Shemya Tropospheric Refraction Errors,
ROME AIR DEVELOPMENT CENTER GRIFFISS AFB N Y
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An attempt was made to characterize the Shemya, Alaska, troposphere to determine the tropospheric refraction errors in range and angle. Subsequently, various correction methods for these errors were investigated for a radar based at Shemya, Alaska, and operating at low elevation angles of 0 deg to 2.5 deg. The troposphere was characterized in terms of refractivity N profiles which were derived from airborne refractometer measurements made over a two-week period in June 1973. A cessna 310 mounted refractometer of the Vetter-Thompson type was used. The range and angle shifts and their standard deviations that the Shemya radar would experience due to this troposphere were determined by computer ray tracing through a spherically stratified troposphere. The average shifts varied from about 330 feet to 150 feet in range and from about 8 mr to 4 mr angle as the elevation angle increased from 0 deg to 2.5 deg and out to a 300 NM range. The corresponding standard deviations varied from about 10 feet to 7 feet in range and from about 1 mr to .2 mr in angle. Three correction methods are considered. The best correction method was found to be that based on the linear model.
- Atmospheric Physics
- Active and Passive Radar Detection and Equipment