2008 report
Progress: 60%
Ice Tethered Platforms (ITP) combined with CTD profiler, ADCP, acoustic transponder, sea-ice thermistor chain and atmospheric sensors, including some spectroradiometer and seismometers
The Ice Tethered Platforms (ITPs) subsystems for DAMOCLES considered in this report, concern exclusively the CTD profilers. Actually there are two systems operating in the Arctic Ocean. One is developed by the Arctic Group at the Woods Hole Oceanographic Institution (PIs: John Toole, Andrey Proshutinsky and Richard Krishfield) in the USA. The other one is developed by METOCEAN (Canada). The WHOI system is derived from the MacLane CTD profiler. The METOCEAN system is using an ARGO float CTD profiler. The two systems are transmitting the data in near real time to a surface unit by using inductive modem along a steel cable. In both cases the surface unit is equipped with an Iridium transmitter to transfer the data to the laboratory on shore for immediate data processing.
The quality of the CTD data is quite comparable since both systems are operating with identical Seabird CTD sensors. The main differences come from the mechanical system used for profiling up and down. The WHOI system is using an electrical motor activating wheels rolling along the plastic jacketed steel cable. The METOCEAN system is using the ARGO float controlling buoyancy for profiling up and down at a lower speed (10 cm/s) compared to the WHOI system capable of profiling at 25 cm/s. In the context of DAMOCLES, a POPS system was deployed during 24 hours from fast-ice in Storfjord (Svalbard) for testing the system in shallow waters but at a high repetition rate. These tests were conclusive. The initial array operated during DAMOCLES was composed of three POPS deployed in September 2006 during a cruise on board the Russian ice breaker Kapitan Dranitsyn. Five DAMOCLES partners are directly contributing to this effort: IOPAN (2 POPS), UPMC (2 POPS), AARI (2 ITPs), SIO (2 ITPs), Tartu University (1 POPS). The unit price for each ITP CTD profilers have been fixed at about 65000€ and each POPS at 60000€.
Two Ice Tethered Platforms (ITP/POPS) by UPMC, one Ice Mass Balance system (IMB) by CRREL, sixteen meteorological buoys by UNIHAM and three tiltmeters by SAMS, were deployed during Damocles airborne operations on April 2007. All the airborne operations were conducted from two Canadian aircrafts equipped with skis for landing on sea-ice: a DC3 and a Twin Otter chartered by DNSC for Damocles to the Borek aviation company based in Calgary (Canada). One Polar Ocean CTD Profiling System built by Metocean and measuring temperature and salinity from surface down to 1000m depth every other day, was deployed approximately 100 miles south of Tara on April 26, 2007 at 86.09°N and 133.28°E. Another POPS was deployed 300m from Tara on April 27, 2007. One tiltmeter was deployed on April 25, 2007, during the met buoy air dropping operation in the vicinity of the North Pole. The Twin Otter landed at about 89.30°N and 130°E to deploy the tiltmeter. A second tiltmeter was deployed at Tara and a third one north of Greenland. One Ice Mass Balance system (IMB) was deployed nearby Tara on April 23 and 24, 2007. Tara was located at about 88°N and 130°E at that time. This IMB unit was replacing the one deployed at Tara last September 2006 and destroyed during the winter. All these instruments are transmitting in real time to satellites (Argos and Iridium) and this is essential for Damocles to reduce time access to data for forecasting applications. In addition several other instruments were deployed at Tara during spring 2007 Damocles airborne activities including: three Ramses radiometers (including one in the water under sea ice) for the visible part of the solar spectrum a tethersounding system for the lower atmosphere (<2km altitude) and an array of five seismometers distributed within a 1km diameter circle around Tara. The 10m meteorological mast was reinforced and sensors (damaged during the past winter) were removed and replaced.
The shipborne ITP deployments were done during the German icebreaker 'Polarstern' cruise ARKXXII/2 in July-October 2007 and the Russian icebreaker 'Fedorov' cruise in July-September 2007. Seven different types of ice buoy systems were deployed on drifting ice floes during the 'Polarstern' cruise:
1. Three Ice Tethered Profiler platforms (WHOI ITPs) measuring 3 times/day TSD profiles with 1m vertical resolution between depth of 8 to 760m with profiling CTD unit (SBE 41CP) on a wire tether. They use an inductive modem to communicate the data to surface unit (SU) which records GPS position and relays data via IRIDIUM satellite modem connection to a server at WHOI. Two of the ITP are financed by AWI in a frame of IPY and one is DAMOCLES contribution.
