Southern Ocean Observations of AWI South Atlantic Workshop, San Ceferino, 9 May 2007 Andreas Macrander Alfred-Wegener-Institut für Polar- und Meeresforschung, Bremerhaven Deployment of ice-adapted APEX float. Polarstern ANT XXIII/ , 63°S 52°W, 01 Oct Deployment of PIES + 2 PopUps. Polarstern ANT XXIII/ , 41°S 04°E, 29 Aug © A. Macrander 2006

Ice-adapted Argo Floats in the Weddell Sea / ACC Ice-capable Argo floats APEX (Webb) NEMO (Optimare) ISA: Ice Sensing Algorithm aborts ascent if T<-1.75°C in upper 50 m iStore: interim storage of under- ice profiles, delayed trans- mission next ice-free season RAFOS: acoustic tracking under ice; range of sound sources ~500 km Float communication: ARGOS/Iridium Boebel, AWI 2006 ISA/iStore Temperature profiles from the Weddell Sea 03/2005 – 02/2006. Gray areas at the surface indicate sea ice cover. AWI RAFOS sound source in Weddell Sea and 500 km range. Black: in operation, red: deployments 2007/2008. Blue: planned future deployments. | | | | | | | | | | | | | | 2006 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Depth [m] Temperature [°C] Sea Ice Klatt, AWI 2006

Ice-adapted Argo Floats in the Weddell Sea / ACC AWI plans for 2007/2008 Further deployments of ice-capable APEX and NEMO floats with ISA,iStore, RAFOS →Weddell Gyre →South Orkney →0°W Completion of RAFOS sound source array for under-ice tracking Baranski, AWI 2007 All 118 AWI Argo float deployments since Surface fixes shown on map. Large Panel: Color = Latitude. Floats # with ISA. Floats with iStore marked by →. ISA ↑ iStore

Moored PIES + PopUp Array for ACC monitoring and GRACE validation: PIES (Pressure sensor equipped Inverted Echo Sounder, URI) PopUp (Optimare) for interim data retrieval IrDA transmission of data to PopUp PopUps automatically release after 1 – 2 years, data transfer via Iridium PIES recovered by Polarstern after 2 – 4 ½ years Costs: € 5000 per PopUp PopUp PopUp Burn-wire release IrDA data link PIES Burn-wire release RV Polarstern, ANT XXIII/7, Deployment of PIES 537-1, © A. Macrander 2006

GRACE validation by PIES ACC array FESOM model: Auto-correlation of monthly FESOM OBP anomalies with FESOM OBP at 50°S 1°E. 700 km Gauss filter. PIES ACC array positions marked in black. FESOM data: Ralph Timmermann, Figure: Carmen Böning. AWI PIES array in ACC – extended GoodHope section 2d array layout optimized for comparison of in-situ OBP and GRACE gravity measurements. All PIES at T/P crossover points for additional altimetry/SSH estimates 2000 x 2000 km area of correlated monthly OBP variability in South Atlantic, both in FESOM model and GRACE OBP time series correlated with GRACE, r = 0.69 ACC array 2002 – 2005: PIES GRACE GFZ RL03 GSM+GAC Monthly averages. Böning, AWI 2006 Macrander, AWI 2006

C-PIES timeseries retrieved from PopUp First successful PopUp operation: ANT11-2 (C-PIES185,PopUp06) at 50°S 01°E deployment PopUp release  variability 5 ms ↔ 200 m vertical displacement of the thermocline (  T = 5°C) OBP variability 0.1 dbar on weekly timescales current ≤ 20 cm/s, topographically steered PIES Deployments:   ~2008  ~2009  PopUp releases 2007/8/9. Topex/Poseidon altimetry ground tracks and Smith&Sandwell bathymetry in background C-PIES #185 data from PopUp #06 at ANT11-2. Daily averages. Traveltime OBP near-bottom current Macrander, AWI 2007            ANT 11-2 Macrander, AWI 2007

AWI GRACE/GoodHope PIES array 2 PIES ANT 7,11 3 PIES 2005-~2008 ANT 5,7,9 6 PIES 2006-~2008 all  AWI Plans for PIES emergency exchange 4 PIES ~regular exchange + ≤3 PIES new deployments ~PopUps for 1 C-PIES and 4 PIES Vessels R/V Polarstern Feb 2008 – Good Hope section only, very tight schedule R/V G.O.Sars Feb 2008 – CPT↔ Bouvet. more time – if taking place R/V Meteor 2008 Montevideo – Ascension – CPT – too far north S.A.Agulhas – Gough relief? …NN ?? GoodHope/GRACE ACC array – PIES positions:  AWI array at T/P crossover points,  further T/P crossovers, no PIES at present  positions proposed by Mark Wimbush !!rec. 2008!! Macrander, AWI 2007