WHOI -- AOMIP 10/20/2009 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 Motivation [Holloway, 2007] [Nguyen et al., 2009] Questions: 1)Source of Upper Halocline Water? 2)Volume budget of source water? Svalbard

WHOI -- AOMIP 10/20/2009 Regional Configuration of MITgcm ECCO2: High- Resolution Global- Ocean and Sea-Ice Model 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]

WHOI -- AOMIP 10/20/ Mean August velocity magnitude (top 100m)m/s

WHOI -- AOMIP 10/20/2009 Snap shots  winter late spring late summer winter B B’

WHOI -- AOMIP 10/20/2009 oCoC Mean Temperature A A’

WHOI -- AOMIP 10/20/2009 Densewater formation on shelves Surface T / S contours: S > 33.25, Sea-ice area = 95% [Woodgate, 2005] BB’ profile 1

WHOI -- AOMIP 10/20/2009 Heat Loss, Ice and Dense-water and Halocline water productions [Cavalieri 1994] Heat Loss:H L = (8.64  10 4 ) A F net Ice Production:V i = (8.64  10 4 ) H L / (  i L) Salt Production:S F =  i V i 0.69 s w Dense Water:V D = S F / [  e s e –  w s w ] Halocline Water**:V H = V D (s e – 32) / (32.85 – 32), s e > = S F / [  h s h –  w s w ], s e < ** Assumptions: a.sea-ice production yields enriched water with salinity increases psu b.enriched water mixes with mixed-layer water to produce halocline water c.cold halocline water has an average salinity s h =32.85 psu d.enriched water has salinity s e > s h Variables: F net : total ocean-to-atmosphere heat flux A: open-water area L: latent heat of fusion  i, V i : sea-ice density and volume  e, s e : enriched water density and salinity  w, s w : background water density and salinity

WHOI -- AOMIP 10/20/2009 Ice productions in Region 1

WHOI -- AOMIP 10/20/2009 Densewater transport from shelves into Arctic interior Summer 2002 [Pickart, 2005] C C’ Model C C’ August Observations

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

WHOI -- AOMIP 10/20/2009 Net Halocline Water Production Source Period Dense WaterHalocline Water Cavalieri, [1994]  0.04 Sv --- This study………  0.03 Sv0.09  0.03 Sv

WHOI -- AOMIP 10/20/2009 Numerical Calculation (1) Source Period Dense WaterHalocline Water Cavalieri, [1994]  0.04 Sv --- This study………  0.03 Sv0.09  0.03 Sv  0.05 Sv 0.18  0.09 Sv

WHOI -- AOMIP 10/20/2009 Numerical Calculation (2) Source Period Dense WaterHalocline Water Cavalieri, [1994]  0.04 Sv --- This study………  0.03 Sv0.09  0.03 Sv  0.05 Sv 0.18  0.09 Sv  0.09 Sv

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