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Scientific projects |
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| Oceanography |
| Project Number: |
S-269 |
| Project Title: |
Field study of density currents
on the western Weddell slope and shelf |
| PI: |
Muench, ESR, U.S.A. |
| Summary: |
Dense waters form along the continental shelves of the southwestern and western Weddell Sea, consequent to densification through sea ice formation, and in the sub-ice cavities beneath the Filcher-Ronne and possibly the Larson ice shelves. These waters collect on the shelves, mixing to varying extents with the ambient waters, then cascade down the steep upper continental slope as density currents. Subject to the earth's rotational influence, they veer to the left. In their final equilibrium state, these currents flow north at a slight downward angle to the isobaths. For practical purposes, they flow approximately along the continental slope of the western Weddell Sea. The several discrete sources of dense water contribute to a northward, slope-trapped bottom flow that appears much like a thick (up to 400 m), continuous sheet of dense water extending from near the shelf break down nearly to the base of the slope. Observations of these features along the western Weddell margin are limited. Results from the 1992 ISW-1 experiment suggest that, viewed in the horizontal, the deep flows penetrate north along the slope as a tongue having a slight downslope trend. There was evidence, also, of a tongue-like inflow of deep water from the vicinity of the Larson Ice Shelf, situated along the Antarctic Peninsula. The ISW-1 results led to estimates of a 5-6 Sv northward flow in this deep current. These estimates were based on time-series current observations and upon dynamic height computations that were corrected for total flow using results from drifting current meters. The overall scope of the north-flowing waters is defined by the temperature, salinity and dissolved oxygen distributions. While we, therefore, have a general idea of the flow pathway, of its general configuration and of its total transport, we have no information on the smaller-scale features that we would expect to impact the internal flow dynamics. Such features include, for example shear layers, turbulent patches and entrainment-related internal waves. Close examination of the temperature and salinity profiles within the deep flows show considerable vertical structure, consistent perhaps with a vertical layering of waters that originated from different shelf sources.
These earlier observations have allowed us to put together a general idea of the behavior of the deep density currents that flow north along the western Weddell margin. However, they have also raised significant questions concerning these currents. The work that is proposed is this subproject proposal is intended to address these questions. It will build upon the observational basis established during the ISW-1 and other earlier programs. Occurring later in the season than ISW, it also provides a temporal follow-up experiment in the sense of seasonal variability. |
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| Project Number: |
S-270 |
| Project Title: |
Identification of source water masses
involved in deep and bottom water formation along the western Weddell
Sea continental shelf. |
| PI's: |
Schröder and Hellmer,
AWI, Germany |
| Summary: |
The formation of dense bottom water by mixing of highly ventilated, salty shelf waters with the warm and salty waters of circumpolar origin and the interaction of both with very cold Ice Shelf Water in the Weddell Sea is of major importance for the renewal of the bottom water in the world ocean. In 1992, measurements during the US-Russian drift station ISW-1 over the continental slope along the coast of the Antarctic Peninsula (Fig. 1) gave a first enroute view of the stratification and pathways of deep and bottom water masses in the western Weddell Sea. More recent expeditions onboard RV POLARSTERN in 1993, 1995, 1996, and 1998 together with data from the Brazilian/German expeditions of 2000 and 2001 show large spatial and temporal variations in the T/S- characteristics of the dense water masses in the northwestern Weddell Sea. These variations are a result of mixing processes which act over different time scales (seasonal, interannual to decadal) and involve waters with different histories from various sources along Weddell Sea's western rim. Therefore, the measured and calculated volumes of the newly formed Weddell Sea Bottom Water still affected with big uncertainties, range from 1.5 to 6 Sv. Even less is known about the quantities ventilating Weddell Sea's deep water, which has direct access to the world ocean through the deep passages in the South Scotia Ridge. Model studies using virtual drifter show the sensitivity of the deep and bottom water formation and spreading on sea ice concentration and the position of dense water injections along the western Weddell Sea continental shelf break. For the understanding of the formation processes of different bottom water types and for an accurate estimate of the ventilation of the deep Weddell Sea it is necessary to measure the source water mass characteristics as close as possible to their origin. The retreat of ice shelves like Filchner-Ronne, and Larsen A, B, and C are of special interest with regard to the modification of shelf waters on the continental shelf and in the sub-ice cavity. In addition, the calving of large tabular icebergs has a dramatic impact on the composition and the amount of sinking dense water masses (collaboration with Gordon and Muench), which leads to a high variability in both T/S-characteristics and volume of newly formed bottom water. |
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| Project Number: |
S-271 |
| Project Title: |
Deep and bottom water formation:
Transformation of shelf waters |
| PI: |
Rhein, University Bremen, Germany |
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| Project Number: |
S-343 |
| Project Title: |
Turbulent exchange in the ice-ocean boundary layer |
| PI: |
McPhee, McPhee Research Company, Stanton, NPS Monterey, U.S.A. |
| Summary: |
The surface heat and mass balance of sea ice is highly dependent on the exchange of heat, mass, and momentum via turbulence in the boundary layer that develops when the ice is in motion relative to the underlying water. Understanding how turbulence distributes the combination of solar radiation penetrating the ice cover and latent heat exchanges at the ice/ocean interface, is crucial in understanding the summer evolution of the ice cover, as well as the exchange of nutrients and biota between the ice and upper ocean.
