AN INVESTIGATION INTO THE USE OF TEMPERATURE GRADIENTS AS AN IN-FLIGHT WARNING OF IMPENDING CLEAR-AIR TURBULENCE.
AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS
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This paper discusses a study that was undertaken to investigate the technique of using in-flight temperature gradients to forecast impending clear-air turbulence CAT and some recent studies concerning the relationship between jet stream winds and turbulence. Results of the study indicate that a horizontal temperature gradient observed in flight by direct sensing methods is not a conclusive indicator of impending turbulence. However, an improved inflight indicator of CAT is needed. If winds obtained from rawinsondes were to be computed at 2000-ft intervals or less at the time of the original reduction of data by operational units, the maximum values of av. wind speed change of wind directionchange of height could easily be computed, coded, and transmitted as part of the standard upper-air code transmission in the same way as other special parameters. If the value of av. wind speed change of wind direction change of height over 2000-ft layers could be computed as described by Kronebach J. Appl. Meteorology 3119-125 1964 and included in the parameters analyzed by the National Meteorological Center, Suitland, Maryland, the writers feel that a substantial improvement could be made to CAT forecasts using rawinsonde data.