Characteristics of small-scale gravity waves in the Arctic winter mesosphere

Using the long-term data sets observed with an OH all-sky imager, a Fabry-Perot Interferometer at Resolute Bay Observatory, Canada (74.7 degrees N, 94.9 degrees W), Microwave Limb Sounder and reanalysis data, we study the characteristics of small-scale gravity waves (GWs) with the horizontal wavelength less than 20 km in the Arctic winter mesosphere during 2014-2016.

Most GWs propagate nearly against the mesospheric and stratospheric winds, consistent with the wind filtering theory. A small amount (7 of 36 cases) of small-scale GWs in large regions (area >1/2 of the whole image) propagate nearly westward with slower phase speeds, larger horizontal wavelengths, and longer periods than those in limited regions. We also find that multiple GWs with different propagating directions can sometimes occur simultaneously.