# Presentation: 134980

## 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/7 586-5, 63°S 52°W, 01 Oct 2006.

- Deployment of PIES + 2 PopUps. Polarstern
- ANT XXIII/7 537-1, 41°S 04°E, 29 Aug 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

*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.

## 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

- All 118 AWI Argo float deployments since 1999. Surface fixes shown on map.
- Large Panel: Color = Latitude. Floats # 36-118 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 1⁄2 years
-                 *Costs*: € 5000 per PopUp

- IrDA data link

- RV Polarstern, ANT XXIII/7, Deployment of PIES 537-1, 29.08.2006

## 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 2002-2005 correlated with GRACE, r = 0.69

## C-PIES timeseries retrieved from PopUp

- First successful PopUp operation:
- ANT11-2 (C-PIES185,PopUp06) at 50°S 01°E
- deployment 24.09.2007
- PopUp release 24.04.2007
-  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:  2002-2005  2005 - ~2008  2006 - ~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.

## AWI GRACE/GoodHope PIES array

- 2 PIES 2002-2005 ANT 7,11
- 3 PIES 2005-~2008 ANT 5,7,9
- 6 PIES 2006-~2008 all 
_**AWI Plans for 2008**_
- 5 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