Comparison of lab based and solar reflectance based calibration of aureole camera
Date of Award
Doctor of Philosophy (Ph.D.)
First Committee Member
Kenneth J. Voss, Committee Chair
Aerosols play an important role in the Earth's radiative transfer and the remote sensing of the environment. One major difficulty in precisely quantifying the aerosol effects is the uncertainties in aerosol characterization. An aureole camera can provide important ground measurement for characterizing the aerosol size distribution and optical properties. Careful calibration of the aureole camera and correct radiometric interpretation of acquired images are essential to the quality of the retrieved aerosol properties. In my dissertation, I carefully removed many hard-to-notice uncertainties related to lab based calibration. Most importantly, the often ignored point spread function effect of the aureole camera optical system that can cause more than a 3% error is identified and removed. The measured point spread function spans 7 orders of magnitude of intensity and covers distances up to 250 pixels (or 14°) away from the image of a point source. The effect of the point spread function on the radiometric interpretation of the optical system is simulated and experimentally proven with a specially designed small field-of-view device. The correct interpretation and calibration procedure of the aureole camera is thus detailed. With all the calibration and interpretation problems cleared, the traditional lamp based calibration and a Solar Reflectance Based Calibration were performed and compared. The Solar Reflectance Based Calibration removes the uncertainties of individual lamps. I found that the two calibration methods agree within 4%, which is comparable to the uncertainties reported by other authors [Schmid and Wehrli, 1995; Schmid et al., 1998].A preliminary aerosol retrieval scheme based on aureole and aerosol optical depth measurements is also described.
Physics, Atmospheric Science; Physics, Optics
Du, Hong, "Comparison of lab based and solar reflectance based calibration of aureole camera" (2004). Dissertations from ProQuest. 2136.