Our goal is to continuously measure three-dimensional velocity, temperature, and conductivity at at least two levels in the ice-ocean boundary layer, at resolutions resolving turbulence well into the inertial subrange. These data will provide mean u, T, S properties along the vertical turbulent fluxes of momentum, heat, and salinity. In addition, very high resolution (0.25 m) upward and downward looking acoustic Doppler current profilers will provide detailed current shear and Reynolds stress profiles. These data will provide the quantitative estimates of the eddy viscosity and diffusivity profiles in the upper ocean necessary for realistic modeling of scalar distributions and fluxes in the ice/upper ocean system. If the drift of ISPOL-1 brings us to within range of the continental shelf break, the turbulence measuring system is designed for depths in excess of 500 m, and may be used for limited studies of the bottom boundary layer. This would add a useful dimension to the experiment, by making direct flux measurements in a density flow transporting cold bottom water off of the eastern Antarctic Peninsula shelf.
Our proposed work is complementary to the profiling CTD/LADCP system proposed by R. Muench. His system will provide the mixed layer and upper pycnocline properties necessary to relate surface driven turbulent fluxes to exchanges between the upper ocean and the underlying Weddell Deep Water. |
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| Bathymetry |
| Project Number: |
S-272 |
| Project Title: |
High resolution bathymetry along the western
Weddell Sea shelf break |
| PI: |
Schenke, AWI, Germany |
| Summary: |
The seafloor topography of the western
Weddell Sea and in particular along the continental shelf of the Eastern
Antarctic Peninsula (EAP) is completely unknown. The only reasonable
bathymetric information in this region was obtained during the previous
drift station US/Russian Ice Station Weddell (Fig.
1) and from few isolated soundings, taken by icebreakers in this
region. The existing bathymetric charts reveals along the eastern
continental slope of the Antarctic Peninsula relatively smooth morphological
structures, formed possibly by sedimentation and glaciation/deglaciation
processes.
Long wave undulating structures of the seafloor topography were discovered
from satellite radar altimetry, visible in the free-air gravity anomalies.
However, due to the unknown densities of the Earth's upper crust and
due to the sea ice coverage, this information does not truly represent
the shape of the seafloor. Multibeam data, collected during the "Polarstern"-expedition
ANT X/7 (1993) and ANT XIV/3 (1997) in this region, give some evidence
that the continental shelf may be similarly structured as the continental
shelf off the Filchner-Ronne Ice Shelf. Several pronounced submarine
deep sea channels have been discovered from the bathymetric data collected
during the mentioned expeditions. In order to created a fundamental
data set for marine geoscientific studies in this region, multibeam
data should be collected during the entire cruise. The measured data
will be used, in addition, for updating the AWI Bathymetric Charts
of the Weddell Sea (AWI BCWS) sheets 1:1,000,000, No 551 and 556.
