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Title: Radiometric calibration of the high resolution dynamics limb sounder
Author: Peters, Daniel Michael
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2004
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The High Resolution Dynamics Limb Sounder (HIRDLS) is part of NASA's Earth Observing System (EOS). The system provides satellite instrumentation to observe the extent, cause and consequences of climate change. HIRDLS is a radiometer designed to monitor the chemistry and dynamics of the atmosphere at a high vertical and horizontal resolution from the upper troposphere to the mesosphere. Its radiometric, spectral and field of view pre-flight calibrations have taken place at Oxford in a purpose-built facility. This thesis describes the radiometric calibration. Radiance measurement traceability (the absolute radiometric uncertainty) is increasingly important for monitoring long term climate change. This area has been given particular attention. This thesis shows how this traceability has been achieved. The In Flight Calibrator (IFC) has been subjected to extensive testing and calibration which are described. Two large external blackbody targets have been used to provide calibration radiance to HIRDLS in the test facility. The uncertainties in these radiances have been assessed. The targets have facilitated the pre-flight measurement of the radiometric calibration parameters that are required before flight and allowed the in-flight calibration algorithm to be tested. The pre-flight radiometric calibration has proved invaluable to HIRDLS. If the calibration had not taken place and the instrument was assumed to be linear and "self calibrating" the atmospheric temperature retrieval accuracies would have been limited to at best 4.3 K. Using the calibration data and a simple non-linear correction this work has improved the highest accuracy to 0.8 K. This result justifies the effort put into the pre-flight radiometric calibration of HIRDLS.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available