WindTracer® Evolution and Recent Measurement Results

Abstract

In this paper we describe the evolution of Lockheed Martin Coherent Technologies' (LMCT) 25 year WindTracer ® technology. We also present experimental results from recent ground-based measurement campaigns that demonstrate measurement accuracy in both single-and dual-Doppler configurations with a primary emphasis on wind energy applications. Results and lessons learned from a recent airborne measurement campaign for airborne wind profiling applications are also included. WindTracer ® EvolutionLMCT's WindTracer ® technology has been evolving over the past 30 years. The earliest system [1] was a research grade Doppler wind lidar employing a 10 Hz, 10 mJ, flash-lamp pumped non-eye-safe 1.06 micron wavelength Nd:YAG laser and a 20 cm aperture. This sensor first demonstrated boundary layer measurements to ranges greater than 5 km in 1988. In the early 1990's amplifiers were added in a series of steps and by 1991 the energy was increased to 1 J. This lidar system demonstrated greater than 26 km vertical wind profiles at Kennedy Space center in conjunction with a shuttle launch in the early 1991 [2].In the late 1980s, Coherent Technologies also began developing eyesafe technologies. By 1990 an eye-safe, 26 mJ, 5.7 Hz, 2.091 um, Tm,Ho:YAG lidar was developed [3]. The laser technology quickly advanced throughout the 1990s; with flashlamp pumped laser pulse energies up to 100 mJ being demonstrated, meanwhile diode pumped 10 mJ 100 Hz systems were also developed.All the earliest systems had large optical footprints and required an experienced operator, but by mid-1990 turnkey diode-pumped systems were developed for airborne operation [4,5]. By1999 very compact, diode-pumped, transceiver products called the MAG 1 and MAG-1A were developed. These 2um, 2 mJ, 500 Hz systems employed 10 cm apertures [6]. Portable 9'x8'x8' lidar shelters with full hemispherical scanners were also developed. These shelters had sufficient room inside for several operators, even though the systems could also be operated remotely or autonomously. Much of the early history through 2004 is described in greater detail in reference 5.In 2007, the wind lidar system was redesigned to take advantage of low cost telecom components, e.g., a DFB diode master oscillator. This system employs a 1.6 um Er:YAG power oscillator, producing 2.3 mJ pulses at 750 Hz with a 12.5 cm aperture. Of the diode pumped systems, this most recent WindTracer® transceiver (WTX) has demonstrated the longest measurement range (> 33 km), due to the shorter wavelength and larger aperture. In 2013, a 6'x5'x6' shelter was developed for applications requiring more compact footprints. Recently, under the AFRL Precision Air Drop program, the container is being redesigned to an even smaller footprint (4'x3.5'x3') with a predicted total weight below 700 lbs. Both compact systems employ the standard WTX sensor. WindTracer ® Validation ExperimentsRecently, LMCT has conducted two research programs demonstrating WindTracer ® measurement accuracy in both single-and dual-Doppler wind vector retrieva...

Doppler Wind Lidar From UV to NIR: A Review With Case Study Examples

“…The NOAA conducted a high-resolution wind field detection with the highest spatial resolution of 30 m based on shipboard (Wulfmeyer et al, 2000) and land-based system (Newsom and Banta, 2003) using the C-DWL of a similar design. With the promotion of 2-µm laser and data-processing techniques, Lockheed Martin Coherent Technologies, Inc. has commercialized the WindTracecr series C-DWL system (Gatt et al, 2015).…”