SHRINKING SNOWCAPS

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SHRINKING SNOWCAPS RISING PRODUCTIVITY
RESPONSE OF THE ARABIAN SEA ECOSYSTEM TO RECENT
CLIMATE CHANGE
Joaquim I. Goes Helga do Rosario Gomes ,
Bigelow Laboratory, ME, USA
Fei Chai, University of
Maine, ME, USA
Sergio de Rada John
Kindle, Naval Research Laboratory, MS, USA
John Fasullo, NCAR, Boulder, CO, USA

Richard Barber, Duke University,

Prabhu Matondkar, National Institute of
Oceanography, Goa, INDIA Rashmin Dwivedi,
Space Applications Centre, ISRO, INDIA,
Adnan
Al-Azri, Sultan Qaboos University, Muscat, OMAN
NASA Grant No - NNX07AK82G
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ARABIAN SEA - A UNIQUE ECOSYSTEM
Comes under the influence of seasonally reversing
monsoon winds
Winds drive one the most energetic current
systems and the greatest seasonality in
phytoplankton productivity and carbon fluxes
observable in all oceans
Intensity of winds is regulated by thermal
gradient between land and the sea
Between 1992-1996, the US spent 50M on the
Arabian Sea JGOFS
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SUMMER MONSOON
Schematic showing the reversal in wind direction
during the southwest monsoon (Jun-Sept),
superimposed on satellite derived chlorophyll
fields
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WINTER MONSOON
Schematic showing snow cover extent and wind
direction superimposed on an ocean color
chlorophyll image for the northeast monsoon
season (Nov-Feb).
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Interannual changes in chlorophyll in the core of
upwelling region along coast of Somalia
Goes et al. (2005) - Science
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Trend line showing anomalies (departures from
monthly means) of snow cover extent over
Southwest Asia and Himalayas-Tibetan Plateau
between 1967 and 2003.
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Schematic showing the SW Monsoon response of the
Arabian Sea to snow cover over the
Himalayan-Tibetan Plateau
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OBJECTIVES
Identify salient trends in atmospheric and
oceanographic data sets and synthesize these
observations into a coherent diagnosis of climate
variability
Develop a coupled physical-biological model
capable of simulating changes in the circulation
of the Arabian Sea and improving understanding of
the response of the Arabian Sea ecosystem to
climate change.
Synthesis of field and satellite data
Observations from a recent (Mar-April 2009) field
study
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COUPLED MODEL DEVELOPMENT
Physical Model

• Naval Coastal Ocean Model (NCOM)
• 1/8-degree
• 30S to 30N, 30.5E to 121.5E
• Mercator grid (12km)
• 40 Layer s/z (19/21
• Data Assimilative

Ecosystem Coupling
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Carbon, Silicate, Nitrogen Ecosystem Model
(CoSiNE) Chai et al. 2002 Dugdale et al. 2002
Air-Sea Exchange
Small Phytoplankton P1
Micro- Zooplankton Z1
Biological Uptake
Total CO2 TCO2
Grazing
NO3 Uptake
NH4 Uptake
Predation
Nitrate NO3
Iron
Excretion
Ammonium NH4
N-Uptake
Meso- zooplankton Z2
Fecal Pellet
Advection Mixing
Iron
Grazing
Fecal Pellet
Diatoms P2
Lost
Iron
Detritus-N DN
Detritus-Si DSi
Si-Uptake
Sinking
Physical Model
Silicate Si(OH)4
Dissolution
Sinking
Sinking
Chai et al., 1996 2003
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Model SST (color contour). Three tide gauge
stations evaluating modeled SSH (red) vs.
observed (black) from Jan 2006 to Jul 2007.
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Sea Surface Salinity (1st Feb 2006)
Comparison of Sea Surface Salinity from NCOM IO
Model (left) with World Ocean Atlas Data. Model
currents overlaid on both figures.
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• Biology (Sep 30-Oct 7, 2006)

• Chlorophyll from NCOM IO Model (left) vs. SeaWIFS
  (right). Model currents overlaid on both figures.

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NEXT STEPS
Run Coupled Model with NCEP/NCAR winds and
Satellite SeaWinds to assess whether trends
observed in satellite derived chlorophyll maps
are reproducible.
Modify Coupled Model to include oxygen to
understand the seasonal and inter-annual changes
in the oxygen field
Use model outputs to assess potential impacts of
climate biological productivity and fishery
resources of the Arabian Sea
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SeaWiFS derived chlorophyll fields during the
peak southwest monsoon growth season of 1997 and
2006
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The oxygen minimum zone and the spread of hypoxia
in the Arabian Sea
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The role of eddies in the spread of hypoxia in
the Arabian Sea
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Oman Nov 2008 -Jan 2009
Cochlodinium polykrikoides
Bloom associated with low oxygen waters Produced
large quantities of mucous Desalination plants
and refineries shut down
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Oman Nov 2008 -Jan 2009
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PHYTOPLANKTON BLOOM OF 2003
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NOCTILUCA MILIARIS BLOOM IN THE GULF OF OMAN,
24TH JAN 2006
Dinoflagellate, thrives in (cold) lt22oC, nutrient
rich and oxygen poor waters
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ARABIAN SEA PHYTOPLANKTON COMMUNITY STRUCTURE
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FIELD STUDIES IN THE ARABIAN SEA MARCH APRIL
2009
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MARCH-APRIL 2009
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NOCTILUCA - MICROSCOPY
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ALTERATIONS IN FOOD WEB STRUCTURE?
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THANK YOU