Comparison of Fractional Sky Cover data retrieved from Visible and Infrared All-Sky Imagers

Description

The Solmirus Corporation has been funded by the U.S. Department of Energy (Grant DE-SC-0008650) to develop a diurnal fractional sky cover (FSC) data product utilizing the infrared (IR) radiometrically-calibrated data from their All Sky Infrared Visible Analyzer (ASIVA) instrument. Nighttime FSC has long been a critical programmatic gap in ARM’s observational data set and is an important factor in understanding the life cycle of clouds, one of the central themes of the ASR program. The FSC algorithms have been fully developed and this poster paper presents a 3-month comparison of daytime ASIVA data to that retrieved from the Total Sky Imager (TSI). Comparison data are derived from Solmirus' ASIVA Campaign conducted at the ARM SGP site from May 21 to July 27, 2009. The cloud decision analysis is fundamentally different between the IR and visible spectrum. The TSI essentially measures optical thickness of a cloud and the ASIVA IR channel measures cloud emission. A primary goal of this research has been to investigate the correlation between FSC data products derived via these two different techniques. Correlations between these two datasets will be discussed in this poster paper as well as additional analysis techniques being developed to improve this correlation.