All-sky infrared cloud clutter

The all-sky infrared mapper Scorpio has been developed at TNO-FEL. This system operates in the 3 - 5 micrometers and 8 - 13 micrometers wavelength bands, and creates calibrated all-sky images in 80 seconds with a resolution of 0.8 mrad. This cloud mapper is used to obtain infrared images of the sky (mainly at 10 micrometers ) in an on-going study for statistical properties of the sky and cloud infrared radiation, i.e., infrared clutter and cloudiness. Scorpio is also useful for more general cloud and sky background studies. In this paper all-sky images are presented together with all-sky clutter maps. A method is developed to obtain these clutter maps and to derive clutter information from these clutter maps. An analysis of clutter variations with cloud height and with elevation is presented. Preliminary results show a dependence between clutter and cloud height and elevation.