During the entire leg multibeam-data will be collected using the HYDROSWEEP
DS-2 system, in order to improve the general knowledge about the seafloor
topography and its morphological structures in this region and to
improve and enlarge the data basis for the AWI BCWS. The bathymetric
data will be supplied after scientific use at the AWI to the IHO Data
Centre for Digital Bathymetry (DCDB). In areas where new submarine
features, like prominent seamounts or distinctive tectonic features
may be discovered, a short systematic survey with parallel tracklines
should be carried out, covering the whole structure in order to enable
a consolidated morphogenetic interpretation and naming, if time and
ice condition allow. Special studies of small scale sea floor structures
and the texture will be possible using sidescan and backscatter data
collected by the HYDROSWEEP-system during the drift trajectory, due
to the slow movement of the ship. Beside the survey of the seafloor
topography, sub-bottom profiling will be carried out using the PARASOUND-system
on RV "Polarstern". The operating and the digital recording of Parasound
data will be performed within this work package; the data will be
utilized to study the structures of the upper sediment layers. |
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| Meteorology |
| Project Number: |
S-259 |
| Project Title: |
Energy balance at the ice surface from spring
to summer |
| PI's: |
Helbig and Bareiss, University Trier, Germany |
| Summary: |
During the spring/summer transition sea ice and snow properties change considerably in response to warming and freezing within the snow and ice pack. One important process that occurs during this period is the formation of superimposed ice. Results from prior expeditions in the Weddell Sea in 1997, (ARK VII/2) show that superimposed ice that may form layers of some decimeters is relevant for the survival of ice floes in the summer period. Due to this process up to 30% of the total sea ice thickness can be formed by superimposed ice. The warming and freezing of the temperature gradients in the snow pack is mainly caused by changes of the radiation fluxes at the surface of the snow and to a lesser extent by an increase of air temperatures (advection of warm air). Results of our observations will be included in state-of-the-art thermodynamic sea ice models, which do not all consider superimposed ice formation so far. In a pilot study in 2002 at the Kongsfjorden (Svalbard) extensive experiments were performed.
During ISPOL, we intend to investigate the meteorological boundary conditions for superimposed ice formation and its importance for Antarctic sea ice. The field study comprises measurements of the surface heat budget at the snow/ice interface. We will deploy radiometers (pyranometers and pyrgeometers) on an array to measure incoming and outgoing short-wave and long-wave radiation at sites that must be coordinated with the project of Haas. Routine meteorological variables such as air temperature, humidity, wind speed and direction will be obtained from an Automatic Weather Station (AWS). Turbulent fluxes of heat will be obtained from the group of Launiainen and/or Andreas/Guest who perform direct measurements of the sensible and latent heat flux by the eddy correlation method.
As surface albedo is extremely important for the melting process, we will also carry out albedo measurements. The surface albedo of the snow pack is obtained from the ratio of incoming and reflected short-wave global radiation. In addition to this spectral albedo of various surface types will be measured with a spectroradiometer at 256 wavelengths from 396 to 1075 nm. The areal coverage of surface types such as snow-covered ice, leads and melt ponds will be derived from Helicopter based digital camera records. The camera must be mounted below a helicopter moving with constant speed and height. |
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| Project Number: |
S-267 |
| Project Title: |
Surface fluxes and air-ice coupling in the western
Weddell Sea |
| PI: |
Launiainen , Finnish Institute of Marine Research
(FIMR), Finland
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| Summary: |
Contribution of our sub-project aims to: 1) Determination of local air-ice-ocean fluxes and coupling, by field measurements and processs studies, including air-ice surface temperature and fluxes, and ice thermodynamics. 2) Derivation of areal GCM sub-grid scale representative fluxes, composed from contributions from over ice, open water, cracks and leads. The study will be carried out by the field measurements (cf. above) and high resolution 1 and 2 D modelling and, comparing the field and model data with GCM model fields (ECMWF, NCEP/NCAR). 3) Study of ice dynamics and kinematics, as seen from the point of view of an important factor controlling point 2 above, and, as the mechanism of ice transport and fresh water balance in the Weddell Sea. From several studies above, we got experience from the Weddell Sea. The goals were similar, in a regional scale, in the just finished BALTEX-BASIS (Baltic Air-Sea-Ice Study) project, coordinated by FIMR, as well. By final coplanning and coordination with other sub-projects,our study should well fit with the scope of ISPOL-1 and those of iAnZone/SCOR, ASPECT/SCAR and IPAB/WMO.
