Refractive-index structure parameter in the planetary boundary layer: comparison of measurements taken with a 10.6-microm coherent lidar, a 0.9-microm scintillometer, and in situ sensors.

An optical technique is described that determines the path-averaged value of a refractive-index structure parameter at 10.6 microm by use of a pulsed coherent CO(2) lidar in direct detection and hard-target returns. The lidar measurements are compared with measurements taken by a 0.9-microm scintillometer and temperature probe (with humidity corrections). The experimental results show good agreement for C(n)(2) >or= (-14) m(-2/3). With respect to practical applications the new technique permits C(n)(2) lidar measurements in a neutral meteorological situation to an unstably stratified convective boundary layer over long ranges (1 km or more).