Multi-sensor Calibration and Validation of the NASA-ALVICE and UWO-PCL NDACC Water Vapour Lidars

The Purple Crow Lidar (PCL) has recently participated in a water vapour validation campaign with the NASA/GSFC Atmospheric Laboratory for Validation Inter-agency Collaboration and Education (ALVICE) Lidar. The purpose of this calibration exercise is to ensure that water vapour measurements, submitted to the Network for the Detection of Atmospheric Composition Change (NDACC) data base, are of sufficient quality for use in detecting long term changes in water vapour mixing ratio, particularly in the upper troposphere and lower stratosphere (UTLS). The field campaign took place at the University of Western Ontario Environmental Research Field Station, near London, Ontario, Canada, from May 23rd to June 10th 2012 and resulted in 57 hours of measurements taken over 12 clear nights. On each night a minimum of one RS92 radiosonde was launched. In addition, 3 cryogenic frost-point hygrometer (CFH) sondes were launched on clear nights over the course of the campaign. Measurements were obtained from near the surface up to ~20 km by both lidar systems, the radiosondes, and the CFH balloons. These measurements will be used to calibrate profiles of water vapour mixing ratio by the newly relocated PCL. Initial comparisons between the sondes and lidars will be presented as well as derived corrections for the retrieval of water vapour mixing ratio in both the troposphere and lower stratosphere.