Front Detection in Chlorophyll and SST Satellite Imagery - Ocean's ...
Front Detection in Chlorophyll and SST Satellite Imagery - Ocean's ...
Front Detection in Chlorophyll and SST Satellite Imagery - Ocean's ...
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<strong>Satellite</strong> Oceanography of <strong>Front</strong>s<br />
as Biological Hotspots<br />
Igor Belk<strong>in</strong><br />
University of Rhode Isl<strong>and</strong><br />
Collaborators:<br />
Peter Cornillon <strong>and</strong> David Ullman (URI)<br />
Jay O’Reilly, Kim Hyde, <strong>and</strong> Teresa Ducas (NOAA)<br />
Supported by NASA <strong>and</strong> NOAA<br />
Presented at Oceans: Challenges <strong>and</strong> Opportunities<br />
Porto, 14 May 2013
Questions <strong>and</strong> Answers<br />
Question: What is an oceanic front?<br />
Answer: <strong>Front</strong> – sharp, narrow boundary between<br />
two water bodies<br />
Question: Are they similar to atmospheric fronts that<br />
can be seen on TV weather forecasts?<br />
Answer: Yes!<br />
Question: Can we see oceanic fronts?<br />
Answer: Yes!
River Plume <strong>Front</strong> (Eel River, California)
Columbia River Plume <strong>Front</strong><br />
http://www.nwfsc.noaa.gov/research/divisions/fed/oceanecology.cfm
Kuroshio east of Japan
Kuroshio off Taitung County
<strong>Front</strong> off Taitung County
“L<strong>in</strong>e <strong>in</strong> the Sea” From Space<br />
Space Shuttle<br />
Atlantis (STS-46)<br />
<strong>Front</strong> !<br />
100 km<br />
Yoder et al., 1994, Nature
The same front up close (from ship deck)<br />
Rhizosolenia cells<br />
~1 m<br />
Yoder et al., 1994, Nature
Birds <strong>and</strong> <strong>Front</strong><br />
Red-necked Phalaropes (Phalaropus lobatus) sit on<br />
an oceanic front feed<strong>in</strong>g on krill (Thysanoessa sp<strong>in</strong>ifera).<br />
Credit: CondorExpressPhotos
Lights of the World From Space<br />
Squid <strong>and</strong> <strong>Front</strong>
Squid Fisheries at the Falkl<strong>and</strong> <strong>Front</strong>
Chl<br />
Data:<br />
NASA’s<br />
SeaWiFS<br />
Buenos Aires<br />
Low light imag<strong>in</strong>g data collected by<br />
U.S. Air Force Defense Meteorological<br />
<strong>Satellite</strong> Program. Data process<strong>in</strong>g by<br />
the NOAA National Geophysical Data<br />
Center. Courtesy Chris Elvidge.<br />
Image credit: Valeria<br />
Falabella from the<br />
Wildlife Conservation<br />
Society <strong>and</strong> the Sea &<br />
Sky Project.
