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, spherical-scanning radiometer. It measures surface reflectance across eight spectral channels. The first four channels (444, 551, 650, and 860 nm) align with spectral bands from the Multi-angle Imaging SpectroRadiometer (MISR) on the Terra satellite for validation. The remaining four channels characterize water vapor (944 nm), aerosol optical depth at longer wavelengths (1028 and 1650 nm), and photosynthetically active radiation (400-700 nm). PARABOLA measurements can be used to derive the surface bidirectional reflectance factor and sky and surface radiances. A complete scan of both the sky and ground hemispheres takes approximately 3 minutes.