Effects of Horizontal Wind Structure on a Gravity Wave Event in the Middle Atmosphere Over Syowa (69^°S, 40^°E), the Antarctic

Abstract

Nightly mean potential energy of gravity waves (GWs) per unit mass (Ep) over Syowa Station (69°S, 40°E) was calculated from temperature profiles observed by the Rayleigh/Raman lidar from 2011 to 2015. The Ep values in the upper stratosphere and lower mesosphere were significantly enhanced on 8–21 August 2014, except on 12 August. A ray‐tracing analysis showed that large‐scale GWs emitted from various latitudes could be refracted and forced to converge above Syowa due to the poleward tilting of the polar night jet with altitude. It should be noted that Ep on 12 August was smaller than the other values during the enhancement, despite similar polar night jet conditions. A synoptic‐scale disturbance, which passed on 12 August, could have blocked the GWs from propagating upward through critical level filtering. These results suggest that convergence of the wave should be considered as a part of the intermittency of the GWs.

Winter 2018 major sudden stratospheric warming impact on midlatitude mesosphere from microwave radiometer measurements

“…The similar gradient change is a characteristic of the mesospheric CO profiles in boreal winter from ground-based and satellite observations ( Fig. 4 in Koo et al, 2017;Fig. 5 in Ryan et al, 2017).…”

Lidar observations of large-amplitude mountain waves in the stratosphere above Tierra del Fuego, Argentina

“…However, a large-amplitude mesospheric mountain wave with 67 K peak-to-peak amplitude was observed by ground-based lidar for a short duration of 2 h above Lauder, New Zealand, which is also a gravity wave hot spot 35,36 . At southern high latitudes, intra-annual and seasonal gravity wave statistics are available from a number of lidar stations in Antarctica [22][23][24][25] . They all indicate increased gravity wave activity during winter, but likely do not capture the strongest events due to their location within the polar vortex.…”

“…Therefore, our lead question is: can local, continuous and high-temporal-and high-vertical-resolution observations of gravity waves in the lee of the Andes enhance our knowledge about the magnitude of the momentum that is deposited in the stratosphere? Such observations can be accomplished using powerful, vertically-pointing Rayleigh lidars as operated at few locations world-wide [21][22][23][24][25][26][27] . To specifically target the worlds's largest gravity waves, we installed the Compact Autonomous Rayleigh lidar (CORAL) at Rio Grande, Tierra del Fuego, Argentina, for night-time measurements of atmospheric temperature.…”

Retrieval of intrinsic mesospheric gravity wave parameters using lidar and airglow temperature and meteor radar wind data

“…In order to retrieve hor-izontal wavelengths larger than the field of view (FOV) of the imager, Takahashi et al (2009) and Fritts et al (2014) analysed keogram representations of airglow imager data. In addition to process studies, also large-period observations of OH layer emissions with imaging instruments are employed to derive statistics and seasonal variations in GW parameters at different locations (Walterscheid et al, 1999;Nakamura et al, 1999;Suzuki et al, 2004;Li et al, 2016Li et al, , 2018Shiokawa et al, 2009).…”