Decomposition of the tropical wave divergence

1 May 2024

Photo: V.Neduhal

Divergence power spectra averaged for latitudes 10°N−10°S and (a) 20–30 hPa, (b) 100–200 hPa layers. Spectra are evaluated separately for the Rossby, EIG, WIG, Kelvin, and MRG waves.

The divergence of the horizontal wind is an essential variable for characterizing atmospheric general circulation, along with the vertical component of relative vorticity. In particular, divergence is critical for understanding tropical flows. However, the amplitude of the divergence associated with different components of wave circulation in the tropics has not been known - not until now and within uncertainty limits of atmospheric reanalysis data.
The new research paper by Valentino Neduhal and colleagues from the Atmospheric Dynamics and Predictability Group at MI presents a novel method for the quantification of divergence associated with the Kelvin waves, mixed Rossby-gravity (MRG) waves, Rossby and inertia-gravity waves, and applied it to the ERA5 reanalysis data. They show that the Kelvin and MRG waves constitute up to approximately 25% of divergence in the tropical upper troposphere - mainly Kelvin waves. Details and further results: https://doi.org/10.1029/2023JD040427

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More information

Publication
Neduhal, V., N. Žagar, F. Lunkeit, I. Polichtchouk, and Ž. Zaplotnik, 2024: Decomposition of the horizontal wind divergence associated with the Rossby, inertia-gravity, mixed Rossby-gravity and Kelvin waves on the sphere. Journal of Geophysical Research: Atmospheres, 129, e2023JD040427. https://doi.org/10.1029/2023JD040427

DFG-funded project TRR181

Contact
Valentino Neduhal
Universität Hamburg
CEN – Center for Earth System Research and Sustainability
Telefon: +49 40 42838-9203
Email: valentino.neduhal@uni-hamburg.de