PNNL

Abstract

The Atmospheric Radiation Measurement program Raman Lidar was upgraded in 2004 with a new data system that provides simultaneous measurements of both the photomultiplier analog output voltage and photon counts. This paper describes recent improvements to the algorithm used to merge these two signals into a single signal with improved dynamic range. The impact of modifications to the algorithm are evaluated by comparing profiles of water vapor mixing ratio from the lidar with sonde measurements. The modifications that were implemented resulted in a reduction of the mean bias in the daytime mixing ratio from a 4% dry bias to well within 1%.