While the Next Generation Weather Radar (NEXRAD) program's Weather Surveillance Radar - 1988 Doppler (WSR-88D) was designed primarily to detect and observe significant and hazardous weather events, the radar is easily able to detect airborne biological targets. These biological targets have been observed in WSR-88D products since early in the NEXRAD program and have, at times, caused significant impact on the meteorological interpretation of those products. This presentation will detail the technical capabilities of the WSR-88D system, show examples of the WSR-88D observation of bird targets, and discuss the impact of those observations on meteorological decisions. In addition, the presentation will consider ornithological uses of WSR-88D data and products.
Classic Examples of Nocturnal Migration Liftoff Using
the Des Moines, IA, WSR-88D
by Karl Jungbluth, National Weather Service Forecast Office, Des Moines, IA
Johnston, IA 50131-1908
(515) 270-4501, ext. 766
Iowa birders know that passerine migrants are more numerous along river valleys than in the corn and soybean fields nearby. Radar imagery confirms this, and data from the Des Moines WSR-88D will be used to show classic examples of nocturnal migration liftoff in central Iowa. Low elevation scans clearly relate the maximum bird concentrations to river valleys and reservoirs on the imagery. WSR-88D radars nationwide could be used to map important bird areas and illustrative examples could be used to champion the conservation of riparian corridors. A small portion of the talk will also show signatures of migrating birds on wind profiler data (vertically pointing Doppler radars) across the central United States. Profiler data can provide information on the altitudes at which birds migrate but probably cannot be used to discriminate species. In conclusion, weather radars can be used to show that migration is a phenomena by illustrating where birds are migrating at any given time, at what altitude, and where they liftoff and land.
In the spring of 1997, 1998 and 1999 I operated a 3-cm radar at Brock University. The radar counts electronically the numbers of biological targets in the height range from about 250 m to 950 m. Over the same time period I downloaded base reflectivity images from the 0.5 degree beam of the Weather Radar (WSR-88D) located at Buffalo, New York. The Weather Radar 0.5-degree beam is centered at a height of about 600-m above the 3-cm radar. A comparison of numbers of biological targets on the 3-cm radar and the base reflectivity dbZ value over Brock University allows estimation of how the two quantities are related in the same range of heights. Results of the three-year study are presented and some comments are made about how the dbZ values of base reflectivity can be used to estimate numbers of birds aloft.
Further information on this talk and other studies by the author can be found at www.physics.brocku.ca/faculty/black.html
Doppler radars such as the WSR-88D generate precise data that are seductively quantitative, by which we mean that one can often tell exactly "how much" without knowing "of what" and "how fast" without sorting out speed from direction and wind. However, there are many ways to identify biological echoes on large radars, many times even below the level of Phylum. Examples will be presented of quantitative work on radars designed for meteorology, involving roosting bird and waterfowl movements, tracking radar, and ongoing research involving extensive censuses on the ground in the north-central Midwest and special, transportable bird-counting radars.
Contrary to the field biologist's instinct, the most efficient way to conduct coordinated radar and visual observations is usually to use radar images to determine where to go to look for birds. Estimation of numbers or biomass of low-flying birds away from the immediate vicinity of the radar are complicated by the radar's "pencil beam" interacting with the geometry of the curving earth and the possibility of refraction at night or in early morning. Ground-truthing observations almost always produce new insights into avian biology because of the novel perspective attained by an instrument that can reach right across whole landscapes. With regard to ground truthing, there is (or at least should be) room for the field naturalist and the talented amateur to contribute mightily to an emerging science by helping to correlate distinctive radar echoes with visual or aural observations. In the future the possibility of polarization diversity on upgraded operational Doppler radars has the potential to bring radar ornithology to a new level of sophistication and capability.
Since 1992, the Spring and Fall migrations of the large kettles of Broad-winged Hawks, (et al), have been observed at the NEXRAD Radar Stations at Houston/Galveston, Corpus Christi, and other locations. In the Fall of 1995, it was noticed that the highly reflective kettles seen on the Reflectivity portrayal could also be seen on the Velocity portrayals at similarly located and configured area of high velocities. It is evident that the velocity seen is the velocity of the hawks streaming between kettles. The high velocities, often several times the speed of the surrounding winds, have become a primary tool in the identification of Broad-Winged kettles. Confirmation by ground truth has occurred so frequently that the writer holds that identification of kettles can be made by radar alone, without the need for ground truth. This greatly increases the area of study that can be covered. Until recently this kind of study could be made only at a Weather Service office, and only the Reflectivity portrayals were Internet available. About a year ago, a new service called "WeatherTAP.com" became available which, among other things, offers Reflectivity, Velocity and Vad Wind Profiles, the basic portrayals used in hawk studies. The format is very like the Weather Service format, and magnification is 1X, 2X, 3X, and 4X. Data is from the 0.5 degree beam (lowest beam setting) only, but this setting is the most used in bird study. And most important, all of the available Reflectivity, Velocity and Wind Profile portrayals that the NWS produces (at weather station chosen) are available within about 3 to 5 minutes after they are available at that weather station. Portrayals are also adequate for hawk counting method and for cell-phone instructions to roaming vehicles.
