Evaluation of Visibility Sensors at the Eglin Air Force Base Climatic Chamber

摘要

Three transmissometers and five forward-scatter meters were evaluated for measuring fog, haze, rain, and snow in the large test chamber of the Eglin Air Force Base Climatic Laboratory. Methods were developed for generating moderately uniform and stable fog and haze conditions. Fog densities equivalent to Runway Visual Range (RVR) values of 100 to 600 feet were achieved; such fog densities are rare in nature and were the primary reason for undertaking the chamber tests. No unusual characteristics of the chamber fogs were noted. Laser transmissometers with 40- and 250 foot baselines served as standard sensors for the tests. Because of inhomogeneities in the chamber, only the 40-foot baseline gave good correlations with most of the test sensors. Consequently, one of the forward-scatter meters, the EG&G 207, was used as a secondary standard for high visibility (RVR above 1000 feet) conditions. With appropriate corrections, all the test sensors met the 15 percent root-mean-square error pass-fail criterion for measuring dense fog. (Author)