Data from: Quantitative ornithology with a commercial marine radar: standard-target calibration, target detection and tracking, and measurement of echoes from individuals and flocks ...

• Main Authors: Urmy, Samuel S., Warren, Joseph D.
• Format: Dataset
• Language: English
• Published: Dryad 2017
• Subjects: Radar; Ornithology; Sterna dougallii; radar cross-section; Sterna dougalli; Sterna hirundo; Gull Island; Montagu
• Online Access: https://dx.doi.org/10.5061/dryad.45gb4; https://datadryad.org/stash/dataset/doi:10.5061/dryad.45gb4

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 ... : Raw radar files from tern colony on Great Gull Island, NYZipped archive containing 200 raw radar sweeps recorded as NetCDF files on 22 July 2014 on Great Gull Island, NY. Each file contains a single sweep of the radar's antenna, with three variables. The variable "amplitude" contains 2-D array of radar reflectivities in polar coordinates. Amplitudes are recorded as 16-bit signed integer values from the digitizer: to convert them to voltages, divide by the variable's "max_counts" metadata value (which is equal to 32764 for all files in this archive). The other two variables, "pulse_number" and "range", are the values corresponding to the amplitude array's azimuth and radial axes. Analysis scripts for these files are found in the article's supplementary online information.raw_radar.zip ...