Work

The Mechanism of Scale Selection for Mixed Rossby‐Gravity Waves in the Upper Troposphere and the Upper Stratosphere

Year: 2024

Type: article

Abstract: Mixed Rossby‐gravity (MRG) waves play a significant role in tropical variability. Their kinetic energy spectra exhibit maximal amplitudes at synoptic scales in the upper troposphere and at planetary scales in the upper stratosphere. The mechanism for different scale selection in the two regions has remained elusive. Here, we use a spherical barotropic model with the background zonal wind profiles derived from ERA5 reanalysis to show that the recently introduced MRG wave excitation mechanism wave‐mean flow interactions produces MRG waves with the observed scale properties in the two regions. Simulations with idealized zonal jets show that the jet position determines the MRG scale selection: the closer the jet to the equator, the smaller the scale of the excited MRG waves. Therefore, midlatitude jets, such as found in the upper stratosphere, support the excitation of planetary‐scale MRG waves.

Source: Geophysical Research Letters

DOI: 10.1029/2024gl110811

Authors: S. I. Mahó, N. Žagar, F. Lunkeit, S. Vasylkevych

Institution: Universität Hamburg

Language: English

Topic: Meteorological Phenomena and Simulations

Subfield: Atmospheric Science

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,900

Funders: Deutsche Forschungsgemeinschaft, Universität Hamburg