Edmund A. Murphy

In Situ Measurement of Waves and Turbulence in the T-REX Campaign

The Air Force Research Laboratory participated in the NSF Terrain Rotor Experiment (TREX) from 20 March through 6 April 2006, which included 3 intensive observation periods (IOPs) of the 15 IOPs of the two month T-REX campaign. AFRL focused on the higher altitude turbulence associated with mountain waves. The AFRL flew thermosondes to measure optical turbulence up to 30km. They include a radiosonde to measure meteorological data. Standard radiosondes were also launched to sense atmospheric data including atmospheric wave signatures. These instruments were launched from the windward side of the Sierra Nevada Mountains in order to try to examine the atmosphere at high altitudes. Fifteen thermosondes launches and 10 radiosonde launches were successful. Many of the launches showed evidence of mountain waves, some accompanied by high levels of optical turbulence

Comparison of Isoplanatic Angles Derived from Thermosonde and Optical Measurements

A comparison of isoplanatic angles derived from balloon- borne in-situ measurements of the index of refraction structure constant profiles and remote optical measurements of stellar intensity fluctuations using an isoplanometer is shown. Concurrent data taken over a six day period in the spring of 1986 show reasonably good agreement between the methods considering normal atmospheric variability. Possible reasons for differences between individual measurements are discussed.

Heterodyne CO2 DIAL and its measurements

The Geophysics Directorate of Phillips Laboratory has recently completed redesign of a heterodyne CO2 differential absorption lidar which can simultaneously measure range resolved radial velocity, aerosol backscatter, and differential absorption. The transportable system utilizes two CO2 transversely excited atmospheric (TEA) lasers which can be discretely tuned to many of the rotational lines compromising the 00 degree 1 to 10 degrees 0 vibrational bands of CO2. These lines span a spectral region from about 9.2 to 10.8 micrometers and allow for the DIAL measurement of some minor atmospheric molecular constituents as well as many anthropogenic organic species which have absorption bands in this spectral region. Transmission and reception is coaxial via a single shared 12 inch telescope and hemispherical scanner. Complete spectral processing of the heterodyne signals provides not only backscatter and differential absorption information but also radial wind velocity. Each TEA laser produces a line dependent pulse energy of 20-80 mJ at up to 150 Hz. Presently, the system is processor limited to a net pulse rate of 140 Hz. Results shown will include time-height cross-sections of cirrus backscatter, comparisons of CO2 DIAL-derived water vapor profiles with simultaneous surface and radiosonde in-situ measurements, and wind velocity profiles in the troposphere.