For the ISPOL-1 campaign we plan to contribute the following measurements and studies:
a) Ship near-site surface flux and ice/snow observations. A sonic anemometer and a profile mast will be erected in a near- site ice field (<400m). Turbulent fluxes (momentum, heat) defined by the eddy flux and profile method will be compared and bulk coefficients (roughness lengths) studied. The latent heat flux will also be estimated. An in-ice(snow) temperature chain will be deployed for the ice thermodynamics studies and, regular snow/ice measurements will be carried out (snow/ice thickness, surface roughness measurements/video, density, moisture).
b) A remote autonomous (own power supply and HF data transmission) flux station will be deployed in a distance, up to 10 nm, from the ship site. The station includes a sonic anemometer (momentum, sensible heat), radiation sensors and an in/ice temperature chain. A measurement site different (surface roughness, albedo) from the ship site one is preferred. (A kind of station was tested in 2001 in the northern Baltic Sea; for maintenance, it is reasonable to be visited by men approx. 5 days intervals).
c) One meteorological and (at least) 3 location/air pressure drifting (Argos) buoys are deployed on sea ice floes and left in the area. Their data serve the goal 3 above and those of IPAB/WMO.
We favour our sub-project (our contribution) to be coordinated with that of Bareiss (University of Trier) and, especially, with the one of Andreas and Quest (CRREL+Naval Postgraduate School). The various contributions will nicely complete each others. By proper coordination and task share a very good sub-project/set of sub-projects can be formed, to get good efforts. As a national framework, our sub-project is a contribution to FINNARP program. |
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| Sea Ice Physics |
| Project Number: |
S-259 |
| Project Title: |
Changes of ice physical properties during the onset
of summer melt |
| PI: |
Haas, AWI, Germany |
| Summary: |
During the spring/summer transition, sea ice and snow properties change considerably in response to warming and the eventual reversal of temperature gradients within the snow and ice. Most well known is the ablation and desalination of the upper ice layers of second- and multi-year ice in the Arctic. However, before these large obvious changes due to surface ablation commence, actually ice growth takes place at the snow/ice interface. This is due to snow melt water percolating down towards the colder snow/ice interface, where it refreezes. In the Antarctic where snow thickness is much greater and where surface ablation is much less relevant, recent observations show that superimposed ice may actually form layers of some decimeters in thickness. At the end of summer, ice floes in certain areas may consist almost exclusively of superimposed ice, which is responsible for the survival of the floes. Simultaneously, surface gap layers form underneath the superimposed ice. These host extremely high diatom standing stocks. The environmental conditions for their development is not clear so far, and there is a dispute whether they are mainly formed by biotic or abiotic factores.
The meteorological boundary conditions for superimposed ice formation are little studied, as it has not been recognized so far to be important for the history of an ice floe. The first objective of this study is to investigate the main processes and boundary conditions for superimposed ice and gap layer formation, in recognition of their importance for Antarctic sea ice, and their possible importance for Arctic sea ice in case of environmental changes due to future climate change. This will be performed by means of combined measurements of ice properties and the energy budget at the ice and snow surface. Superimposed ice formation results in marked increases of radar backscatter as visible in satellite data. Therefore, our study aims to provide ground-truth information for coincident remote sensing studies. Here, we intend to order ENVISAT-SAR data simultaneous with our field experiment.
The results of our observations will be included in state-of-the-art thermodynamic models of sea ice growth, which do not at all consider superimposed ice formation so far.The second goal of this project is the determination of changes in the ice thickness distribution. Clearly, these changes will be dominated by a steady decrease of thickness due to summer melt. However, it is unknown to what extent the ice cover melts inside the closed pack ice, and how it contributes to the freshwater budget before the floes actually fracture and break apart in the MIZ. It is also unknown how thin ice is distributed into thick ice categories during deformation events. A drift station offers the unique opportunity to monitor these changes in a certain ice field. |
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| Project Number: |
S-265 |
| Project Title: |
Melt processes of sea ice and the validation of
remote sensing satellite data |
| PI's: |
Lyttle, Massom & Worby, Antarctic CRC, Australia |
| Summary: |
We propose to investigate the melt and decay process of sea ice, and their interaction with the ocean structure and the biological processes. These studies will also use field measurements to help validate of satellite sensors. Satellite data will also be used to extent the field results to a larger region.
