Decomposition of the horizontal wind divergence associated with the Rossby, mixed Rossby-gravity, inertia-gravity, and Kelvin waves on the sphere

Neduhal, Valentino (author), Žagar, Nedjeljka (author), Lunkeit, Frank (author), Polichtchouk, Inna (author), Zaplotnik, Žiga (author)

The paper presents a new method for the decomposition of the horizontal wind divergence among linear waves on the sphere: inertia-gravity (IG), mixed Rossby-gravity (MRG), Kelvin and Rossby waves. The work is motivated by the need to quantify the vertical velocity and momentum fluxes in the tropics where the distinction between the Rossby and gravity regime, present in the extratropics, becomes obliterated. The method leads to divergence power spectra as a function of latitude and pressure. The spectra follow the same power laws as the vertical kinetic energy spectra for different wave types. The key novel aspect of the work is the coexistence of wave types at the same zonal wavenumbers. Applied to ERA5 data in August 2018, the new method reveals that the zonally-integrated Kelvin wave divergence makes up about 19% of the upper-troposphere divergence within 10°S–10°N. The MRG wave divergence has four times smaller magnitude. The relative roles of the two waves vary with scale. Overall small roles of the Kelvin and MRG waves in the tropical divergence is explained by decomposing their kinetic energies into rotational and divergent parts. The beta effects produces less then 5% of the tropospheric divergence associated with Rossby waves. The majority of divergence belongs to IG modes and is nearly equipartitioned between the eastward- and westward-propagating IG modes in the upper troposphere, whereas stratospheric partitioning depends on the background flow.

• Language: English
• Keywords: meteorology
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication version: Version of Record
• Publication date: 29.04.2024
• Year: 2024
• Number of pages: 20 str.
• Numbering: Vol. 129, iss. 9, art. no. e2023JD040427
• PID: 20.500.12556/RUL-156065
• UDC: 551.5
• ISSN on article: 2169-897X
• DOI: 10.1029/2023JD040427
• COBISS.SI-ID: 194571779
• Publication date in RUL: 07.05.2024

Record is a part of a journal

• Title: Journal of geophysical research : Atmospheres
• Shortened title: J. geophys. res., Atmos.
• Publisher: John Wiley & Sons
• ISSN: 2169-897X
• COBISS.SI-ID: 311465

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: meteorologija

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: J1-9431
• Name: Prispevek Rossbyevih in inercijsko-težnostnih valov k vertikalni hitrosti in pretoku gibalne količine v ozračju