Investigation of vertical wavenumber spectra during sudden stratospheric warming (SSW) events over the Indian region

ABSTRACT

The vertical wavenumber (VWN) characteristics during sudden stratospheric warming (SSW) events (2003–2016) is investigated for the first time using temperature observation of Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on-board Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite (for the altitude range of 20–70 km) and ERA-Interim reanalysis data (for the altitudes of 0.1–20 km). Highly negative VWN spectral slope value (approximately) of −4.82 (at 25° N, 77° E) and −4.41 (at 35° N, 77° E) at 40–50 km altitude is observed during the 2013 SSW event, a sort of which is not perceived in any other SSW events (2003–2016). The combined effect of planetary waves (PWs) with wavenumber 1 and 2 during 2013 SSW may be responsible for such distinctive observation near the peak temperature altitude. This study elicits the importance of polar vortex portraying that lower latitudes are affected if only the vortex splits and presents the first of its kind VWN characteristics during SSW events.

Acknowledgments

The authors are grateful to SABER on board TIMED team members for providing valuable temperature data (http://saber.gats-inc.com/browse_data.php#). ERA-Interim global model reanalysis (http://apps.ecmwf.int/) is acknowledged with sincere thanks. This work is supported by the Department of Space, Government of India. We express our sincere gratitude to the two anonymous reviewers and editor for their valuable suggestions which improved the paper.

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