The quasi 2‐day wave observed in the polar mesosphere: Comparison of the characteristics observed at Tromsø and Poker Flat

Abstract

[1] A comparison of the quasi 2-day wave (Q2DW) observed at Tromsø (69.6°N, 19.2°E) and Poker Flat (65.2°, 147.6°W) is presented at four heights of 70, 76, 82, and 88 km using wind data taken for $4 years, from 1 November 1998 to 7 November 2002. The characteristics of the Q2DW such as seasonal variation, occurrence of period of maximum amplitude, ratio of meridional to zonal amplitudes, shape of altitude profile of phase, and modulation of amplitude at a 4-10 days rate found at Poker Flat are very similar to those found at Tromsø reported by Nozawa et al. [2003]. The activity of the Q2DW is higher in winter than in summer for meridional and zonal components at the two sites. Long-term variation (i.e., seasonal variation) of the Q2DW is found to be similar between the two sites, while short-term variations (i.e., over several days) do not synchronize well with each other. The ratio of amplitudes of the Q2DW between the two sites varies mainly between 0.5 and 2, and there is no significant preference toward either site. Phase differences of Q2DWs between the two sites are examined, and it is found that in-phaselike events are more frequently seen than out-of-phase-like events at 76, 82, and 88 km in winter and at 88 km in summer. This can be interpreted to mean that the zonal wave number of the Q2DW appears to be 2 or 4 more often than 3 in the polar upper mesosphere. These results suggest that observed Q2DWs have features consistent with the Rossby gravity wave mode, but the amplitude and phase of the Q2DW are affected significantly by local sources. A possibility that the observed Q2DW is an eastward moving wave is also discussed.

The wintertime two-day wave in the polar stratosphere, mesosphere and lower thermosphere

“…This wave is believed to be one of a series of waves generated by barotropic instabilities in the polar night jet (e.g., Venne and Stanford, 1982; Hartmann, 1983;Prata, 1984;Lait andStanford, 1988 andManney et al, 1988). Nozawa et al (2003b) suggested that the polar MLT-region wintertime two-day wave may be an E2 wave connected to these stratospheric oscillations -but this could not confirmed in the absence of longitudinal measurements. Palo et al (2007) reported an E2 wave in the mid-latitude, summer, southern-hemisphere MLT region occurring simultaneously with a W3 wave.…”

Signatures of the 2-day wave and sudden stratospheric warmings in Arctic water vapour observed by ground-based microwave radiometry

“…In this study we concentrate on the investigation of the Q2DW. At mid-latitudes, the Q2DW is most pronounced in the summer mesosphere and only at high latitudes has the Q2DW been observed near winter solstice (Nozawa et al, 2003;Sandford et al, 2008;Tunbridge and Mitchell, 2009).…”

“…Recent studies discussed a strong Q2DW activity around winter solstice at high latitudes (Nozawa et al, 2003;Sandford et al, 2008;Tunbridge and Mitchell, 2009) related to an eastward-propagating E2 wave using wind measurements from meteor radars and geopotential height from Aura MLS.…”

Anomalous two‐day wave behavior during the 2006 austral summer

“…In January of that same year, Lieberman [1999] observed the two-day wave as a mesospheric disturbance packet containing W2 component with a period of about 3.5 days, as well as W3 and W4 components mentioned above. Nozawa et al [2003] suggested the predominace of W2 and W4 components over W3 in the higher northern latitudes between 76-88 km altitude. Recently, Wu et al [2008] noted a strong W2 component of the two-day wave signature in the equatorial upper mesosphere during January 2006 with a period slightly shorter than 2 days.…”