Planetary waves in the upper stratosphere and lower mesosphere during 2009 Arctic major stratospheric warming

P Kishore,M Venkat Ratnam,I Velicogna,J H Jiang,G N Madhavi

doi:10.5194/angeo-30-1529-2012

Abstract

Abstract. The AURA-MLS daily mean temperatures and zonal wind from NASA-MERRA reanalysis for latitudes between 60° N and 80° N are used to investigate the planetary wave (PW) characteristics in the stratosphere and lower mesosphere during sudden stratospheric warming (SSW) (November 2008 to March 2009). Here, we used a novel method called empirical mode decomposition (EMD) to extract the PWs from the temperature data. The EMD is an interesting approach to decompose signals into locally periodic components, the intrinsic mode functions (IMFs), and will easily identify the embedded structures, even those with small amplitudes. The spectral analysis reveals prevailing planetary wave periods of ~6-day, ~8-day, ~15-day, and ~21–23-day in IMFs 1, 2, 3, and 4, respectively. Clear upward propagation of these waves (20–30 days) is observed, suggesting that sources for these oscillations are in the troposphere.

Highlights

The Northern Hemisphere (NH) winter stratosphere is characterized by the occurrence of midwinter sudden warmings (e.g., Labitzke, 1977, 1982)
In the present paper we report the planetary wave (PW) of 3– 30 days, which are present in the AURA Microwave Limb Sounder (MLS) temperature, and NASA-MERRA reanalysis zonal wind data during November 2008 to March 2009
The onset of the major stratospheric warming (SSW) is at day 24 (24 January 2009) and it is defined by the zonal mean zonal wind reversal at 10 hPa over 60◦ N latitude. These results are consistent with that reported by Manney et al (2009) that during the 2008–2009 winter, a major warming occurred with reversal of zonal wind and temperature gradient on 24 January 2009

Summary

Introduction

The Northern Hemisphere (NH) winter stratosphere is characterized by the occurrence of midwinter sudden warmings (e.g., Labitzke, 1977, 1982). In the present paper we report the PWs of 3– 30 days, which are present in the AURA MLS temperature, and NASA-MERRA reanalysis zonal wind data during November 2008 to March 2009 (winter 2009).

Results

Conclusion