We will be conducting a large scale field experiment in October and November, 2002 in the East Antarctic Sea ice Zone. This experiment includes plans for extensive validation of satellite remote sensing instruments, including those on board the Aqua and Envisat satellites. We are approved P.I.'s for the validaion of AMSR-E products in the sea ice zone in a separate NASA proposal entitled "Validation Studies for Data Products from the Earth Observing System AQUA Platform and EOS-Related Spectroscopic Studies" (Proposal Number Aqua-0055-0063, Dr. Massom P.I.). ISPOL-1 will be an excellent chance to extend these studies to a different region and season.
Ice melt processes: We propose to use aerial photography and targeted sampling of floes to document the detailed changes of regional ice conditions during the melt season. This includes changes in floe size and shape, ice concentration and snow and ice thickness. The use of a high resolution digital camera, and repeat flights between the same floes, will allow us to estimate the horizontal melt rates of individual floes and compare this to estimates of vertical melt rates. This will also enable us to estimate the fresh water flux to the upper ocean for comparison with oceanographic estimates. These results will be compared with data from satellite sensors (primarily high-resolution SAR data) to extend the results over larger regions. Ridging statistics from the aeiral photos can also be compared with those collected using lasar profiles (Haas).
Snow characteristics: We propose to collect a time series of detailed measurements of snow physical properties (grain size, salinity, temperature, wetness, density, oxygen isotopes, etc.) These will be compared with data from satellite sensors to validate algorithms results, in particular to investigate the impact of snow wetness, and temperature on snow thickness retrievals from EOS AMSR data. Results from these snow data will also help estimate the larger scale thermodynamics and melt processes which occur during the spring to summer transition, and the role of the snow cover in helping preserve the sea ice. We will also collect sea ice samples for oxygen isotope measurements to determine the snow ice content in the sea ice.
Sea ice dynamics and drift characteristics: We propose to deploy several (5-7) small buoys on sea ice floes to measure the sea ice drift and deformation. The location of these drifters will correspond to regions covered by aerial photography. These drifters will record their position hourly using GPS receivers. Data from these buoys (in addition to the drift of the ice camp) will be used to determine the regional deformation of the sea ice in the region. These drift speeds will be compared with velocities derived from sequential satellite SAR images and other satellite data sources. Depending on funding, these buoys may be self-recording, or will transmit their data via satellites, and they may also be configured with meterological sensors. Some of the buoys may remain after the the experiment to continue to monitor the drift and deformation of the sea ice. |
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| Sea Ice Biology
and Biogeochemistry |
| Project Number: |
S-258 |
| Project Title: |
Ice algea ecology |
| PI: |
Dieckmann, AWI, Germany |
| Summary: |
The aim of the proposed work is to make a detailed characterisation of the
physical and chemical environment of summer sea ice, with an emphasis on sites supporting rich biological assemblages. These intensive investigations will be used to improve our understanding of the limits to algal growth and the forcing of the community structure. The implication, during eventual melting on particulate flux will be assessed. This field programme offers a rare opportunity to sample the same habitats in detail and over a long period.
Sea ice samples will be taken using established techniques that allow collection with the minimum contamination. The physico-chemical environment will be investigated through in situ measurements of oxygen, pH, alkalinity, nitrate, ammonia, nitrite, phosphate, silicate, salinity, temperature. The species composition of the biological assemblages will be determined and this information complimented by measurements of chlorophyll, biogenic silicate, the concentration of particulate organic carbon and nitrogen (POC, PON). These measurements will be supplemented by phytoplankton and zooplankton species identification for community structure. The restraints on biological activity will be investigated using this data in conjunction with isotope data on dissolved and particulate organic matter. The measurements are vital if we are to describe the biogeochemical environment of summer sea ice and make deductions about the cycling and fate of carbon within and from sea ice. In addition to measurements on ice core samples and brines, appropriate measurements will also be made on water column samples, in particular water
layers directly below the ice. Determination of in situ photosynthetic activity and community respiration will be made by oxygen measurements using in situ optodes and primary production chambers.
