Quality Assessment of Weather Radar Wind Profiles during Bird Migration

Abstract

Quality assessment of weather radar wind profiles during bird migrationHolleman, I.; van Gasteren, J.R.; Bouten, W. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ABSTRACTWind profiles from an operational C-band Doppler radar have been combined with data from a bird tracking radar to assess the wind profile quality during bird migration. The weather radar wind profiles (WRWPs) are retrieved using the well-known volume velocity processing (VVP) technique. The X-band bird radar performed range-height scans perpendicular to the main migration direction and bird densities were deduced by counting and normalizing the observed echoes. It is found that the radial velocity standard deviation ( r ) obtained from the VVP retrieval is a skillful indicator of bird migration. Using a threshold of 2 m s Ϫ1 on r , more than 93% of the bird-contaminated wind vectors are rejected while over 70% of the true wind vectors are accepted correctly. For high bird migration densities the raw weather radar wind vectors have a positive speed bias of 8.6 Ϯ 3.8 m s Ϫ1, while the quality-controlled wind vectors have a negligible speed bias. From the performance statistics against a limited area numerical weather prediction model, it is concluded that all (significant) bird contamination is removed and that high-quality weather radar wind profiles can be obtained, even during the bird migration season.

Bird migration flight altitudes studied by a network of operational weather radars

“…Typical C-band weather radar technical parameters are listed in [31]. Range/azimuth resolution equalled 1 km/1°, 1 km/1°, 250 m/1° and 240 m/0.5° for the four radars, respectively.…”

Radar wind profilers and avian migration: a qualitative and quantitative assessment verified by thermal imaging and moon watching

“…). However, it has also been known from S‐ and C‐band weather radar networks, such as NEXRAD or OPERA, that these remote‐sensing systems register bird movements (Gauthreaux, Mizrahi & Belser ; Koistinen ; Holleman, Van Gasteren & Bouten ; Dokter et al . ).…”

Structures of Bragg Scatter Observed with the Polarimetric WSR-88D

“…Our observations show that this type of reflectivity field is only one of several types that can be detected from Bragg scatterers, which we describe herein. Flying birds and insects are known to cause problems with the interpretation of radar wind profiler data (Wilczak et al 1995;Lehmann 2012) and WSR-88D wind measurements (Wilson et al 1994;Holleman et al 2008). A minimal detectable C 2 n at 10 km for KOUN of 3.5 3 10 215 m 22/3 is achieved in the short-pulse mode of operation.…”