Response of the Arctic freshwater budget to extreme NAO forcing

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Response of the Arctic freshwater budget to
extreme NAO forcing
How is the arctic freshwater budget connected to
the NAO ? In this presentation Repeat NAO
(1969) leads to the arctic retaining its
freshwater in Beaufort gyre. Repeat NAO (1989)
causes an export of freshwater from the Arctic to
the North Atlantic. Main Arctic-Atlantic
freshwater exports are via Canadian Archipelago
and Fram Strait (50 and 30). In NAO forcing,
the freshwater export from Fram and Canadian
Archipelago to the North Atlantic increases by
roughly the same amount (650 km3/yr). Implicatio
ns for Labrador Sea deep convection and climate
prediction models that lack a Canadian
Archipelago.
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Model set-up

• Run set-up
• MITgcm simulation of the arctic using open
  boundary conditions from CUBE 49 (Uvel, Vvel,
  S,T)
• Resolution 210x192x50 (av. Horizontal resolution
  in arctic 36 km) resolve sills and straits.
• Initial SALT and THETA from Polar Hydrographic
  climatology (Steele et al.,)
• PIOMAS (Pan-Arctic Ice-Ocean Modeling and
  Assimilation System ) sea ice distribution
• NCEP daily forcing (Tair, 10m wind, precip,
  long/short wave, humidity)
• No salinity restoring
• 12 yr run 1992-2001.
• RUNS
• Control run (run13) 1992-2001
  
• NAO-high as control, but repeat NAO year 1989
  wind field
• NAO-low as control, but repeat NAO year 1969
  wind field

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Regional Model Domain
ARCTIC MASK
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NAO FORCING
REPEAT FORCING OF EACH YEAR FOR 10 YEARS
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CONTROL RUN (1992-2001 NCEP daily forcing)
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NAO (11 yr repeat 1989)
ATMOSPHERE
Precip 2800
Evap749
OCEAN Storage Liquid 60338 Trend -1000 Ice
19521 Trend -395 Total 79859 Trend
-1395 IN 7529 OUT
-9027 Change -1497 Imbalance -102
Bering 2414
LAND Run-off
Bering (ice) 292
R 2023
Canadian Arch. (Ice) 143
Barents Sea 597
Barents (Ice) 201
Fram Strait (water) 1489
Fram Strait (ice) 3411
Canadian Arch. (Water) 2436
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NAO- (11 yr repeat 1969)
ATMOSPHERE
Evap635
Precip 2800
OCEAN Storage Liquid 68910 Trend 604 Ice
18523 Trend -625 Total 87433 Trend
-21 IN 7352 OUT 7350 Change
2 Imbalance 23
Bering 2438
LAND Run-off
Bering (ice) 55
R 2023
Canadian Arch. (Ice) 37
Barents Sea 537
Barents (Ice) 224
Fram Strait (water) 1745
Fram Strait (ice) 2444
Canadian Arch. (Water) 1766
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OBSERVED (Serreze et al. 2006)
ATMOSPHERE
Evap1299
Precip 3253
OCEAN Storage Liquid 74345 Ice
10449 Total 84794 IN 9494 OUT
10372 Imbalance -878
Bering 2489
LAND Run-off
Bering (ice) N.A.
R 3000
Canadian Arch. (Ice) N.A.
Barents Sea 340
Barents (Ice) N.A.
Fram Strait (water) 2405
Fram Strait (ice) 2265
Canadian Arch. (Water) 3153
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Vertical freshwater (1992-2000)NAO
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Vertical freshwater (1992-2000)-NAO
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Total freshwater volume (liqicesnow) and ice
movement (av. 2001)
1969 forcing
1989 forcing
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LIQUID
ICE
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Fluxes
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Atlantic Water penetration
1969 forcing
1989 forcing
NAO increases the amount of warm, salty Atlantic
Water in the Arctic
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Next Step The impact of a closed Canadian
Archipelago on the freshwater budget, some what
representative of coarse resolution models