Home » Airborne Measurements » TWiLiTE - Tropospheric Wind Lidar Technology Experiment
TWiLiTE - Tropospheric Wind Lidar Technology Experiment
Instrument Completed In March 2009.
Instrument completed in March 2009. Engineering flights on NASA ER-2 underway.
Contact PI
Airborne Measurements
Scanning direct detection molecular Doppler lidar
Bruce Gentry
NASA Goddard
Laboratory for Atmospheres Code 613.1 Greenbelt, MD 20771 USA
ManufacturerNASA GSFC
DimensionsApprox 0.7m(H) x 0.7m(W) x1.2m(L)
WeightApprox 500 lbs
Power Source TypeApproximate power total is 1KW; 700W (25A) of 28VDC + 280W of 110VAC
Inlet Apertures50 cm diameter uv grade window in bottom of aircraft
Heating/Cooling Requirements
Airspeed/Altitude RequirementsUp to 200 m/s; Up to 20 km
Operators RequiredAutonomous
Ground RequirementsTBD
Suitable PlatformsDesigned for autonomous operation on high altitude research aircraft e.g. NASAGlobal Hawk, WB57 or ER-2.
Data SystemThe command, data handling and storage is managed by a single onboard computer. Atmospheric returns are by detected by photomultiplier tubes and sampled by 3 channels of photon counting electronics. Raw data are stored to disk and processed post flight on the ground
Measured ParameterMeasures vertical profiles of radial wind speed. Telescope/scanner rotates in azimuth with fixed nadir angle of 45 degrees to provide multitple perspectives of horizontal wind field
Measurement TechniqueMolecular backscatter Doppler lidar
Operational ModeNadir viewing from high altitude; conical step stare scanning pattern to produce multiple azimuth VAD scan of horizontal wind field
Time Resolution10 s integration at each azimuth position; 8 point, 360 deg scan in 96 s
Horizontal ResolutionDetrmined by airspeed. 10s @ 200 m/s = 2 km for single radial wind profile.
Other ResolutionVertical sampling =50 m; Vertical resolution of wind data <250 km
PrecisionHorizontal projected wind speed <1.5 m/s from 20 km to surface
AccuracyHorizontal projected wind speed <2.0 m/s from 20 km to surface
RangePlatform dependent. Approx 6 hours for WB57
Calibration Method
LimitationsAttenuation by clouds degrades, or eliminates, performance below
6 Apr 2011 14:05