Large-amplitude Inertia Gravity Waves over Syowa Station: Comparison of
PANSY Radar and ERA5 Reanalysis Data
Abstract
We examined large-amplitude inertia gravity waves (GWs) over Syowa
Station, Antarctica, comparing PANSY radar data and ERA5 reanalysis from
October 2015 to September 2016. Focusing on large-amplitude events with
a large absolute momentum flux (AMF), hodograph analysis was applied to
estimate the wave parameters and found that the percentage of these
waves with a downward phase velocity increased with altitude. Vertical
wavelengths shortened, intrinsic periods lengthened, and horizontal
wavelengths became longer with increasing altitude. Southward
propagation of GWs was predominant in the stratosphere. Compared to a
previous study, the wave parameters’ altitude variation remained
consistent, but horizontal and vertical wavelengths were longer in this
study. ERA5 underestimated AMF by about 1/5 between 5 and 12.5 km, with
a larger underestimation at higher altitudes. The underestimation was
related to the power spectra of horizontal and vertical winds,
particularly vertical winds. The greater underestimation in the
stratosphere might be due to ERA5’s vertical grid spacing and shorter
vertical wavelengths of dominant GWs.