INTERPRETATION OF GRAVITY-WAVES OBSERVED IN THE MESOPAUSE REGION AT STARFIRE OPTICAL-RANGE, NEW-MEXICO - STRONG EVIDENCE FOR NONSEPARABLE INTRINSIC (M, OMEGA) SPECTRA

Sixty-five hours of Na lidar observations of vertical and horizontal w inds, temperature, and Na density were obtained during eight different nights in 1994 and 1995 at the Starfire Optical Range, New Mexico, us ing a 3.5 m diameter telescope. The high-resolution data are used to s tudy the spectra of gravity wave perturbations in the mesopause region . Wave activity was strong during the observations. The average varian ces of temperature, relative atmospheric density, horizontal wind, and vertical wind were 80 K-2, 28 (%)(2), 1100 m(2)/s(2), and 4.3 m(2)/s( 2), respectively. The temperature, relative density, and horizontal wi nd spectra are generally consistent with the large body of published m easurements and with the predictions of gravity wave theory. The obser ved temporal frequency (omega(0)) and vertical wave number (m) spectra of vertical winds are both very shallow. The indices of the omega(0) 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+/-0.03 and - 1.48+/-0.03, and the mean value is -1.1. In contrast, the indices of t he horizontal wind ill spectra vary between -2.8+/-0.10 and -3.2+/-0.1 3 with a mean of -3.0. These large differences imply that the underlyi ng intrinsic spectra are not separable. However, the observed vertical wind rn spectra are not consistent with the nonseparable theories whi ch predict index values near +1. By using mathematical and numerical m odels, we show that the observed m spectra are distorted by Doppler an d critical layer effects associated with the height-varying mean wind field. This distortion is greatest at high values of nz and leads to o bserved vertical wind m spectra which are steeper than the underlying intrinsic spectra. Although the intrinsic spectra are definitely shall ower (i.e., indices more positive) than the observations, it is not po ssible to determine if the measurements are entirely consistent with a ny of the nonseparable wave dissipation theories.