BirdCast is a cooperative pilot project that used three independent methods to monitor the spring migration of birds through the mid-Atlantic region of the United States. Those independent methods are: NEXRAD radar images both filtered (Geomarine, GM) and unfiltered (Clemson Radar Ornithology Lab, CROL), nocturnal flight call recording (Bioacoustics unit of the Cornell Lab of Ornithology, BACLO), and citizen ground truthing (Philadelphia Academy of Sciences and BirdSource, BS, a joint project of the Cornell Lab of Ornithology and the National Audubon Society). The project covers the spring migration between 1 April and 31 May 2000. The project has three primary goals: (1) Determine the extent of the spring migration, using independent methods throughout the mid-Atlantic region with the potential to develop technologies to cover a broader region. (2) Pinpoint specific migration stopover locations throughout the region, and (3) Notify individuals when pesticide use could be harmful to migrating birds. Internet technologies developed by BS will be used for data collection, storage, and dissemination. Access to all information will be provided at the BirdCast website (http://www.birdcast.org). CROL will provide twice daily NEXRAD images and commentary in an attempt to forecast flights through the region. GM will provide NEXRAD images (with all weather information removed) at 2-h intervals. The BACLO have established five nocturnal flight-recording stations in the regions that will upload nightly flight call counts to BS. BS and the Academy of Sciences have recruited individuals who will report daily bird observations using ground truthing protocols developed by CROL.
During the evening of November 9, 1996, spurious, coherent reflectivity echoes were
observed on the WSR-88D radar at Buffalo, NY. Shortly after sunset the radar-derived
Vertical Wind Profile (VWP) in the first 1-2 km of the atmosphere began to indicate
strong northerly winds. The realtime wind observation from the Buffalo radiosonde at
about the same time indicated weak southwest to west winds through the lower atmosphere.
The discrepancy in radar-derived vs. observed winds was most likely due to a bird migration
that began just after sunset. This paper shows the evolution of the bird migration as
observed on the Buffalo radar and compares radar-derived winds with actual radiosonde
winds and hourly forecast winds available through the ETA numerical forecast model.
Bird migrations follow identifiable patterns related to season, time of day, direction
of movement and height above the ground. The study shows how radar-derived winds can be
compared to radiosonde data and forecast wind profiles from high resolution numerical
model data to confirm bird migration patterns.
The link to our "Research" page is: www.wbuf.noaa.gov/research.html - then just click on the "Bird Study".
Radar detection of non-meteorological echoes is not a recently discovered application (Eastwood 1967, Edwards 1959). However, with the proliferation of high quality doppler radars in association with the National Weather Service (NWS) modernization and restructuring, many new occurrences of this phenomenon have been reported. Shortly after the WSR-74S s-band radar was replaced with the more powerful and sensitive WSR-88D s-band doppler radar at the NWS office in Binghamton, NY in September of 1993, the periodic appearance of a ring shaped echo configuration was noticed during the late summer and early fall near the time of sunrise. The primary purpose of this investigation was to determine the exact source of the echo using ground truth verification and to understand how the targets were creating this unique return.
To view the entire document, go to the address http://www.nws.noaa.gov/er/bgm/birds/birds.htm
Avian Research Laboratory. Geo-Marine, Inc. Suite 22-A 3160 Airport Rd, Panama City, FL 32404.
The Avian Hazard Advisory System (AHAS) was developed to use NEXRAD weather radar data and National Weather Service (NWS) weather data to forecast and monitor bird activity. The monitoring of birds in near real time uses algorithms developed by Geo-Marine, Inc to isolate biological targets from weather. Removing the weather returns permits subsequent processing to retrieve information on bird strike risk to be fully automated Development of additional algorithms to isolate specific classes of biological targets is underway. These new radar datasets are in Geographic Information System (GIS) format and are being used for improving bird strike risk models and for conservation and ecological applications.