Abstract
This study presents comparisons between vertical water vapor profile measurements from a Raman lidar and a new pre-production broadband differential absorption lidar (DIAL). Vaisala’s novel DIAL system operates autonomously outdoors and measures the vertical profile of water vapor within the boundary layer 24 h a day during all weather conditions. Eight nights of measurements in June and July 2018 were used for the Toronto water vapor lidar inter-comparison field campaign. Both lidars provided reliable atmospheric backscatter and water vapor profile measurements. Comparisons were performed during night-time observations only, when the York Raman lidar could measure the water vapor profile. The purpose was to validate the water vapor profile measurements retrieved by the new DIAL system. The results indicate good agreement between the two lidars, with a mean difference (DIAL–Raman) of 0.17 ± 0.14 g/kg. There were two main causes for differences in their measurements: horizontal displacement between the two lidar sites (3.2 km) and vertical gradients in the water vapor profile. A case study analyzed during the campaign demonstrates the ability for both lidars to measure sudden changes and large gradients in the water vapor’s vertical structure due to a passing frontal system. These results provide an initial validation of the DIAL’s measurements and its ability to be implemented as part of an operational program.
Highlights
Vertical profile measurements of water vapor are an essential meteorological observation, with respect to numerical weather prediction (NWP) and global climate modeling [1,2,3]
differential absorption lidar (DIAL) systems utilize the difference between laser wavelengths centered on and off a water vapor absorption line to measure the water vapor mixing ratio (WVMR) [6]
The night of July 10/11 provided a comparison between the Vaisala DIAL and York Raman lidars when the atmospheric conditions were not changing rapidly
Summary
Vertical profile measurements of water vapor are an essential meteorological observation, with respect to numerical weather prediction (NWP) and global climate modeling [1,2,3]. Compared to radiosondes and passive remote sensing instruments (e.g., microwave radiometers) for profiling atmospheric water vapor, lidar-based technologies have the advantage of providing higher temporal and vertical resolution observations continuously.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have