Radiosonde observations of a wintertime meridional convergence of gravity waves around 60°S in the lower stratosphere

• Published in: Geophysical Research Letters
• Main Authors: Moffat-Griffin, T., Colwell, S.R., Wright, C.J., Hindley, N.P., Mitchell, N.J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2020
• Subjects: Antarctic; Antarc*
• Online Access: http://nora.nerc.ac.uk/id/eprint/527810/; https://nora.nerc.ac.uk/id/eprint/527810/1/2020GL089740.pdf; https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL089740

Satellite observations show that there is a wintertime hotspot of gravity wave activity, located mainly over the ocean, around 60°S in the stratosphere However, the sources of the gravity waves making up this hotspot are varied, complex and remain unclear. Here we use radiosonde observations from 11 Antarctic stations, and selected small islands close to 60°S to examine the horizontal directional pseudo‐momentum flux and energy density distributions of upward propagating gravity waves in the lower stratosphere. This paper shows, for the first time, that short vertical wavelength gravity waves in the lower stratosphere clearly propagate meridionally towards 60°S during the winter months. This result supports previous studies that show that this belt of gravity wave activity over the ocean is contributed to by wave sources outside 60°S.