2. One Polar Ocean Profiling System (Metocean POPS) financed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC, Tokyo, Japan) was deployed but unfortunately had to be recovered after on-site tests failed, most likely due to wire damage during the deployment.
3. One Ice Tethered Acoustic Current profiler (ITAC) measuring ocean current velocity profiles from 2m under the ice to a depth of around 500m with ADCP mounted 50 cm under the ice floe and linked by a cable to the surface unit with a GPS receiver and an IRIDIUM modem. A 2nd GPS was positioned about 98m away in line with the wooden beam and the ITAC SU to allow the recording of the ice floe and thus the ADCP orientation. Data are sent daily via the IRIDIUM link to Optimare and as a backup also relayed via the ARGOS system once a week.
4. One Arctic Ocean Flux Buoy (AOFB) for measurements of small scale processes in the surface layer under the ice from Tim Stanton at the NPS in Monterey, USA. It was equipped with one set of T, S, D sensors and an FSI current meter measure small-scale variability a few meters below the ice as well as RDI 300KHz Acoustic Doppler Current Profiler measuring velocity profiles of the top 80m of the water column. Similarly to the ITP, a surface unit relays the information back to the NPS via IRIDIUM. A wind generator provides additional power to extend the operating life of the system.
5. Ice Mass Balance Buoy (IMBB) from IABP was also deployed within the 'Super Buoy Array' for ice, snow and meteorological observations.
6. Webcams from NOAA and met buoys were also deployed.
The 'Super Buoy Array' deployment took place on September 13/14 around the Lomonosov ridge between 86°40' to 87°24'N, on the edge between the Amundsen and Makarov basins. One ITP, IATC, AOFB, IMBB and the webcam were deployed in a close vicinity on the same ice flow for integrated measurements of atmospheric, ocean and ice parameters.
For the deployment on ice the first challenge was to find a suitable ice floe in the relatively thin and sparse ice cover. One or more survey flights were conducted by helicopter, landing on potentially usable floes and drilling a few holes with a 2' electrically powered ice auger. Once a floe was identified, the ship had to dock onto the ice floe. In case of the buoys mounted partially under the ice floe, an initial survey of the ice floe - a coarse survey of ice floe thickness using the EM31 canoe in conjunction with 2' drilling and visual observation of ice surface features, such as melt-ponds and ridges once the gear was transported to the ice by crane, Akio and Nansen sledges or helicopter, the deployments, including any necessary ice hole drilling, commenced. The mechanical drilling of the hole for the ITAC (using 10 and 11' ice auger flights, an ice-saw, an ice-scoop, and ice chisels) required considerable effort and time and may thus be aided by a hot-water system, similar to that employed by WHOI, in the future.
Three Ice Tethered Profiler platforms of WHOI type were deployed from the Russian icebreaker 'Fedorov' in September 9-11, 2007. Each of theses ITPs was accompanied by the ice mass balance buoys (IMBB). Two ITPs (and IMBB) are still active in December 2007, one stopped to transmit the data after two weeks of deployment.
At the end of 2007 5 POPS (CTD/ITP) are operational in the Arctic: 3 POPS were deployed late August 2006 and 2 more POPS were deployed in April 2007. There are 4 ITPs (WHOI type) deployed for DAMOCLES in summer 2007 from 'Fedorov' and 'Polarstern'. This grand total of 9 ITPs by Damocles was complemented by about the same number of ITPs from various programs (including two ITPs installed by AWI from 'Polarstern' and a few more ITPs deployed by the WHOI Arctic group) bringing the total of ITPs deployed in the Arctic Ocean up to 18 before the end of this year in the context of IPY. There will be an attempt for recovering the 3 POPS deployed last August 2006 before exiting the Arctic Ocean through Fram Strait in October 2007 and the POPS deployed nearby Tara in April 2007.
