A Potential Remote-Sensing Technique for Thermospheric Temperature with Ground-Based Resonant Atomic Oxygen Raman Lidar
Abstract
We propose a remote-sensing technique to measure temperature in the lower thermosphere with a resonant Raman lidar. A ground-based pulsed laser operating at 630.0304 (636.3776) nm excites [exp-3] P [sub-2] ([exp-3] P [sub-1]) multiplet level of the ground electronic state of atomic oxygen in the atmosphere to the electronically excited [exp-1] D [sub-2] state and the back-scattered photons at 636.3776 (630.0304) nm, while the atom transitions to [exp-3] P [sub-1] ([exp-3] P [sub-2]), are detected. Using the backscattering Raman cross sections calculated here we show: (1) For the range of altitudes in the lower thermosphere where the fine-structure multiplets of atomic oxygen are in thermodynamic equilibrium with the local translational temperature (LTE) and the electronically excited intermediate state [exp-1] D [sub-2] remains relaxed primarily by collisions with N(sub-2) and O(sub-2), the ratio of the backscattered signal can be used to obtain temperature. (2) Higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are in LTE and the electronically excited intermediate state [exp-1] D [sub-2] is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the atomic oxygen density and local temperature. (3) Still higher up, for the range of altitudes where the fine-structure multiplets of atomic oxygen are not in LTE and the electronically excited intermediate state [exp-1] D [sub-2] is relaxed primarily by spontaneous emission of a photon, the Stokes and anti-Stokes backscattered signal can be used to obtain the density of the [exp-3] P [sub-2] and [exp-3] P multiplet levels of the ground electronic state of atomic oxygen.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA443529
Entities
People
- Phan D. Dao
- Ramesh D. Sharma
Organizations
- Air Force Research Laboratory