Projects per year
Abstract
Nearly all general circulation models significantly fail to reproduce the observed behaviour of the southern wintertime polar vortex. It has been suggested that these biases result from an underestimation of gravity wave drag on the atmosphere at latitudes near 60° S, especially around the "hot spot" of intense gravity wave fluxes above the mountainous Southern Andes and Antarctic peninsula. Here, we use Global Positioning System radio occultation (GPS-RO) data from the COSMIC satellite constellation to determine the properties of gravity waves in the hot spot and beyond. We show considerable southward propagation to latitudes near 60° S of waves apparently generated over the southern Andes. We propose that this propagation may account for much of the wave drag missing from the models. Furthermore, there is a long leeward region of increased gravity wave energy that sweeps eastwards from the mountains over the Southern Ocean. Despite its striking nature, the source of this region has historically proved difficult to determine. Our observations suggest that this region includes both waves generated locally and orographic waves advected downwind from the hot spot. We describe and use a new wavelet-based analysis technique for the quantitative identification of individual waves from COSMIC temperature profiles. This analysis reveals different geographical regimes of wave amplitude and short-timescale variability in the wave field over the Southern Ocean. Finally, we use the increased numbers of closely spaced pairs of profiles from the deployment phase of the COSMIC constellation in 2006 to make estimates of gravity wave horizontal wavelengths. We show that, given sufficient observations, GPS-RO can produce physically reasonable estimates of stratospheric gravity wave momentum flux in the hot spot that are consistent with measurements made by other techniques. We discuss our results in the context of previous satellite and modelling studies and explain how they advance our understanding of the nature and origins of waves in the southern stratosphere.
Original language | English |
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Pages (from-to) | 7797-7818 |
Number of pages | 22 |
Journal | Atmospheric Chemistry and Physics |
Volume | 15 |
Issue number | 14 |
DOIs | |
Publication status | Published - 16 Jul 2015 |
Fingerprint
Dive into the research topics of 'The southern stratospheric gravity wave hot spot: individual waves and their momentum fluxes measured by COSMIC GPS-RO'. Together they form a unique fingerprint.Projects
- 1 Finished
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The South Georgia Wave Experiment (SG-WEX)
Natural Environment Research Council
2/12/13 → 1/12/16
Project: Research council
Profiles
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Nicholas Mitchell
- Department of Electronic & Electrical Engineering - Professor Emeritus
Person: Honorary / Visiting Staff
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Corwin Wright
- Department of Electronic & Electrical Engineering - Royal Society University Research Fellow
- Centre for Climate Adaptation & Environment Research (CAER) - Co-Director
Person: Research & Teaching, Core staff
Equipment
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Balena High Performance Computing (HPC) System
Facility/equipment: Equipment
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High Performance Computing (HPC) Facility
Steven Chapman (Manager)
University of BathFacility/equipment: Facility