If you're in the Northeast or Mid-Atlantic US, I post the nightly radar each morning at ~6:40am on my website www.woodcreeper.com. If you're in the Southeast, especially Florida, you can get similar information at badbirdz2.wordpress.com, a site I started a few years ago and have passed on to two very ambitious Miami birdwatchers, Angel and Mariel Abreu. I'm working on ways to make the data presented on these sites more informative, but at least for now they provide a database of radar loops for most nights during both spring and fall migration (the database is searchable too!). In many cases local birders have commented on the nightly posts, offering a measure of ground-truthing to the data. In the future I hope to integrate reporting tools which will make the data more quantifiable. For now, though, it would be great if some of the NFC folks would stop by and participate in the discussion, which would definitely add a new and welcome dimension to our understanding of migration and migrant tracking.
Thanks to Jeff and Bryan for starting the conversation on radar. Cheers David ____________________________________________________ David A. La Puma, Ph.D. Dept. of Ecology, Evolution, & Natural Resources Online Teaching Portfolio: http://www.woodcreeper.com/teaching Lockwood lab: http://rci.rutgers.edu/~jlockwoo Websites: http://www.woodcreeper.com http://badbirdz2.wordpress.com Photos: http://www.flickr.com/photos/woodcreeper On Tue, Sep 1, 2009 at 11:53 PM, Bryan Guarente <dafekt...@yahoo.com> wrote: > NFC-enthusiasts, > Jeff pointed out the radar echoes tonight which are pretty impressive, > especially along the Carolina and Virginia coasts. Being a meteorologist > and a birdwatcher, this is of great interest to me. For those who are > interested in sources of information about the weather patterns aside from > using the radar to detect objects, you can get some information on my > personal website: > http://homes.comet.ucar.edu/~guarente/birdweather/index.htm<http://homes.comet.ucar.edu/%7Eguarente/birdweather/index.htm> > I have compiled the links I often use for my own meteorological exploration, > as well as sites that would be useful specifically for bird migration. > > I personally am a fan of checking the forecast streamlines for bird > migration as this is a good predictor of which nights will be good for > migration, but does not necessarily dictate when there will be detectable > NFCs, as other meteorological factors play in to this. To see the > streamlines you can go here: > http://homes.comet.ucar.edu/~guarente/birdweather/stream.htm<http://homes.comet.ucar.edu/%7Eguarente/birdweather/stream.htm> > Streamlines show the direction weightless particles would travel if released > in the wind field. > > All times on this page are plotted on the top of the images, but they are > noted in UTC. To see the current UTC time, you can go here: > http://www.time.gov/timezone.cgi?UTC/s/0/java Also, the maps differ in > height from the surface through 700mb (or hPa). These maps use pressure as > the height coordinate, but can be roughly thought of as 900mb = .5km above > sea-level, 850mb = 1.0km above sea-level, and 700mb = 1.5km above > sea-level. The "Surface" maps plotted here are the surface of the earth > following topography. Sorry to all those individuals outside of the US, I > only have access to the US model data, so I cannot currently plot other > locations aside from North America. > > Where the current streamlines have a component pointing toward the south > the radar echoes are brightest, except for where there is significant > topography to block the radar beam (the western 1/3 of the US). > > Back to the radar: I am hoping someone will be able to point me in the > direction of a publication that discusses the radar cross-section or > backscattering properties of a bird in flight. Are there any papers out > there about this? I have found the papers that mention that birds show up > on radar, but none of them seem to mention the backscattering properties of > the birds. > > The current radars in the United States are very sensitive to the size of > the object they are reflecting waves off, up to a point. This can mean very > different echoes for drizzle drops, rain drops, small hail, very large hail, > and birds because of the > scattering<http://en.wikipedia.org/wiki/Scattering>regime in which it lies > (click link to read wikipedia article about > scattering). Most particles in the atmosphere that are detected by weather > radars are in the Rayleigh > scattering<http://en.wikipedia.org/wiki/Rayleigh_scattering>regime, but birds > don't always fit in this regime, often extending in to the > Mie scattering <http://en.wikipedia.org/wiki/Mie_theory> regime which is > not ideal for US weather radar detection. However, that is assuming that a > bird is a sphere, which is a poor assumption. I am hoping to get my hands > on some papers about the scattering properties of birds that show how the > radar waves reflect, but have yet to find any. There are some algorithm > papers available by Dinevich, but these lack the actual scattering > properties. Anyone have a reference for me? > > Thanks for any references you may have, > > Bryan Guarente > Instructional Designer > The COMET Program > University Corporation for Atmospheric Research > Boulder, CO > > -- NFC-L List Info: http://www.NortheastBirding.com/NFC_WELCOME http://www.NortheastBirding.com/NFC_RULES http://www.mail-archive.com/nfc-l@cornell.edu/maillist.html --
