<title>Intercomparison of optical turbulence observations in a mountain-valley system</title>

Abstract

The Airborne Laser Concepts Testbed (ABL ACT) is located on White Sands Missile Range (WSMR), NM and is used to explore and develop new methods for tracking, pointing, and compensation of laser beams. All of these efforts require a knowledge ofthe optical turbulence along the propagation path. The site utilizes a 52.6 km propagation path over a desert basin between two mountain peaks (North Oscuro Peak (NOP) and Salinas Peak (SP)). Characterization of the optical turbulence at ABL ACT is challenging due to the long path length in the atmospheric boundary layer and the complex terrain of the site. A suite of instrumentation is being used to approach the problem; a sodar, fme wire probes, a pupil plane imager, a differential image motion monitor (DIMM), and a scintillometer. In addition, a weather station senses ambient temperature, humidity, pressure, wind speed and direction, and solar radiation-received both horizontally and parallel to the mountain west-facing slope at NOP. Salient features of each instrument as well as the parameters sensed, including pathweighted effects, are discussed. Comparisons of results obtained from different sensors are shown and discussed such as derived from the scintillometer, and pupil plane imager. Special emphasis is given to the optical turbulence conditions at the mountain ridge at NOP which were quantified from observations of fme wire sensors and a sodar (sonic detection and ranging). The results are explained in terms ofthe geometry ofthe site and the mountain-valley wind regime.

Preliminary VHF radar and high-data-rate optical turbulence profile observations using a balloon-ring platform

“…15 Other Air Force Research Laboratory turbulence measurement programs included aircraft and scintillometer observations, 16 combined aircraft and radar observations, 17 turbulence measurements using a kite and tethered blimp platform, 18 and measurements in complex terrain using an ensemble of sensors (scintillometer, differential image motion monitor, sodar, and tower-mounted fine wire sensors). 19 Similar fine wire probe systems were used on the aircraft, kite/tethered blimp experiments, and on the tower. This design was modified for the fine wire systems as described in this paper for use on the balloon-ring platform.…”