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The role of the Southern Ocean in the carbon cycle
Metadata record for data from ASAC Project 133 See the link below for public details on this project. Surface carbon dioxide (CO2) observations are integral to understanding the role of the Southern Ocean in the global carbon cycle, and to developing reliable predictions of biogeochemical responses to altered climatic conditions. Carbon dioxide (CO2) observations made in surface waters of the Australian sector of the Southern Ocean between the years 1991 and 2002 were used to estimate the seasonal variability in the fugacity of CO2 (fCO2) and net air-sea carbon fluxes. The results showed a net annual uptake of CO2 by the surface ocean over the entire region. The greatest seasonal uptake and lowest fCO2 values were observed in Spring/Summer in the sub-Antarctic zone (SAZ: 44 degrees S-50 degrees S) and in the Seasonal Sea-ice Zone (SIZ: south of 62 degrees S). The seasonal maximum in uptake for these regions is consistent with increased phytoplankton biomass and shoaling mixed layers over the Spring/Summer period. The High Nutrient Low Chlorophyll waters between 50 degrees S and 62 degrees S, also had maximum uptake in summer, but less compared to the SAZ and SIZ regions. Winter surface waters were close to or slightly above equilibrium, with respect to atmospheric CO2. The reduced uptake in winter appeared due to deeper mixing, lower biomass, and air-sea CO2 exchange. The highest fCO2 values in Winter were observed under or near the seasonal sea-ice where entrainment of deeper CO2-rich waters and ice cover would maintain high surface fCO2 values. The smallest seasonal amplitude in the surface fCO2 and net air-sea fluxes was found from 51 degrees S to 54 degrees S, a region on the southern edge of the SAZ and between the North sub-Antarctic Front and North Polar Front. The uptake estimates derived from the data were in good agreement with the CO2 flux climatology of Takahashi (2002), except in the SAZ and SIZ where we observed greater and less uptake, respectively. Data for this project are available for download - the dataset consists of a data files, and some excel files, which provide further information about each data file (cruise, dates, etc). Furthermore, the column headings used in the data files are as follows: Cruise - name of the cruise which collected the data Date - UTC Time - in UTC Latitude - decimal Longitude - decimal Sst - Sea Surface Temperature in degrees C Teq - Temperature of surface water at which the CO2 measurement is made. Sal - Salinity Patm - atmospheric pressure in hectopascals Shipspd - ship speed in knots Windspd - wind speed in knots Winddir - wind direction in degrees xCO2 - Mole fraction of CO2 in air (dry) equilibrated with surface water and at equilibrator water temperature xCO2air - Mole fraction of CO2 in atmosphere, dry pCO2 - partial pressure of carbon dioxide in surface water
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The Role of Appendicularians in Southern Ocean Carbon Flow and Trophodynamics
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Data acquisition: Samples were collected using a 1.5 metre diameter Ring net (150 micron metre mesh) with a wide cod-end on the base (volume approximately 40 Litres). Vertical trawls were to 20 m (unless otherwise specified). Deployment speed was determined by wave conditions with hauling speed at slowest possible speed available by the gantry (approximately than 2 meters per second). The net was rinsed with sea water before the cod-end was removed and the contents determined by observing a sub-sample under the light microscope. Appendicualrians were separated and preserved while the remaining contents of the cod-end were sieved through 120 micrometre mesh and preserved to be sorted more accurately on return to the laboratories. The appendicularians were quantified and sorted under light microscopes with additional randomly selected individuals being prepared for Scanning Electron Microscopy (SEM) imaging to enable identification to species level and some Oikopleura gaussica stomach's where dissected for SEM dietary analysis. Data processing: Data are being processed using 'statistica 6' (and possibly PRIMER or PATN) to determine correlations with physical parameters obtained from underway data, the CTD and the microbial biologist. Dataset Format: Database is an excel spreadsheet Parameters: Leg - identification number of southern bound legs Event number - deployment number Station - leg number . sample point number CTD - number of corresponding CTD (conductivity, Temperature Depth sample point) Date - date/month/year Time (UTC) Latitude Longitude NET (mesh (micro meters) type) - Net type and mesh size in micro meters (150) DEPTH (m) - vertical trawl depth APPENDICULARIANS - count of appendicularians from ship and laboratory based sorting Fritiliaria drygalski - count of Fritillaridae's from ship and laboratory based sorting Oiklopleura gaussica - count of Oikopleuridae's from ship and laboratory based sorting Alive - count of live appendicularians from ship based sorting SEM IMAGE - individual appendicularians and/or O. gaussica stomach SEM images have been taken SEM Stub number - stub number that is first two numbers of SEM images SAMPLE TYPE - BARCODE Zooplankton - cod-end contents sieved and preserved Appendicularians - sorted from cod-end Live - live appendicularians (now preserved) Other 1- samples that did not fit in to the above categories or additional samples for station Other 2- additional samples for station that did not fit in to the above categories This work was completed as part of ASAC projects 2655 and 2679 (ASAC_2655, ASAC_2679).
