Science.gov

Sample records for joint global ocean

  1. Ocean Carbon Cycle Data from the Joint Global Ocean Flux Study (JGOFS)

    DOE Data Explorer

    The U.S. JGOFS program, a component of the U.S Global Change Research Program, grew out of the recommendations of a National Academy of Sciences workshop in 1984. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP). Data are available throughout the U.S. JGOFS web site at http://usjgofs.whoi.edu/ and from the U.S. JGOFS Data System at http://usjgofs.whoi.edu/jg/dir/jgofs/. Major named segments of the project are: Bermuda Atlantic Time Series (BATS) Study, Hawaii Ocean Time-series (HOT) Study, Equatorial Pacific Process Study, North Atlantic Bloom Experiment (1989), Arabian Sea Process Study, and the Southern Ocean Process Study.

  2. Aircraft remote sensing of phytoplankton spatial patterns during the 1989 Joint Global Ocean Flux Study (JGOFS) North Atlantic bloom experiment

    NASA Technical Reports Server (NTRS)

    Yoder, James A.; Hoge, Frank E.

    1991-01-01

    Mesoscale phytoplankton chlorophyll variability near the Joint Global Ocean Flux study sites along the 20 W meridian at 34 N, 47 N, and 59 N is discussed. The NASA P-3 aircraft and the Airborne Oceanographic Lidar (AOL) system provides remote sensing support for the North Atlantic Bloom Experiment. The principal instrument of the AOL system is the blue-green laser that stimulates fluorescence from photoplankton chlorophyll, the principal photosynthetic pigment. Other instruments on the NASA P-3 aircraft include up- and down-looking spectrometers, PRT-5 for infrared measurements to determine sea surface temperature, and a system to deploy and record AXBTs to measure subsurface temperature structure.

  3. Airborne oceanographic lidar participation in the US Joint Global Ocean Flux Study (JGOFS)

    NASA Technical Reports Server (NTRS)

    Hoge, Frank E.; Swift, Robert N.

    1991-01-01

    The U.S. JGOFS is part of a major international field experiment which the National Science Foundation (NSF) is conducting during the decade. It will combine ship and aircraft data collected in both the Atlantic and Pacific oceans. The primary data collected by the Airborne Oceanographic Lidar (AOL) is laser-induced chlorophyll fluorescence together with the concurrent laser-induced water Raman backscatter and phycoerythrin fluorescence. Passive solar-induced up-welling radiances and down-welling solar irradiance are also acquired. Results from the 1989 Atlantic mission as well as plans for use of the new long-range Wallops P-3 during the upcoming Equatorial Pacific mission are presented.

  4. Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2013-01-01

    Phytoplankton are free-floating algae that grow in the euphotic zone of the upper ocean, converting carbon dioxide, sunlight, and available nutrients into organic carbon through photosynthesis. Despite their microscopic size, these photoautotrophs are responsible for roughly half the net primary production on Earth (NPP; gross primary production minus respiration), fixing atmospheric CO2 into food that fuels our global ocean ecosystems. Phytoplankton thus play a critical role in the global carbon cycle, and their growth patterns are highly sensitive to environmental changes such as increased ocean temperatures that stratify the water column and prohibit the transfer of cold, nutrient richwaters to the upper ocean euphotic zone.

  5. Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2014-01-01

    Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.

  6. The relationship between delta C-13 of organic matter and (CO2(aq)) in ocean surface water - Data from the JGOFS site in the northeast Atlantic Ocean and a model. [Joint Global Ocean Flux Study

    NASA Technical Reports Server (NTRS)

    Rau, G. H.; Takahashi, T.; Des Marais, D. J.; Repeta, D. J.; Martin, J. H.

