PARABOLA
Portable Apparatus for Rapid Acquisition of Bidirectional Observation of the Land and Atmosphere

The Portable Apparatus for Rapid Acquisition of Bidirectional Observations of the Land and Atmosphere (PARABOLA) is a passive ground-based sphere scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) coincide with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation purposes. The last four channels are used for the characterization of water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and measurements of photosynthetically active radiation (400-700 nm). The measurements from PARABOLA can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both sky and ground hemispheres takes approximately 3 minutes.