Measurement of reflectance factors under daily and intermittent irradiance variations.

A technique for measuring reflectance factors in diurnal and intermittent cloud insolation conditions using hand-held radiometers has been developed. Simultaneously collected reference panel and total insolation measurements were obtained during the South Texas summer growing season (April and May 1980) at Weslaco, Tex., using the GSFC MARK2 three-band hand-held radiometer. The estimated reflectance factors of four reference panels using the hand-held radiometer agreed closely with the expected reflectance as measured with a laboratory spectrophotometer over a wide range of insolation readings (from 20 to 91 mW/cm(2)). These results indicate that this technique could prove useful for achieving uniform reflectance factor measurements for remote sensing studies.