Evaluating the precision of a transverse excitation atmospheric based CO2 Doppler lidar system with in situ sensors

A ground based, mobile, scanning Doppler lidar system used for atmospheric boundary layer research is described. The system is designed to operate safely in urban areas and has an eye safe wavelength of 10.6 µm, a range capability of up to 9 km (dependent on atmospheric conditions) and a range resolution of 112 m. Results are presented from an intercomparison campaign that was undertaken in September 2002 to compare several UFAM (UK Universities Facilities for Atmospheric Measurements) instruments with traditional in situ balloon borne instrumentation. A comparison between lidar and balloon derived horizontal wind profiles is given along with an estimation of the magnitude of the random error in the lidar Doppler velocity estimates. Measurements were made over heterogeneous terrain up to a height of 1 km, with a maximum velocity difference of 0.53 m s-1 between the derived wind profiles over a height range of 400 m. The magnitude of the random error in the velocity estimates was found to be 0.41 m s-1 for a signal to noise greater than -6 dB. Keywords: Doppler lidar, atmospheric boundary layer