Incident irradiance will be measured at the surface of the ice, and underwater sensors will be deployed to measure in situ light levels. There is a weather station for standard measurements. Small sediment traps will be deployed under the ice to collect sedimenting particulate material. These will be left for weekly periods (or shorter depending on conditions) at depths to be determined. Samples will be split: one for archive, organism and fecal pellet enumeration will be preserved in formalin. The remaining splits will provide samples for POC/PON, biogenic silicate, chlorophyll and delta13C-POC.
Divers will be deployed to secure underwater equipment under the sea ice and do video surveys of the sea ice topography and associated organisms. It is expected that most of the work will be done on the ice from huts. This will facilitate the continuous recording of important parameters. |
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| Project Number: |
S-260 |
| Project Title: |
Dissolved organic matter in sea ice and at the
ice water interface |
| PI: |
Thomas, University Bangor, U.K. |
| Summary: |
The study (2 month time series) has two main components conducted:
-To conduct comprehensive measurements of particulate and dissolved organic and inorganic constituents of summer sea ice. Central to these will be measurements of dissolved organic matter (DOC/ DON/ DOP) in platelet ice assemblages.
-At the same time standing stocks of bacteria, algae, protozoa and metazoa components of the biological assemblage that develops during the sampling period will be measured. This will improve our understanding of the limits to algal growth and the forcing of the community structure.
-To measure the export and the nature of particulate and dissolved organic matter sedimenting from sea ice over time and asses the nature of the flux to the underlying sediments. |
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| Project Number: |
S-261 |
| Project Title: |
Ice algea: An important source of DMS? |
| PI: |
Stefels, University Groningen, Netherlands |
| Summary: |
Dimethyl Sulphide (DMS) is a volatile compound that is studied intensively because its oxidation products are involved in the formation of condensation nuclei and clouds. It thereby affects the albedo of skies and clouds and is thus highly relevant for "global change" discussions and models. Antarctic waters are estimated to contribute 10-30% to the global DMS flux. Considering these large amounts of DMS transferred to the atmosphere, it is conceivable that the oceanic productivity affects climate over a large area of the Antarctic continent and possibly over a much larger area of the Southern Ocean. Bio-physical processes in the Antarctic coastal waters and ice edges are therefore potentially very relevant in the context of global climate studies.
The estimations on Antarctic DMS flux are, however, based on a very limited number of data. From the data available, we know that extremely high concentrations of DMS in the water are often related to the presence of the alga Phaeocystis antarctica (Gibson et al.1990) There is also some data on DMSP (the algal precursor of DMS) from ice algae, which can be orders of magnitude higher than in the surrounding waters (Kirst et al. 1991). The efficiency of conversion of this DMSP into DMS and the subsequent flux to the atmosphere are, however never studied.
DMS fluxes are typically calculated by using a bulk aerodynamic approach. With this approach fluxes are calculated from the product of the concentration difference driving the flux and a kinetic factor, known as the transfer velocity (Liss and Merlivat, 1986; Wanninkhof, 1992). This kinetic term is uncertain and is highly dependent on meteorological conditions such as wind speed and temperature, which leads to disparities in calculated fluxes as high as 80% (Smith et al., 1996). In order to draw conclusions on the effect of the high DMS concentrations found during the Antarctic spring and summer on the climate, a more accurate measurement of the DMS flux is required.
The possibility to set-up sampling devices on the ice would give us the perfect scene for incubation experiments in order to study the effects of abiotic factors on the production and conversion of DMSP and DMS in ice communities and to study the spatial variability of DMSP and DMS production in ice and in the surrounding waters coupled to direct flux measurements. Although you might argue that the flux of DMS from the water will be prevented by ice formation, there is good reason to believe that a fair amount of DMS will originate from the ice algal community itself. Especially Phaeocystis antarctica is known to form thick patches on the ice surface.
In short, the objectives of our project are:
(1) to investigate the spatial heterogeneity of DMS and DMSP of sea ice and (if possible) its surrounding waters, in relation to a variety of biological and chemical parameters.
(2) directly measure the DMS fluxes from the ice and (if possible) its surrounding waters using the gradient flux and relaxed eddy accumulation techniques.
