Southern Argentina Agile Meteor Radar: Initial assessment of gravity wave momentum fluxes

• Published in: Journal of Geophysical Research: Atmospheres Vol. 115; no. D19
• Main Authors: Fritts, D. C., Janches, D., Hocking, W. K.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 16-10-2010; American Geophysical Union
• Subjects: Acoustics; Atmospheric sciences; Diurnal variations; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geophysics; Gravity waves; Latitude; Mesoclimatology; Meteors; MLT forcing; momentum flux; Radar; Tidal amplitude; Tides; South America; Drake Passage; Antarctic Ocean; Argentina; Tierra del Fuego; High latitude; altitude; Mid latitude; springs; Zonal wind; Summer; exhibits; Variance; diurnal variations; amplitude; dynamics; Momentum transfer; Winter; Spring(season); stratosphere; Composite analysis; Gravity; monthly average; Anticorrelation; correlation; meteors; Gravity wave; Radar observation; hot spots; radar methods
• ISSN: 0148-0227; 2169-897X; 2156-2202; 2169-8996
• DOI: 10.1029/2010JD013891

The Southern Argentina Agile Meteor Radar (SAAMER) was installed on Tierra del Fuego (53.8°S) in May 2008 and has been operational since that time. This paper describes tests of the SAAMER ability to measure gravity wave momentum fluxes and applications of this capability during different seasons. Test results for specified mean, tidal, and gravity wavefields, including tidal amplitudes and gravity wave momentum fluxes varying strongly with altitude and/or time, suggest that the distribution of meteors throughout the diurnal cycle and averaged over a month allows characterization of both monthly mean profiles and diurnal variations of the gravity wave momentum fluxes. Applications of the same methods for real data suggest confidence in the monthly mean profiles and the composite day diurnal variations of gravity wave momentum fluxes at altitudes where meteor counts are sufficient to yield good statistical fits to the data. Monthly mean zonal winds and gravity wave momentum fluxes exhibit anticorrelations consistent with those seen at other midlatitude and high‐latitude radars during austral spring and summer, when no strong local gravity wave sources are apparent. When stratospheric variances are significantly enhanced over the Drake Passage “hot spot” during austral winter, however, MLT winds and momentum fluxes over SAAMER exhibit very different correlations that suggest that MLT dynamics are strongly influenced by strong local gravity wave sources within this “hot spot.” SAAMER measurements of mean zonal and meridional winds at these times and their differences from measurements at a conjugate site provide further support for the unusual momentum flux measurements.