Temperature tides determined with meteor radar

Abstract

Abstract.A new analysis method for producing tidal temperature parameters using meteor radar measurements is presented, and is demonstrated with data from one polar and two mid-latitude sites. The technique further develops the temperature algorithm originally introduced by Hocking (1999). That earlier method was used to produce temperature measurements over time scales of days and months, but required an empirical model for the mean temperature gradient in the mesopause region. However, when tides are present, this temperature gradient is modulated by the presence of the tides, complicating extraction of diurnal variations. Nevertheless, if the vertical wavelengths of the tides are known from wind measurements, the effects of the gradient variations can be compensated for, permitting determination of temperature tidal amplitudes and phases by meteor techniques. The basic theory is described, and results from meteor radars at Resolute Bay (Canada), London (Canada) and Albuquerque (New Mexico, USA) are shown. Our results are compared with other lidar data, computer models, fundamental tidal theory and rocket data. Phase measurements at two mid-latitude sites (Albuquerque, New Mexico, and London, Canada) show times of maximum for the diurnal temperature tide to change modestly throughout most of the year, varying generally between 0 h and 6 h, with an excursion to 12 h in June at London. The semidiurnal tide shows a larger annual variation in time of maximum, being at 2-4 h in the winter months but increasing to 9 h during the late summer and early fall. We also find that, at least at mid-latitudes, the phase of the temperature tide matches closely the phase of the meridional tide, and theoretical justification for this statement is given. We also demonstrate that this is true using the Global Scale Wave Model (Hagan et al., 1999). Median values for the temperature amplitudes for each site are in the range 5 to 6 Kelvin. Results from a more northern site (Resolute Bay) show less consistency between the wind tides and the temperature tides, supporting suggestions that the temperature tides may be zonally symmetric at these high latitudes (e.g.Correspondence to: A. Hocking (mardoc-inc@rogers.com) Walterscheid and Sivjee, 2001).

Eureka, 80° N, SKiYMET meteor radar temperatures compared with Aura MLS values

“…Also, if the comparison is found suitable, and diurnal variations in gradient and pressure are sufficiently low, we can get diurnal effects (i.e. tides) from meteor echoes without extra assumptions, as employed by Hocking and Hocking (2002), on the relation between wind and temperature tides (that is, that the vertical wavelengths are the same). Yuan et al (2006) in a mid-latitude lidar study show temperature and wind tidal data with sometimes major differences in vertical wavelength.…”

Radar meteor decay rate variability and atmospheric consequences

“…Also added to the same plot are data from the SKiYMET radar at Socorro in New Mexico (previously at Starfire -e.g. see Liu et al, 2002;Hocking and Hocking, 2002), and the Genesis radar in Australia, both during its normal location at Delamere (35.5 • S) and during a campaign at Learmonth (22.2 • S) (Fuller, private communication). More data are available from all these sites, but the point here is simply to illustrate that the Resolute Bay are not atypical.…”

Characteristics of Arctic winds at CANDAC-PEARL (80° N, 86° W) and Svalbard (78° N, 16° E) for 2006–2009: radar observations and comparisons with the model CMAM-DAS

“…We use two MWR (Meteor Wind) radars of similar design (Hall et al, 2003;Hocking and Hocking, 2002 Manson et al, 2006) are included in two sections of this paper: provision of "polar-projection" plots up into the mesosphere, to help understand longitudinal variability of background winds in the broad hemispheric context (Sect. 3); and then in Sects.…”