EMPIRICAL ESTIMATES OF ERRORS IN DOUBLE-THEODOLITE WIND MEASUREMENTS
ARMY ELECTRONICS COMMAND WHITE SANDS MISSILE RANGE NM ATMOSPHERIC SCIENCES LAB
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The paper presents the results of an empirical study conducted at White Sands Missile Range, New Mexico, to estimate the errors in winds obtained by the manual double-theodolite wind system. A series of pilot balloon flights was conducted as a part of the tests. Each balloon was tracked simultaneously by the double-theodolite system and the very precise Contraves cinetheodolite system. The cinetheodolite system was used as a standard for evaluation of the double-theodolite system. Differences between the two systems were considered to be errors in the double-theodolite system. An observation interval of 20 seconds was used for the manual double-theodolite system the observation interval for the cinetheodolite system was 1 second. Each balloon was tracked for 520 seconds. The double-theodolite data were reduced for observation intervals of 20, 40, 60, 80, 100, and 120 seconds. The reduced data, wind speed and direction, were compared with the cinetheodolite data for corresponding time periods. Similar evaluations were made by comparing the mean winds, measured independently by the two systems, through specified altitude layers. Layer thicknesses of 100, 200, 300, 400, and 500 feet were considered. The paper presents a discussion of the tests, the data reduction procedures, and results obtained. The decrease in errors for increased observation interval and increased layer thickness is discussed. The variation of measurement error with altitude is also presented.