East Coast Plumes and Blooms: Building a

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East Coast Plumes and Blooms Building a
Chlorophyll Budget for the Mid-Atlantic Bight
Jennifer Bosch, Oscar Schofield, Scott Glenn and
Josh Kohut Rutgers Coastal Ocean Observation Lab
OOXVII 2004 Fremantle, Australia
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Our efforts have focused on understanding
material transport and transformation for the
broad continental slope in the Mid-Atlantic
Bight.
Todays talk will focus on the nearshore sources
of chlorophyll and the sinks on outer the
shelf. Data collected as part of the LATTE
effort.
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Mid-Atlantic Bight is changing
Long term changes
Short term events
There are zones of recurrent hypoxia/anoxia along
new Jersey. It is one of the largest concerns
for state water quality managers.
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Major nearshore coastal contributions of
chlorophyll to the MAB using the 2002 2003
annual data sets
Coastal Blooms
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What percentage of the high chlorophyll signal
along the coast is related to the Hudson River
plume?
Approach
Use Channel Ratios of nLws to define high CDOM
water consistent with Hudson and Delaware Rivers
(Johnson et al. 2003)
(Oliver et al. 2004)
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SeaWiFS nLw 421, 443, 490, 510, 555, 670
Blue Red 490 670
We use the low values of nLw_490nLw_670 to
indicate high CDOM. Values in between 1.9 and
4.3 we use to designate large coastal blooms.
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SeaWiFS nLw490nLw670
Plume detection using Ocean Color Sensors
April 15, 2003
May 4, 2004
1-km Resolution
May 4, 2004
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Plume detection using Ocean Color Sensors THE
NEXT STEPS FOR LATTE 2005
May 4, 2004
360-m Resolution
May 4, 2004
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Total Chlorophyll (mg m-3)
Total Chlorophyll (mg m-3)
1.20E07
1.40E07
2002
2003
1.20E07
1.00E07
1.00E07
8.00E06
8.00E06
6.00E06
6.00E06
4.00E06
4.00E06
2.00E06
2.00E06
0.00E00
0.00E00
River
Coastal Bloom
Shelf
Total
River
Non-River
2-Year Mean Percent of Total Chlorophyll
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Chlorophyll mg/m3
2002
2003
2002
2003
2002
2003
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NJSOS Endurance Line Seasonal Cross-Shelf
Optical Backscatter Transects
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Summary

• Episodic events (1-2 weeks duration) represent a
  significant fraction of the annual chlorophyll
  budget in the MAB
• Any climate based approach must include episodic
  events because it represents 43 of the total
  chlorophyll budget
• Band ratioing is a highly effective tool for
  classifying blooms and rivers in the MAB because
  NJ waters are uniquely organically rich
• Chlorophyll associated with rivers accounts for
  10-20 of the episodically derived chlorophyll.
  Coastal blooms account for 26
• Plume material is transported off shore by
  hydrographic super-highways. Material converges
  at the 60m isobath over a period of 1-2 weeks and
  then dissipates due probably to export flux and
  grazing
• The export flux fraction accumulates in the MAB
  cold pool hypothetically due to export flux