The carbon cycle in the Australian sector of the Southern Ocean. Data from VMS - 2010-2011
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The Southern Ocean is one the most significant regions on earth for regulating the build up of anthropogenic CO2 in the atmosphere, and the capacity for carbon uptake in the region could be altered by climate change. The project aims to establish a time series of anthropogenic carbon accumulation. The work will be used to identify processes regulating the CO2 uptake and to test models that predict future uptake. These data were collected on the VMS voyage of the Aurora Australis in the 2010-2011 field season. Data include pH, carbon dioxide, alkalinity and spectrometer data.
Ctenophores of the Southern Ocean
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This dataset is a document describing the Ctenophores of the Southern Ocean. It lists all the known species and with illustrated diagrams provides a guide to their taxonomic identification. The document is available for download as a pdf from the provided URL.
Southern Ocean Calcareous Zooplankton Response to Ocean Acidification
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Metadata record for data from AAS (ASAC) project 3046. Public The overall objective is to characterise the response of Southern Ocean calcareous zooplankton to ocean acidification resulting from anthropogenic CO2 emissions. Simulated increases in anthropogenic CO2 suggest a reduction in the calcification rates of calcareous organisms. A change in the calcification in the Southern Ocean may cause marine ecosystem shifts and in turn alter the capacity for the ocean to absorb CO2 from the atmosphere. We plan to take advantage of naturally-occurring, persistent, zonal variations in Southern Ocean primary production and biomass to investigate the effects of CO2 addition from anthropogenic sources on Southern Ocean calcareous zooplankton communities. A download file containing an excel spreadsheet of data can be found at the provided URL. Project objectives: The overall objective of this project is to characterise the impacts of recent, primarily anthropogenic, increases in atmospheric CO2 and related changes in the carbonate chemistry on shell formation by calcareous zooplankton in the Australian sector of the Southern Ocean. Calcareous zooplankton (e.g. planktonic foraminifera and pteropods) will be collected using plankton nets at five Southern Ocean localities during high seasonal flux periods. Planktonic foraminiferal and pteropod species and abundances, calcification rates and geochemistry (stable isotope and trace-metal) will be determined on plankton tow samples. Data from recent plankton tow samples will be compared with data deposited historically in the Southern Ocean and recovered from existing deep ocean sediment cores to provides insights about the extent to which modern carbon conditions may have already generated ecological impacts. The project will also provide a baseline of the present-day impact of ocean acidification and can be used to monitor the influence of future anthropogenic CO2 emissions in Southern Ocean ecosystems. Taken from the 2008-2009 Progress Report: Progress against objectives: Because of logistical delays to the Aurora Australis shipping schedule, ship time for this project was deferred to the 2009/2010 season. We have made progress in analysing other materials form previous voyages which will assist in the sampling design for the upcoming season. We are making good progress in planning the upcoming voyage currently scheduled for late 2009. Taken from the 2009-2010 Progress Report: Progress against objectives: Project scientists participated in Voyage 2 of the Aurora Australis, from Hobart to Casey Station in December 2009. Using the Rectangular Midwater Trawl we collected a total of eight plankton samples for examination of calcareous plankton distribution and shell characteristics in the summer Southern Ocean. We were targeting pteropods and planktonic foraminifera, two sets of calcifiers whose calcification response to ocean acidification we had previously reported on in publications in Nature Geoscience, Biogeosciences Discussions, and Deep-Sea Research Part II (in press). Project participants included collaborators from Australian National University and Scottish Natural Heritage, UK. There were low abundance of planktonic calclfiers in this particular seasons and sector, but we consider the initial collection a god start. Samples included approx. 18 pteropods; other samples are still being held by Biosecurity Australia and will be examined as soon as they are released. Other samples have already been sent to researchers at the Australian Institute of Marine Science for genetic (RNA) sequencing. This latter collaboration is a key one which will help answer questions about evolutionary responses to ocean acidification; if there are genotypes which are more or less vulnerable to acidification we may already be seeing selective pressure in the ecosystem and a change in the structure of assemblages as "winners" and "losers" are differentially affected by the impact.
