Date of Award:

1997

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Physics

Advisor/Chair:

Vincent B. Wickwar

Abstract

Temperature observations of the middle atmosphere have been carried out from September 1993 through July 1995 using a Rayleigh backscatter lidar located at Utah State University (42°N, lii0W). Data have been analyzed to obtain absolute temperature profi les from 40 to 90 km. Various sources of error were reviewed in order to ensure the quality of the measurements. This included conducting a detailed examination of the data reduction procedure, integration methods, and averaging techniques. eliminating errors of 1-3%. The temperature structure climatology has been compared with several other mid-latitude data sets. including those from the French lidars, the SME spacecraft, the sodium lidars at Ft. Collins and Urbana, the MSISe90 model, and a high-latitude composite set from Andenes, Norway. In general, good agreement occurs at mid-latitudes, but areas of disagreement do exist. Among these, the Ctah temperatures are significantly warmer than the MSJSe90 temperatures above approximately 80 km, they are lower below 80 km than any of the others in summer, they show major year-to-year variability in the winter profiles, and they differ from the sodium lidar data at the altitudes where the temperature profiles should overlap. Also, comparisons between observations and a physics based global circulation model, the TIME-GCM, were conducted for a mid-latitude site. A photo-chemical model was developed to predict airglow intensity of OH based on output from the TIME-GCM. Many discrepancies between the model and observations were found , including a modeled summer mesopause too high , a stronger summer inversion not normally observed by lidar, a fall-spring asymmetry in the OH winds and lidar temperatures but not reproduced in the TIME-GCM equinoctial periods, larger winter seasonal wind tide than observed by the FPl, and a fai lure of the model to reverse the summenime mesospheric jet. It is our conclusion these discrepancies are due to a gravity wave parameterization in the model that is too weak and an increase will effectively align the model calculations with our observations

Included in

Physics Commons

Share

COinS