University of Notre Dame Triple Lidar System

Sponsor:  Office of Naval Research DURIP (Grant Number: N00014-15-1-2852)

Under a DURIP grant, this project developed a novel remote sensor for probing the lower atmosphere, with unique applications to nominally inaccessible locations such as the coastal marine boundary layer, highly complex terrain, wind turbine wakes and helicopter downwash. The Triple-Lidar assemblage developed is a commercial outgrowth of antecedent foundational research by the PI and his collaborators in the USA as well as the simultaneous, independent technology development efforts of European scientists. The system is based on cutting-edge wind Doppler Lidar technology, wherein each Lidar of the triumvirate measures the line-of-sight component of the wind. Controllable integrated steering of Lidar beams as well as their focus position by a master computer allow measurements within a hemispherical cone in a three-dimensional continuum of points, with a full top angle of ~ 180o and probe volumes from ~ 60 m out to (6-9 km), depending on the range resolution and angles of sight. Three line-of-site velocities so measured enable retrieval of the full wind velocity vector, without making any assumptions on the flow as required in single or dual- Lidar deployments. The instrument is able to produce detailed, full-scale, time-varying, three-dimensional maps of wind velocities, turbulence levels and Reynolds stresses, covering horizontal areas of tens of square kilometers, heights up to ~ 1km and a myriad of measurement surfaces including ‘mobile’ virtual towers. Measurement uncertainties are lower than those achieved by down-scaled wind tunnel testing or computer modeling. The system is the first ever commercial Triple-Lidar acquisition in the US. The system is portable, and can be conveniently transported to domestic and foreign field sites. Its first field deployment was in the Perdigão field experiment in Northeastern Portugal during May 01, 2017 to June 15, 2017 (https://perdigao.nd.edu/). Its second deployment was at the CASPER West field study at Point Mugu coastal site during September 27 to October 26, 2017 (http://met.nps.edu/~qwang/casper/home/home.php).

The system was constructed by Halo Photonics Limited (Company No. 05485368), Unit 2, Bank Farm, Brockamin, Leigh, Worcestershire WR6 5LA, UK. Significant technical modifications were made after the receipt in collaboration with the manufacturer.