ULS float and AITPs
The ULS floats developed for Damocles are intended to deliver information concerning the sea-ice thickness distribution at various locations over long period of time (> 1 year). The floats are freely drifting under sea-ice at constant pressure (isobaric). The float depths was selected between 50 and 100m under sea-ice in order to optimize (1) max accuracy for sea ice thickness detection (few centimetres) and (2) max detection range (>100km) for acoustic signal propagation at low frequency (780hz up to 1560hz) taking into account stratification of the water masses in the upper layer. The ULS floats will be located under sea-ice during free drifts by triangulation from acoustic Ice Tethered Platforms (AITP), 6 times per day (every 4 hours). The ULS floats are based on the PROVOR floats equipped with an internal buoyancy controlled device (hydraulic pump and bladders). The ULS is similar to the ASL transducer already in use on moorings under sea-ice by IOS (Canada). A high precision in situ pressure transducer (PAROSCIENTIFIC) is integrated with the ULS to provide in situ pressure and float depth within a few centimetres accuracy. The float is equipped with an acoustic SOFAR transmitter (1560Hz) to signal its position occasionally but in real time (once a day) and a RAFOS receiver (780Hz) to be located 6 times per day afterwards.
As far as budget is concerned UPMC is responsible for providing the acoustic components of the USLs including the ULS and the SOFAR and RAFOS components. AQUATEC is responsible for the acoustic modem. KANNAD (former MARTEC) and IFREMER are responsible for the development of the ULS float (integration of the PROVOR technology, the ULS/ASL technology, the SOFAR/RAFOS technology and the AQUATEC acoustic modem technology).
ULS and AITP mechanical prototypes have been developed by KANNAD and integration and software development and testing is almost done. Next steps will include basin test to validate buoyancy and vertical stability buoyancy adjustment. In December 2007 authorization to build and integrate 10 AITP and 8 ULS float should be provided from DAMOCLES. Then at sea trials (close Guidel) will take place at the end of January 2008 with one ULS and 3 AITP if acoustic sources are available. This will be focused on functional validation. At the end of March 2008 7 AITPs and 4 ULS floats should be shipped to the Resolute Bay for the deployment from Canada (Eureka), planned in spring 2008.
Met buoys
Sixteen meteorological buoys (CALIB type) were procured from METOCEAN and transport with DC3 from Canada via LYR to Tara. Buoy calibration took place in Longyearbyen and at Tara. On April 23, 24 and 25, 2007, met buoys were deployed from air during three Twinotter flights in an area 500km by 500 km centered around Tara. In most cases they were air dropped and descended on parachutes, only one had to be deployed by hand. These buoys are transmitting air pressure, air temperature and are located several times a day via the Argos system installed on board NOAA satellites.
Sea gliders under sea-ice
Gliders are autonomous underwater vehicles, designed to monitor for long time periods the interior of vast ocean areas at lower cost than oceanographic ships and moorings. Buoyancy control allows gliders vertical motions and additionally gliders use their shape and small fins to induce simultaneous horizontal motions. In summary, changing buoyancy together with the hydrodynamic structure allow gliders to carry out saw-tooth trajectories between the ocean surface and a defined depth along prescribed directions. In DAMOCLES, three gliders designed by ENSIETA will be fitted with acoustic modems and will be used to establish a link between the set of AITPs and the Lagrangian floats equipped with ULS. The gliders will also collect CTD data which will be transferred to transponders mounted on the AITPs. The deep Seaglider with under ice capabilities developed by APL Seattle will used in Fram Strait to complement data from oceanographic moorings with high resolution CTD sections.
