Density Measurements with Combined Raman-Rayleigh LIDAR (Light Detection and Ranging)
Abstract
A combined Raman-Rayleigh Lidar(Light Detection And Ranging) has recently been implemented at the Air Force Geophysics Laboratory's ground-based lidar station to measure neutral density from the lower stratosphere to the upper mesosphere. Rayleigh Lidar reliability measures relative densities in the region above 30 km. In this region, atmospheric extinction can be neglected and backscattering is primarily due to Rayleigh scattering. However, when density measurements are needed for the lower stratosphere two complications arise: the contribution of aerosol (Mie and Rayleigh) signal and the effect of aerosol attenuation. Vibrational Raman scattering, being an elastic process for molecules only, can be used to resolve the first ambiguity. The second difficulty requires an inversion technique to help determine the attenuation profile from the Lidar signal and provide a transmission correction of this signal. For the lower stratosphere, the technique adopted in this laboratory is a three-step treatment of data. In step (1) Klett inversion is applied on the elastic scattering signal (Mie and Rayleigh) to obtain a transmission altitude profile. In step (2) the molecular signal from the Raman Lidar is corrected for atmospheric attenuation. In step (3), Raman data for below 25 km is spliced to Rayleigh data for above 25 km to give the entire profile of neutral density. Application of this analysis to experimental data will be shown and discussed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 03, 1989
- Accession Number
- ADA203561
Entities
People
- Dwight Sipler
- G. Davidson
- Phan Dao
- W. P. Moskowitz
- Wayne Klemetti
Organizations
- Air Force Research Laboratory