Squid<br />
Fisheries
<strong>Chlorophyll</strong><br />
Bloom Along<br />
Falkl<strong>and</strong> <strong>Front</strong>
Albacore migration along the TZCF<br />
TZCF<br />
TZCF = Transition Zone Chl <strong>Front</strong><br />
Polov<strong>in</strong>a et al., 2001,<br />
Progress <strong>in</strong> Oceanography
MAY<br />
JUNE<br />
JULY<br />
TZCF<br />
Albacore<br />
AUGUST<br />
SEPTEMBER<br />
The spatial distribution of albacore CPUE<br />
(albacore/boat-days) from the US troll fishery<br />
shown as dots for May–Sep, 1998 overla<strong>in</strong> with<br />
the TZCF <strong>in</strong>dicated by the 0.2 mg/m3 surface<br />
chlorophyll isopleth.<br />
Polov<strong>in</strong>a et al., 2001,<br />
Progress <strong>in</strong> Oceanography, Fig.5
Swordfish <strong>and</strong> Subtropical <strong>Front</strong><br />
Hawaii<br />
NOAA R ⁄ V Townsend Cromwell meridional survey tracks (1996–2000) <strong>and</strong><br />
swordfish monthly catches per confidential set dur<strong>in</strong>g March–April 1996–1999. All<br />
catch data are from the Federal longl<strong>in</strong>e logbook program (Ito et al., 1998).<br />
Seki et al., 2002, Fisheries Oceanography, Fig. 1b<br />
Art source: http://pirate.shu.edu/~hendersh/Assignments/Assignment%20Ma<strong>in</strong>%20Page%20Homework%20Proj/Assgn%20Fish%20Id%20p149/fish.htm
Cayula-Cornillon Algorithm<br />
for <strong>Front</strong> <strong>Detection</strong><br />
<strong>in</strong> <strong>Satellite</strong> <strong>Imagery</strong>
<strong>Front</strong> <strong>Detection</strong>: Histogram Algorithm
World Atlas<br />
of Oceanic <strong>Front</strong>s
Atlantic Ocean<br />
FEB<br />
AUG
Indian Ocean, Boreal W<strong>in</strong>ter
Indian Ocean, Boreal Summer
Pacific Ocean, Boreal W<strong>in</strong>ter
Pacific Ocean, Boreal Summer
New Algorithm<br />
For <strong>Front</strong> <strong>Detection</strong>
USA<br />
Stepwise fronts
USA<br />
Chl bloom<br />
at <strong>SST</strong> front
<strong>Chlorophyll</strong><br />
Bloom Along<br />
Falkl<strong>and</strong> <strong>Front</strong>
<strong>SST</strong><br />
<strong>SST</strong><br />
(zoom)<br />
Chl<br />
ZOOM!<br />
Chl bloom<br />
at <strong>SST</strong> front<br />
Taylor <strong>and</strong> Ferrari, 2011
BOA: Algorithm for <strong>Chlorophyll</strong> <strong>Front</strong>s<br />
(Belk<strong>in</strong> <strong>and</strong> O’Reilly, 2009)<br />
• Algorithm preserves features endemic to<br />
Chl fields: (a) Chl blooms; (b) Chl<br />
enhancements along hydrographic fronts.<br />
• Ma<strong>in</strong> novelty: contextual median filter that<br />
preserves the Chl features of <strong>in</strong>terest.<br />
• Tested on Chl <strong>and</strong> <strong>SST</strong> imagery, 1997-2012.<br />
• Reference: Belk<strong>in</strong>, I.M., <strong>and</strong> J.E. O’Reilly (2009) An<br />
algorithm for oceanic front detection <strong>in</strong><br />
chlorophyll <strong>and</strong> <strong>SST</strong> satellite imagery, Journal of<br />
Mar<strong>in</strong>e Systems, 78 (3), 317-326.
<strong>SST</strong> <strong>Front</strong>s
<strong>Front</strong>s from New York to Nova Scotia<br />
Chl <strong>SST</strong>
<strong>Front</strong>s <strong>in</strong> Mid-Atlantic Bight<br />
Chl <strong>SST</strong>
Conclusions<br />
• <strong>Front</strong>s play major roles as ecosystem<br />
boundaries, migration pathways,<br />
feed<strong>in</strong>g <strong>and</strong> spawn<strong>in</strong>g grounds etc.<br />
• Biologically-important Chl <strong>and</strong> <strong>SST</strong><br />
fronts can be reliably mapped from<br />
satellite data<br />
• In-situ studies of biophysical<br />
<strong>in</strong>teractions <strong>in</strong> frontal zones must be<br />
conducted at front-resolv<strong>in</strong>g scales
Break<strong>in</strong>g News<br />
The BOA algorithm has been<br />
officially adopted by NOAA for<br />
operational production of Chl<br />
frontal maps<br />
Daily maps of Chl fronts generated<br />
by BOA will become freely<br />
available from NOAA <strong>in</strong> July 2013
Sunset at the tidal mix<strong>in</strong>g front, Georges Bank<br />
THANK YOU!
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