    1992-01-01

    Consistent with the hypothesis that plankton delta C-14 and (CO2(aq)) are inversely related, increases in both sinking and suspended particulate organic matter (POM) delta C-13 detected by the Joint Global Ocean Flux Study (JGOFS) were highly negatively correlated with mixed-layer (CO2(aq)). A model of plant delta C-13 by Farquhar et al. (1982) is adapted to show that under a constant phytoplankton demand for CO2 an inverse nonlinear suspended POM delta C-13 response to ambient (CO2(aq)) is expected. Differences between predicted and observed suspended POM delta C-13 vs. (CO2(aq)) trends and among observed relationships can be reconciled if biological CO2 demand is allowed to vary.

  7. Dynamical Interpolation of Mesoscale Flows in the TOPEX/ Poseidon Diamond Surrounding the U.S. Joint Global Ocean Flux Study Bermuda Atlantic Time-Series Study Site

    NASA Technical Reports Server (NTRS)

    McGillicuddy, D. J.; Kosnyrev, V. K.

    2001-01-01

    An open boundary ocean model is configured in a domain bounded by the four TOPEX/Poseidon (TIP) ground tracks surrounding the U.S. Joint Global Ocean Flux Study Bermuda Atlantic Time-series Study (BATS) site. This implementation facilitates prescription of model boundary conditions directly from altimetric measurements (both TIP and ERS-2). The expected error characteristics for a domain of this size with periodically updated boundary conditions are established with idealized numerical experiments using simulated data. A hindcast simulation is then constructed using actual altimetric observations during the period October 1992 through September 1998. Quantitative evaluation of the simulation suggests significant skill. The correlation coefficient between predicted sea level anomaly and ERS observations in the model interior is 0.89; that for predicted versus observed dynamic height anomaly based on hydrography at the BATS site is 0.73. Comparison with the idealized experiments suggests that the main source of error in the hindcast is temporal undersampling of the boundary conditions. The hindcast simulation described herein provides a basis for retrospective analysis of BATS observations in the context of the mesoscale eddy field.

  8. Dynamical Interpolation of Mesoscale Flows in the TOPEX/Poseidon Diamond Surrounding the U.S. Joint Global Ocean Flux Study Bermuda Atlantic Time-Series Study Site

    NASA Technical Reports Server (NTRS)

    McGillicuddy, Dennis J., Jr.; Kosnyrev, V. K.

    2001-01-01

    An open boundary ocean model is configured in a domain bounded by the four TOPEX/Poseidon (T/P) ground tracks surrounding the US Joint Global Ocean Flux Study Bermuda Atlantic Time-Series Study (BATS) site. This implementation facilitates prescription of model boundary conditions directly from altimetric measurements (both TIP and ERS-2). The expected error characteristics for a domain of this size with periodically updated boundary conditions are established with idealized numerical experiments using simulated data. A hindcast simulation is then constructed using actual altimetric observations during the period October 1992 through September 1998. Quantitative evaluation of the simulation suggests significant skill. The correlation coefficient between predicted sea level anomaly and ERS observations in the model interior is 0.89; that for predicted versus observed dynamic height anomaly based on hydrography at the BATS site is 0.73. Comparison with the idealized experiments suggests that the main source of error in the hindcast is temporal undersampling of the boundary conditions. The hindcast simulation described herein provides a basis for retrospective analysis of BATS observations in the context of the mesoscale eddy field.

  9. Bio-optical profile data report: Joint Global Ocean Flux Study, Hawaii Ocean Time-Series, HOT-3, R/V Moana Wave, 6-10 January 1989

    NASA Technical Reports Server (NTRS)

    Collins, Donald J.; Rhea, W. Joseph; Tran, An Van

    1990-01-01

    Time-series measurements of the incident surface downwelling irradiance and vertical profiles of the Bio-optical properties of the ocean have been measured during the third cruise of the Hawaii Ocean Time-Series to the ALOHA site, 22 degrees 56.4 minutes N, 157 degrees 54.6 minutes W, north of the island of Oahu, Hawaii, during the period January 6 to 10, 1989. A summary of these data is presented to permit investigators an overview of the data collected. The data are available in digital form for scientific investigators.

