Cloud Base from Surface-Based Infrared Brightness Temperature and Ceilometers

Near-nadir measurements of downwelling infrared brightness temperature have been collected from a mobile platform during a wide variety of low cloud cases. The potential to relate brightness temperature to cloud base height is considered with use of adiabatic and environmental lapse rates, while considering limitations associated with atmospheric absorption. Cloud base reports from nearby ASOS stations and from a collocated mobile Vaisala CL31 ceilometer are used as reference. Potential applications could include time-space mapping of cloud cover extent, small-scale cloud structural variations, and cloud base height changes in association with air mass changes.