Sixty four hours of Na lidar observations of vertical and horizontal winds, temperature, and Na density were obtained during 8 different nights in 1994 and 95 at the Starfire Optical Range, NM using a 3.5 m diameter telescope. The high resolution data are used to study the spectra of gravity wave perturbations in the mesopause region. Wave activity was strong during the observations. The average variances of temperature, relative atmospheric density, horizontal wind, and vertical wind were repectively, 80 K2, 28 (%)2, 1100 m2/s2, and 4.3 m2/s2. The temperature, relative density, and horizontal wind spectra are generally consistent with the large body of published measurements and with the predictions of gravity wave theory. The temporal frequency (w) and vertical wave number (m) spectra of vertical winds are both very shallow. The indices of the w spectra vary between -0.59±0.13 and -1.2±0.09 and the mean value is -0.76. The indices of the m spectra vary between -0.83±0.04 and -1.48±0.03 and the mean value is -1.1. In contrast, the indices of the horizontal wind m spectra vary between -2.8±0.10 and -3.2±0.13 with a mean of -3.0. These large differences imply that the underlying intrinsic spectra are not separable. However, the observed vertical wind m spectra are not consistent with the nonseparable theories which predict index values near +1. By using mathematical and numerical models, we show that the observed spectra are distorted by Doppler and critical layer effects associated with the height varying mean wind field. This distortion is greatest at high values of m and leads to observed vertical wind spectra which are much steeper than the underlying intrinsic spectra. Although the intrinsic spectra are definitely shallower (i.e. indices more positive) than the observations, it is not possible to determine if the measurements are entirely consistent with any the nonseparable wave dissipation theories.
Figure 1 Vertical wave number spectra of relative atmospheric density, temperature T', and vertical wind w' perturbations. n is the total number of spectra used to compute the 8 night mean spectra.
Figure 2 Temporal frequency spectra of relative atmospheric density, temperature T', and vertical wind w' perturbations. n is the total number of spectra used to compute the 8 night mean spectra.
Figure 3 Scaled sum of the mean radial wind spectra from each of the 4 off-zenith beams and the scaled zenith beam (vertical wind) mean spectrum. The photon noise floors have been subtracted from the spectra.
Figure 4 Vertical wave number spectra of total horizontal winds (zonal plus meridional). n is the total number of radial wind spectra used to compute the 5 night mean spectrum.
Figure 5 Comparison of the relationships between the total horizontal wind, relative atmospheric density, and temperature spectra predicted using the gravity wave polarization relations.
Figure 6 Measured mean vertical wind m spectrum and the model spectra predicted by the separable Linear Instability Theory (Eq. (20)) and the nonseparable Diffusive Filtering Theory (Eq. (21)).
