Characteristics of inertia-gravity waves (IGWs) at high latitude in Antarctica are investigated using radiosondes launched daily at Jang Bogo Station (74°37′S, 164°13′E), a new Antarctic station that has been operating since 2014, in the troposphere (z = 2–7 km) and lower stratosphere (z = 15–22 km) for 25 months (December 2014 to December 2016). The vertical propagation of IGWs exhibits strong seasonal variations in the stratosphere, with an enhancement (reduction) in downward (upward)-propagating IGWs from May to mid-October. In the troposphere, both upward- and downward-propagating IGWs have similar occurrence rates without seasonal variations. The intrinsic phase velocity of IGWs mostly direct to the west (isotropic), while the ground-relative phase and group velocities are dominant in the east and southeast (northeast), respectively, in the stratosphere (troposphere). The intrinsic frequency, vertical wavelength, and horizontal wavelength of IGWs averaged in the troposphere (stratosphere) are 3.57f (1.93f; where f is the Coriolis parameter), 1.48 (1.48) km, and 63.06 (221.81) km, respectively. The wave energy in the stratosphere has clear seasonal variations with large values in autumn and spring, while that in the troposphere is smaller without obvious seasonal variations. Zonal and meridional momentum fluxes averaged in the stratosphere (troposphere) are −0.008 (−0.0018) and −0.0005 (0.001) m 2 /s 2 , respectively. The momentum flux of downward-propagating IGWs in the stratosphere is mostly positive in both zonal and meridional directions, whereas the directional preference is not obvious in the troposphere. In Part 2, sources of the observed IGWs in the troposphere and stratosphere will be examined.
Bibliographical noteFunding Information:
The authors thank two anonymous reviewers for their careful reading of the manuscript and helpful comments. This study was conducted while the third author (H. Y. C.) was in her sabbatical leave. This work was supported by research fund PE18020 from Korea Polar Research Institute. The authors appreciate the support of the Korea Polar Research Institute for the radiosonde data. The authors would also like to thank for providing access to the reanalysis data sets ERA-Interim (http://apps.ecmwf.int/datasets/data/), CFSv2 (http://rda.ucar.edu), MERRA and MERRA2 (https://goldsmr5.gesdisc. eosdis.nasa.gov/), and NCEP/DOE R2 (http://www.cdc.noaa.gov/). Further thanks to the Antarctic Meteo-Climatological Observatory of the Programma Nazionale di Ricerche in Antartide for the provision of radiosonde data from Mario Zucchelli Station (http://www.climantaride.it).
All Science Journal Classification (ASJC) codes
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science