The further testing of ENSIETA STERNE glider was done in order to provide the needed information about the dynamics of the vehicle and about the performance of the on-board sensors. Already achieved under ice glider capabilities include CTD recording, new dive control through sharp density fronts, new heading control. Under ice positioning based on TOAs is in progress. At the surface, the satellite communication (Iridium/GPS) and surface routing based on bathymetry and current were implemented ((see Task8.1 part of this report). 12 deployments were performed in the English Channel during Brest trials aimed to validate the new steering and diving capabilities. The Baltic tests in the Bothnian Sea were done with cooperation of ENSIETA, FIMR and UPMC, using sound sources launched within a distance of 50 km for a period October 2007 to January 2008. First attempt to launch Sterne glider done on October 23-26 had to be aborted due to iridium antenna cable failure. On November 22 there was a second series of trials, started with initial weighting and balancing of the glider. Launching was done in bad sea conditions and there was no satellite communication just after launching (rough sea). Iridium message was received after 4 hours of mission but no GPS, next series of Iridium messages were successfully received but without GPS fix. There has been no more contact since October 26 (3,5 significant waves, 5m max) and no TOA were received. Based on this trial it is concluded that a satellite communication antennas should be improved, while this is a critical part of a glider and wing resistance should be increased. Moreover, synchronisation of the SeaScan board should be done off-line and up dated on line. A new prototype of the STERNE glider will be provided in March 2008 and an integration of positioning algorithm is in progress in both HUT and ENSIETA.
The Seaglider SN127 was procured from the Seaglider Fabrication Center (SFC) in Seattle in spring 2007. The Seaglider was equipped with the SeaBird temperature and conductivity sensors, Wetlab scatterometer and fluorometer, Aanderaa oxygen optode, Druck pressure sensor and Iridium modem for communication. An integration of RAFOS hardware was also considered but due to a short time it was decided as a next step for summer 2008 after completing first field tests. Before delivery the instrument had been thoroughly tested in a tank and during field tests in the Pudget Sound by the manufacturer and finally trimmed (ballasted) for the Greenland Sea and Fram Strait water density ranges (see deliverable D8.3-7). A plan of the first Seaglider mission in Fram Strait was worked up in details, including different recovery scenarios and backup solutions. The Iridium account (SIM card) for 'DAMOCLES Seaglider' was acquired from DAMOCLES resources and activated. After arriving to Bremerhaven the glider went successfully through all pre-deployment tests in lab conditions and was shipped to Reykjavik to be loaded onboard the ship. The deployment in Fram Strait was scheduled for the MSM05/5 cruise of RV 'Merian'. The Seaglider was prepared for deployment on August 1 but unexpectedly it failed to pass the pre-deployment tests performed on board prior a final launch in spite of successful tests on land. The self-test failed (the phone could not detect a signal strength) and direct communication failed (the phone did not answer to AT). The glider's modem exhibited inconsistent behavior. Given the symptoms it was suspected that SG127 had some problem with the modem hardware, perhaps a loose connector that got jagged into place during recent shifting of the glider. The value of the Fram Strait deployment had to be weighted against the increased risk. Finally, to avoid the possible loss of instrument due to communication problems the deployment was cancelled and the glider was returned to the manufacturer for repairs. The planned Seaglider operations had to be postponed until the next year. After checking the returned Seaglider the SFC in Seattle confirmed that communication problems had resulted from a modem hardware failure. The repaired SG127 will be sent back to AWI in December 2007 and prepared for the next field tests.
Bottom moored systems
Arrays of mooring in main gateways
Understanding the mechanisms that regulate the inflow of Atlantic water from the Atlantic through the Nordic Seas into the Arctic Ocean through the Barents Sea and Fram Strait, and its variation due to a mix of both local and remote forcing requires continuous monitoring of oceanic fluxes through the main gateways. To estimate the transport of mass, heat and salt to the Arctic Ocean, in the frame of WP8 we continue bottom moored arrays that have been running successfully for about a decade (partly in EU-funded projects VEINS and ASOF-EC-N) and that have provided crucial insight in the propagation of signals from the North-Atlantic into the Arctic. These input mooring lines are located off Norway (62°N Svinøy; 2moorings, UoB), in Fram Strait (16 moorings; AWI, NPI) and across the Barents Sea Opening (5 moorings; IMR). Observations in the Barents Sea Opening and at the Svinøy section are carried on using existing arrays with some required modifications while an optimally cost-effective observatory was developed and implemented in Fram Strait where intense mesoscale activity and the strongly variable recirculation of Atlantic water demand an innovative improvement of the existing system.
