The system described here was designed to use two commercially available scanning spectroradiometers, a desk top calculator, and software to obtain simultaneous readings of incident and reflected radiation. To use such laboratory instruments in a hostile environ-ment, it was necessary to develop support apparatus. A weatherized, portable module to house the data storage and readout apparatus; heated casings for spectroradiometers; power systems; and an over-ice instrument support boom are included. Problems with poor cosine response of the instruments were largely overcome. A process for using integrating spheres under both clear and overcast conditions is being developed. The system was specifically designed to measure the spectral reflectance of snow and ice in the Great Lakes. Similar systems can be used for any field or laboratory application where incident flux might change during the spectroradiometer scan. Data collected showed large differences in the spectral reflectances of certain types of freshwater ice. However, for some ice types under certain atmospheric conditions, such as brash ice under clear or partly cloudy skies, it is difficult to determine a unique spectral signature since spectral reflectances are not only diurnally dependent but also site specific.