Analysis of Whole-Sky Imager Data to Determine the Validity of PCFLOS models

Models used to predict the probability of a cloud-free line-of-sight PCFLOS from the ground to space have existed since the 1960s. Unfortunately, an adequate data set has not been available to check the validity of these models until the deployment of the Whole-Sky Imager WSI system in 1989. Now that a three-year database has been collected from the WSI system, it is possible to validate, or refute, the existing models. This study investigates the most generally accepted models. Specifically, we investigate three questions 1 Is the Lund and Shank-lin PCFLOS model assumption of azimuthal independence valid 2 Does the Lund and Shanklin sub-sampling of data via the use of a template adequately correlate to both the full image and the grid image and, 3 Do the Lund and Shanklin and SRI model estimates correlate to the WSI observations. The primary contribution of this study is the development of a methodology which employs time series analysis techniques to evaluate and ultimately corroborate the assumption of azimuthal independence....Whole-sky imager, PCFLOS, Time series analysis.