The RV 'Merian' cruise MSM05/6 planned for the exchange of moored array in Fram Strait in September 2007 has been cancelled due to the severe failure of ship engines. The limited ship time obtained in September thanks to a courtesy of the Norwegian Polar Institute on board RV 'Lance' allowed for recovery of 7 and deployment of 8 moorings of the total number of 12 moorings operated in Fram Strait by AWI. The easternmost mooring was damaged in spring 2007, the most likely by a fishing boat, and its remains could not been recovered. Two AWI moorings in the western part of the strait could not be exchanged due to heavy ice conditions. Three of the newly deployed moorings in the eastern part (F4, F5, F6) have been equipped with acoustic modems (HAM.Nodes) for data transmission (see deliverable D8.3‑8). For the this deployment three systems equipped with the ITC2002a transducer were built for the long range data transmission from moorings F4, F5 and F6. One additional node for the short range data transfer from the westernmost mooring F6 to the central mooring with a satellite link is pending due to a delay with field tests of the latter. In the first step there is no acoustic data transfer along a single mooring, at each of three moorings one current meter located at the depth of 750m was directly connected as ahost to the HAM.Node deployed below. Data collected by current meters will be send to the acoustic westernmost mooring to test reliability of the long range acoustic data transfer in Fram Strait. However, the failure of RV 'Merian' suppressed a deployment and necessary tests of the central mooring equipped with the profiling top and underwater winch (for details see deliverable D8.3‑8). For the first field test only a short deployment of this system was planned with recovery after 1-3 weeks to test the performance of the winch and profiler in field conditions under strong currents in the West Spitsbergen Current. Due to very limited ship time on RV 'Lance', not allowing for adeployment and following recovery of the complicated and difficult to handle moored system, the field tests of the central mooring had to be postponed until the next year. The fully integrated system will be deployed in summer 2008.
In the Barents Sea Opening the DAMOCLES moorings were deployed after recovery of DAMOCLES moorings deployed in 2006. Near the Norwegian coast two bottom-mounted ADCPs in trawl proof frames were deployed. Then there are four moorings with Aanderaa current meters. The northernmost mooring as a downward looking ADCP from Aanderaa Instruments placed at about 50 m above bottom, measured the outflow of dense bottom water from the Barents Sea to the Norwegian Sea. This type of instrument was tried for the first in this section. The moorings will be recovered in summer 2008, completing the last time deployment in the Fugløya–Bjørnøya section.
Two moorings in the Svinøy section were served and redeployed in March and October. The master mooring S1 with a nearly continuous time series since 1995, was recovered with a 100% data recovery, and redeployed in the same position (62 deg 49.5N; 4 deg 17.4E) at 500 m depth. The backup mooring S2 – now moved to 600 m depth - was cut by a trawler again in January. The float and the 100 m current meter were picked up by the Norwegian Coast Guard few days later. The deeper part of the mooring was released in March, but unfortunately not recovered after dragging attempts. So this year we had an instrument loss of 2 RCM current meters and a release. The backup mooring is now redeployed on the 500m isobath in position 62°49.9'N, 4°15.8'E. Additionally, we recovered and redeployed the deep mooring at 2000 m depth in position 63 deg 58.4 N, 1 deg 38.8 E , now with current meters 100m and 500m above the sea bed. Through the IPY, the Damocles program in the Svinøy section is now completed with contributions from the iAOOS and Poleward programs. Through iAOOS we intend to concentrate on the western branch of the Norwegian Atlantic Current, and 4 Pressure Inverted Echo Sounders (PIES) and 2 additional mooring will be deployed were deployed in November in the vicinity of the 2000 m isobath. A McLane Moored Profiler (MMP) with a profiling CTD to capture the baroclinic transport is scheduled for deployment in spring 2008. Thus we are close to reach our overall goal of developing the Svinøy section as complete and sustainable, simple and robust upstream reference-system for monitoring the Atlantic inflow (AI) toward the Arctic Ocean.
- Boundary moorings
To provide better knowledge of the exchange processes between the boundary and the interior of the Arctic Ocean with the ultimate goal of understanding and quantifying how much this exchange affects the ice cover the work focuses on moored observations along the circum-Arctic boundary. DAMOCLES is not be able to equip the Arctic with the necessary number of transport arrays, but this work is done in collaboration with US, Russian and Canadian efforts (notably the NABOS and CABOS experiments) to ensure a good coverage at two sites along the Eurasian slope: a mooring array at roughly 32°E north of Spitsbergen and a mooring array in the Laptev Sea. Moored CTD/velocity profilers in the boundary current arrays were deployed to obtain high horizontal and vertical resolution of thermohaline intrusions and mesoscale activity.
