SOUTHERN OCEAN SITE DESCRIPTIONS
Table of Contents
Site: Weddell Sea (Northwestern Station) ............................................................................................. 2
Site: Rothera Time Series (RaTS) .......................................................................................................... 11
Site: New Zealand Ocean Time Series .................................................................................................. 14
Site: Weddell Sea/Greenwich Meridian................................................................................................ 18
Site: Weddell Sea proper ..................................................................................................................... 24
Site: Weddell Sea Moorings .................................................................................................................. 29
Site : Agulhas Return Current Reference Station .................................................................................. 35
Version Tracking:
Creation/Update date
Updated By
August 2009
Hester Viola
September 2010
Hester Viola
1
Comments
www.oceansites.org
Site: Weddell Sea (Northwestern Station)
Position: ~62°S 44°W – 64°S 42°W
Categories: operating; transport; physical, bottom water
Safety distance for ship operations:
2 km
Short description:


3 moorings maintained since 1999, with CTD/tracer stations occupied at and between the mooring
sites when logistically feasible.
Variables measured :
Moorings: temperature, salinity, water velocities from the bottom to 500 m above bottom at
approximately 100 m intervals. Sampling rates vary from 7.5 to 30 minutes.
CTD/tracer: to within 10 m of the bottom at most stations. Water samples collected for analysis of
CFC, transient tracers

Start date of the timeseries, service interval:
Moorings first deployed 1999; serviced at intervals dictated by available vessel time and local
conditions [2000, 2001, 2005]
Scientific rationale:
The abyssal ocean is filled with cold, dense water that obtains it characteristics on the Antarctic
continental shelf and by mixing while sinking along the slope. Recent estimates of water mass
formation rates using CFC inventories suggest that a total of 8 Sv of Antarctic Bottom Water (AABW)
are formed [Orsi et al. 1999]. The Weddell Sea Gyre transports about 5 Sv of Deep and Bottom water
and thus contributes as much as 50% to the formation of AABW [e.g. Gordon et al. 2001, Fahrbach et
al. 1994, 1995, Meredith et al. 2001]. Streams of relatively low salinity Weddell Sea Deep Water with
temperature between 0° and -0.7°C are found along the outer rim of the Weddell Sea with varying
degree of oxygen saturation (Figure 1) [Gordon et al. 2001]. Between 1989 and 1998 Fahrbach et al.
[2001] deployed a current meter array east of Joinville Island which allowed for the first glimpse at
interannual variability in temperature, thickness and transport of the WSBW formed in the Weddell
gyre region. Starting in April 1999 LDEO/WHOI continued the time series at a down stream location
south of the South Orkney Islands with a small mooring array (Figure 2) [Visbeck et al. 2001]. This
location is easier to maintain since the sea ice covered season is shorter on average.
Groups / P.I.s /labs /countries involved / responsible:
The main effort is supported by LDEO (A. Gordon, W. Smethie, P. Schlosser). One mooring has
been instrumented by WHOI (Toole). Some of the hydrographic work has been carried out in
collaboration with a joint German/Brazilian program (Garcia, Hellmer). Funding has been received by
NOAA, and the field work was made possible by arrangement with the NSF Office of Polar Programs.
2
www.oceansites.org
Status:
The world's deep oceans are filled with water masses formed at the continental margins of Antarctica.
The Weddell Sea is a major source of these so-called Antarctic Deep and Bottom Waters. Relatively
warm, saline Circumpolar Deep Water (CDW) enters the Weddell Gyre to the east of the Greenwich
Meridian. As it traverses the gyre, it feeds bottom water-forming processes on the continental
shelves, and interacts with floating ice shelves to produce a variety of Weddell Deep and Bottom
water types.
This project maintains three deep and bottom water focused moorings south of the South Orkney
Islands in the Northwest Weddell Sea to provide a time series of the combined outflow (currents and
temperature/salinity) of Antarctic Deep and Bottom Water drawn from various sites within the Weddell
Sea. The moorings were initially installed and maintained as part of the NOAA-funded Consortium on
Oceans Role in Climate: AbRupt climate CHangE Studies (CORC-ARCHES) Southern Ocean Modern
Observations program.
Figure 1. Location of the Weddell Sea moorings (red dots) and repeat CTD/Tracer line (dashed line).
Shown schematically are the pathways of deep and bottom waters formed by interaction of WDW with
continental and ice shelf waters.
First installed in April 1999, the moorings have been serviced using ship time made available by other
programs, primarily through the National Science Foundation Office of Polar Programs (OPP), and
principal investigators funded by OPP who graciously allow our team to sail on their cruises. As time
and resources allow during the mooring maintenance cruises, oceanographic stations to collect
3
www.oceansites.org
profiles of conductivity, temperature and tracers (CTD/tracer) are occupied at the mooring sites and at
stations distributed along a line between the mooring locations (Figure 1). The cost of ship time
devoted to the mooring work and associated CTD/tracer stations, typically 3 to 5 days, has been
supported by funding from OCO.
More recently, ship time arrangements have been made with colleagues at the British Antarctic
Survey (BAS), governed by an Agreement of Cooperation between LDEO and BAS. The agreement
with BAS provides for sharing of equipment, personnel and data between LDEO and BAS to allow the
mooring sites to be serviced at nominally two-year intervals, with BAS providing the ship time to do
so. Our collaboration with BAS will continue, so this work is part of an international effort.
The most recent rotation of the moorings was achieved from the BAS vessel RRS Ernest Shackleton
in February-March 2007. The newest of the ARCHES moorings, M4, within the trough feeding Weddell
water into the Scotia Sea is now part of an enhanced array of moorings in the trough, using LDEO
and BAS equipment to better resolve this branch of bottom water spreading.
We now have time series of currents, temperature and salinity of the outflow of dense water from the
Weddell Sea spanning 8 years at M3 [Figure 2], which is positioned within the primary pathway of
outflow of dense Weddell water, and 6 years at M2. The M2 gap of 2005 and 2006 was due to lack of
ship time to re-deploy M2 after recovery in March 2005, but it has now been reinstalled in March 2007.
The time series reveals significant seasonal and interannual variability in the outflow of dense
Weddell Sea water. An annual pulse of the coldest bottom water at the mooring site is evident in the
May-July time frame, which suggests [from the mean bottom speed] export of shelf water into the
deep ocean at the upstream bottom water formation sites in the Dec-Feb period, i.e. austral summer
[a rather unexpected discovery]. However, the exact timing of the outflow events and their
temperature and salinity characteristics vary from year to year.
The extended time series will contribute to an understanding the processes that control the transport
and characteristics of the bottom waters that emanate from the Weddell Sea, as required to better
assess the reaction of the Southern Ocean meridional overturning circulation and associated deep
ocean ventilation to a warming climate. Research questions that could be pursued with the extended
Weddell Sea time series include: are there any ‘environmental’ conditions, e.g. wind, sea ice, Larsen
Ice shelf break-up, or climate oscillations such as the Antarctic Dipole, Southern Annular Mode, that
can account for the seasonal and interannual fluctuations observed in the bottom flow passing the
Weddell Mooring sites? How does the observed behavior of the Weddell MOC compare to model
output? How might the Weddell Sea MOC change with climate warming?
4
www.oceansites.org
Figure 2. M3 temperature and bottom speed time series.
Accomplishments
The performance period covered by this report is 1 July 2008 – 30 September 2008; no OCO funding
was received in FY2007. To date, we have completed all preparations for a cruise on RRS Ernest
Shackleton, to be carried out under a cooperative arrangement with colleagues at the British Antarctic
Survey (BAS) to continue servicing the Weddell moorings, and to expand the array in conjunction with
the BAS and other IPY programs in the region (Figure 3). The configuration of the joint LDEO-BAS
array of moorings is shown in Figure 4.
Data are archived and made available as they are recovered from the moorings at the project web
site: http://www.ldeo.columbia.edu/res/div/ocp/projects/corc.shtml
This web site will be upgraded during the next year.
A preliminary analysis of the time-series data collected to date will be presented at the 2008 Fall The
site has a nearly 8 year record [April 1999 to February 2007] of the currents and thermohaline
stratification within the lower ~500 m of the water column at a mooring (M3) at 4565 m depth, south of
the South Orkney Islands, positioned within the outflow of dense Weddell AABW. The time series
reveals significant seasonal and interannual variability. A pulse of the coldest bottom water is evident
in the May-July period, though the precise timing and duration varies with year. Intensification of the
near bottom stratification is observed as the bottom water attains its coldest values. The coldest
bottom events occurred in 1999 and 2002, while in 2000 it was absent. At bottom temperatures <0.8°C the salinity fluctuations produce a ‘fan-like’ appearance in T/S space suggesting a varied
source of dense shelf water. The coldest bottom water <-1.0°C is relatively salty indicating a source in
the southwest Weddell Sea, about 1300 km along isobaths to the mooring site. The typical bottom
speed at M3 of 10-15 cm/sec implies a shelf water export time during the austral summer. A record at
5
www.oceansites.org
a second mooring (M2) at 3059 m depth displays a much reduced annual cycle, but it too records a
relatively warm period in 2000. Correlations of the M3 time series with NINO3.4 and SAM suggest
that these indices lead M3 on the order of 14-20 months, implying a likely relationship between the
water mass and surface forcing. Both M3 and M2 were reinstalled in March 2007.
Figure 3. Planned mooring recovery/redeployment activities during RRS Ernest Shackleton cruise
scheduled for Jan-Mar 2009.
6
www.oceansites.org
Figure 4. Weddell mooring configurations and positions. RCM current meters will gradually be
replaced with acoustic current meters. Additionally, new temperature and temperature/salinity
recorders are purchased in off-field years and phased into the mooring array to allow for return and
recalibration of older units.
Technology:
The ongoing program has two elements: A repeat hydrographic section across the northwestern
Weddell gyre outflow including observations of trace elements (CFCs and Tritium/Helium) and an
array of three moorings. Two of them are equipped with nominally two current meters, two TS
recorder and several T recorders covering a 500m thick layer above the sea floor. The third mooring
consists of a profiling CTD and current meter package which is capable of obtaining a 1000m long
profile every other day. All moorings have internal recording only and it is not feasible to add
7
www.oceansites.org
telemetry due to heavy sea ice.
Data policy:

