1U. S. Army Research Laboratory

1
Diagnostic Wind Model Initialization Using the
Airborne Doppler Wind lidar Data
Yansen Wang1, Chatt Williamson1, David Emmitt2,
and Steve Greco2
1U. S. Army Research Laboratory 2Simpson Weather
Associates
AMS 4th Symposium on Lidar Atmospheric
Application
2

Brief 3DWF Model Description

• Given a limited number of observations or
  coarsely modeled wind field in a complex terrain,
  the wind field is physically interpolated in such
  way that the mass conservation is satisfied.
  Mathematically, to Minimize the following
  functional (Sasaki, 1970 Sherman 1978)
• . Very accurate boundary treatment, structured
  Cartesian grids.
• Bi-CGSTAB numerical and multigrid numerical
  solvers.
• Building and steep topographic wake
  parameterizations.
• Lidar data assimilation/initialization.
• Vegetation canopy flow parameterization.
• Validation and improvement with observation data
  sets.

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Simulstion in Complex Terrain
3DWF Askervein Hill Simulation
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3DWF wind field at 10m AGL
A
B
AA
A
B
AA
5
Comparison of model results with observations at
Askervein Hill
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• 3DWF model simulation wind field at Salinas
  Valley initialized by the airborne Doppler lidar
  data

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Airborne Doppler Wind Lidar
Aircraft Platform
Optical Particle Counters
PCASP 0.1-3.0 ?m
FSSP 2.5-51 ?m
CAPS 0.45-118 ?m
NPS CIRPAS Twin Otter
Naval Postgraduate School Center for
Interdisciplinary Remotely-piloted Aircraft
Studies
TODWL Instrument 2.0125 µm, coherent detection
2 mJ, 330 nsec (FWHM), 500 Hz 10 cm
telescope two axis scanner, ?30 ?120 deg, side
door mount Weight 425lb Power 1.5KW 7-10
total system efficiency
TODWL Scanner
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TODWL vs. Ft. Ord microwave sounder
TODWL Flight Level
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TODWL Flight Patterns
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TODWL OBSERVATIONS
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3DWF wind field at 10m AGL
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Zoom in a small area
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Comparison with NWS observations
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Summary

• New 3DWF model performed well in a simple low
  hill with strong wind condition.
• Airborne Doppler lidar data can be used for the
  3DWF initialization with an objective analysis
  method.
• The complex Salinas valley case with lidar data
  initialization gives reasonably good results.

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TODWL Characteristics
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0030 UTC 13 March 2002
TODWL sounding looking up (20seconds)
Aircraft flight level
TODWL sounding looking down (20 sec)
Microwave sounding Ft Ord (30 minutes)