Rayleigh-Scatter Lidar Technique for Measurement of Thermospheric Neutral Densities
Abstract
The behavior of the neutral atmosphere in the mesosphere-lower thermosphere (MLT) region from approximately 90-120 km, is significantly affected by space weather. To a great extent, the densities and temperatures in this region form the lower boundary condition for models used to calculate densities throughout the thermosphere. These densities, in turn, affect reentry predictions for satellites and space debris. Unfortunately, the densities between 90 and 120 km are extremely hard to measure on a regular basis with high spatio-temporal resolution. In situ sensing on rockets does not give continuous measurements. Satellites orbit at higher altitudes and remote sensing from these platforms give global coverage while sacrificing fine spatio-temporal coverage.
The Rayleigh-scatter lidar technique has been used for several decades to obtain relative density and absolute temperature measurements primarily in the mesosphere (40-90 km). Depending on the application, the raw lidar data can be post-processed to have spatial resolutions of tens of meters to kilometers and temporal scales of minutes to days. This robust ground-based instrument operates every clear night, and with a network of systems, can obtain strategic global coverage. Recently, the Rayleigh lidar group at Utah State University showed that this remote sensing technique could be extended into the lower thermosphere up to about 115 km (Sox et al., 2018). The Rayleigh lidar relative densities have also been put on an absolute scale (Barton et al., 2016, and Price et al., 2018) by normalizing preexisting lidar data (covering 45-90 km) to densities from reanalysis models (e.g., MERRA2, ERA20C) at about 45 km. We will present how, with further optimization and use of modern detectors, it will be straightforward to obtain absolute neutral temperatures and densities to at least 120 km while maintaining a lower limit below 45 km. A concept for a network of such lidars, along with complementary optical and RF sensors, will also be discussed.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSA32A..08S
- Keywords:
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- 2194 Instruments and techniques;
- INTERPLANETARY PHYSICS;
- 2794 Instruments and techniques;
- MAGNETOSPHERIC PHYSICS;
- 7594 Instruments and techniques;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7894 Instruments and techniques;
- SPACE PLASMA PHYSICS