A Case Study of Atmospheric Conditions at 4-19 km over Vandenberg Air Force Base during Passage of a Cyclone

Abstract Continuous observations from a 50-MHz radar of the vertical profiles of winds, refractivity turbulence structure constant (C2n ), turbulent kinetic energy density (σ2t ) up to two orders of magnitude), and hourly standard deviation of the vertical velocity (σw ) are combined with routine rawinsonde ascents and weather observations to study changes in turbulence intensity over Vandenberg Air Force Base, California, during 21–27 July 2001. Early and late in this period the flow aloft was relatively steady and turbulence intensities in the upper troposphere were very low. For about 36 h around 25 July, the flow at midlevels (about 600–150 hPa) was disturbed by the passage of a cutoff cyclonic circulation center. During the low's passage, C2n and σ2t intensities were enhanced by up to about 15 dB. The enhancements of C2n and σ2t are highly correlated with each other, as well as with the vertical shear of the horizontal wind and synoptic-scale relative vorticity. The increased turbulence intensities a...