Estimating animal densities in the aerosphere using weather radar: To <i>Z</i> or not to <i>Z</i>?

Chilson, Phillip B.; Frick, Winifred F.; Stepanian, Phillip M.; Shipley, J. Ryan; Kunz, Thomas; Kelly, Jeffrey F.

doi:10.1890/es12-00027.1

Cited by 75 publications

(87 citation statements)

References 35 publications

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“…In many ways the complementarity of these approaches is ideal, and we have been involved in developing both (Chilson et al, 2012;Bridge et al, 2013). In many ways the complementarity of these approaches is ideal, and we have been involved in developing both (Chilson et al, 2012;Bridge et al, 2013).…”

Section: Time To Change Horsesmentioning

confidence: 99%

Toward a predictive macrosystems framework for migration ecology

Kelly

Horton

Sykes³

2016

Global Ecol. Biogeogr.

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Concern about the sustainability of intercontinental‐scale migration systems grows apace with global change. Traditional organism‐centred approaches to this problem have provided insights at the population level, but not at the systems level. We are sceptical that an accumulation of data from a species‐by‐species approach will yield an understanding of these systems in the near term. As an alternative, we advocate a new research programme that grows from an explicitly system‐based framework that leverages existing Earth observation infrastructure to make inferences directly at the macrosystem level. We illustrate how this approach can be used to generate and test system‐level predictions, using NEXRAD radar data as an example. We urge organismal ecologists to recognize that some of the most urgent migration questions are at the macrosystem scale and that tackling these questions requires an interdisciplinary approach if we are to make progress at a pace that exceeds that of climate change.

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Section: Time To Change Horsesmentioning

confidence: 99%

Toward a predictive macrosystems framework for migration ecology

Kelly

Horton

Sykes³

2016

Global Ecol. Biogeogr.

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“…Bats often emerge from caves in large numbers around sunset, particularly Mexican free-tailed bats (Tadarida brasiliensis) in Texas and Oklahoma. Evening dispersion patterns have been studied for these bats (Horn and Kunz 2008;Frick et al 2012), and it may be possible to derive number density of bats or other bioscatterers using radar data (Chilson et al 2012a). Insect scattering properties using nonpolarimetric radar have also been occasionally examined.…”

Section: Introductionmentioning

confidence: 99%

Polarimetric Radar Observations of Biological Scatterers in Hurricanes Irene (2011) and Sandy (2012)

Broeke

Matthew²

2013

Journal of Atmospheric and Oceanic Technology

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Biological scatterers, consisting of birds and insects, may become trapped near the circulation center of tropical cyclones, particularly if a well-developed eyewall is present. These scatterers may be observed using weather radar, where they may appear to the radar operator as areas of light precipitation. Polarimetric radar characteristics of these scatterers, informed by additional observations of known bioscatter, include a combination of very high differential reflectivity (3-7.9 dB) and very low copolar correlation coefficient (0.3-0.8). Polarimetric radar observations of bioscatter are presented for Hurricane Irene (2011) and Hurricane Sandy (2012). In these storms, the bioscatter signature first appeared at the 0.58 elevation angle at a distance of 100-120 km from the radar. The signature appeared on successively higher tilts as the circulation center neared the radar, and its areal coverage in constant altitude plan position indicator (CAPPI) slices was primarily governed by the distribution of convection in the eye and by the timing of landfall. The highest altitude at which the signature appears may represent the inversion level within certain tropical cyclone eyes. For Hurricane Irene, inland observations of oceanic bird species support biological transport. Knowledge of the bioscatter signature has value to meteorologists monitoring tropical cyclones within the range of a polarimetric radar, possible value for estimating inversion height changes within the eyes of well-structured tropical cyclones, and value to biologists who wish to estimate the magnitude of biological transport in tropical cyclones.

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“…The reflectivity factor (dBZ) in the remaining resolution cells was converted to radar equivalent reflectivity factor (Ze) in mm 6 /m 3 , and Ze was used to calculate total bird reflectivity ( η ) in cm 2 /km 3 (Chilson et al. ). To determine the number of birds km −3 , total biological reflectivity in a resolution cell is divided by the radar cross section of a bird (e.g.…”

Section: Methodsmentioning

confidence: 99%

Detecting bird movements with L‐band avian radar and S‐band dual‐polarization Doppler weather radar

Gauthreaux

Shapiro

Mayer

et al. 2018

Remote Sens Ecol Conserv

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Marine surveillance radars with X‐band (3‐cm) and S‐band (10‐cm) wavelengths not only detect birds but also record return from insects, rain, ground objects and rough seas that often make discrimination of echoes from birds difficult. We compare the density of bird tracks recorded by an L‐band (ca. 23‐cm wavelength) avian radar at the Dallas/Fort Worth International Airport that does not detect insects and rain with the amount of mean bird reflectivity in resolution cells of a dual‐polarization S‐band Doppler weather surveillance radar. Radar data files of 1.5° scans gathered near midnight from January through May for the years 2014, 2015 and 2016 were processed by filtering radar resolution cells to retain only those with backscatter differential phase values characteristic of birds flying more or less perpendicular to the radar beam. In general, increases and decreases in the density of bird movements were correlated significantly between the two radars, but the low R2 values confirm that results obtained from one radar cannot be used to make quantitative estimates for the other. A decrease in the mean biomass index of migrating birds from January through May, and the difference in coverage volume and resolution between the two radars likely account for the low R2 values. Each type of radar has advantages and provides important information on bird movements at different spatial scales.

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Estimating animal densities in the aerosphere using weather radar: To Z or not to Z?

Abstract: Abstract. Weather radars provide near-continuous recording and extensive spatial coverage, which is a

Cited by 75 publications

References 35 publications

Toward a predictive macrosystems framework for migration ecology

Toward a predictive macrosystems framework for migration ecology

Polarimetric Radar Observations of Biological Scatterers in Hurricanes Irene (2011) and Sandy (2012)

Detecting bird movements with L‐band avian radar and S‐band dual‐polarization Doppler weather radar

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