ALBERT

Description: Ocean temperature observations are crucial for a host of climate research and forecasting activities, such as climate monitoring, ocean reanalysis and state estimation, seasonal-to-decadal forecasts, and ocean forecasting. For all of these applications, it is crucial to understand the uncertainty attached to each of the observations, accounting for changes in instrument technology and observing practices over time. Here, we describe the rationale behind the uncertainty specification provided for all in situ ocean temperature observations in the International Quality-controlled Ocean Database (IQuOD) v0.1, a value-added data product served alongside the World Ocean Database (WOD). We collected information from manufacturer specifications and other publications, providing the end user with uncertainty estimates based mainly on instrument type, along with extant auxiliary information such as calibration and collection method. The provision of a consistent set of observation uncertainties will provide a more complete understanding of historical ocean observations used to examine the changing environment. Moving forward, IQuOD will continue to work with the ocean observation, data assimilation and ocean climate communities to further refine uncertainty quantification. We encourage submissions of metadata and information about historical practices to the IQuOD project and WOD.

Description: Published

Description: 689695

Description: 4A. Oceanografia e clima

Description: JCR Journal

Description: Author Posting. © American Meteorological Society, 2013. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 43 (2013): 2132–2141, doi:10.1175/JPO-D-12-0182.1.

Description: Repeated occupations of two hydrographic sections in the southwest Pacific basin from the 1990s to 2000s track property changes of Antarctic Bottom Water (AABW). The largest property changes—warming, freshening, increase in total carbon, and decrease in oxygen—are found near the basin’s deep western boundary between 50° and 20°S. The magnitude of the property changes decreases with increasing distance from the western boundary. At the deep western boundary, analysis of the relative importance of AABW (γn 〉 28.1 kg m−3) freshening, heating, or isopycnal heave suggests that the deep ocean stratification change is the result of both warming and freshening processes. The consistent deep ocean changes near the western boundary of the southwest Pacific basin dispel the notion that the deep ocean is quiescent. High-latitude climate variability is being directly transmitted into the deep southwest Pacific basin and the global deep ocean through dynamic deep western boundary currents.

Description: BMS, SEW, and BT were supported by the Australian Climate Change Science Program, funded jointly by the Department of Climate Change and Energy Efficiency and CSIRO. Funding for AM was provided through NOAA GrantNA110AR4310063.

Description: 2014-04-01

Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing 10 (2018): 331, doi:10.3390/rs10020331.

Description: The Southern Ocean is the focus of many physical, chemical, and biological analyses due to its global importance and highly variable climate. This analysis of sea surface temperatures (SST) and global teleconnections shows that SSTs are significantly spatially correlated with both the Antarctic Oscillation and the Southern Oscillation, with spatial correlations between the indices and standardized SST anomalies approaching 1.0. Here, we report that the recent positive patterns in the Antarctic and Southern Oscillations are driving negative (cooling) trends in SST in the high latitude Southern Ocean and positive (warming) trends within the Southern Hemisphere sub-tropics and mid-latitudes. The coefficient of regression over the 35-year period analyzed implies that standardized temperatures have warmed at a rate of 0.0142 per year between 1982 and 2016 with a monthly standard error in the regression of 0.0008. Further regression calculations between the indices and SST indicate strong seasonality in response to changes in atmospheric circulation, with the strongest feedback occurring throughout the austral summer and autumn.

Description: B.S.F. is supported by the NASA/South Carolina Space-grant Graduate Assistantship. A. Macdonald acknowledges support from NOAA Grant #NA160AR4310172.

Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 15 (2018): 5847-5889, doi:10.5194/bg-15-5847-2018.

