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Point vs. VAD scans for complex terrain. G. D. Emmitt and C. O’Handley WG SBLW Destin, FL January 27-30, 2009. Overview. - PowerPoint PPT Presentation
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Point vs. VAD scans for complex terrain
G. D. Emmitt and C. O’HandleyWG SBLWDestin, FL
January 27-30, 2009
Overview The conical scan is the traditional pattern used to obtain vertical profiles of the wind field with an airborne Doppler wind lidar. Nadir or zenith pointing scanning wedges are ideal for this type of scan.
A bi-axis scanner has been operated on a Navy Twin Otter for more than 6 years and was installed on a Navy P3 for use in a field experiment to study typhoons.
The bi-axis scanner enables a broad range of scanning patterns. A subset of the possible patterns is critical to obtaining useful wind profiles in the presence of complex terrain or small (~ 100's of meters) organized atmospheric structures (rolls, updrafts, waves, etc).
Several scanning strategies have been tested in flights over the Monterey Peninsula and within tropical cyclones. Combined with Google Earth (on-board) and satellite imagery overlays, new realtime adaptive scanning algorithms are being developed and tested.
TODWLscanner
STV
Particleprobes
SurfaceTemperatureSensor
The instrument
• 2µm coherent detection (CTI MAG1A)• 2 mJ ; 500 Hz• 10 cm two axis scanner, side door mounted• GUI with realtime instrument control and data
display• Range: .3 – 21km depending upon aerosols• Accuracy: < .10 m/s in three components• Weight: 700lb Power: 700 W
Scanning options
• Nadir step-stare conical (3 – 12 positions) for vertical profiles for u, v, w & aerosols
• Zenith step-stare (u, v, w)• Forward sweeping (prospecting for OLEs and
shear layers ahead of aircraft• Nadir point scans (u,v,w) in complex terrain
and organized flows (e.g. OLEs)
0 1000 2000 3000 4000 5000 6000EAST/W EST D ISTAN C E (M )
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SC AN PATTER N FO R "PO IN T SC AN "3 C O M PLETE SC AN SG S: 64 M /S , H T: 1950 M , D W ELL: 2 SECBLAC K: 1200 MR ED : 750 MBLU E: 300 M
FLIG H T TR ACK
0 1000 2000 3000 4000 5000 6000EAST/W EST D ISTAN C E (M )
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SC AN PATTER N FO R "VAD "2 C O M PLETE SC AN SG S: 64 M /S , H T: 1950 M , D W ELL: 2 SECBLAC K: 1200 MR ED : 750 MBLU E: 300 M
FLIG H T TR ACK
Ridge and Valley
-45000 -44000 -43000 -42000 -41000 -40000
10000
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15000SCAN C O VERAG ERED : VADS 10 - 13, F ILE 1226 (SW TR ACK)BLACK: PO INT, 1241 (NE TR ACK)LO S 'S EN D AT 950 M M SL
POINT
Speed Comparison Over High Complex Terrain
Valley Floor
-54000 -53000 -52000 -51000 -50000 -49000
1000
2000
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6000SCAN C O VER AG ER ED : VAD S 4 - 6 , F ILE 1231 (SW TR AC K)BLACK: PO IN T, 1237 (N E TRAC K)LO S 'S END AT 150 M M SL
Speed comparisons over valley floor
POINT
-2000 -1500 -1000 -500 0 500 1000 1500 2000
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STAR TIN G PO IN T(A IR C R AFT LO C ATIO N )
TAR G ET PO IN T
TAN G ENT PO IN T
SAM PLE PO IN T SC AN G EO M ETR Y
FLIG HT TRACK
Acknowledgements
• Most of our research on profiling in complex terrain and the implications to model validation/initialization has been funded under an SBIR through the Army Research Office (Dr. Walter Bach).
• Additional funds were provided by the Integrated Program Office of NPOESS (Dr. Stephen Mango)