Loading...
Please wait, while we are loading the content...
Similar Documents
Thor: cloud thickness from off beam lidar returns
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Kolasinski, John Yetzer, Ken Varnai Sr., Tamas McGill, Matthew Cahalan, Robert F. |
| Copyright Year | 2004 |
| Description | Conventional wisdom is that lidar pulses do not significantly penetrate clouds having optical thickness exceeding about tau = 2, and that no returns are detectable from more than a shallow skin depth. Yet optically thicker clouds of tau much greater than 2 reflect a larger fraction of visible photons, and account for much of Earth s global average albedo. As cloud layer thickness grows, an increasing fraction of reflected photons are scattered multiple times within the cloud, and return from a diffuse concentric halo that grows around the incident pulse, increasing in horizontal area with layer physical thickness. The reflected halo is largely undetected by narrow field-of-view (FoV) receivers commonly used in lidar applications. THOR - Thickness from Off-beam Returns - is an airborne wide-angle detection system with multiple FoVs, capable of observing the diffuse halo, detecting wide-angle signal from which physical thickness of optically thick clouds can be retrieved. In this paper we describe the THOR system, demonstrate that the halo signal is stronger for thicker clouds, and validate physical thickness retrievals for clouds having z > 20, from NASA P-3B flights over the Department of Energy/Atmospheric Radiation Measurement/Southern Great Plains site, using the lidar, radar and other ancillary ground-based data. |
| File Size | 8518313 |
| Page Count | 67 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20040171257 |
| Archival Resource Key | ark:/13960/t5cc5zn7r |
| Language | English |
| Publisher Date | 2004-06-01 |
| Access Restriction | Open |
| Subject Keyword | Meteorology And Climatology Aerial Reconnaissance Cloud Cover Receivers Radiation Measurement Photons Optical Thickness Beams Radiation Optical Radar Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
