PW - Low OxygenPW - Hi NutrientsPW versus AW in N:P spaceUpper Arctic Ocean Circulation and VentilationPW - Low OxygenNPEOSWYDDISSOLVED OXYGEN- High at surface (ventilated from atmosphere)- Low = OLD water (long time since at surface)or= Evidence of high biological activityTHUS – Pacific Water has LOW Dissolved OxygenPacific WaterFalkner et al, 2005 DSRAWPWPW - Hi NutrientsSILICATE, NITRATE, PHOSPHATE- High from source in PacificBUT – not conservative(CH20)106(NH)16(H3PO4) + 138 O2= 106 CO2+ 122 H2O + 16 HNO3+ H3PO4Biogenic matter + oxygen = Carbon Dioxide + Water + NUTRIENTSFixing of nutrients and Carbon to make biogenic matterDecay of biogenic matter using up Oxygen, forming nutrientsTry to create a “tracer” that is conservative “Quasi-conservative Tracer”“NO” and “PO” – Broecker, 1974- cope with growth and decayNO = 9 NO3+ O2PO = 135 PO4+ O2N:P ratiosNO:PO ratiosN* (N star) – Gruber and Sarmiento, 1997- indicates nitrogen fixation and denitrificationN* = 0.87 [N – 16 P + 2.9 µmol kg-1]Redfield-Ketchum-Richards Model (Redfield et al, 1963)PW versus AW in N:P spaceNITRATE:PHOSPHATE RELATIONSHIPdifferent in AW and PW= For a Nitrate value, PW have more Phosphate= Slope set by Redfield= Exact lines may changeNO3(pw) = 14.828 x PO4(pw) – 12.16 (Falck, 2001)BUT work out % influence of PW and AW(..but certainly no better than 10%.... assumes ice melt, P and runoff same as AW.... denitrification .. and other such processes)PWAW% PW in upper 30mJones, Anderson and Swift, GRL, 1998Distribution of Atlantic and Pacific waters in the upper Arctic Ocean: Implications for circulationUpper Arctic Ocean Circulation and VentilationPhoto PSC/UWCIRCULATION CHANGESShift in rivers outflow Retreat and recovery of CHL Shift of Pacific/Atlantic FrontHALOCLINE BASICSFormation possibilitiesWestern versus Eastern ArcticDifferent branches of PWRudels et al,1996TRACING PW versus AW HALOCLINEPW lower salinity, smoother TSPW lower dissolved oxygenPW higher nutrients (esp Silicate)AW/PW NO3:PO4 ratioMECHANISMS OF SHELF-BASIN EXCHANGEWinddriven upwelling and mixing of AW with PWPotential vorticity conservation, following topographyDense water outflow from polynyasEddies (AC, ~ scale of Rossby radius)Winddriven undercurrents (Yoshida jet)Tides and inertial