A Numerical Analysis of Some Practical Aspects of Airborne Urea Seeding for Warm Fog Dispersal at Airports

Abstract

A two-dimensional Eulerian model of warm fog dispersal by airborne hygroscope particle seeding is used to evaluate some practical aspects of urea seeding at airports. It is found that although turbulence and wind shear reduce the effectiveness of single-line seeding to a point where it is of no practical value, seeding over a wide area (1?10 mi2) can result in practically useful visibility improvements in the approach zone and over the runway of airports. The quantity of material and the cost of the wide-area seeding technique depend upon fog intensity, fog type, and cross-runway wind speed. For typical fog, approximately 80,000 lb hr?1 of urea costing $40,000 per hour are needed to keep the visibility above ½ mi. The figures are reduced to approximately 36,000?58,000 lb and $18,000?29,000 per hour, respectively, if the visibility needs only to be raised to ¼ mi.