1. Airborne Doppler lidar surface returns: data products other than tropospheric winds
G. D. Emmitt and C. O’Handley
Simpson Weather Associates
Charlottesville, VA.
Hangzhou, China
October, 2002

2. TODWL: the program (Twin Otter Doppler Wind Lidar)
SPAWAR and ONR 35/SBIR Program provided the lidar and supported its integration into the CIRPAS Twin Otter
IPO has co-funded the lidar adaptation to the Twin Otter.
IPO has solely funded the mission planning, flight hours, data collection and the post flight installation of the lidar in a trailer for inter-flight research.

3. TODWL : the aircraft
Navy Twin Otter operated by CIRPAS out of Marina, CA
Unpressurized (~ 10 ft normal operations)
Cruise speeds kts
Equiped with:
GPS/INS
Dropsonde
aerosol probes
temperature, water vapor, turbulence sensors

5. TODWL : the instrument 2µm coherent detection 4-6 mJ (330 nsec pulse)
80 Hz
water cooled
~7-10% total system efficiency
10 cm two axis scanner, side door mounted
GUI with realtime instrument control and data display
Weight: 250lb Power: 1.5 KW

6. TODWL 2-axis scanner

7. The Experiments
Airborne missions over various water bodies (open ocean, surf zone, large rivers, lakes and wetlands) in the vicinity of Monterey, CA
Laboratory studies using a water slide to simulate observations at differing incidence angles

8. Objectives
Check out the operations of an airborne 2µm coherent, semi-hemispherical scanned DWL
Investigate the utility of water surface returns at 2µm for space-based and airborne DWLs (ocean, lake, river, & wetlands)
Compare DWL wind soundings with RAOBs, microwave sounders, met towers, ground-based DWLs and assorted surface observations
Investigate the use of an airborne DWL to provide cal/val data for scatterometers and RadarSat
Demonstrate the application of LAHDSSA for future space-based DWL missions.
Collect aerosol data along with lidar data to assist in the interpretation of signals from the LAS

9. 0030 UTC March 2002 TODWL sounding looking up (20seconds)
Aircraft flight level
Microwave sounding
Ft Ord (30 minutes)
TODWL sounding
looking down (20 seconds)

10. Water surface returns as a function of incidence angle at 2µm with a coherent Doppler lidar

11. Modeled reflectance from ocean surface
along wind direction
Cross wind direction
Modeled reflectance from ocean surface
for a wind speed of 7.5m/s (Tratt, 2002)

12. TODWL returns collected over Monterey Bay, 12 March 2002
1600
Water surface returns
1400
LAS returns
1200
Range from aircraft (meters)
1000
800
600
400
200
Nadir angle
Relative spectral amplitude (range corrected)
using 400 shot integration

13. Single shot data used to obtain 400 shot average
Water surface
Single shot data used to obtain 400 shot average
at ~3 degrees off nadir

14. Single shot data used to obtain 400 shot average
Water surface
Single shot data used to obtain 400 shot average
at ~33 degrees off nadir

15. TODWL signal as a function of nadir angle

16. LAS
Water
Spectrum for range gate 20 associated with the
data shown in previous slide. The data has not
been fully corrected for the aircraft forward motion

17. Observing ocean wave motion and the atmospheric
Layer Adjacent to the Surface (LAS)

18. Monterey Bay
12 March 2002

22. Organized Large Eddies within the Marine Atmospheric Boundary Layer
Investigation of
Organized Large Eddies
within the
Marine Atmospheric Boundary Layer

28. Summary In addition to horizontal and vertical winds, an airborne
Doppler lidar can be used to study water surface motions
and their correlations with aerosols. These correlations
have significance in the interpretation of data obtained
with space based lidars and also the parameterization
of fluxes over water surfaces at wind speeds above those
that produce whitecaps. The investigation of Organized
Large Eddies will be among the objectives of future
TODWL flights

29. Acknowledgements
This work was funded by the Office of Naval Research through the Center for Interdisciplinary Remotely-piloted Aircraft Studies and by the Integrated Program Office of NPOESS

30. TODWL Twin Otter Doppler Wind Lidar First Flight Series
Navy Twin Otter
Operated by CIRPAS
Equipped for aerosol
sampling
First Flight Series
11-15 Feb. 2002
PIs: Emmitt and Bluth
2 m lidar
10 cm scanner
(1st of its kind)
Signals 5 km ahead
of aircraft for backscatter
calibration using particle
probes
VADS to measure
LOS component of
aircraft TAS
Funded by USN and IPO

31. CTI
TODWL obtaining a wind profile above the aircraft

32. Particle Probe Cluster

33. Cloud Streets over Monterey Bay, February, 2002

34. TODWL: participants
Simpson Weather Associates (SWA) G. D. Emmitt Science lead C. O’Handley Data processing and advanced algorithm development S. Greco Ancillary data from sounders, buoys, numerical models and other data sources for comparison

35. Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS)
R. Bluth Platform lead Nava Roy Software support Haf Jonsson Aerosol probe data responsibility Mike Duncan Project oversight Roy Woods Pilot and aircraft systems engineer Mike Hubbell Chief pilot

36. Coherent Technologies Incorporated (CTI) Steve Shertz (steves@ctilidar
Coherent Technologies Incorporated (CTI) Steve Shertz TODWL would not have happened without his technical support Phil Gatt Project responsibility within CTI. Also provided experience based input to the operations of the TODWL lidar Rod Munson Software support University of Alabama at Huntsville (UAH) David Bowdle Aerosol/Lidar backscatter

37. University of Washington (UW) Ralph Foster (ralph@apl. washington
University of Washington (UW) Ralph Foster Arranged for RADARSAT data collection over the Monterey Bay during TODWL flights Robert Brown Involved in the interpretation of QuikScat and RADARSAT data taken during TODWL under-flights United States Geological Survey (USGS) John Costa Arranged for surface flow velocity observations on the San Joaquin River during TODWL overflights.
NOAA Environmental Technology Laboratory (ETL) M. Hardesty Helped arrange for lidar operations during TODWL over flights A. Brewer Operated NOAA’s lidars during the overflights