A Fabry-Perot interferometer (FPI) system was deployed in Kelan (38.7°N, 111.6°E), center China in November 2011, which observes the airglows at wavelengths of 892.0 nm, 557.7 nm, and 630.0 nm from OH and OI emissions in the upper atmosphere, to derive the wind and temperature at heights around 87 km, 97 km, and 250 km, respectively. From late 2011 through 2013 a series of more than 4500 measurements at each height are validated according to manufacture data quality criteria. By using these data, the morphology of wind in the mesosphere and thermosphere is investigated in this study. Preliminary results are as follows:(1) As for the diurnal variation, meridional and zonal winds at heights of 87 km and 97 km, which are derived through 892.0 nm and 557.7 nm airglows, usually range from À50 m/s to 30 m/s and À50 m/s to 50 m/s, respectively, with typical random errors of about 6-10 m/s at 87 km and 2-3 m/s at 97 km. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, westward at middle night, and back to eastward at dawn. The monthly mean winds are in good agreement with those of HWM93 results. Meridional and zonal winds at a height of 250 km, which are derived through 630.0 nm nightglow, range from À110 m/s to 80 m/s with typical random errors of about 8-10 m/s. Meridional winds usually are northward at dusk, southward at middle night, and back to northward at dawn; and zonal winds usually are eastward at dusk, zero at middle night, and westward at dawn; and they are also well consistent with HWM93 results. (2) As for the seasonal variation, meridional winds at the heights of 87 km and 97 km have a visible annual variation at 12-17 LT and with a little semiannual variation at all other hours, but the zonal winds at the heights of 87 km and 97 km have a semiannual variation all night. The seasonal dependence of the winds, both meridional and zonal winds, at the height of 250 km is generally annual, but isolated cases of semiannual variation are observed. (3) The horizontal winds at 250 km evidently respond to the two storms of July 2012, apparent enhancement of the velocity of the southwestward wind. But no other obvious storm effects can be found from the winds at 87 km and 97 km during the same period.
A newly installed meteor radar has been installed to measure winds in the mesosphere and lower thermosphere (MLT) over Wuhan (114.4 • E, 30.6• N). In the present study, a database of the first 25 months (February 2002-February 2004 of observations has been analyzed to investigate the climatology of mean winds and tides. The daily average zonal wind is charactered by a strong shear in solstices and an intense eastward flow in summer. The daily average meridional wind is northward in winter and southward in other seasons. There are some discrepancies between the radar mean winds and the HWM93 model winds. The summer zonal winds and meridional winds from the model are obviously weaker than our observations. The analysis on tides indicates that the diurnal tide is dominant at Wuhan. The seasonal variability is observed in both the diurnal and semidiurnal tidal amplitudes with the maximum values occurring usually near the equinoxes. Compared with the Global Scale Wave Model (GSWM00), the observed results generally show a smaller diurnal tidal amplitude and a larger semidiurnal tidal amplitude.
Winds measured by an all-sky meteor radar have been used to investigate the terdiurnal tide in the mesosphere and lower thermosphere (MLT) region over Wuhan (30.6 • N, 114.4• E). We present a climatology of the terdiurnal tide at low-mid latitude site during the period of April 2002 to December 2004. The terdiurnal peak is distinct in the long-term power spectrum of the wind. The monthly and seasonal mean maximum amplitudes have values of 7 m/s and 5 m/s, respectively. The short-term amplitudes can occasionally reach up to 30 m/s, and at times the terdiurnal tide is as large as the diurnal and semidiurnal ones. It seems that the meridional component is more regular than the zonal one. An obvious annual variation is observed in the meridional phases with a phase leading in winter than that in summer. The annual variation for the terdiurnal tidal amplitude is not obvious, and is variable from year to year in our observations. This seasonal trend is slightly different from earlier studies at other locations.
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