Evaluation of Snow Water Equivalent by Airborne Measurement of Passive Terrestrial Gamma Radiation

Abstract

Recent research studies have investigated an airborne gamma radiation detection system to determine the water equivalent of snowpacks in nonmountainous areas. Snow attenuates natural gamma emissions from the soil, and the magnitude of attenuation is related to the mass of the water blanket between the soil and the detector. Gamma spectral and total counting rates are collected and recorded by an airborne system using 14 4‐ by 4‐inch sodium iodide (NaI (Tl)) crystals. These data are corrected for soil moisture, background radiation, and effects of air density. Extensive snow depth and density measurements were taken to determine ‘ground truth’ water equivalent under the flight path. Results of the first year of research indicate that gamma spectral data may be expected to give areal measurement of snow water equivalent within at least 0.2–0.5 inch over favorable terrain. The use of total count data is even more promising but requires methodology still under development for eliminating background interference.

Construction and exploration of pollutant consumption oxygen equivalent treatment costs in municipal wastewater treatment plants

“…CO 2 equivalent was used as Ruden researched on Diels-Alder reaction in 1975 [10]. In addition, there are many other equivalent indicators such as dose equivalent [11], snow water equivalent [12], TNT equivalent [13], and so on. In the field of sewage treatment, the literature of equivalent research is very little.…”

Remote sensing of snow depth and snow water equivalent

“…In this case, the natural terrestrial gamma radiation emitted from the potassium, uranium, and thorium radioisotopes in the upper layer of soil is sensed from a an aircraft flying ≈150 m above the ground (Carroll and Carroll, 1989;Peck et al, 1971). Water mass in the snow cover attenuates, or blocks, the terrestrial radiation signal.…”

Remote sensing of snow and ice / La télédétection de neige et de glace

“…The attenuation is proportional to the snow mass. Thus the mass or water equivalent of the snow cover can be measured and averaged over the length of a flight line (Kogan et ai, 1965;Peck et al, 1971;Grasty era/., 1974). However, problems still exist with the operational use of this important tool: continuous monitoring requires continuous low-altitude flying and thus this method is limited to measurement of snow over the relatively flat terrain.…”