Vertically propagating low-frequency inertia-gravity waves (IGWs) are retrieved from meteor radar winds observed at King Sejong Station (KSS: 62.22°S, 58.78°W), Antarctica. IGW horizontal winds extracted from temporal band-pass filtering in regular time-height bins show the frequent occurrence of IGWs with the downward phase progression and the counterclockwise rotation of their horizontal wind vectors with time (i.e., upward energy propagation) near the mesopause region throughout the whole year of 2014. The vertical wavelengths of the observed IGWs roughly range from 14 km to more than 20 km, which is consistent with previous observational studies on the mesospheric IGWs over Antarctica. Stokes parameters and rotary spectra computed from the hodographs of the IGW horizontal wind components reveal that the intrinsic frequencies of the upward propagating IGWs are |f|−3|f| with seasonal variations of the relative predominance between |f|−2|f| and 2|f|−3|f|, where f is the Coriolis parameter at KSS. The hodograph analysis also indicates that the N-S propagation is dominant in austral summer, while the NE-SW propagation is pronounced in austral winter. The propagation direction is discussed in relation to the generation of IGWs due to dynamical imbalances occurring in the tropospheric and stratospheric jet flow systems. Ray tracing results indicate that the N-S propagation in summer may be due to the jet flow systems roughly north of KSS and the NE-SW propagation in winter may be either the SW propagation from the jet flow systems northeast of KSS or the NE propagation (around the South Pole) from the south of Australia and Southern Indian and Pacific Oceans.
Bibliographical noteFunding Information:
This work was supported by research fund PE17020 from Korea Polar Research Institute. ERA-Interim data are available through http://apps.ecmwf.int. MERRA products are available through http://disc.sci.gsfc.nasa.gov/daac-bin/DataHoldings.pl. HWM14 is available as a part of the supporting information of Drob et al.  at http://onlinelibrary.wiley.com/doi/10.1002/2014EA0000089. DWM07 and NRLMSISE-00 are available through http://ccmc.gsfc.nasa.gov/modelweb. Geomagnetic (Ap) and solar activity (F10.7) indices are downloaded at ftp://ftp.ngdc.noaa.gov/STP/GEOMAGNETIC_DATA/INDICES/KP_AP. Meteor radar observational data employed in this study and IGW analysis results are available upon request (firstname.lastname@example.org). The authors would like to express their appreciation for the valuable comments by reviewers. The comments significantly improved the original manuscript.
©2017. American Geophysical Union. All Rights Reserved.
All Science Journal Classification (ASJC) codes
- Space and Planetary Science