MSFC/GHCC 1 2 micron pulsed ground based lidar Non-Contact Velocity Measurements on Simulated River Surfaces Using Coherent Doppler Lidar Preliminary Results Prepared by J. Rothermel* and S.C. Johnson (NASA MSFC) P.A. Kromis (Computer Science Corporation) Earth Science Department NASA Marshall Space Flight Center Updated by D. Bowdle** (University of Alabama in Huntsville)

MSFC/GHCC 2 2 micron pulsed ground based lidar MSFC Coherent Doppler Wind Lidar  Initiated April 1999  Purpose: CDWL technology validation Atmospheric properties research Space CDWL concepts investigation CDWL targets research Student Instruction  Location: MSFC Building 4467 GSFC van (proposed) Van or trailer (future) Aircraft (future)  Initial components: Transceiver, 50 mJ, 6.6 Hz, microns, FL pumped 10 cm telescope from Schwartz Electro-Optics, Inc. Full hemispheric scanner (Bldg. 4467) Data acquisition & processing

MSFC/GHCC 3 2 micron pulsed ground based lidar Long-term Objective Streamflow Measurement with Doppler Lidar  Complement proposed microwave radar measurements  Relationship among surface velocity profile, bottom topography, and discharge  Based on phased approach  Controlled experimental conditions (initial phase)  Collaborations with USGS, U. Washington (later phases) Doppler lidar is only technique that can directly measure the influence of near-surface winds

MSFC/GHCC 4 2 micron pulsed ground based lidar Background Water surface velocity measurements depend on:  Lidar wavelength  Surface roughness  Incidence (or nadir) angle  Turbidity  Surface contaminants (e.g., foam)  Depth of penetration (of order millimeters at 2 micron)  Near-surface wind velocity

MSFC/GHCC 5 2 micron pulsed ground based lidar Target Target Lidar Lidar ~350 m range (Very) Preliminary Experiment at MSFC

MSFC/GHCC 6 2 micron pulsed ground based lidar Water Slide Geometry Water slide Nadir Angle Slit Water Flow Lidar Beam

MSFC/GHCC 7 2 micron pulsed ground based lidar Experiment Parameters  MSFC Doppler lidar, 6.6 Hz,  m  Velocities toward lidar are negative (-)  Water discharge nozzles: weirgate on new waterslide  Water slide surface composition: plexiglass  Lidar beam footprint: ~10 cm  Discharge depth: several mm (variable)  Nadir angles at target: 30, 60 deg  Integration: 20 pulses  Range gate, velocity plots: 210 m, centered on target  Range gate, range plots: 38.4 meters  Range to target: ~350 meters  Minimum range: ~150 meters  Number of good range gates in air near target: ~5

MSFC/GHCC 8 2 micron pulsed ground based lidar

MSFC/GHCC 9 2 micron pulsed ground based lidar

MSFC/GHCC 10 2 micron pulsed ground based lidar

MSFC/GHCC 11 2 micron pulsed ground based lidar

MSFC/GHCC 12 2 micron pulsed ground based lidar

MSFC/GHCC 13 2 micron pulsed ground based lidar

MSFC/GHCC 14 2 micron pulsed ground based lidar Conclusions and Plans Conclusions  Velocity standard deviation for hard target is ~0.1 m/s.  Velocity decreases slowly as reservoir empties, allows integration  Surface tension effects from untreated plexiglass slide surface create  flow channeling, with variable water layer thickness  non-riverine water surface microstructure  Sanding the plexiglass surface reduces surface tension effects  virtually eliminates flow channeling  nearly mirror smooth water surfaces Plans  Resume lidar operations (after minor repairs)  Test runs with variable flow velocity and layer thickness  Test runs with controlled surface condition