Southern Ocean Carbon Cycle
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Metadata record for data from ASAC Project 2592 See the link below for public details on this project. The Southern Ocean is one the most significant regions on earth for regulating the build up of anthropogenic carbon in the atmosphere, and the capacity for carbon uptake in the region could be altered by climate change. The project aims to use repeat ocean sections to detect anthropogenic carbon storage, identify key processes regulating the amount of storage, and to test models that predict future uptake. The data are broken down by season and voyage, and a word document providing further details about the project is also available as part of the download file.
Iron content of Southern Ocean phytoplankton: implications for carbon transfer to the deep sea
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Metadata record for data from ASAC Project 2297: Iron content of Southern Ocean phytoplankton: implications for carbon transfer to the deep sea. Data on size-fractionated distribution of suspended trace elements (including iron) in marine particles taken from the surface Southern Ocean south of Australia. Data for 4 size-fractions at 4 stations along ~142 degrees E are included. Explanation of codes used in the dataset: The isotope of the element of interest is listed down column A. LR refers to low resolution and MR medium resolution (that is the resolution of the ICPMS analytical instrument). So Mn55(LR) is the manganese isotope 55 ran in low resolution. SFP1_2um_B2_1: SFP=size-fractionated particles 1=station 1 2um=2micron filter size B2=blank 2 1=replicate 1 RSD%=relative standard deviation in % Blank=field blank Blk/sample%=blank-to-sample ratio in % CRMs_261102=certified reference materials (ran on 26 Nov 2002) Scaled up=previous column times multiplication factor (a serial dilution was used) Blk=blank subtracted certified=the value certified by the manufacturer of the reference material SLRS_1in25_1= the CRM 'SLRS', ran with a 1 in 25 dilution factor, replicate 1 DigBlk1_1=digestion blank 1, replicate 1 See the link below for public details on this project.
