Rayleigh lidar observations of mesosphere temperature structure

Abstract

Ground‐based observations of atmospheric density profiles to 92 km were obtained for four successive seasons between summer 1989 and spring 1990. These results were obtained with a powerful Rayleigh lidar facility located at Wright Patterson Air Force Base (Dayton, Ohio). This instrument combined a 14‐W XeF laser transmitter with a 2.54‐m receiver mirror to observe returns from altitudes between 40 and 95 km. Analysis of the scale height dependence of the density profiles produced temperatures with a measurement error of about 5 K (∼2.5%) at 90 km when the lidar data was averaged for 20 min. and smoothed in height over 2.7 km. Examination of these profiles for the total of 18 nights showed that there often existed in the mesophere a layer of enhanced temperatures when compared with the U.S. standard profile. The layer centroid height was about 85 km for summer and 70 to 75 km for winter. Data obtained for the equinoctial periods showed the amplitude of these layers to be weak. The winter temperature profiles showed evidence forlong‐period waves passing through the region of the thermal anomaly while the equinox profiles revealed more sporadic wave activity with shorter vertical wavelengths. Both the winter and summer temperature data displayed regions where the observed lapse rate approached the adiabatic lapse rate. In the summer the wave activity near the inversion layer was weak.

Observed coupling of the mesosphere inversion layer to the thermal tidal structure

“…It was first discovered in falling sphere observations by Schmidlin [1975]. The amplitude of the enhancement observed is typically ~25 K but can be as high as 100 K [Meriwether et al, 1994]. The rate of occurrence is nearly continuous (>85%) for winter but sporadic for summer (<40%).…”

“…Temperature profiles were retrieved through the application of the hydrostatic law and the ideal gas equation of state [Meriwether et al, 1994]. The starting altitude of the analysis is determined by using the altitude at which the ratio of noise to signal is 6%, which typically was within the range of 80 -90 km for data averaged over one hour and smoothed over 3 kin.…”

Vertical velocities associated with gravity waves measured in the mesosphere and lower thermosphere with the EISCAT VHF radar

“…Lidar observations have in fact revealed temperature lapse rates approaching the adiabatic in the upper mesosphere (e.g. Wilson et al, 1991;Meriwether et al, 1994), and as temperature lapse rates approach the adiabatic, the associated value of N tends towards zero, so gravity waves of even middle periods can become trapped in a duct bounded by such regions.…”

“…Gardner et al, 1989;Mitchell et al, 1991;Wilson et al, 1991;Meriwether 1993;Senft et al, 1993;Meriwether et al, 1994) or MF, MST and incoherent scatter radars to measure wind perturbations (e.g. Vincent and Reid, 1983;Meek et al, 1985a, b;Vincent and Fritts, 1987;Fritts and Yuan, 1989; RuÈ ster and Reid, 1990;Fritts et al, 1992;Nakamura et al, 1993;Gavrilov et al, 1995).…”

The Potential for Atmospheric Path Length Compensation in Stellar Interferometry

“…Lidar has provided useful measurements of gravity waves and temperature structure in the high atmosphere, and of molecular and dust components (Pal et al 1996 ;Ansmann, Riebesell, & Weitkamp 1990 ;Carswell et al 1991 ;DÏAltorio et al 1993 ;Meriwether et al 1994 ;Duck, Whiteway, & Carswell 1998 ;Whiteway & Carswell 1994 ;Whiteman, MelÐ, & Ferrare 1992). Doppler lidar has also measured velocities in the high atmosphere (Rothermel et al 1991 ;Gal-Chen, Xu, & Eberhard 1992).…”