Description: Since the start of the industrial revolution, human activities have caused a rapid increase in atmospheric carbon dioxide (CO2) concentrations, which have, in turn, had an impact on climate leading to global warming and ocean acidification. Various approaches have been proposed to reduce atmospheric CO2. The Martin (or iron) hypothesis suggests that ocean iron fertilization (OIF) could be an effective method for stimulating oceanic carbon sequestration through the biological pump in iron-limited, high-nutrient, low-chlorophyll (HNLC) regions. To test the Martin hypothesis, 13 artificial OIF (aOIF) experiments have been performed since 1990 in HNLC regions. These aOIF field experiments have demonstrated that primary production (PP) can be significantly enhanced by the artificial addition of iron. However, except in the Southern Ocean (SO) European Iron Fertilization Experiment (EIFEX), no significant change in the effectiveness of aOIF (i.e., the amount of iron-induced carbon export flux below the winter mixed layer depth, MLD) has been detected. These results, including possible side effects, have been debated amongst those who support and oppose aOIF experimentation, and many questions concerning the effectiveness of scientific aOIF, environmental side effects, and international aOIF law frameworks remain. In the context of increasing global and political concerns associated with climate change, it is valuable to examine the validity and usefulness of the aOIF experiments. Furthermore, it is logical to carry out such experiments because they allow one to study how plankton-based ecosystems work by providing insight into mechanisms operating in real time and under in situ conditions. To maximize the effectiveness of aOIF experiments under international aOIF regulations in the future, we therefore suggest a design that incorporates several components. (1) Experiments conducted in the center of an eddy structure when grazing pressure is low and silicate levels are high (e.g., in the SO south of the polar front during early summer). (2) Shipboard observations extending over a minimum of  ∼ 40 days, with multiple iron injections (at least two or three iron infusions of  ∼ 2000kg with an interval of  ∼ 10–15 days to fertilize a patch of 300km2 and obtain a  ∼ 2nM concentration). (3) Tracing of the iron-fertilized patch using both physical (e.g., a drifting buoy) and biogeochemical (e.g., sulfur hexafluoride, photosynthetic quantum efficiency, and partial pressure of CO2) tracers. (4) Employment of neutrally buoyant sediment traps (NBST) and application of the water-column-derived thorium-234 (234Th) method at two depths (i.e., just below the in situ MLD and at the winter MLD), with autonomous profilers equipped with an underwater video profiler (UVP) and a transmissometer. (5) Monitoring of side effects on marine/ocean ecosystems, including production of climate-relevant gases (e.g., nitrous oxide, N2O; dimethyl sulfide, DMS; and halogenated volatile organic compounds, HVOCs), decline in oxygen inventory, and development of toxic algae blooms, with optical-sensor-equipped autonomous moored profilers and/or autonomous benthic vehicles. Lastly, we introduce the scientific aOIF experimental design guidelines for a future Korean Iron Fertilization Experiment in the Southern Ocean (KIFES).

Description: This research was a part of the project titled the Korean Iron Fertilization Experiment in the Southern Ocean (KOPRI, PM 16060) funded by the Ministry of Oceans and Fisheries, Korea. This work was partly supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (no. 2015R1C1A1A01052051); the Korea-Arctic Ocean Observing System project (K-AOOS) (KOPRI, 20160245) funded by the MOF, Korea; and the KOPRI project (PE18200). Alison M. Macdonald was supported by NOAA grant no. NA11OAR4310063 and internal WHOI funding.

Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 4973-4990, doi:10.5194/bg-10-4973-2013.

Description: The Great East Japan Earthquake and tsunami that caused a loss of power at the Fukushima nuclear power plants (FNPP) resulted in emission of radioactive isotopes into the atmosphere and the ocean. In June of 2011, an international survey measuring a variety of radionuclide isotopes, including 137Cs, was conducted in surface and subsurface waters off Japan. This paper presents the results of numerical simulations specifically aimed at interpreting these observations and investigating the spread of Fukushima-derived radionuclides off the coast of Japan and into the greater Pacific Ocean. Together, the simulations and observations allow us to study the dominant mechanisms governing this process, and to estimate the total amount of radionuclides in discharged coolant waters and atmospheric airborne radionuclide fallout. The numerical simulations are based on two different ocean circulation models, one inferred from AVISO altimetry and NCEP/NCAR reanalysis wind stress, and the second generated numerically by the NCOM model. Our simulations determine that 〉 95% of 137Cs remaining in the water within ~600 km of Fukushima, Japan in mid-June 2011 was due to the direct oceanic discharge. The estimated strength of the oceanic source is 16.2 ± 1.6 PBq, based on minimizing the model-data mismatch. We cannot make an accurate estimate for the atmospheric source strength since most of the fallout cesium had left the survey area by mid-June. The model explained several key features of the observed 137Cs distribution. First, the absence of 137Cs at the southernmost stations is attributed to the Kuroshio Current acting as a transport barrier against the southward progression of 137Cs. Second, the largest 137Cs concentrations were associated with a semi-permanent eddy that entrained 137Cs-rich waters, collecting and stirring them around the eddy perimeter. Finally, the intermediate 137Cs concentrations at the westernmost stations are attributed to younger, and therefore less Cs-rich, coolant waters that continued to leak from the reactor in June of that year.

