Cloud statistics measured with a ground-based Infrared Cloud Imager

The Infrared Cloud Imager (ICI) is a ground-based instrument for measuring spatial cloud statistics. ICI uses an uncooled microbolometer detector array to record downwelling infrared atmospheric emission in the 8-14 mum spectral band with 320times240 pixels. The ICI system has been deployed at Poker Flat Research Range near Fairbanks, Alaska, at Barrow, Alaska, and in central Oklahoma. With a water vapor emission correction, the ICI system can detect clouds, classify them as to their general type (clear, haze, low clouds, mid clouds, and high clouds) and produce a continuous and consistent day-night record of spatial cloud statistics. The ICI data show that single-pixel sensors, which rely on temporal statistics to determine spatial cloud statistics, tend to slightly underestimate cloudiness