Submesoscale coherent eddy in Greenland Sea NoClim II, module D (ProClim) WP1 ’A mode of deep ventilation’ Discovered in GS during ESOP II (Gascard et al. 2002) A homogeneous water column, cold core Vertical extension, 2000 m The horizontal scale of 10 km Stationary? Long-lived ? Kasajima et al. (2006)

SCV observations 1997 May 2001 Oct April 2003 May 2003 Sep. Second eddy 2003 May 2001 March 2002 Aug. References Gascard et al Wadhams et al Wadhams et al (the second one) Budeus et al.2004 Active migration in 2003

SCV Vertical ventilation ? ? ? Formation  where does the core water come from? (Migration  where is it transported?) Dissolution  where is the core water finaly released? (How about the life time ?) Measurements of the chemical tracers in the core in 2003 SF 6, CFCs, nutrients, (carbon) Direct velocity measurements with LADCP

SF 6 profiles outside of the eddy Inside of the Eddy SF 6 measurements 2003 Sep May

Time evolution of SF 6 diffusion (From Mandags kollokvium by Truls) 75 N

Possible core water end-members Surface water  high CFCs, oxygen concentrations  core water is cold, water in winter SF 6 water  relatively high SF 6 concentration Mixture 1 (20% SW + 80% GSAIW) Mixture 2 (20% SW* + 80% GSAIW) θ (°C) Salinity Oxygen (µmol kg -1 ) CFC-11 (pmol kg -1 ) CFC-12 (pmol kg -1 ) SF 6 (fmol kg -1 ) Eddy (Sep. 2003) SW (NoClim cruise April 2001) GSAIW (Sep. 2003) Possible SW* (assumed)

SCV in 1999 Cold surface water in winter (cold core water, high CFCs, oxygen) Returned Atlantic Water (Little SF 6 ) SCV 2003 Cold surface water in winter (cold core water, high CFCs, oxygen) Greenland Sea Arctic Intermediate Water  Not in the central GS The parents waters are found in the central GS High SF 6 water is lifted up toward the surface and cooled 20 % cold surface + 80 % GSAIW 1999 SCV and 2003 SCV are not the same one  Life time is not several years

Unit : m/s Black Green Red Blue N-S section in SCV

S N NS Direct velocity measurements by LADCP (a)EW-comp. (b)NS-comp. Geostrophic flow (EW-comp.) (a) (b) 0.2m/s -0.2m/s 0.3m/s -0.2m/s Budeus et al Max. Speed 0.2m/s at the radius 9km

Angular velocity = vorticity x 1/2 Radial velocity Azimuthal velocity -f/2-f/2 = vorticity observed earlier Vorticity is overestimated by including background flow

Vel. obsevation = -f/2 + back ground flow SCV vorticity is assumed to be -f / 2 Trajectory of SCV Southward migration ?!? x(t)= x o + Ut + R exp(iωt) Mean flow radius

Vel. obsevation – (-f/2) Average = mean flow - mean flow = vertical shear flow NS The rotation axis is tilted From the study of tropical cyclones ; The effects of the background vertical shear on the cyclones 1.Tilts the rotation axis downshear. 2.Turns the moving direction (to the left from the shear vector)

x(t)= (x o +Ut+R exp(iωt)) ∙C ∙ A The background shear turns the migration direction northward. Shear effect Shear vector Mean flow θ Φ Vertical shear vector C |V shear | A = cosΦ sinΦ -sinΦ cosΦ

SCV is formed in the Greenland Sea by the mixture of 20 % of cold surface water and 80 % of intermediate water. The source of the core water isprincipally from the upper intermediate layer in the central GS. Conclusion The direct velocity measurements reveal high shear in the SCV, which plays an important role in the migration direction. The background flow/shear has changed since 2003?