In 2006 the bottom mooring was deployed by IOPAS during the Russian icebreaker Kapitan Dranitsyn. This work was done with cooperation with the Nansen and Amundsen Basins Observational System (NABOS) and the mooring belongs to the NABOS net. The mooring was situated over the Arctic Ocean continental slope, at the Laptev Sea, north of Severnaya Zemlya at the position 80º44.94'N and 103º29.91'E. The mooring recovery, data download, maintenance and redeployment were planned for summer 2007. All works should be performed together with the NABOS, onboard the Russian icebreaker 'Yamal'. Because time devoted to the MMP maintenance during the cruise was very short, after consultation IOPAS has decided to purchase new MMP device, to exchange it instead redeployment of the same instrument. New rope, batteries etc. were purchased as well. All material was stored in Kirkenes. Unfortunately, shortly before start of cruise, use of 'Yamal' was canceled and RV 'Viktor Buynitski', the ship provided by Russian NABOS partners was offered. This vessel was not able to navigate in the ice condition occurred in the mooring region. Finally, operation of the MMP mooring recovery was canceled. After consultation with DAMOCLES partners, it was decided to use the MMP device and rope to assembly a new mooring and deploy it from RV 'Lance' in October 2007 in Fram Strait. Thanks to help from the Norwegian Polar Institute, German Alfred Wegener Institute and American Woods Hole Oceanographic Institution, the entire mooring has been completed. All parts were shipped to Longyearbyen and loaded onboard RV 'Lance'. Unfortunately weather conditions during the October cruise did not allow to lunch any instruments or moorings. All parts of the MMP mooring are at the moment stored at NPI in Tromso, waiting for opportunity to be deployed in next year.
The second profiling mooring was deployed also north of Svalbard as a part of existing NABOS network during the Russian icebreaker Kapitan Dranitsyn in 2006. The McLane profiler (MMP) with a acoustic current meter (ACM) and a was deployed at the depth of 2000 m next to the conventional multiyear NABOS mooring located at the depth of 1010m. Both moorings are located at the continental slope in the boundary current and should be recovered in 2007. The same as in case of the Laptev Sea profiling mooring, the ice conditions in autumn 2007 did not allow to reach the mooring location thus it was left in the water for the second year of deployment and will be recovered in 2008.
- Storfjorden moored array
The strength and properties of the Storfjorden plume is measured through the DAMOCLES period by two ADCP moorings, one at the sill and one at the slope, equipped with MicroCat salinity sensors. An existing trawl-proof bottom-mounted ADCP system has been used to monitor the overflow at the Storfjorden sill (76º 58.08¢N, 019º 14.95¢ E), since summer 2003 under the Polar Ocean Climate Processes (ProClim) project funded by the Norwegian Research Council. ProClim will be terminated by the end of 2006 and the moored system is be maintained during DAMOCLES. During a cruise in 2006, the ADCP system was deployed at the sill on 13 August 2006 from RV Håkon Mosby.
A second system was proposed under DAMOCLES to be deployed at the shelf-break off Sørkapp of Spitsbergen on the path of the Storfjorden overflow. From the allocated budget of WP8, one Workhorse Sentinel 300kHz ADCP (with 2x256 MB memory card, 3 extra battery packs and an external battery case) and two SBE37SM Microcats were purchased early in 2006.
The existing bottom-mounted system comprises an RDI Workhorse Sentinel 300kHz ADCP with external battery case, a SBE37SM MicroCat and a releaser installed in an aluminum trawl-proof frame, attached to a concrete block of 2.5x2.5x0.37 m dimensions. The weight of the concrete block is about 2.5 (1.6) t in air (water). The frame with instruments (acoustic release, ADCP, Microcat and the battery pack) and floatation elements installed is 300 kg in air. Overall height of the installation is 86 cm.
After month 12 of DAMOCLES, the following two improvements have been
made regarding bottom-mounted systems of GFI/UIB. The improvements are a result of experience gained by maintaining a trawl-proof bottom-mounted ADCP system at the Storfjorden sill (76º 58.08'N, 019º 14.95'E), since summer 2003.