delayed mode data: The mooring and CTD data are available to the public in delayed mode, to
allow for preliminary processing of the data prior to public release. All available data can be
accessed from the project web site.
Data management: Under development.
Societal value / Users / customers:
The site is perfect to document changes in rates and types of bottom waters formed in the Weddell
Sea. Even subtle changes in the climate system would be detectable and at some point can be
compared with climate model solution. Note, however, that this is a region of the world where climate
model simulations are quite inadequate. At this point assessments of the state of the global climate
systems, such as the IPCC process are our customers.
Role in the integrated global observing system:
The global observing system is very thin in the Southern Hemisphere. Seasonal sea ice cover and its
rather high latitude limit the amount of information that can be gained by space based measurements.
Thus sites like this one contribute crucial and unique information that will be hard to get any other
way.
Contact Person:


for enquiry about addition of instrumentation or sensors to the site or for possible ancillary
measurements during cruises to the site:
Prof Arnold Gordon
(agordon@ldeo.columbia.edu)
for information about the site or data :
Bruce Huber (bhuber@ldeo.columbia.edu)
Links / Web-sites:


for Project information :
for data access :
http://www.ldeo.columbia.edu/res/div/ocp/projects/corc.shtml
http://www.ldeo.columbia.edu/res/div/ocp/projects/corc.shtml
compiled/ updated by: Bruce Huber (January 2009)
8
www.oceansites.org
Figure 1:
Potential
temperature
section
south of the South Orkney Islands
with the location of the mooring
array
superimposed.
Inset:
Bathymetric map of the Weddel
Sea Gyre indicating the position of
several streams of newly formed
Weddell Sea Bottom Water
[Gordon et al. 2001] and the
CORC/ARCHES repeat section
and mooring array
[reproduced from Visbeck et al,
2001].
9
www.oceansites.org
Figure 2: Potential temperature time series as obtained from repeat hydrographic sections in the
northwestern Weddell gyre. Diamonds denote the mean temperature between 2600 and 3200 m
water depth near 62.5°S 43.5°W (near M2). Squares denote the mean temperature between 4000
and 4600 m water depth near 63.5°S 42.0°W (near M3). The bars covers the total range of observed
temperatures. The thin gay lines represent the 40h low pass filtered temperatures averaged over all
sensors at mooring M2 and M3 respectively. The stars are the plume mean temperatures from
Fahrbach et al. (2001) at their upstream array location. The solid line connects the plume mean with
the coldest temperature found during each survey [reproduced from Visbeck et al, 2001].
10
www.oceansites.org
Site: Rothera Time Series (RaTS)
Position: Marguerite Bay (67S, 68W), on the western Antarctic Peninsula
Categories: physical, biogeochemical, biological
Safety distance for ship operations:
There is often a mooring deployed at the RaTS site to augment the quasi-weekly CTD profiling and
sampling. Vessels should thus avoid working around the RaTS site to a distance of at least 1nm,
without having previously checked whether a mooring is in place.
Short description:


1 repeat CTD station, plus associated sampling for biogeochemical/biological variables
Variables measured :
 CTD (temperature, conductivity, depth) profiling to ~450m
 Photosynthetically-active radiation profiled to ~450m
 Fluorescence profiled to ~450m
 Oxygen Isotopes sampled at 15m
 Chlorophyll sampled at 15m
 Nutrients sampled at 15m
 Other biological parameters sampled at 15m
Start date of the timeseries, service interval: Started late 1997; repeat measurements ~weekly,
subject to ice. (Profiling through hole cut in ice in winter).
Ancillary measurements. Through collaborations and soft funding, we periodically are able to deploy
a mooring at the RaTS site to augment the quasi-weekly CTD profiling and sampling. This typically
features sediment traps, upward-looking ADCP, moored CTDs, moored current meters, and
temperature loggers.
Scientific rationale:
Antarctica as a whole is unusual in having a very deep continental shelf with relatively little freshwater
or sediment input from rivers. It is, however, highly influenced by oceanographic processes
associated with both surface ice and continental shelf ice. The Antarctic coastal marine system
exhibits a marked seasonality, and also variability on a range of scales from interannual to
Milankovitch. The RaTS site is towards the southern end of the Antarctic Peninsula, a region which
has seen among the highest rates of regional climatic warming of the past 50 years. As the time
series continues, we will be able to investigate the role of oceanographic variability on a range of
timescales and its influence on the Antarctic marine ecosystem. We have already discerned the
impact of ENSO variability on the physical ocean system, and are currently tracking its progression
through the associated biogeochemical and ecological system. These ongoing measurements are
needed to discern the evolution of the interdisciplinary marine environment in a region of rapid climate
change.
11
www.oceansites.org
Groups / P.I.s /labs /countries involved / responsible:
Mike Meredith (BAS, UK) for physics
Andrew Clarke (BAS, UK) for biogeochemistry and biology
Status:


Ongoing
funding provided to the British Antarctic Survey by the UK Natural Environment Research Council
as part of BAS's Long-Term Monitoring and Survey remit (LTMS)
Technology:
CTD and Niskin bottle sampling from small boat in Antarctic summer. When ice-covered, the sampling
site is measured by cutting a hole through the ice, and conducting sledge-based profiling and
sampling. A fixed mooring is periodically deployed at the RaTS site, through collaborations and soft
funding bids.
Data policy:
delayed mode data: public (available on request)
Data management:
At present, profile data are relayed to UK by satellite (email). Some discrete samples analysed on
base at Rothera Research Station; others returned to UK annually for laboratory analysis. Data are
quality controlled at BAS, and lodged with the British Oceanographic Data Centre (BODC) for
archiving and distribution - http://bodc-nerc.blogspot.com/2008/10/rothera-time-series-rats-data.html.
Typically, data are available for up to 1 year behind present, since cal/val is applied annually to most
measurements.
Contact Person:
Mike Meredith (physics, CTD, oxygen isotopes)
Andrew Clarke (biology, biogeochemistry)
Links / Web-sites:

for Project information : some brief description on
http://www.soc.soton.ac.uk/JRD/HYDRO/drake/rats.php
A more up-to-date website is being developed.
compiled / updated by: Mike Meredith (December 2004; revised December 2008).
12
www.oceansites.org
Figure: Temporal progression of the upper-layer temperature at the RaTS site, for the period 19982006. Note, in particular, the very deep mixed layers in the austral winters of 1998 and 2003, caused
by the ENSO events that were then decaying. Data coverage extends up to present date.
13
www.oceansites.org
Site: New Zealand Ocean Time Series
Position: 41.2 S 178.5 E and 46.6 S 178.5 E
Categories: Observatory for physical, meteorological, biogeochemical measurements, CO2, particle
flux, chlorophyll
Safety distance for ship operations: 10 n miles
Short description:

2 moorings:
subtropical waters (STM) 41.2 S 178.5 E;
subantarctic waters (SAM) 46.6 S 178.5 E

Variables measured :
 70 m depth (irradiance (10 minute mean), chlorophyll fluorescence (10 minute mean),
temperature (hourly), salinity (hourly); temperature and salinity only at STM.
 90 m depth CO2 (ten minute mean) at SAM only
 100-150 m depth current speed and direction (10 minute mean), temperature (hourly), salinity
(hourly);
 1500 m depth downward particle flux (mass flux, POC, PIC, opal, PON) every 5-15 days,
current speed and direction (10 minute mean), temperature (hourly).
 3100 m depth current speed and direction (10 minute mean), temperature (hourly) at STM only
 Start date of the timeseries, service interval:
The moorings have been deployed since October 2000. They were serviced every 4 months up
until 2005 and have been turned around every 6-8 months since this time. During each servicing
voyage, additional data are also collected (underway nutrients, deep CTD casts, plankton, ADCP,
etc).
Scientific rationale:
The location of the Subtropical Front or Convergence, east of New Zealand, provides the opportunity
to obtain detailed time-series data in each of two distinct waters masses - subtropical and
subantarctic waters. In particular, these water masses exhibit different biological signals, with
subtropical waters characterised by a classical spring and autumn phytoplankton bloom cycle,
whereas subantarctic waters are perennially High Nitrate-Low Chlorophyll due to low dissolved iron
concentrations.
Our two identical moorings were designed to examine the degree of coupling between pelagic and
deep water events in each of these water masses. We can assess if this coupling is stronger in the
more productive subtropical waters relative to the subantarctic water mass. The latter, comprises a 10
degree N-S circumpolar ring and thus represents around 50% of the ice-free waters of the Southern
Ocean. Thus, the data from the subantarctic water mooring will be of particular interest to the
Southern Ocean biogeochemical community.
Groups / P.I.s /labs /countries involved / responsible:
The Ocean Ecosystems group at NIWA (NZ) runs the moorings with Craig Stewart, Steve Chiswell
14
www.oceansites.org
and Phil Sutton responsible for the mooring design and physical instrumentation, Scott Nodder for the
deepwater traps, Philip Boyd for the bio-optical instruments, and Kim Currie for the SAMI pCO2
sensor. We have close links with other NIWA groups working on Ocean Colour (Matt Pinkerton). We
have links with other Southern Ocean mooring groups from Australia (Tom Trull, Bronte Tilbrook).
Status:



operating
long-term plans
funding status, source of funding: New Zealand
Technology:



deep-moored sensors
data downloaded every 4 months up until 2005, now every 6-8 months
SST measurements: Seabird MicroCATs on mooring
Data policy:

delayed mode data: not public at present – data dissemination via publications (Nodder et al.
2005)
Data management: internal at present – to be discussed later in 2009
Societal value / Users / customers:
Through assessment of the annual cycles of phytoplankton stocks and export of carbon to depth we
are able to provide data to other New Zealand end-users on seasonal and interannual variability of
these properties that will determine the carry capacity of local waters, and their ability to sequester
carbon. We also have links with other groups with moorings in Southern Ocean waters (CSIRO) and
can thus compare our findings at various sites in subantarctic waters.
Role in the integrated global observing system:
Contact Person: Scott Nodder/ Philip Boyd (s.nodder@niwa.co.nz, p.boyd@niwa.co.nz )
Links / Web-sites: http://www.agu.org/pubs/crossref/2005/2004JC002833.shtml - paper by Nodder et
al., summarising the first year of the mooring deployments (2000-2001).
Compiled / updated by: Scott Nodder (January 2009)
15
www.oceansites.org
Figure 1: Spring bloom, October 2000 (ref: SeaWiFS, NASA, Orbimage with processing by NIWA).
The waters east of New Zealand are a natural laboratory to study Subantarctic (SA), Subtropical (ST)
and Subtropical Front/Convergence (STC) waters. The SA “ring” comprises 50% of the open
Southern Ocean.
Figure 2: Location of NZs two deep-ocean biophysical moorings: STM and SAM in subtropical (STW)
and subantarctic (SAW) waters, respectively. The mean annual sea surface temperature field is
superimposed in the background with the 500 m bathymetric contour also shown. STW, Subtropical
Water; SAW, Subantarctic Water; STF, Subtropical Front; EAUC, East Auckland Current; ECC, East
Cape Current; SC, Southland Current; WCC, Wairarapa Coastal Current; and WE, Wairarapa Eddy.
[Copyright: American Geophysical Union, 2005; ref: S.D. Nodder, P.W. Boyd, S.M. Chiswell, M.H.
Pinkerton, J.M. Bradford-Grieve, M.J.N. Greig (2005). Temporal coupling between surface and deep
ocean biogeochemical processes in contrasting subtropical and subantarctic water masses,
southwest Pacific Ocean, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, C12017,
doi:10.1029/2004JC002833, 2005].
16
www.oceansites.org
17
www.oceansites.org
Site: Weddell Sea/Greenwich Meridian
Position: 59°S 0° to 69°S 0°
Categories: operating; Observatory, Transport; physical, sea ice
Safety distance for ship operations: subsurface moorings 2 nm from each mooring
Short description:



5 moorings (positions see table 1)
Variables measured: currents, T, S, p, sea ice (for details see table 1)
Start date of the time series, service interval: First deployment 1996. Last redeployment in 2008.
The available mooring technology allows three year mooring periods. The required ship time is
provided by AWI with the icebreaking research vessel “Polarstern.”
Scientific rationale:
On the Greenwich Meridian water masses enter the formation areas of bottom water from the east,
newly formed bottom water fills the basin from the west and Maud Rise represents a topographic
feature which has the potential to induce the formation of a large polynya with consequent deep water
formation in the open ocean. Therefore the Greenwich Meridian is a key area where the status of the
Weddell Sea as a water mass formation area can be monitored
The measurements consist of large scale hydrographic sections with a repeat cycle between 2 and 4
years and moored instruments to avoid effects of alising. The observed parameters are used to
estimate water mass properties and transports are temperature, salinity, CO 2, CFCs, currents and ice
thickness. The moored observing system is maintained in the Weddell Sea Convection Control
(WECCON) project since 1996 with minor modifications. Current meter moorings were exchanged in
1998, 1999, 2001, 2003, 2005 and 2008. A redeployment is planned for the austral summer
2010/2011. The moorings are mainly equipped with current meters, temperature and conductivity
sensors (Tab.1). The mooring work occurs in cooperation with the University Bergen, Norway.
Additional to the moorings, vertically profiling floats are deployed in the context of the Argo programme.
The moorings carry sound sources for RAFOS location of the floats. Upward looking sonars in 150 m
depth are installed on 4 moorings in the framework of WCRP’s Antarctic Sea-Ice Thickness Project
(AnSITP) to determine the sea ice transports (http://www.awi-bremerhaven.de/Research/IntCoop/Oce
/ansitp/index.html). In 1996, 1998, 1999, 2001, 2003, 2005, 2008 hydrographic surveys were carried
out along the Greenwich Meridian with a CTD-probe (Conductivity/Temperature/Depth) combined with
a rosette water sampler). A repeat of this transect is planned for 2010/2010. The continuation is
envisaged.
To monitor the ACC transports a series of PIES is deployed In a final state 8 PIES will be located along
a Jason track from the northern end of the mooring line toward South Africa.
Groups / P.I.s /labs /countries involved / responsible:
Eberhard Fahrbach and Olaf Boebel (Alfred-Wegener-Institut für Polar- und Meeresforschung)
Status:



operating
time horizon / long-term plans: funding assured until 2010/2011
funding status, source of funding: The project is part of the Southern Ocean research project of the
Alfred-Wegener-Institut für Polar- und Meeresforschung within the framework of the PACES
18
www.oceansites.org
Programme of the Helmholtz-Gemeinschaft Deutscher Forschungszentren.
Technology:



moored sensors see Tab. 1
SST measurements: only during CTD transects.
Profile measurements: In the moorings only point measurements in different levels see Tab. 1.
Data policy:

delayed mode data: available after recovery, processing and evaluation
Data management:


Metadata scheme : See AWI data bank and CLIVAR data system
Possibilities of evolution to comply with a more general JCOMM GTS scheme: Installation of
profilers to allow quasi real time data transfer according technical feasibility and funding.
Societal value / Users / customers: Science
Role in the integrated global observing system:
The moorings provide data to monitor the status of a significant water mass formation area. However,
they are very much influenced be the local conditions. Therefore, repeat hydrography has to cover a
larger area to extend the observations over different water mass regimes. The repeat sequence of 2
to 4 years includes a large risk by aliasing and can not replace the moored instruments. We expect
that the moorings will be part of the Southern Ocean Observing System (SOOS). The focus and
related to that the location might shift towards the acoustic float tracking for which the location of the
sound sources might need to be adapted.
Contact Person: Gerd Rohardt: Gerd.Rohardt@awi.de
Links / Web-sites:

for Project information:
Eberhard Fahrbach (Eberhard.Fahrbach@awi.de)

for data access : Gerd.Rohardt@awi.de
Compiled / updated by : Eberhard Fahrbach (March 2009)
19
www.oceansites.org
227
0
229
230
231
232
1000
Depth (m)
2000
3000
4000
Aanderaa Current Meter
SBE CT or CTD
LongRanger ADCP
CMR Upward Looking Sonar
String of SBE CT-Sensors
5000
Sound Source
52
54
56
58
60
62
64
66
68
S 70
Latitude
Figure
Moorings deployed in February 2008 along the Greenwich Meridian.
Table 1 Moorings deployed on the Greenwich meridian
Mooring
Latitude
Water
Depth
Longitude
Date
Instrument
Serial
Instrument
Time
Type
Number
Depth
(m)
1. Record
AWI232-9
20
68° 59.74’ S
3419
11.03.2008
(m)
ULS
57
150
www.oceansites.org
00° 00.17’ E
AWI231-8
66° 30.68’ S
14:00
4546
00° 01.81’ W
AWI230-6
66° 01.13’ S
00° 04.77’ E
21
3577
AURAL
085
366
ADCP
6240
450
AVT
9782
750
RCM 11
144
1800
SBE37
2086
3300
RCM 11
486
3300
07.03.2008
ULS
56
150
22:00
SBE37
1236
200
SBE37
449
300
SBE37
2088
400
ADCP
825
450
SBE37
2089
500
SBE37
2090
600
SBE37Pu
1237
700
AVTP
10928
700
SQ
30
850
AVT
9180
1800
SBE37
237
4500
AVT
9186
4500
08.03.2008
AVTP
3517
200
14:00
SBE37Pu
1229
200
SBE37
2091
300
SBE37
2092
400
SBE37
2093
500
SBE37
2094
600
SBE37Pu
2237
700
RCM 11
295
700
AVTP
9188
1600
SBE37
2099
3400
www.oceansites.org
AWI229-8
63° 58.03’ S
5195
00° 003.10’ W
AWI227-10
59° 04.10’S
00° 04.88’ W
4630
RCM 11
504
3400
28.02.2008
ULS
64
150
18:00
SBE 37
2098
200
SBE37
2096
300
ADCP
5373
350
SBE16
2416
400
SBE37
2099
500
SBE37
2100
600
SBE37Pu
2396
700
AVTP
10925
704
SQ
29
850
AVT
9390
2000
SBE37
2101
5150
AVT
10499
5150
SBE37P10
1565
4580
25.02.2008
14:00
Abbreviations:
ADCP
RD-Instruments, Self Contained Acoustic Doppler Current Profiler
AVTCP
Aanderaa Current Meter with Temperature-, Conductivity-, and Pressure Sensor
AVTP
Aanderaa Current Meter with Temperature- and Pressure Sensor
AVT
Aanderaa Current Meter with Temperature Sensor
RCM 11
Aanderaa Doppler Current Meter
SBE16P#
SeaBird Electronics intern recording CTD measuresTemperature, Conductivity, and
Pressure, Type: Seacat; P# indicates the Depth Rating, e.g. P1 up to 1000psi or P3
up to 3000psi
ULS
Upward Looking Sonar; Christian Michelsen Research Inc.
SBE26
SeaBird Electronics to measure the Bottom Pressure
SBE37
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
SBE37Pu
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
including external Pump
SBE37PuP#
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
22
www.oceansites.org
including external Pump and Pressure Sensor; P# indicates the Depth Rating, e.g. P3
up to 3000psi or P7 up to 7000psi and P35 for 3500 dbar
SQ
Sound Source for SOFAR-Floats
SR
Sound Recorder
23
www.oceansites.org
Site: Weddell Sea proper
Position: 63° 28.77’ S 52° 05.77’ W to 68° 59.70’ S 06° 56.70’ W
Categories: operating; Observatory; physical, sea ice
Safety distance for ship operations: subsurface moorings 2 nm from each mooring
Short description:



8 moorings
Variables measured: currents, T, S, p, sea ice (for details see table 1)
Start date of the timeseries, service interval:
First deployment 1989. Interruption 1996 until 2005. Last redeployment in 2008.
The available mooring technology allows two year mooring periods. The required ship time is
provided by AWI with the icebreaking research vessel “Polarstern.”
Scientific rationale:
In the Weddell Sea proper newly formed bottom and deep water is accumulated and provides a
naturally low passed record of the time history of bottom and deep water formation. Additionally the
Weddell Sea proper represents particular ice conditions which are supposed to be representative for
the Atlantic sector of the Antarctic Ocean.
The measurements consist of large scale hydrographic sections with a repeat cycle between 2 and 4
years and moored instruments to avoid effects of alising. The observed parameters are used to
estimate water mass properties and transports are temperature, salinity, CO 2, CFCs, currents and ice
thickness. The moored observing system is maintained in the Weddell Sea Convection Control
(WECCON) project since 1996 with various modifications. Current meter moorings were redeployed
in 2005 after a break in 1996 and redeployed in larger number in 2008. A redeployment is planned for
the austral summer 2010/2011. The moorings are equipped with current meters, temperature and
conductivity sensors and some with bottom pressure recorders (Tab.1). Additional to the moorings,
vertically profiling floats are deployed in the context of the ARGO programme. The moorings carry
sound sources for RAFOS location of the floats. Upward looking sonars in 150 m depth are installed
in the framework of WCRP’s Antarctic Sea-Ice Thickness Project (AnSITP) to determine the sea ice
transports. In 1989, 1990, 1993, 1996, 1998, 2005, 2008 hydrographic surveys were carried out in the
Weddell Sea with a CTD-probe (Conductivity/Temperature/Depth) combined with a rosette water
sampler). A repeat of this transect is planned for 2010/2011. The continuation is envisaged.
Groups / P.I.s /labs /countries involved / responsible:
Eberhard Fahrbach (Alfred-Wegener-Institut für Polar- und Meeresforschung)
Status:



operating
time horizon / long-term plans: Funding assured until 2010/2011. It is planned to maintain the
measurements to quantify decal variability.
funding status, source of funding:
24
www.oceansites.org
The project is part of the Southern Ocean research project of the Alfred-Wegener-Institut für Polarund Meeresforschung within the framework of the PACES Programme of the HelmholtzGemeinschaft Deutscher Forschungszentren.
Technology:



moored sensors see Tab. 1
SST measurements: only during CTD transects.
Profile measurements: In the moorings only point measurements in different levels see Tab. 1.
Data policy:

delayed mode data: data available after recovery, processing and evaluation.
Data management:


Metadata scheme: See Pangaea WDC-D and CLIVAR data system
Possibilities of evolution to comply with a more general JCOMM GTS scheme : Installation of
profilers to allow quasi real time data transfer according technical feasibility and funding.
Societal value / Users / customers: Science
Role in the integrated global observing system:
The moorings provide data to monitor the status of a significant water mass formation area. However,
they are very much influenced be the local conditions. Therefore, repeat hydrography has to cover a
larger area to extend the observations over different water mass regimes. The repeat sequence of 2
to 4 years includes a large risk by aliasing and can not replace the moored instruments. We expect
that the moorings will be part of the Southern Ocean Observing System (SOOS). The focus and
related to that the location might shift towards the acoustic float tracking for which the location of the
sound sources might need to be adapted.
Contact Person: Gerd Rohardt: Gerd.Rohardt@awi.de
Links / Web-sites:

for Project information:
Eberhard Fahrbach (Eberhard.Fahrbach@awi.de)