(3) to study the controlling factors of DMSP and DMS production by ice algae in incubation experiments.
The acquired knowledge will improve our understanding of how ice, oceans, and atmosphere are linked via the flux of climatically important gases. It will provide essential and basic information on the influence of biological production on DMS emission to the atmosphere around Antarctica and improve scenarios of climate forcing by ice/ocean-atmosphere interactions and the significance of the Antarctic. |
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| Project Number: |
S-263 |
| Project Title: |
Iron, sulphur and biological interactions during
the process of sea ice melting |
| PI's: |
Tison et al., DSTEG Brussels, Lancelot et al., ESA Brussels, and
Chou et al., LOCGE Brussels, Belgium |
| Summary: |
This field project comes in support of a long-term research program aiming to assess to which extent ice-covered polar oceans contribute to processes regulating the Earth's Climate. The program involves a new multidisciplinary consortium combining the expertise of glaciologists, biologists, geochemists and ecosystems-modelers of the Université Libre de Bruxelles (ULB). This ULB consortium fits into a larger network of active collaboration involving several laboratories all over Europe (B, I, D, F, UK, NL).
The main goal of the project is to study, understand and quantify the physical and biogeochemical processes associated with the sea ice biota that govern the emissions of marine gases of climatic significance. These processes are indeed presently unknown and therefore not integrated into Oceanic Biogeochemical Climate Models (OBCMs). In this context, particular attention will be paid to Carbon Dioxide (CO2) and Dimethyl Sulphide (DMS), both actively involved in the sea ice microbial metabolism. On a global level, CO2 is well known for its efficient greenhouse gas behavior, while DMS has the recognized potential to stabilize the climate against warming by controlling the incident solar energy via the production of aerosols and cloud condensation nuclei. It has now been demonstrated that iron can play a crucial role in controlling phytoplanktonic productivity and the biological carbon pump in the Southern Ocean. The work programme will thus in addition focus especially on the biogeochemical cycle of iron (origin, availability and fate) in the sea ice environment.
The research methodology will be highly interdisciplinary and combine field investigations, process-oriented studies both "in situ" and in the laboratory, and modeling work in order to quantify key biological, geochemical, and physical interactions between sea ice, the ocean and the atmosphere, and to elucidate the controlling mechanisms. Cores collected during field surveys will be used to characterize the distribution of Fe, CO2, DMS and other related physico-chemical and biological parameters in sea ice. Chemical transformation of iron during melting of sea ice and the associated biological and chemical processes will also be studied in the field. Investigations on the mechanisms regulating iron bio-availability and on the iron isotopes bio-signature will be conducted under laboratory-controlled conditions on cultures of polar micro-organisms. Each topic will involve the development of new methodologies including, e.g., fluorescent probes, molecular methods (PCR, DGGE), iron isotope analysis (MC-ICP-MS), iron flow injection analysis (Fe-FIA), extraction and gas chromatography for gaseous DMS. Modeling efforts will involve the development of a new sea ice biogeochemical model (SIMCO). Its parameterization will rely on the results obtained during the process studies described above. The online coupling of the SIMCO model with the existing, and currently being improved, model for the upper layer of the Southern Ocean (SWAMCO) should yield an original data set of CO2 and DMS fluxes between the ocean and the atmosphere in polar oceans. These would then be available to ultimately be fed into more general circulation models.
The program specifications described above thus fit adequately in the objectives and tasks of ISPOL1, more specifically:
- To investigate physical, biogeochemical and biological processes controlling the transformation and interactions in the atmosphere-ice-ocean system from austral spring to summer,
- To improve our understanding of the seasonal interaction between biota and sea ice. |
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| Project Number: |
S-318 |
| Project Title: |
Zooplankton development in and underneath the
ice |
| PI: |
Schiel, AWI, Germany |
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| Water Column
Biology |
| Project Number: |
S-273 |
| Project Title: |
Antarctic pack ice: biological processes and
interaction with the pelagial |
| PI's: |
Spindler & Werner, IPÖ Kiel, Germany |
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| Related Projects |
| Project: |
GOAL (Grupo de Oceanografia de Altas Latitudes) |
| University: |
Fundação Universidade do Rio Grande (FURG) |
| Country: |
Brasil |
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