UV climate over the Southern Ocean south of Australia, and its biological impact - Dissolved Organic Carbon (DOC) results
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Minicosm design: Three successive experiments to a maximum incubation of 14 days were performed from mid November to early January in the summer of 2002/03 in a temperature controlled shipping container housing six 500 L polythene tanks or minicosms. Domes of UV transmissive PMMA in the roof of the container directly above the minicosms allowed ambient sunlight to be reflected to the tanks through tubes of anodised aluminium. These tubes reflected greater than 96% of the incident radiation irrespective of wavelength. Light perturbation to each minicosm was achieved by screening materials that attenuated UV wavelengths. UV stabilised polycarbonate removed wavelengths shorter than 400 nm, transmitting only photosynthetically active radiation (PAR) and provided the control treatment (PAR). In minicosm 2, a mylar screen removed UVB wavelengths (280 - 320 nm), providing a treatment (UVA) with PAR and UVA. Minicosms 3, 4 and 5 (UVB1, 2 and 3 respectively) were screened by borosilicate glass of 9, 5, and 3 mm thickness, transmitting ambient light (including UVR) at the equivalent water depths (ED, k=0.4) of 7.15, 5.38 and 4.97 meters respectively. Minicosm 6 (UVB4) was screened with PMMA that transmitted ambient light at an ED of 4.43 m. Light measurements: Measurements of downwelling UV and PAR were obtained using biometer and Licor sensors mounted on the roof of the minicosm container. A Macam, double grating spectroradiometer measured the spectral irradiance on the roof of the container. This was then weighted with the erythemal action spectrum and correlated to that obtained by the UV biometer. The Macam was used to measure the spectral irradiance at the cross of the UV biometer. The spectral intensity of light wavelengths were measured laterally and vertically in the minicosm screened only by UV-transmissive PMMA irradiance. These measurements were used to model the light field within the minicosm. In all other light treatments the Macam measured the spectral irradiance immediately below the water surface and in the centre of the minicosm. The model was then used to predict the spectral distribution and intensity of other light treatments. These measurements were repeated at interval throughout the season to determine whether solar elevation influenced transmission of ambient downwelling irradiance to the minicosms. UV and PAR sensors fixed to the outside of the minicosm container, together with the modelled light climates within each minicosm beneath each light treatment, predicted the quantify the light to which each experimental treatment was exposed. This work was conducted as part of ASAC project 2210. The download file contains three excel spreadsheets, plus three accompanying word documents which provide detailed methods used in the collection of these data, plus more information about the experiments. The fields in this dataset are: Day Treatment UVA UVB PAR - photosynthetically active radiation
Southern Ocean Sea Ice Extent and Area
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This indicator is no longer maintained, and is considered OBSOLETE. INDICATOR DEFINITION The northern limit of the pack ice as defined by the 15% concentration of sea ice determined by the SSM/I instrument or its replacement. TYPE OF INDICATOR There are three types of indicators used in this report: 1.Describes the CONDITION of important elements of a system; 2.Show the extent of the major PRESSURES exerted on a system; 3.Determine RESPONSES to either condition or changes in the condition of a system. This indicator is one of: CONDITION RATIONALE FOR INDICATOR SELECTION Climate is affected by complex interactions between the sea ice and the atmosphere and ocean. The sea ice extent and concentration is determined by the oceanic and atmospheric forcing. There is evidence of variations in the sea ice extent and concentration on a synoptic time scale as storms pass through the region, and variations in sea ice extent on a multi-year time frame with forcing caused by the Antarctic circumpolar wave. Over the past 20 years, there is limited evidence of an increase in spatial ice extent and in the length of time that ice is present. Continued monitoring of sea ice extent and concentration may provide insights into the dynamics of the Southern Ocean and help to predict future climate. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM NASA uses a combination of satellite passive microwave sensors to measure the brightness values over sea ice covered regions. They then use an algorithm (referred to as the 'team' algorithm) to calculate the ice concentration and to determine the ice edge. The data are available globally on a daily or monthly basis. RESEARCH ISSUES Currently, NASA intends to maintain a series of satellite microwave sensors to continue to monitor sea ice extent and concentration. Ongoing research to interpret the data are currently being carried out at the AAD and the Antarctic and Southern Ocean CRC. Links with other indicators The sea ice extent and concentration has a large impact on the surface salinity and temperatures. Thus strong links with sea surface salinity and sea surface temperatures.
