Characterization of Global Ocean Turbidity from MODIS Aqua Ocean Color Observations

1
Characterization of Global Ocean Turbidity from
MODIS Aqua Ocean Color Observations
Wei Shi1 and Menghua Wang2 (GOVERNMENT PRINCIPAL
INVESTIGATOR) 1CIRA, , 2NOAA/NESDIS/STAR

Requirement Ecosystems (1) Advancing
understanding of ecosystems to improve resource
management, (2) Healthy and productive coastal
and marine ecosystems that benefit
society. Science How to characterize and
quantify global ocean turbidity for both open
ocean and coastal waters, understand different
ocean and atmospheric processes that control the
variability of ocean turbidity? Benefit Better
understand global ocean ecosystem and water
quality, help refining the ocean and atmosphere
models and improve the prediction accuracy.
MODIS Kd(490) CLIMATOLOGY IN US EAST COAST DURING
2002 - 2008
October
January
July
April

• The NIR-SWIR combined atmospheric correction
  algorithm and a new Kd(490) algorithm have been
  used to derive Kd(490) data to study and quantify
  seasonal global ocean turbidity for both the
  global open ocean and coastal turbid waters.
• Global ocean turbidity shows significantly
  seasonal Kd(490) variations with highs in the
  boreal (or austral) spring and summer and lows in
  the winter for the northern (or southern)
  hemisphere.
• Global clear waters with Kd(490) gt0.05 m-1 and
  0.05 m-1 ltKd(490) lt0.1 m-1 account for 83 and
  13of the global ocean coverage.
• Turbid waters with Kd(490) over 0.3 m-1 are all
  located along the coastal regions, river
  estuaries, and inland lakes with a global
  coverage of 23?106 km2, accounting for 812
  of the total global continental shelf area.

m-1
5.0
0.0

• Seasonal phytoplankton bloom dominates the global
  geographic perspective of the modestly turbid
  waters (for waters with 0.1 m-1 lt Kd(490) 0.3
  m-1).
• In the coastal region, high turbidity (Kd(490) gt
  0.3 m-1) is attributed to the high loading of
  sediment concentration due to various physical
  processes, such as sediment re-suspension, river
  run off

SEASONAL GLOBAL OCEAN Kd(490)
MECHANISMS FOR MODESTLY TURBID AND HIGHLY TURBID
WATERS
Kd(490) in July, 2005 (scale 0.03-1.0 log)
Kd(490) in July, 2005 (scale0-5)
nLw(645) in July 2005? (scale 0-6)
Chlorophyll-a Concentration in July, 2005 (scale
0.1-32 log)
m-1
0.03
1.0
log

• Amazon River estuary ranks the worlds most
  turbid region with the mean Kd(490) value 5
  m-1.The highly turbid waters include (1) Chinas
  east coast region, (2) U.S. east coast region and
  northern Gulf of Mexico, (3) Amazon River
  estuary, (4) La Plata River estuary, (5) Ganges
  River estuary and Gulf of Martaban in the Bay of
  Bengal, (6) Caspian Sea, (7) North Sea Region and
  (8) Gulf of Carpentaria between Australia and New
  Guinea.
• In US East Coast, turbid waters are primarily
  located in the Chesapeake Bay, Delaware Bay, and
  Pamlico Sound within the Outer Banks. Highly
  turbid regions with Kd(490) gt 2 m-1 are located
  at the upper Chesapeake Bay and Delaware Bay.

Science Challenges Inter-annual variability of
the global ocean turbidity and its relation to
the decadal and long term ocean and atmospheric
variability. Next Step Regional studies of the
seasonal and inter-annual ocean
turbidity. Transition Plan Transition newly
developed Kd(490) algorithm for the operational
use.