for data access : Gerd.Rohardt@awi.de
Compiled / updated by : Eberhard Fahrbach (March 2009)
25
www.oceansites.org
206 207 216
0
217
208
209
500
1000
Depth (m)
1500
2000
2500
3000
3500
Aanderaa Current Meter
SBE CT or CTD
LongRanger ADCP
CMR Upward Looking Sonar
Joinville I.
4000
4500
Sound Source
to Kapp Norvegia
5000
0
200
400
600
800
Distance (nm)
Figure 1
Moorings deployed in March 2008 in the Weddell Sea.
Table 1 Moorings deployed along transect from Kapp Norvegia towards Joinville Island
Mooring
Latitude
Water
Depth
Longitude
Date
Instrument
Serial
Instrument
Time
Type
Number
Depth
(m)
1. Record
AWI244-1
68° 59.70’ S
2927
06° 56.70’ W
AWI245-1
69° 03.68’ S
26
66° 36.89’ S
SQ
23
850
SQ
24
850
SBE 16
2415
300
16:00
4466
17° 25.89’ W
AWI209-5
13.03.2008
(m)
15.03.2008
16:00
4864
18.03.2008
www.oceansites.org
27° 07.08’ W
AWI208-5
6° 36.85’ S
20:00
4770
36° 24.43’ W
AWI217-3
64° 23.63’ S
4456
45° 52.38’ W
AWI216-3
63° 54.03’ S
3516
49° 04.68’ W
AWI207-7
63° 42.74’ S
2500
50° 50.55’ W
AWI206-6
63° 28.77’ S
52° 05.77’ W
27
950
SQ
34
800
SBE37P
220
4800
SBE37
230
4850
21.03.2008
ULS
62
150
16:00
ADCP
3813
300
SBE16
1979
300
SBE37
435
4680
SBE37
2234
4730
24.03.2008
SQ
32
850
14:00
SBE37
250
4150
SBE37
240
4350
RCM 11
296
4351
26.03.2008
SBE37
2392
3350
16:00
SBE37
2393
3400
SBE37
439
3450
RCM 11
298
3451
27.03.2008
ULS
60
150
20:00
AVTP
10872
250
SBE 16
2414
251
AVT
10503
750
SQ
36
850
SBE37
2610
2100
SBE37
2297
2200
AVT
10530
2300
SBE37
436
2490
RCM 11
619
2490
ULS
61
150
AVTP
9206
250
SBE37
1228
500
www.oceansites.org
AVT
9201
501
SBE16
2422
700
SBE37
438
900
RCM 11
508
901
Abbreviations:
AVTCP
Aanderaa Current Meter with Temperature-, Conductivity-, and Pressure Sensor
AVTP
Aanderaa Current Meter with Temperature- and Pressure Sensor
AVT
Aanderaa Current Meter with Temperature Sensor
RCM 11
Aanderaa Doppler Current Meter
SBE16P#
SeaBird Electronics intern recording CTD measuresTemperature, Conductivity, and
Pressure, Type: Seacat; P# indicates the Depth Rating, e.g. P1 up to 1000psi or P3
up to 3000psi
ULS
Upward Looking Sonar; Christian Michelsen Research Inc.
SBE26
SeaBird Electronics to measure the Bottom Pressure
SBE37
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
SBE37Pu
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
including external Pump
SBE37PuP#
SeaBird Electronics, Type: MicroCat, to measure Temperature and Conductivity
including external Pump and Pressure Sensor; P# indicates the Depth Rating, e.g. P3
up to 3000psi or P7 up to 7000psi and P35 for 3500 dbar
SQ
Sound Source for SOFAR-Floats
SR
Sound Recorder
28
www.oceansites.org
Site: Weddell Sea Moorings
Description:
The world's deep oceans are filled with water masses formed at the continental margins of Antarctica.
The Weddell Sea is a major source of these so-called Antarctic Deep and Bottom Waters. Relatively
warm, saline Circumpolar Deep Water (CDW) enters the Weddell Gyre to the east of the Greenwich
Meridian. As it traverses the gyre, it feeds bottom water-forming processes on the continental
shelves, and interacts with floating ice shelves to produce a variety of Weddell Deep and Bottom
water types.
This project maintains three deep and bottom water focused moorings south of the South Orkney
Islands in the Northwest Weddell Sea to provide a time series of the combined outflow (currents and
temperature/salinity) of Antarctic Deep and Bottom Water drawn from various sites within the Weddell
Sea. The moorings were initially installed and maintained as part of the NOAA-funded Consortium on
Oceans Role in Climate: AbRupt climate CHangE Studies (CORC-ARCHES) Southern Ocean Modern
Observations program.
Figure 1. Location of the Weddell Sea moorings (red dots) and repeat CTD/Tracer line (dashed line).
Shown schematically are the pathways of deep and bottom waters formed by interaction of WDW with
continental and ice shelf waters.
First installed in April 1999, the moorings have been serviced using ship time made available by other
programs, primarily through the National Science Foundation Office of Polar Programs (OPP), and
principal investigators funded by OPP who graciously allow our team to sail on their cruises. As time
and resources allow during the mooring maintenance cruises, oceanographic stations to collect
profiles of conductivity, temperature and tracers (CTD/tracer) are occupied at the mooring sites and at
29
www.oceansites.org
stations distributed along a line between the mooring locations (Figure 1). The cost of ship time
devoted to the mooring work and associated CTD/tracer stations, typically 3 to 5 days, has been
supported by funding from OCO.
More recently, ship time arrangements have been made with colleagues at the British Antarctic
Survey (BAS), governed by an Agreement of Cooperation between LDEO and BAS. The agreement
with BAS provides for sharing of equipment, personnel and data between LDEO and BAS to allow the
mooring sites to be serviced at nominally two-year intervals, with BAS providing the ship time to do
so. Our collaboration with BAS will continue, so this work is part of an international effort.
The most recent rotation of the moorings was achieved from the BAS vessel RRS Ernest Shackleton
in February-March 2007. The newest of the ARCHES moorings, M4, within the trough feeding Weddell
water into the Scotia Sea is now part of an enhanced array of moorings in the trough, using LDEO
and BAS equipment to better resolve this branch of bottom water spreading.
We now have time series of currents, temperature and salinity of the outflow of dense water from the
Weddell Sea spanning 8 years at M3 [Figure 2], which is positioned within the primary pathway of
outflow of dense Weddell water, and 6 years at M2. The M2 gap of 2005 and 2006 was due to lack of
ship time to re-deploy M2 after recovery in March 2005, but it has now been reinstalled in March 2007.
The time series reveals significant seasonal and interannual variability in the outflow of dense
Weddell Sea water. An annual pulse of the coldest bottom water at the mooring site is evident in the
May-July time frame, which suggests [from the mean bottom speed] export of shelf water into the
deep ocean at the upstream bottom water formation sites in the Dec-Feb period, i.e. austral summer
[a rather unexpected discovery]. However, the exact timing of the outflow events and their
temperature and salinity characteristics vary from year to year.
The extended time series will contribute to an understanding the processes that control the transport
and characteristics of the bottom waters that emanate from the Weddell Sea, as required to better
assess the reaction of the Southern Ocean meridional overturning circulation and associated deep
ocean ventilation to a warming climate. Research questions that could be pursued with the extended
Weddell Sea time series include: are there any ‘environmental’ conditions, e.g. wind, sea ice, Larsen
Ice shelf break-up, or climate oscillations such as the Antarctic Dipole, Southern Annular Mode, that
can account for the seasonal and interannual fluctuations observed in the bottom flow passing the
Weddell Mooring sites? How does the observed behavior of the Weddell MOC compare to model
output? How might the Weddell Sea MOC change with climate warming?
30
www.oceansites.org
Figure 2. M3 temperature and bottom speed time series.
Accomplishments
The performance period covered by this report is 1 July 2008 – 30 September 2008; no OCO funding
was received in FY2007. To date, we have completed all preparations for a cruise on RRS Ernest
Shackleton, to be carried out under a cooperative arrangement with colleagues at the British Antarctic
Survey (BAS) to continue servicing the Weddell moorings, and to expand the array in conjunction with
the BAS and other IPY programs in the region (Figure 3). The configuration of the joint LDEO-BAS
array of moorings is shown in Figure 4.
Data are archived and made available as they are recovered from the moorings at the project web
site: http://www.ldeo.columbia.edu/res/div/ocp/projects/corc.shtml
This web site will be upgraded during the next year.
A preliminary analysis of the time-series data collected to date will be presented at the 2008 Fall AGU
meeting:
Eight Year time series of the outflow of Weddell Sea Bottom water
Arnold L. Gordon, Bruce A. Huber, Darren McKee, Xiaojun Yuan
Lamont-Doherty Earth Observatory of Columbia University
We present a nearly 8 year record [April 1999 to February 2007] of the currents and thermohaline
stratification within the lower ~500 m of the water column at a mooring (M3) at 4565 m depth, south of
the South Orkney Islands, positioned within the outflow of dense Weddell AABW. The time series
reveals significant seasonal and interannual variability. A pulse of the coldest bottom water is evident
in the May-July period, though the precise timing and duration varies with year. Intensification of the
near bottom stratification is observed as the bottom water attains its coldest values. The coldest
bottom events occurred in 1999 and 2002, while in 2000 it was absent. At bottom temperatures <0.8°C the salinity fluctuations produce a ‘fan-like’ appearance in T/S space suggesting a varied
31
www.oceansites.org
source of dense shelf water. The coldest bottom water <-1.0°C is relatively salty indicating a source in
the southwest Weddell Sea, about 1300 km along isobaths to the mooring site. The typical bottom
speed at M3 of 10-15 cm/sec implies a shelf water export time during the austral summer. A record at
a second mooring (M2) at 3059 m depth displays a much reduced annual cycle, but it too records a
relatively warm period in 2000. Correlations of the M3 time series with NINO3.4 and SAM suggest
that these indices lead M3 on the order of 14-20 months, implying a likely relationship between the
water mass and surface forcing. Both M3 and M2 were reinstalled in March 2007.
Figure 3. Planned mooring recovery/redeployment activities during RRS Ernest Shackleton cruise
scheduled for Jan-Mar 2009.
32
www.oceansites.org
Figure 4. Weddell mooring configurations and positions. RCM current meters will gradually be
replaced with acoustic current meters. Additionally, new temperature and temperature/salinity
recorders are purchased in off-field years and phased into the mooring array to allow for return and
recalibration of older units.
Contact person:
Project Manager: Bruce A. Huber
Senior Staff Associate
Lamont-Doherty Earth Observatory
of Columbia University;
61 Route 9W
Palisades, NY 10964-8000
tele: 845 365-8329
fax: 845 365-8157
bhuber@ldeo.columbia.edu
33
www.oceansites.org
Co-Investigator: Arnold L. Gordon
Professor of Oceanography
Lamont-Doherty Earth Observatory
of Columbia University;
61 Route 9W
Palisades, NY 10964-8000
tele: 845 365-8325
fax: 845 365-8157
agordon@ldeo.columbia.edu
34
www.oceansites.org
Site : Agulhas Return Current Reference Station
Project Name: NOAA PMEL Ocean Climate Stations (OCS)
Position: Nominally 38.5S, 30E
Equatorward of Agulhas Return Current
Categories: Air-Sea Flux, Observatory; meteorological, physical, biogeochemical
Safety distance for ship operations: 5 nm (9 km)
Short description:








1 surface buoy with slackline (reverse catenary) mooring
Variables measured:
Surface: wind speed and direction (from a sonic anemometer), air temperature, relative
humidity, rain, shortwave and longwave radiation, 1m sea surface temperature and
salinity, barometric pressure; air and sea surface pCO2.
Subsurface temperature at 25m. Subsurface sensors will increase after first year, pending
funding.
Ocean currents at 15 m
All physical measurements are recorded at least every 10 minutes. Carbon
measurements are every 3 hours.
Start date of the time series: planned for Oct 2010-11-1
Service interval: once per year
Scientific rationale:
Similar to the Kuroshio Extension Observatory (KEO), the planned Agulhas Return
Current (ARC) reference station will be located just equatorward of a western
boundary current extension, where heat, carried poleward by the western boundary
current is lost to the atmosphere. As such, both are in regions of intense air-sea
interactions. The planned ARC station woold contribute to large collaborative
process studies and have strong international partners. Funding is initially through
NSF to expedited the deployment of ARC to coincide with the NSF-funded Agulhas
Current Transport experiment, led by Dr. Beal (RSMAS). Longterm NOAA funding is
pending. Shiptime for ARC is being provided through the Agulhas and Somali
Current Large Marine Ecosystem (ASCLME) project. For phase 1, the ARC mooring
would carry a reduced suite of sensors to monitor air-sea heat, moisture,
momentum, and CO2 fluxes, surface temperature and salinity and near-surface
35
www.oceansites.org
currents. In phase 2, additional subsurface sensors will be included. All surface and
subsurface data are telemetered to shore in near-realtime and made available
through the project website: http://www.pmel.noaa.gov/ocs/ in a variety of formats
including the standard OceanSITES data format.
Groups / P.I.s /labs /countries involved / responsible:
Dr. Meghan Cronin NOAA / PMEL (ARC lead)
Mr. Christian Meinig NOAA / PMEL (ARC Lead Engineer)
Dr. Christopher Sabine NOAA / PMEL (ARC Lead Carbon Scientist)
Status:



planned
time horizon / long-term plans: Long-term
funding from NSF (for year 1) from NOAA-OCO (pending, continued)
Technology:


Moored / autonomous sensors
real-time telemetry: Daily-averaged and spot meteorological, SST and SSS data
transmitted via Service Argos. Hourly surface meteorological and subsurface physical
data transmitted via Iridium. Carbon has daily transmissions of 3-hour measurements via
Iridium.
 SST measurement: self-contained sensor attached to bridle at 1m below surface
 Profile measurements: Sensors will be included after 2010, pending funding. Sensors
would be attached to slackline mooring (pressure sensors should be used to remap
observations onto nominal depths).
Data policy:

real-time data: All data are public from primary telemetry system (Service Argos for
meteorological, Iridium for subsurface and carbon).
 delayed mode data:
High-resolution data will be made public within 6 months of
recovery.
Data management:





Data
Assembly Center
(DAC):
All
data
will
be
accessible
through
www.pmel.noaa.gov/ocs/data_del.html. Carbon data would be available from the Carbon
Dioxide Information Analysis Center (CDIAC).
Satellite data collection system: Likely Iridium for both physical and carbon data)
Real-time data processing and distribution system: PMEL realtime processing, QA and
web distribution.
Metadata scheme: see website
Possibilities of evolution to comply with a more general JCOMM GTS scheme: in
compliance
Societal value / Users / customers:
36
www.oceansites.org
Agulhas Return Current Reference Station (ARC) users are anticipated to include the
research community, weather and climate forecasting communities, and satellite and
numerical weather prediction products assessments communities.
Role in the integrated global observing system:
The ARC mooring would serve as an air-sea flux reference site and as an observatory for
the Agulhas Return region of the Southern Ocean. This is a data sparse area, and this
mooring is expected to provide an invaluable source of data in a very difficult region to
sample.
Contact Person:


for information about the site or data: Meghan Cronin (Meghan.F.Cronin@noaa.gov)
for information about the carbon component: Chris Sabine (Chris.Sabine@noaa.gov)
Links / Web-sites:


for Project information: http://www.pmel.noaa.gov/ocs/arc.html
for information on carbon system: http://www.pmel.noaa.gov/co2/moorings/
Compiled by: Meghan Cronin (June 2010)
Figure 1. The ARC site (black square), shown in relation to the mean net surface heat flux Qnet into
the ocean in units W/m 2, mean sea level (white contours), and the 3000 m isobath (black contours).
Sea surface height contours can be interpreted as streamlines of the surface geostrophic flow. Qnet is
from the OAFLUX product.
37
www.oceansites.org