AIRBORNE SOIL MOISTURE MEASUREMENT USING NATURAL TERRESTRIAL GAMMA RADIATION

Abstract

Measurements of the natural terrestrial gamma radiation flux near the soil surface are used to infer areal soil moisture. Airborne gamma radiation data are collected over a network of 240 flight lines (each approximately 6 square kilometers) in the upper Midwest and used to calculate real-time, areal soil moisture values. Ground-based soil moisture data collected along calibration flight lines indicate that airborne soil moisture values can be calculated with an RMS error of 3.2 percent soil moisture, which is 40 percent less than the mean standard deviation of the ground-based soil samples. The airborne soil moisture values calculated using data from three primary background surveys tend to be 1.5 percent less than the ground-sampled soil moisture values. Measurements of the natural terrestrial gamma radiation flux near the soil surface are used to infer areal soil moisture. Airborne gamma radiation data are collected over a network of 240 flight lines (each approximately 6 square kilometers) in the upper Midwest and used to calculate real-time, areal soil moisture values. Ground-based soil moisture data collected along calibration flight lines indicate that airborne soil moisture values can be calculated with an RMS error of 3.2 percent soil moisture, which is 40 percent less than the mean standard deviation of the ground-based soil samples. The airborne soil moisture values calculated using data from three primary background surveys tend to be 1.5 percent less than the ground-sampled soil moisture values. © Williams & Wilkins 1981. All Rights Reserved.