  10. The Global Ocean Observing System: One perspective

    NASA Technical Reports Server (NTRS)

    Wilson, J. Ron

    1992-01-01

    This document presents a possible organization for a Global Ocean Observing System (GOOS) within the Intergovernmental Oceanographic Commission and the joint ocean programs with the World Meteorological Organization. The document and the organization presented here is not intended to be definitive, complete or the best possible organization for such an observation program. It is presented at this time to demonstrate three points. The first point to be made is that an international program office for GOOS along the lines of the WOCE and TOGA IPOs is essential. The second point is that national programs will have to continue to collect data at the scale of WOCE plus TOGA and more. The third point is that there are many existing groups and committees within the IOC and joint IOC/WMO ocean programs that can contribute essential experience to and form part of the basis of a Global Ocean Observing System. It is particularly important to learn from what has worked and what has not worked in the past if a successful ocean observing system is to result.

  11. The Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Kester, Dana

    1992-01-01

    A Global Ocean Observing System (GOOS) should be established now with international coordination (1) to address issues of global change, (2) to implement operational ENSO forecasts, (3) to provide the data required to apply global ocean circulation models, and (4) to extract the greatest value from the one billion dollar investment over the next ten years in ocean remote sensing by the world's space agencies. The objectives of GOOS will focus on climatic and oceanic predictions, on assessing coastal pollution, and in determining the sustainability of living marine resources and ecosystems. GOOS will be a complete system including satellite observations, in situ observations, numerical modeling of ocean processes, and data exchange and management. A series of practical and economic benefits will be derived from the information generated by GOOS. In addition to the marine science community, these benefits will be realized by the energy industries of the world, and by the world's fisheries. The basic oceanic variables that are required to meet the oceanic and predictability objectives of GOOS include wind velocity over the ocean, sea surface temperature and salinity, oceanic profiles of temperature and salinity, surface current, sea level, the extent and thickness of sea ice, the partial pressure of CO2 in surface waters, and the chlorophyll concentration of surface waters. Ocean circulation models and coupled ocean-atmosphere models can be used to evaluate observing system design, to assimilate diverse data sets from in situ and remotely sensed observations, and ultimately to predict future states of the system. The volume of ocean data will increase enormously over the next decade as new satellite systems are launched and as complementary in situ measuring systems are deployed. These data must be transmitted, quality controlled, exchanged, analyzed, and archived with the best state-of-the-art computational methods.

  12. The global ocean microbiome.

    PubMed

    Moran, Mary Ann

    2015-12-11

    The microbiome of the largest environment on Earth has been gradually revealing its secrets over four decades of study. Despite the dispersed nature of substrates and the transience of surfaces, marine microbes drive essential transformations in all global elemental cycles. Much has been learned about the microbes that carry out key biogeochemical processes, but there are still plenty of ambiguities about the factors important in regulating activity, including the role of microbial interactions. Identifying the molecular "currencies" exchanged within the microbial community will provide key information on microbiome function and its vulnerability to environmental change. PMID:26659059

  13. Modelling the global coastal ocean.

    PubMed

    Holt, Jason; Harle, James; Proctor, Roger; Michel, Sylvain; Ashworth, Mike; Batstone, Crispian; Allen, Icarus; Holmes, Robert; Smyth, Tim; Haines, Keith; Bretherton, Dan; Smith, Gregory

    2009-03-13

    Shelf and coastal seas are regions of exceptionally high biological productivity, high rates of biogeochemical cycling and immense socio-economic importance. They are, however, poorly represented by the present generation of Earth system models, both in terms of resolution and process representation. Hence, these models cannot be used to elucidate the role of the coastal ocean in global biogeochemical cycles and the effects global change (both direct anthropogenic and climatic) are having on them. Here, we present a system for simulating all the coastal regions around the world (the Global Coastal Ocean Modelling System) in a systematic and practical fashion. It is based on automatically generating multiple nested model domains, using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System coupled to the European Regional Seas Ecosystem Model. Preliminary results from the system are presented. These demonstrate the viability of the concept, and we discuss the prospects for using the system to explore key areas of global change in shelf seas, such as their role in the carbon cycle and climate change effects on fisheries. PMID:19087928

  14. Global ocean circulation by altimetry

    NASA Technical Reports Server (NTRS)

    Wunsch, Carl; Haidvogel, D.

