Global characteristics of the westward-propagating quasi-16-day wave with zonal wavenumber 1 and the connection with the 2012/2013 SSW revealed by ERA-Interim

Wei Li,Shaodong Zhang,Chunming Huang

doi:10.1186/s40623-021-01431-2

Abstract

We analyze global characteristics of the westward-propagating quasi-16-day wave (Q16DW) with zonal wavenumber 1 (W1) in the troposphere and stratosphere using zonal wind, meridional wind, vertical velocity, temperature, geopotential, and potential vorticity data from the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis during one year from December 2012 to November 2013. The amplitudes of the W1 Q16DW are larger in the stratosphere than in the troposphere, and remarkable amplitudes are found at middle and high latitudes in the Northern Hemisphere (NH). More detailed analyses on the temporal variation in the W1 Q16DW show that this wave is significantly enhanced during the 2012/2013 Stratospheric Sudden Warming (SSW) event, and the strong wave most likely provides additional forcing on the splitting of the displaced polar vortex. Analysis of the Eliassen–Palm flux (EP flux) and its divergence of the interaction between W1 Q16DW and quasi-stationary planetary waves with wavenumber 1 during the 2012/2013 SSW event reveals that it causes an upward heat flux and exerts a westward acceleration on the background winds, indicating that this interaction plays an important role in the eastward stratospheric jet reversal. Moreover, the wave is amplified in the occurrence region of barotropic and/or baroclinic instability, suggesting a local source of the growing W1 Q16DW during this SSW event.

Highlights

Atmospheric planetary waves (PWs) are global-scale waves that play a key role in the transport of energy, momentum and chemical species, both vertically and horizontally
Latitudinal and altitudinal variations of the wavenumber 1 (W1) quasi-16-day wave (Q16DW) To investigate the seasonal structure of the W1 mode, we investigated the fitting results of the zonal wind, meridional wind, and temperature during specific months
This is perhaps the first study to investigate in detail the contribution of the W1 Q16DW to the occurrence of the 2012/2013 Stratospheric Sudden Warming (SSW) event and breakdown of the polar vortex

Summary

Introduction

Atmospheric planetary waves (PWs) are global-scale waves that play a key role in the transport of energy, momentum and chemical species, both vertically and horizontally. In this paper, we investigate the contribution of the Q16DW to the zonal-mean flow and polar vortex in detail during the 2012/2013 SSW event.

Results

Conclusion