Submesoscale coherent eddy in Greenland Sea No Clim

Submesoscale coherent eddy in Greenland Sea No. Clim II, module D (Pro. Clim) WP 1 Kasajima et al. (2006) 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 ? ’A mode of deep ventilation’

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

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

1999 May SF 6 measurements 2003 Sep. outside of the eddy Inside of the Eddy SF 6 profiles

Time evolution of SF 6 diffusion 1999 2002 75 N (From Mandags kollokvium by Truls)

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 Eddy (Sep. 2003) -0. 96 34. 882 322 5. 4 3. 0 2. 9 θ (°C) Salinity Oxygen (µmol kg-1) CFC-11 (pmol kg-1) CFC-12 (pmol kg-1) SF 6(fmol kg-1) SW (No. Clim cruise April 2001) -1. 06 34. 865 347 7. 3 3. 8 2. 3 -0. 90 34. 879 Mixture 1 323 (20% SW + 5. 5 80% GSAIW) 2. 8 2. 9 GSAIW (Sep. 2003) -0. 86 34. 883 317 5. 1 2. 6 3. 1 Possible SW* (assumed) - 1. 30 34. 878 342 7. 4 3. 8 2. 3 -0. 95 34. 882 322 5. 6 2. 8 2. 9 Mixture 2 (20% SW* + 80% GSAIW)

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

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

Direct velocity measurements by LADCP N (a) S (b)N S 0. 3 m/s (a) EW-comp. (b) NS-comp. -0. 2 m/s 176 Geostrophic flow (EW-comp. ) 177 178 179 0. 2 m/s Budeus et al. 2004 Max. Speed 0. 2 m/s at the radius 9 km -0. 2 m/s

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

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

N S The rotation axis is tilted From the study of tropical cyclones ; The effects of the background vertical shear on the cyclones 1. 176 177 178 179 Tilts the rotation axis downshear. 2. Turns the moving direction (to the left from the shear vector) Vel. obsevation – (-f/2) - mean flow = vertical shear flow Average = mean flow

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

Conclusion 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 is principally from the upper intermediate layer in the central GS. 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?