Performance evaluation of the new ARM Doppler lidars
Author
Rob K Newsom — Pacific Northwest National Laboratory
Category
Instruments
Description
Comparisons between vertical velocity and signal intensity from the TWP DL (top) and the SGP DL (bottom) during a period of thunderstorm activity on 19 October 2010. These data were acquired while the systems were operated side-by-side as part of acceptance testing at the SGP site.
In 2010 the U.S. Department of Energy’s Atmospheric Radiation Measurement Climate Research Facility acquired three new coherent Doppler lidars. These instruments are now being used to fill a long-standing measurement gap within the ARM Facility by providing long-term measurements of clear-air vertical velocities in the lower troposphere.
Prior to operational deployment, all three Doppler lidars underwent acceptance testing at ARM’s Southern Great Plains (SGP) site in October 2010. During the tests, the systems were run in side-by-side comparisons over a period of several days, and the data were analyzed to evaluate radial velocity differences, as well as measurement precision and bias. The results showed that the lidars produced consistent measurements. Correlation coefficients between radial velocity time series at fixed heights exceeded 0.9 within the atmospheric boundary layer under convective conditions. The measurement precision, which was estimated using two different techniques, was found to be less than 10 cm/s at high signal-to-noise-ratio (SNR) and consistently less than 20 cm/s within the atmospheric boundary layer (below ~2km). At high SNR, the mean velocity differences were quite small (<10 mm/sec), but all three systems showed a tendency for positive bias at low SNR. This poster summarizes the results of the side-by-side intercomparison study.