Description: Irina Rypina was partially supported by Grant NSF-OCE-0725796. This work is funded by the Gordon and Betty Moore Foundation through Grant GBMF3007 to Ken Buesseler.

Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 10 (2013): 6783-6792, doi:10.5194/bg-10-6783-2013.

Description: Microbial nitrous oxide (N2O) production in the ocean is enhanced under low-oxygen (O2) conditions. This is especially important in the context of increasing hypoxia (i.e., oceanic zones with extremely reduced O2 concentrations). Here, we present a study on the interannual variation in summertime nitrous oxide (N2O) concentrations in the bottom waters of the northern Gulf of Mexico (nGOM), which is well-known as the site of the second largest seasonally occurring hypoxic zone worldwide. To this end we developed a simple model that computes bottom-water N2O concentrations with a tri-linear ΔN2O/O2 relationship based on water-column O2 concentrations, derived from summer (July) Texas–Louisiana shelf-wide hydrographic data between 1985 and 2007. ΔN2O (i.e., excess N2O) was computed including nitrification and denitrification as the major microbial production and consumption pathways of N2O. The mean modeled bottom-water N2O concentration for July in the nGOM was 14.5 ± 2.3 nmol L−1 (min: 11.0 ± 4.5 nmol L−1 in 2000 and max: 20.6 ± 11.3 nmol L−1 in 2002). The mean bottom-water N2O concentrations were significantly correlated with the areal extent of hypoxia in the nGOM. Our modeling analysis indicates that the nGOM is a persistent summer source of N2O, and nitrification is dominating N2O production in this region. Based on the ongoing increase in the areal extent of hypoxia in the nGOM, we conclude that N2O production (and its subsequent emissions) from this environmentally stressed region will probably continue to increase into the future.

Description: The preparation of the manuscript was supported by the Mid-career Research Program of the Korea National Research Foundation (No. 2012R1A2A1A01004631) and by Polar Academy Program of the Korea Polar Research Institute. Partial support was also provided by the project titled “Long-term change of structure and function in marine ecosystems of Korea” funded by the Ministry of Land, Transport and Maritime Affairs. Support for A. M. Macdonald was provided through NSF grant No. OCE-0926651.

Description: Author Posting. © American Meteorological Society, 2017. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 47 (2017): 339-351, doi:10.1175/JPO-D-16-0165.1.

Description: A novel multi-iteration statistical method for studying tracer spreading using drifter data is introduced. The approach allows for the best use of the available drifter data by making use of a simple iterative procedure, which results in the statistically probable map showing the likelihood that a tracer released at some source location would visit different geographical regions, along with the associated arrival travel times. The technique is tested using real drifter data in the North Atlantic. Two examples are considered corresponding to sources in the western and eastern North Atlantic Ocean, that is, Massachusetts Bay–like and Irish Sea–like sources, respectively. In both examples, the method worked well in estimating the statistics of the tracer transport pathways and travel times throughout the entire North Atlantic. The role of eddies versus mean flow is quantified using the same technique, and eddies are shown to significantly broaden the spread of a tracer. The sensitivity of the results to the size of the source domain is investigated and causes for this sensitivity are discussed.

Description: This work was supported by the Grant OCE-1356630 from the National Science Foundation (NSF). Rypina also acknowledges NSF Grant OCE-1154641 and NASA Grant NNX14AH29G.

Description: 2017-07-31