1. Formation of the Arctic Upper Halocline in a Coupled Ocean and Sea-ice Model
Nguyen, An T., D. Menemenlis, R. Kwok, Jet Propulsion Laboratory, California Institute of Technology
WHOI -- AOMIP 10/20/2009

2. Motivation Questions: Source of Upper Halocline Water?
[Nguyen et al., 2009]
[Holloway, 2007]
Svalbard
Questions:
Source of Upper Halocline Water?
Volume budget of source water?
WHOI -- AOMIP 10/20/2009

3. Regional Configuration of MITgcm
Integration Period:
Ocean model:
9-km horizontal
50 vertical levels
Surface BC’s: JRA25
Initial conditions: WOA05
bathymetry: GEBCO
KPP mixing [Large et al., 1994]
BC’s: global solution
Sea ice model:
C-grid, ~ 9km
2-category zero-layer thermodynamics [Hibler, 1980, Hibler & Zhang, 1997]
Viscous plastic dynamics [Hibler, 1979]
Initial conditions: Polar Science Center
Snow simulation: [Zhang et al., 1998]
ECCO2: High- Resolution Global- Ocean and Sea-Ice Model
WHOI -- AOMIP 10/20/2009

4. 1992-2005 Mean August velocity magnitude (top 100m) m/s
WHOI -- AOMIP 10/20/2009

5. Snap shots winter late spring late summer winter s B B’
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6. Mean Temperature
A A’ oC
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7. Densewater formation on shelves
Surface T / S
BB’ profile 1
[Woodgate, 2005]
contours: S > 33.25, Sea-ice area = 95%
WHOI -- AOMIP 10/20/2009

8. Heat Loss, Ice and Dense-water and Halocline water productions
[Cavalieri 1994]
Heat Loss: HL = (8.64104) • A • Fnet
Ice Production: Vi = (8.64104) • HL / (ri • L)
Salt Production: SF = ri • Vi • 0.69 • sw
Dense Water: VD = SF / [rese – rw sw]
Halocline Water**: VH = VD (se – 32) / (32.85 – 32) , se > 32.85
= SF / [rhsh – rw sw ] , se < 32.85
** Assumptions:
sea-ice production yields enriched water with salinity increases psu
enriched water mixes with mixed-layer water to produce halocline water
cold halocline water has an average salinity sh=32.85 psu
enriched water has salinity se > sh
Variables:
Fnet: total ocean-to-atmosphere heat flux
A: open-water area
L: latent heat of fusion
ri,Vi : sea-ice density and volume
re, se: enriched water density and salinity
rw, sw: background water density and salinity
WHOI -- AOMIP 10/20/2009

9. Ice productions in Region 1
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10. Densewater transport from shelves into Arctic interior
Model
Observations
C C’
C C’
Summer 2002 [Pickart, 2005]
August
WHOI -- AOMIP 10/20/2009

11. Dense water and Halocline water calculations:
B B’
WHOI -- AOMIP 10/20/2009

12. Net Halocline Water Production
Source Period Dense Water Halocline Water
Cavalieri, [1994]  0.04 Sv
This study………  0.03 Sv 0.09  0.03 Sv
WHOI -- AOMIP 10/20/2009

13. Numerical Calculation (1)
Source Period Dense Water Halocline Water
Cavalieri, [1994]  0.04 Sv
This study………  0.03 Sv 0.09  0.03 Sv
 0.05 Sv  0.09 Sv
WHOI -- AOMIP 10/20/2009

14. Numerical Calculation (2)
Source Period Dense Water Halocline Water
Cavalieri, [1994]  0.04 Sv
This study………  0.03 Sv 0.09  0.03 Sv
 0.05 Sv  0.09 Sv
 0.09 Sv
WHOI -- AOMIP 10/20/2009

15. Summary
Model: realistic polynyas and ice productions compared to observations
Seasonal cycle of dense water in the Chukchi Sea
Dense water  supplies water to the Upper Halocline
 need to compare with observations
Thank You
WHOI -- AOMIP 10/20/2009

16. Extra (1)
[Martin 2004, 2005]
WHOI -- AOMIP 10/20/2009