Physical and biogeochemical dynamics of the subantarctic zone
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This metadata record is a 'Parent' metadata record for ASAC project 2720. See the link for the related 'Child' metadata records. The overall objective is to characterise Southern Ocean marine ecosystems, their influence on carbon dioxide exchange with the atmosphere and the deep ocean, and their sensitivity to past and future global change including climate warming, ocean stratification, and ocean acidification from anthropogenic CO2 emissions. In particular we plan to take advantage of naturally-occurring, persistent, zonal variations in Southern Ocean primary production and biomass in the Australian Sector to investigate the effects of iron addition from natural sources, and CO2 addition from anthropogenic sources, on Southern Ocean plankton communities of differing initial structure and composition. SAZ-SENSE is a study of the sensitivity of Sub-Antarctic Zone waters to global change. A 32-day oceanographic voyage onboard Australia's ice-breaker Aurora Australis was undertaken in mid-summer (Jan 17 - Feb. 20) 2007 to examine microbial ecosystem structure and biogeochemical processes in SAZ waters west and east of Tasmania, and also in the Polar Frontal Zone south of the SAZ. The voyage brought together research teams from Australasia, Europe, and North America, and was led by the ACE CRC, CSIRO Marine and Atmospheric Research, and the Australian Antarctic Division. The overall goal is to understand the controls on Sub-Antarctic Zone productivity and carbon cycling, and to assess their sensitivity to climate change. The strategy is to compare low productivity waters west of Tasmania (areas with little phytoplankton) with higher productivity waters to the east, with a focus on the role of iron as a limiting micro-nutrient. The study also seeks to examine the effect of rising CO2 levels on phytoplankton - both via regional intercomparisons and incubation experiments. Available for download from this metadata record are various datasets collected from the voyage: An image showing a map of the cruise track. An excel document detailing hourly position checks of the ship. An excel document detailing the event log for the voyage. A word document detailing prospective papers produced from the voyage. Finally a link is available for users to access the special volume of publications produced as a result of this voyage.
UV climate over the Southern Ocean south of Australia, and its biological impact - Particulate Organic Carbon (POC) results
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Minicosm design: Three successive experiments to a maximum incubation of 14 days were performed from mid November to early January in the summer of 2002/03 in a temperature controlled shipping container housing six 500 L polythene tanks or minicosms. Domes of UV transmissive PMMA in the roof of the container directly above the minicosms allowed ambient sunlight to be reflected to the tanks through tubes of anodised aluminium. These tubes reflected greater than 96% of the incident radiation irrespective of wavelength. Light perturbation to each minicosm was achieved by screening materials that attenuated UV wavelengths. UV stabilised polycarbonate removed wavelengths shorter than 400 nm, transmitting only photosynthetically active radiation (PAR) and provided the control treatment (PAR). In minicosm 2, a mylar screen removed UVB wavelengths (280 - 320 nm), providing a treatment (UVA) with PAR and UVA. Minicosms 3, 4 and 5 (UVB1, 2 and 3 respectively) were screened by borosilicate glass of 9, 5, and 3 mm thickness, transmitting ambient light (including UVR) at the equivalent water depths (ED, k=0.4) of 7.15, 5.38 and 4.97 meters respectively. Minicosm 6 (UVB4) was screened with PMMA that transmitted ambient light at an ED of 4.43 m. Light measurements: Measurements of downwelling UV and PAR were obtained using biometer and Licor sensors mounted on the roof of the minicosm container. A Macam, double grating spectroradiometer measured the spectral irradiance on the roof of the container. This was then weighted with the erythemal action spectrum and correlated to that obtained by the UV biometer. The Macam was used to measure the spectral irradiance at the cross of the UV biometer. The spectral intensity of light wavelengths were measured laterally and vertically in the minicosm screened only by UV-transmissive PMMA irradiance. These measurements were used to model the light field within the minicosm. In all other light treatments the Macam measured the spectral irradiance immediately below the water surface and in the centre of the minicosm. The model was then used to predict the spectral distribution and intensity of other light treatments. These measurements were repeated at interval throughout the season to determine whether solar elevation influenced transmission of ambient downwelling irradiance to the minicosms. UV and PAR sensors fixed to the outside of the minicosm container, together with the modelled light climates within each minicosm beneath each light treatment, predicted the quantify the light to which each experimental treatment was exposed. This work was conducted as part of ASAC project 2210. The download file contains three excel spreadsheets, plus three accompanying word documents which provide detailed methods used in the collection of these data, plus more information about the experiments. The fields in this dataset are: Day Treatment Carbon Hydrogen Nitrogen C:N ratio