Ecosystem dynamics in Arctic models: role of physical processes K.Popova, A.Yool, Y.Aksenov F. Dupont (EC, Canada), M.Jin (Univ Alaska Fairbanks), E.Hunke (LANL) J. Zhang, M. Steele (Univ of Washington)

AO Primary production Horizontal advection Annual AO primary production is limited by nutrients not light! [except for N.Chukchi sea and NA inflow] Deep winter mixing

Total primary production gC/m2/yr Model intercomparison experiment General agreement between models and models and satellite-derived data. Spatial variability of ice concentration and winter mixing are crucial for good agreement with data on Primary productivity Models disagree what factor (nutrients or light) controls primary production Year 1998

What factors control primary production outside of Pacific and Atlantic inflows? ?

Subsurface Chl-a maximum From Carmack and McLaughlin, 2011 25m 100m Chl-a Nutrients ?

Sub-surface Chl-a maximum (Model estimate) Subsurface contribution to primary production Subsurface contribution to Chl-a About 43% of Total AO primary production is fuelled by SCM Popova et al., 2010, Biogeosciences

Shelf control of AO primary production ? Aagaard et al. (1981)

35 30 25 20 3 2 1 Near bottom salinity Near bottom DIN

Shelf control of AO primary production ? Aagaard et al. (1981)

Shelf control of AO primary production ? Aagaard et al. (1981)

Numerical experiment: no bottom remineralisation (5 years run) Control run (Control-exper)/control 20% reduction of total AO primary production after 5 years

Questions Does water column become homogenised during the brine release? Do physical model reproduce advective formation of upper halocline?

0 10 20 30 years