Several techniques exist for using ground-based measurements of IR radiance to characterize the atmosphere, especially the boundary layer. These methodologies, in contrast to space based observations or active probing techniques, offer a safe, continuous measure of atmospheric parameters at a single location that are highly accurate at altitudes very near the ground (<500m) and can be obtained without the need for human monitoring.Herein we demonstrate the use of data from a BOMEM MR140 spectroradiometer for estimation of temperature and water vapor profiles. Temperature profiles are calculated using a simple process based on temperature invariant spectral points of downwelling mid-wave IR (MWIR) radiance; the basic algorithm was reported in 2000. Results reported here include an update to the fit algorithm as well as qualitative comparisons to field test data obtained in 1999 where an active Raman LIDAR and a balloonsonde measured the vertical temperature profile and vertical water vapor profile during an MR data collection.Once the vertical temperature profile is known, the vertical water vapor profile can be calculated using the same radiometric data. Water vapor profiles are calculated in much the same way as temperature profiles, using a simple inversion process, except different altitude points are based on temperature dependent absorption lines instead of temperature invariant points.
In developing algorithms for remote sensing of chemical and biological warfare agents, it is imperative to have a good understanding of the background radiance signal and environmental characteristics that influence detection. Factors such as thermal contrast, interferent atmospheric constituents, spatial clutter, and temporal variations should all be investigated for both the development and performance modeling of field sensors. To aid in the investigation of these topics as well as to provide data for current simulation tools, JHU/APL has constructed an automated data collection suite capable of simultaneous radiometric measurements in the longwave IR (8µm -12µm) and midwave IR (3µm -5µm) while also measuring a host of relevant atmospheric parameters. The primary radiometric sensor, an ABB Bomem MR304, is mounted on a pan/tilt system that is used to scan regions of interest while periodically generating calibration data. This paper describes the system design requirements, specifications of the individual components, and the overall system performance. In addition, data from field exercises are presented.
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