Measurements of Visibility and Radar Reflectivity During Snowstorms in the AFGL Mesonet

H. Stuart Muench · H. Albert Brown

Jan 1977 · Air Force Geophysics Laboratory, Air Force Systems Command, United States Air Force

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Field experiments were conducted with the AFGL Mesonet and FPS-77 digital radar during snowstorms for evaluation of the use of radar to observe and predict snow. Simultaneous measurements of optical extinction coefficient, radar reflectivity, and snow depth were made, together with determinations of visual range. The measurements verify both the calibration of the visibility instruments and the relationship between visual range and extinction coefficient. A relationship found between extinction coefficient and snowfall rate compares well with relationships found by other investigators. Radar reflectivity is found to be related to extinction coefficient, with the correlation being improved by time averaging and by allowance for velocity of snowflakes from the radar beam to the ground. However, the specification errors are of the order of + or - 42 percent to + or - 65 percent, and with the small spatial and temporal variability of extinction coefficient in snow, the radar is of marginal use where observations are available from the airways network. (Author).