A novel automatic calibration system for water vapor Raman LIDAR

RALMO is operated at MeteoSwiss and provides continuous measurements of water vapor since 2008. Water vapor needs calibration to be used for climatological and meteorological studies. Primarily, RALMO is calibrated against a reference radiosonde. A secondary new calibration system based on an internal LED has been installed to perform automatic relative calibrations correcting for instrumental drifts. This study characterizes the secondary calibration system and validates it against the primary.