Abstract
Abstract. Inertia-gravity waves (IGWs) are an important component for the dynamics of the middle atmosphere. However, observational studies needed to constrain their forcing are still insufficient especially in the remote areas of the Antarctic region. One year of observational data (January to December 2013) by the PANSY radar of the wind components (vertical resolution of 150 m and temporal resolution of 30 min) are used to derive statistical analysis of the properties of IGWs with short vertical wavelengths ( ≤ 4 km) and ground-based periods longer than 4 h in the lowermost stratosphere (height range 10 to 12 km) with the help of the hodograph method. The annual change of the IGWs parameters are inspected but no pronounced year cycle is found. The year is divided into two seasons (summer and winter) based on the most prominent difference in the ratio of Coriolis parameter (f) to intrinsic frequency (ω^) distribution. Average of f∕ω^ for the winter season is 0.40 and for the summer season 0.45 and the average horizontal wavelengths are 140 and 160 km respectively. Vertical wavelengths have an average of 1.85 km through the year. For both seasons the properties of IGWs with upward and downward propagation of the energy are also derived and compared. The percentage of downward propagating waves is 10.7 and 18.4 % in the summer and winter season respectively. This seasonal change is more than the one previously reported in the studies from mid-latitudes and model-based studies. It is in agreement with the findings of past radiosonde data-based studies from the Antarctic region. In addition, using the so-called dual-beam technique, vertical momentum flux and the variance of the horizontal perturbation velocities of IGWs are examined. Tropospheric disturbances of synoptic-scale are suggested as a source of episodes of IGWs with large variance of horizontal perturbation velocities, and this is shown in a number of cases.
Highlights
Inertia-gravity waves (IGWs), i.e. waves for which the restoring force is buoyancy, are ubiquitous in the atmosphere and generally are small scale
Small-scale gravity waves are not resolved by common global circulation models and their forcing is included into the models through parameterisations with different assumptions and tunings according to the goals of the respective model (Alexander et al, 2010)
One year (January to December 2013) of PANSY Mesosphere–Stratosphere– Troposphere/Incoherent Scatter (MST/IS) radar data was analysed for properties of IGWs in the altitude region of 10 to 12 km
Summary
Inertia-gravity waves (IGWs), i.e. waves for which the restoring force is buoyancy, are ubiquitous in the atmosphere and generally are small scale. The importance of their contribution in driving the dynamics of the middle atmosphere has been recognised for a long time. Small-scale gravity waves are not resolved by common global circulation models and their forcing is included into the models through parameterisations with different assumptions and tunings according to the goals of the respective model (Alexander et al, 2010). For better understanding of IGW characteristics and for the improvement of the physical constrains of model parameterisations further observational studies in the southern polar stratosphere are very important. There are studies in the low and midlatitudes examining in detail the properties of gravity waves using high-
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