Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks
Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross-sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the bulk vol...
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ftdryad:oai:v1.datadryad.org:10255/dryad.129876 2023-05-15T18:27:25+02:00 Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks Urmy, Samuel S. Warren, Joseph D. Great Gull Island Long Island Sound 41.2018N 72.1192W New York Block Island Sound 2016-11-08T22:24:40Z http://hdl.handle.net/10255/dryad.129876 https://doi.org/10.5061/dryad.45gb4 unknown doi:10.5061/dryad.45gb4/1 doi:10.1111/2041-210x.12699 doi:10.5061/dryad.45gb4 Urmy SS, Warren JD (2017) Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks. Methods in Ecology and Evolution 8(7): 860-869. 2041-210X http://hdl.handle.net/10255/dryad.129876 radar ornithology seabirds Article 2016 ftdryad https://doi.org/10.5061/dryad.45gb4 https://doi.org/10.5061/dryad.45gb4/1 https://doi.org/10.1111/2041-210x.12699 2020-01-01T15:42:24Z Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross-sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the bulk volume reflectivity cannot be translated into a numerical density. We calibrated a commercial off-the-shelf marine radar using a standard spherical target of known RCS. Once calibrated, the radar was used to measure the RCS of common and roseate terns (Sterna hirundo L. and Sterna dougallii Montagu) tracked from a land-based installation at their breeding colony on Great Gull Island, NY, USA. We also integrated echoes from flocks of terns, comparing these total flock cross-sections with visual counts from photos taken at the same time as the radar measurements. The radar's calibration parameters were determined with 1% error. RCS measurements made after calibration were expected to be accurate within ±2 dB. Mean tern RCS was estimated at -28 dB relative to one square meter (dBsm), agreeing in magnitude with a simple theoretical model. RCS was 3-4 dB higher when birds’ aspect angles were broadside to the radar beam compared with head- or tail-on. Integrated flock cross-section was linearly related to the number of birds. The slope of this line, an independent estimate of RCS, was -32 dBsm, within an order of magnitude of the estimate from individual birds, and near the middle of the frequency distribution of RCS values. These results indicate that a calibrated marine radar can count the birds in an aggregation via echo integration. Field calibration of marine radars is practical, enables useful measurements, and should be done more often. Article in Journal/Newspaper Sterna hirundo Dryad Digital Repository (Duke University) Long Island Montagu ENVELOPE(-26.333,-26.333,-58.417,-58.417) Long Island Sound ENVELOPE(-79.366,-79.366,54.800,54.800) Gull Island ENVELOPE(-55.315,-55.315,49.533,49.533) Block Island ENVELOPE(-62.347,-62.347,67.051,67.051) |
institution |
Open Polar |
collection |
Dryad Digital Repository (Duke University) |
op_collection_id |
ftdryad |
language |
unknown |
topic |
radar ornithology seabirds |
spellingShingle |
radar ornithology seabirds Urmy, Samuel S. Warren, Joseph D. Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
topic_facet |
radar ornithology seabirds |
description |
Marine surveillance radars are commonly used for radar ornithology, but they are rarely calibrated. This prevents them from measuring the radar cross-sections (RCS) of the birds under study. Furthermore, if the birds are aggregated too closely for the radar to resolve them individually, the bulk volume reflectivity cannot be translated into a numerical density. We calibrated a commercial off-the-shelf marine radar using a standard spherical target of known RCS. Once calibrated, the radar was used to measure the RCS of common and roseate terns (Sterna hirundo L. and Sterna dougallii Montagu) tracked from a land-based installation at their breeding colony on Great Gull Island, NY, USA. We also integrated echoes from flocks of terns, comparing these total flock cross-sections with visual counts from photos taken at the same time as the radar measurements. The radar's calibration parameters were determined with 1% error. RCS measurements made after calibration were expected to be accurate within ±2 dB. Mean tern RCS was estimated at -28 dB relative to one square meter (dBsm), agreeing in magnitude with a simple theoretical model. RCS was 3-4 dB higher when birds’ aspect angles were broadside to the radar beam compared with head- or tail-on. Integrated flock cross-section was linearly related to the number of birds. The slope of this line, an independent estimate of RCS, was -32 dBsm, within an order of magnitude of the estimate from individual birds, and near the middle of the frequency distribution of RCS values. These results indicate that a calibrated marine radar can count the birds in an aggregation via echo integration. Field calibration of marine radars is practical, enables useful measurements, and should be done more often. |
format |
Article in Journal/Newspaper |
author |
Urmy, Samuel S. Warren, Joseph D. |
author_facet |
Urmy, Samuel S. Warren, Joseph D. |
author_sort |
Urmy, Samuel S. |
title |
Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_short |
Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_full |
Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_fullStr |
Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_full_unstemmed |
Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
title_sort |
data from: quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks |
publishDate |
2016 |
url |
http://hdl.handle.net/10255/dryad.129876 https://doi.org/10.5061/dryad.45gb4 |
op_coverage |
Great Gull Island Long Island Sound 41.2018N 72.1192W New York Block Island Sound |
long_lat |
ENVELOPE(-26.333,-26.333,-58.417,-58.417) ENVELOPE(-79.366,-79.366,54.800,54.800) ENVELOPE(-55.315,-55.315,49.533,49.533) ENVELOPE(-62.347,-62.347,67.051,67.051) |
geographic |
Long Island Montagu Long Island Sound Gull Island Block Island |
geographic_facet |
Long Island Montagu Long Island Sound Gull Island Block Island |
genre |
Sterna hirundo |
genre_facet |
Sterna hirundo |
op_relation |
doi:10.5061/dryad.45gb4/1 doi:10.1111/2041-210x.12699 doi:10.5061/dryad.45gb4 Urmy SS, Warren JD (2017) Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks. Methods in Ecology and Evolution 8(7): 860-869. 2041-210X http://hdl.handle.net/10255/dryad.129876 |
op_doi |
https://doi.org/10.5061/dryad.45gb4 https://doi.org/10.5061/dryad.45gb4/1 https://doi.org/10.1111/2041-210x.12699 |
_version_ |
1766209509032722432 |