Effects of atmospheric path on airbornemultispectral sensors

Abstract

Experimental data were acquired for a study of the effects of variable atmospheric path on the spectral signals obtained by remote sensors in the optical region of the spectrum. Multichannel optical-mechanical scanners which provide calibrated apparent spectral radiance data were flown over agricultural test sites, and passes were made at several different altitudes between 2000 and 10,000 ft. The quantitative results compare favorably with qualitative theoretical predictions. Optical-mechanical scanners and aerial photographic systems are compared to show the relative importance of potentially detrimental atmospheric path effects with regard to the operation of these systems in remote sensing. then the positive term ~Lv/ah (2) could well dominate, so that the apparent target radiance Lff would increase with altitude. Conversely, if the actual target radiance were quite large, then the negative term a~-n/ah could well dominate, thus producing a decrease in apparent radiance with altitude. The radiance difference between two targets, a and b, of actual radiance L, and L ~, respectively, is given by zlL" .

The utility of radar and other remote sensors in thematic land use mapping from spacecraft

“…It varies with the weather, the time of day, the altitude, and with the nature of the suspended particles, but it is accepted that haze is present in the atmosphere to some extent all over the world. " Horvath, Braithwaite and Polcyn (1969) in a useful discussion of the effect of sensor altitude on the apparent radiance of an object (which fills the sensor's instantaneous field of view) note that the actual radiance is modulated by both (1) atmospheric attenuation through absorption or scattering of the radiation reflected or emitted from the object, and 2atmospheric scattering and emission of unwanted radiation into the field of view. The latter effect is the most significant in the 400-900 n.m. region in increasing the total scene radiance and reducing target radiance contrast.…”