Potential of Airborne Lidar Observations of Water Vapour Transport

Kurzfassung

The combination of a water vapour and a wind lidar on an aircraft enables the study of a variety of atmospheric transport processes associated with reduced predictability over remote and data sparse areas such as oceans. The instrument combination was successfully deployed on board the DLR Falcon research aircraft in the field experiments COPS 2007 (Central Europe), and THORPEX-IPY (Norway) and T-PARC (Japan) in 2008, focusing on boundary layer processes, polar lows, and observations in the vicinity of tropical cyclones and calculated sensitive regions. The lidars can portray the two-dimensional water vapour and wind variability, as well as the horizontal and vertical moisture transport with high accuracy and spatial resolution along the flight path in cloud-free areas. The wind lidar is operated either in conical-scanning mode with 20° off-nadir angle for 3-d wind field profiles, or in nadir-viewing mode for profiles of vertical wind speed. Eddy correlation of the latter with the water vapour lidar data provides profiles of the latent heat flux with high vertical resolution above land or water. Spectral analyses of long-range lidar cross-sections give insight into dominant transport and mixing processes from turbulent to meso-scales. HALO will offer more opportunities to reach data-sparse regions critical to high-impact weather over Europe, such as the North Atlantic Ocean.