OPTIMAL SPATIAL SAMPLING TECHNIQUES FOR GROUND TRUTH DATA IN MICROWAVE REMOTE SENSING OF SOIL MOISTURE

摘要: Abstract Microwave remote sensing of soil moisture is currently being explored by a series both active and passive experiments with the sensor output then related to laboratory measurements made on field-collected samples taken at time microwave data acquisition. In addition diurnal variation, varies widely surface location depth; furthermore, cost sample extraction increases markedly depth. Therefore it desirable identify sampling techniques which give acceptable statistical validity while minimizing effort involved in extraction. Data from an extensive collection program carried out April, 1976 near Perry-Topeka, Kansas were used as input five tests based simple random stratified sampling. relation between desired size depth, applied various field cell sizes corresponding resolution sensor; cells ranging 2.5 40 acres considered, depths 45 cm included. If total number during ground truth mission can be prespecified, optimal allocation preferred; otherwise, should used. As example, top 0–1 layer 20-acre field, 35 would required using whereas only 19 This reduction consequence higher, weighting assigned layers exhibit greatest variability spatial position.