Long-Period Oscillations in the Meteor Region

Simultaneous observations of the 2-day wave at London (43°N, 81°W) and Saskatoon (52°N, 107°W) near 91 km altitude during the two years of 1993 and 1994

“…After a number of tests it turns out that the results of the mean periods are even more consistent if the cuto amplitude is increased (e.g., 15 m/s). All these results strongly suggest that the enhancement or burst of the 2-day activity occurs most frequently near a period of 46±47 h. The periods determined in the present study are therefore found to be smaller than the 51±52 h period generally suggested by the Northern Hemisphere results (e.g., Muller, 1972;Glass et al, 1975;Muller and Nelson, 1978;Kingsley et al, 1978;Stenning et al, 1978;Manson et al, 1978;Salby and Roper, 1980;Tsuda et al, 1988), although these other studies did not distinguish periods on the basis of wave amplitudes as we have.…”

“…Di erent observers report somewhat di erent periods in the range 43±53 h (e.g., Craig and Elford, 1981;Kalchenko, 1987;Salby and Roper, 1980;Massebeuf et al, 1981;Cevolani et al, 1983;Tsuda et al, 1988). In the Southern summer Hemisphere the dominant wave period seems consistently to be fairly close to 48 AE 3 h (e.g., Craig et al, 1980;Craig and Elford, 1981;Phillips, 1989;Poole, 1990;Harris, 1993b), whereas in the Northern summer Hemisphere the period often seems to be 51 AE 2 hours (e.g., Muller, 1972;Glass et al, 1975;Muller and Nelson, 1978;Kingsley et al, 1978;Stenning et al, 1978;Manson et al, 1978;Salby and Roper, 1980;Tsuda et al, 1988). reported summer (June±August) values of 47±50 AE2±5 h. It is possible that these di erences are due to hemispheric di erences in the wave forcing and/or propagation conditions in the middle atmosphere.…”

“…One interpretation put forward to explain the existence of the wave is that it is a manifestation of the Rossby-gravity (3, 0) normal mode forced by the lower atmosphere (Salby and Roper, 1980;Salby, 1981). Salby (1981) attributed the excitation source of the wave to the characteristic unsteadiness of the tropospheric¯ow, or tropospheric``noise''.…”

The two-day wave in the Antarctic and Arctic mesosphere and lower thermosphere

“…The wave has since been extensively studied by ground-based radar. In particular, meteor and MF radars have been used to investigate the vertical structure and climatology of the wave at middle and low latitudes (e.g., Salby and Roper, 1980;Craig et al, 1983;Plumb et al, 1987;Tsuda et al, 1988;Harris and Vincent, 1993;Palo and Avery, 1996;Jacobi et al, 1997;Thayaparan et al, 1997;Jacobi et al, 1998;Gurubaran et al, 2001;Manson et al, 2004;Pancheva et al, 2004;. Satellite observations have been used to investigate the global-scale structure of the wave (e.g., Rodgers and Prata, 1981;Wu et al, 1993;Ward et al, 1996;Lieberman, 1999;Limpasuvan and Wu, 2003;Sandford et al, 2008).…”

A cooperative synchronous observation of winds and tides in the tropical lower stratosphere and mesosphere using VHF radars at Jicamarca and Arecibo.

“…Following COUNTRYMAN and DOLAS (1982), we tried several methods using various fitting procedures, such as DC+24 and/or 12h, DC+24/12h+2/5 days and so on (2-day and 5-day ZONAL WIND JICAMARCA 19-21 NOV 1981 oscillations are considered to be also significant in the mesosphere, e.g., SALBY and ROPER, 1980;MASSEBEUF et al, 1981). Moreover, fitting is made in case that the nighttime data is set to be zero, in order to prevent an extreme interpolation of the missing nighttime data.…”