(1) A sustainable new trawl-proof system is designed with significantly less maintenance expenses and ease in transport and deployment. Two such systems were deployed in summer 2007: at the Storfjorden sill (R.V. Håkon Mosby, 21 July 2007) and at the shelf-break off Sørkapp of Spitsbergen (R.V. Lance, 30 May 2007). The new frames are stainless steel (to avoid any fouling of the ADCP compass) of order 1 ton of total weight which can be deployed and recovered as a whole. The details of the system were described in detail in WP8 deliverable D8.3-2.
(2) Sea-Bird Microcats were updated to pumped versions. An evaluation of the salinity record showed that the absolute magnitude as well as possibly the variability of the salinity is not accurately measured with the SBE37SM, which is not a pumped system. This is both due to the fouling by sediments etc. and not sufficient flushing of the conductivity cell. To overcome this problem we converted SBE37SMs into systems with integral pumps.
The bottom-mounted systems in the Storfjorden area have successfully delivered data of sufficient quality during the first DAMOCLES deployment. Some problems occurred, e.g. one Microcat was lost last year upon the passage of a trawler and a short-circuit terminated ADCP data acquisition earlier than planned. However, these will not affect the overall goals of DAMOCLES. The involvement of UiB in WP8 is nearly 100% complete. The maintenance of the bottom-frames will be conducted through WP3.2. The identified problems above have already been accounted for in the newly-designed frames.
• Tomography array in Fram Strait
The detail description is given in the previous chapter (Task 8.2)
• Freshwater array in western Fram Strait
In September 2005, as a part of the EU funded ASOF-N project, a total of six moorings were installed across the East Greenland Current (EGC) and the shelf region at 78°50' N. Four moorings were installed across the EGC, instrumented with a total of twelve current meters, four temperature/salinity (TS) sensors, four upward looking sonars (ULS) measuring sea ice draft and four Doppler Current Meters (DCMs) measuring ice drift velocity. In addition two moorings were deployed on the East Greenland Shelf, as an effort to measure the freshwater flux there. Of these moorings one was a tube mooring instrumented with two TS sensors. The second mooring on the shelf, close to the tube mooring, was instrumented with an Acoustic Doppler Current Profiler (ADCP) measuring the currents over a range of 150 meter. In this way T, S and currents should be measured also on the shelf, in the second year of deployments of moorings on the East Greenland Shelf. This setup was the basis for the final data collection with respect to freshwater fluxes during the ASOF-N project, which ended in 2006, but also provides the first freshwater flux data points for DAMOCLES.
The freshwater array was deployed on the first DAMOCLES cruise on Lance in September 2006. Four moorings were installed across the EGC, instrumented with a total of twelve current meters, four temperature/salinity (TS) sensors, four upward looking sonars (ULS) measuring sea ice draft and four Doppler Current Meters (DCMs) measuring ice drift velocity. In addition two moorings were deployed on the East Greenland Shelf, as an effort to measure the freshwater flux there. Of these moorings one was the Aanderaa TS string. The second mooring on the shelf, close to the tube mooring, was instrumented with an Acoustic Doppler Current Profiler (ADCP) measuring the currents over a range of 150 meter. In this way T, S and currents should be measured also on the shelf, in the second year of deployments of moorings on the East Greenland Shelf. All these moorings should be recovered in autumn 2007.
The annual mooring recovery/deployment cruise with RV Lance to Fram Strait in 2007 was seriously hampered by extensive sea ice. The NPI moorings covering the transport out of Fram Strait could not be reached, and on the CTD section across Fram Strait we were not able to do stations in the East Greenland Current. At the same time, these unfortunate conditions allowed us to allocate time to the AWI moorings covering the West Spitsbergen Current and the recirculation area. This will result in some gaps in the data, but provided that the moorings survive a two year deployment most of the instruments will log throughout the period. The failure to recover/redeploy may thus be more a delay than a total loss. Therefore the plans connected to the NPI moorings in Fram Strait are not changed. We still have the 1997-2006 time series to address and share with the modellers, and as mentioned in the point above it is likely that most of the data will be recovered in 2008.
