P4.21 Pulsed Doppler Lidar for Terminal Area Monitoring of Wind and Wake Hazards

Pulsed Doppler lidar is the infrared equivalent of pulsed Doppler radar. Instead of raindrops, however, lidars reflect off naturally-occurring dust particles (aerosols). The aerosols have negligible fall velocities and so trace the wind field nearly perfectly. Up until the mid-1990’s, Doppler lidars were limited to research implementations and short-duration, human-in-the-loop deployment for a variety of atmospheric research applications. At that time, significant engineering resources were brought to bear and the first commercially available, autonomous systems were developed and fielded by the end of the decade. The WindTracer pulsed Doppler lidar represents this tremendous leap ahead in terms of reliable, unattended, continuous operations. These advances have enabled successful long-term installations at two airports over the past three years for the purposes of windshear and turbulence alerting as well as wake vortex monitoring. Figure 1 shows a typical configuration for groundbased wind sensing. The equipment shelter (see Figure 1) contains the Doppler lidar equipment and is the location from which the actual remote sensing takes place. The environmental equipment shelter includes the scanner, the transceiver and the signal processor. Inside the shelter, the transceiver is mounted vertically and kinematically attaches to the rooftop scanner. Laser radiation emanates from the transceiver and is directed into the atmosphere by the computer-controlled scanner. The backscattered laser radiation is collected and processed by the transceiver, control electronics, and signal processor to produce various data products. These data products are then displayed locally and/or broadcast to other locations. The environmental equipment shelter is connected to the remaining equipment locations via an Ethernet connection. The Remote Operator Station contains the primary Doppler lidar remote control and monitoring station and is connected to the shelter via an Ethernet connection. RASP GUI stands for Real Time Advanced Signal Processor (RASP) Graphical User Interface (GUI). operations. Additional workstations can be set up to receive and display output products, and even control system. Table 1 lists the nominal transceiver parameters. This paper presents a summary of recent development and airport installations using the 2 μm