Home » Airborne Measurements » Raman Airborne Spectroscopic Lidar (RASL)
Raman Airborne Spectroscopic Lidar (RASL)
First Test Flights Successful In Summer, 2007
RASL is available to community users through collaborative arrangements with NASA.
please contact the PI at david.n.whiteman@nasa.gov
Airborne Measurements
RASL is an airborned Raman lidar offering day and night measurements of water vapor mixing ratio, aerosol backscatter coefficient, aerosol extinction and aerosol depolarization using 355 nm laser output. In addition, experimental measurements of cloud liquid water and others are available during the nighttime.
David N. Whiteman
Code 613.1 Building 33, Room D404 NASA/GSFC Greenbelt, MD. 20771
301 614 - 6703
Dimensionsapproximately 4'x4'x6' installed in KingAir
Weightapproximately 1800 lbs
Power Source Type220 A at 28 VDC
Inlet Aperturesuses standard King Air optical window port.
Heating/Cooling Requirementscustom radiator used to cool flashlamp pumped laser
Airspeed/Altitude Requirementsup to 29,000 ft on King Air approximately 100 m/s
Operators Required1 required
Ground Requirementschilled water source for ground test of laser.
Suitable Platformscan be made compatible with DC-8 and P-3 and like aircraft.
Data System7 channel analog to digital and photon counting data acquisition controlled by Labview.
Measured Parameterwater vapor mixing ratio, aerosol backscatter coefficient, aerosol extinction coefficient, extinction-to-backscattrer ratio, aerosol depolarization, experimental measurements in cloud liquid water content, droplet radius and number density, rotational Ram
Measurement Techniquepublished Raman lidar techniques
Operational Modedownward looking from KingAir
Time Resolution1-2 second for aerosol backscatter and depolarization, 10 second for extinction, 5 seconds water vapor mixing ratio (night) up to 30 seconds water vapor (day)
Horizontal Resolutionfrom 100m - 5 km depending on parameter
Other Resolutionrange resolution from 100 - 300 m
Precision10% or less in general
Accuracy10% or less
Range650 - 700 nm range on KingAir before re-fueling
Calibration Methodstandard Raman lidar techniques.
LimitationsNo upward looking extension
Whiteman, D. N., G. Schwemmer, T. Berkoff, H. Plotkin, L. Ramos-Izquierdo, G. Pappalardo, Performance modeling of an airborne Raman water vapor lidar, Appl Opt, 40, No. 3, 375-390. (2001)
first simultaneous measurements of aerosol extinction and water vapor (day and night) mixing ratio demonstrated in 2007. Additional measurements demonstrated: aerosol backscatter and depolarization, cloud liquid water. Rotational Raman temperature profiling has since been added to the system. Funding source : NASA Expected readiness date : summer, 2007
12 Oct 2009 10:35