Gravity wave characteristics in the mesopause region revealed from OH airglow imager observations over Northern Colorado

Abstract

Using 5 years of all-sky OH airglow imager data over Yucca Ridge Field Station, CO (40.7°N, 104.9°W), from September 2003 to September 2008, we extract and deduce quasi-monochromatic gravity wave (GW) characteristics in the mesopause region. The intrinsic periods are clustered between approximately 4 and 10 min, and many of them are unstable and evanescent. GW occurrence frequency exhibits a clear semiannual variation with equinoctial minima, which is likely related to the seasonal variation of background wind. The anomalous propagation direction in January 2006, with strong southward before major warming starting in 21 January and weak southward propagation afterward, was most likely affected by stratospheric sudden warming. The momentum fluxes show strongly anticorrelated with the tides, with~180°out of phase in the zonal component. While in the meridional component, the easterly maximum occurred approximately 2-6 h after maximum easterly tidal wind. However, the anticorrelations are both weakest during the summer. The dissipating and breaking of small-scale and high-frequency GW's components could have a potential impact on the general circulation in the mesopause region.

Characteristics of mesospheric gravity waves over the southeastern Tibetan Plateau region

“…[] and Tang et al . [] both report that the zonal momentum fluxes present a semiannual variation with eastward momentum fluxes at the solstices and westward momentum fluxes at the equinoxes. The zonal momentum fluxes at Qujing station are mainly eastward in all seasons, which suggests that orographic features have a significant impact on the momentum flux distributions in the MLT region.…”

“…The propagation directions of GWs are all northeastward in summer and southwestward or westward in winter at Northern Hemisphere sites. The GW propagation directions at Qujing station are significantly different from other imager observation at northern middle latitudes in winter [e.g., Li et al ., ; Nakamura et al ., ; Hecht et al ., ; Tang et al ., ]. Li et al .…”

“…[] and Tang et al . [] presented that most GWs propagated southwestward in winter at Urbana, IL (40°N, 88°W), and Yucca Ridge Field Station, CO (40.7°N, 104.9°W), respectively. We will explain the unique GW propagation directions below.…”

“…In winter, most of GWs propagate southeastward at Qujing. Figure 6 presents the global distributions of GWs observed by airglow imagers in summer and winter [Walterscheid et al, 1999;Hecht et al, 2001;Ejiri et al, 2003;Medeiros et al, 2003Medeiros et al, , 2004Nakamura et al, 2003;Tang et al, 2005;Suzuki et al, 2009aSuzuki et al, , 2009bLi et al, 2011a;Tang et al, 2014]. The propagation directions of GWs are all northeastward in summer and southwestward or westward in winter at Northern Hemisphere sites.…”

First OH Airglow Observation of Mesospheric Gravity Waves Over European Russia Region

“…The ripples have average horizontal wavelength of is 8.5 ± 1.7 km, observed periods of 4.2 ± 1.2 min, and observed phase speeds of 37.3 ± 14.2 m/s. The ranges and distributions have no obvious difference in the distributions of GW parameters compared with other observation stations in both the Northern and Southern Hemispheres (Bageston et al, ; Dalin et al, ; Ejiri et al, ; Kim et al, ; Li, Liu, et al, ; Li, Xu, et al, ; Li et al, ; Medeiros et al, ; Nakamura et al, ; Narayanan & Gurubaran, ; Nielsen et al, ; Suzuki et al, ; Tang et al, , ).…”