An Analysis of Natural Variations in European Sky and Terrain Radiance Measurements
Abstract
A data set, first described in AFGL-TR-81-0275, Johnson (1981), which contains nearly 500 arrays representing measurements of sky and terrain radiance values, is reviewed and further illustrated with respect to naturally occurring radiance variations. The measurements were made using radiometer systems mounted on a C-130 aircraft during a series of European flights associated with the NATO Program OPAQUE, Fenn (1978) and Johnson et al. (1979). Radiance measurements throughout the 4 pi field surrounding the aircraft during seventeen separate flight episodes are presented and discussed with respect to their variability as a function of altitude, look angle, cloud cover and spectral band. The measurements were made in spectral bands having mean wavelengths of 478, 577, 664 and 765 nm, and under meteorological conditions ranging from fully overcast to clear and cloudfree. With appropriate caveats, examples of typical overcast, broken cloud and clear day radiance distributions are illustrated. Whereas these data illustrate substantial variations in the radiance distribution from day to day, there are determinable patterns that may provide boundary conditions for a very generalized attempt of classification. Thus, as were the data displayed in the earlier companion report, Johnson (1981), these data are appropriate for use in the development of operationally useful predictive models as illustrated in Hering (1981).
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1981
- Accession Number
- ADA120487
Entities
People
- Richard W. Johnson
- Wayne S. Hering
Organizations
- Air Force Research Laboratory