Large scale radar ornithology - Aarhus Universitet · 2011-11-29 · Large scale radar ornithology...
Transcript of Large scale radar ornithology - Aarhus Universitet · 2011-11-29 · Large scale radar ornithology...
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Large scale radar ornithology
Large scale radar ornithologyworkshop "Trends in radar ornithology", Aarhus, DenmarkHans van Gasteren
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ContentsHistorical overviewTypes of large scale radars used in ornithologyTechnical issues regarding radar coverageTrack-While-Scan image processing - introductionPros & cons with small scale radar
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Historical overview large scale radar• Migration across the southern North Sea
• Lack 1959a,b, 1960, 1961, 1963a, b, Eastwood (& Rider) 1963, 1965, 1967
• Migration between the America’s• Nisbet & Drury 1964, 1967, Richardson 1976, 1978, 1979, 1982, Larkin 1980,
Williams & Williams 1977, 1978, Stoddard et al. 1983, Gauthreaux & Belser 1998a, b, 2005, Gauthreaux 1970, 1992
• Bird migration & flight safety• North America: DeFusco et al. 1986, Larkin 1994, Blokpoel 1969-1973• Europe: Buurma 1995, Buurma & Bruderer 1991, Ruhe 2005, 2008, Van Belle et
al. 2007, Shamoun-Baranes et al. 2008
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Large scale bird movements, 10-10-1980, Northern-Netherlands
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Application of surveillance radars
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Application of Doppler weather radars
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Detection range & cross section example for MPR at 10, 100 and 1000cm²
Small
Large
Distance
Det
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n (0
..1) © Carpet 2.0 by TNO, Netherlands
“small songbird” “Herring Gull” “flock of birds”
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Curved earth, coverage diagram & elevation blocking obstacles
0 20 40 60 80 100
500
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distance (km)
altit
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(m)
- 2 beams- Curved earth- obstacles
-Max. flight altitude
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DEM, blocking obstacles, curved earth, elevation of the beam
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Resolution & pulsed volumes with birds or rain
rain
birds
high res low res one low resolution radar cell
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Processed signal with range
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0 1 2 3 4 5 6 7 8 9 10range (km)
sign
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Processed signal
Schematic A-scope (video) signal processingRaw signal, STC and CFAR with range
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sign
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STC
CFAR
Raw signal
Raw signal minus STC with range
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0 1 2 3 4 5 6 7 8 9 10range (km)
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Raw signal - STC
Ingested bird
- STC
-CFAR
False alarms
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Processed signal with range, without clutter detection
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Processed signal w ith clutter
Schematic A-scope clutter mask (binary or dynamic)
Clutter
Processed signal with range
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0 1 2 3 4 5 6 7 8 9 10range (km)
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Processed signalIngested bird
False alarms
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Example PPI image processing Note bird echoes underneath binary clutter map
binary clutter mask dynamic clutter mask© TNO, ROBIN-system
decreasing Pd , increasing FAR, but:
improvement with TWS- algorithm
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TWS continuous algorithm, example of the ROBINLite-system
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TWS-algorithm on 10 successive images ROBIN system (operational ~15 years in RNLAF)
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Differences large & small scale radarsLarge scale radar
• C-, S- or L-band • ~400-1250kW peak power
• working ranges ~10-150km• overview “total” migration• medium/higher part of migration layer, ~0.1 / >4km as 2D PPI
• strong: timing, routes, # flocks, avg speed/direction
Small scale radar
• X-, or S-band• ~10-25kW peak power up to 180kW for tracking radars• working ranges <5km• detailed local migration patterns• lower part of migration (0-2km)
• 10° at 5km range ~ 1.8km) • strong: # flocks/birds, height, speed/direction, landscape courses. (tracking radar: wing beat, identification, 3D+time paths, quantification)
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Image processing for birds (left) and weather (right), 13 October 2009, 6:00utc