    1991-01-01

    The overall objectives of this project are to determine the general circulation of the oceans and many of its climate and biochemical consequences through the optimum use of altimetry data from TOPEX/POSEIDON and related missions. Emphasis is on the global-scale circulation, as opposed to the regional scale, but some more local studies will be carried out. Because of funding limitations, the primary initial focus will be on the time-dependent global-scale circulation rather than the mean; eventually, the mean circulation must be dealt with as well.

  15. NSF final project report planning and implementation of the U.S. Joint Global Ocean Flux Study (U.S. JGOFS)

    SciTech Connect

    Livingston, Hugh D.

    1996-07-01

    Conducted planning and implementation of ocean carbon dioxide hydrographic surveys ocean process studies, time-series studies of Bermuda and Hawaii, and sponsored scientific workshops for those activities.

  16. Global survey of CO{sub 2} in the oceans

    SciTech Connect

    1996-12-31

    Since 1990, the US Department of Energy has supported a Global Survey of CO{sub 2} in the Oceans. This project arose from a long history of DOE-supported research into the fate of the energy-related pollutant CO{sub 2}, including its fate in the oceans. The survey is a key component of the international JGOFS (Joint Global Ocean Flux Study) and is closely associated with the international WOCE (World Ocean Circulation Experiment). In the course of this project, the Science Team that oversees the project has established close links with investigators involved in NOAA`s complementary Ocean Atmosphere Carbon Exchange Study (OACES) as well as with numerous international investigators.

  17. GLobal Ocean Data Analysis Project (GLODAP): Data and Analyses

    DOE Data Explorer

    Sabine, C. L.; Key, R. M.; Feely, R. A.; Bullister, J. L.; Millero, F. J.; Wanninkhof, R.; Peng, T. H.; Kozyr, A.

    The GLobal Ocean Data Analysis Project (GLODAP) is a cooperative effort to coordinate global synthesis projects funded through NOAA, DOE, and NSF as part of the Joint Global Ocean Flux Study - Synthesis and Modeling Project (JGOFS-SMP). Cruises conducted as part of the World Ocean Circulation Experiment (WOCE), JGOFS, and the NOAA Ocean-Atmosphere Exchange Study (OACES) over the decade of the 1990s have created an important oceanographic database for the scientific community investigating carbon cycling in the oceans. The unified data help to determine the global distributions of both natural and anthropogenic inorganic carbon, including radiocarbon. These estimates provide an important benchmark against which future observational studies will be compared. They also provide tools for the direct evaluation of numerical ocean carbon models. GLODAP information available through CDIAC includes gridded and bottle data, a live server, an interactive atlas that provides access to data plots, and other tools for viewing and interacting with the data. [from http://cdiac.esd.ornl.gov/oceans/glodap/Glopintrod.htm](Specialized Interface)

  18. Decadal Changes in Global Ocean Chlorophyll

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Conkright, Margarita E.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The global ocean chlorophyll archive produced by the Coastal Zone Color Scanner (CZCS) was revised using compatible algorithms with the Sea-viewing Wide Field-of-view Sensor (SeaWIFS), and both were blended with in situ data. This methodology permitted a quantitative comparison of decadal changes in global ocean chlorophyll from the CZCS (1979-1986) and SeaWiFS (Sep. 1997-Dec. 2000) records. Global seasonal means of ocean chlorophyll decreased over the two observational segments, by 8% in winter to 16% in autumn. Chlorophyll in the high latitudes was responsible for most of the decadal change. Conversely, chlorophyll concentrations in the low latitudes increased. The differences and similarities of the two data records provide evidence of how the Earth's climate may be changing and how ocean biota respond. Furthermore, the results have implications for the ocean carbon cycle.

  19. Notes on global climate and ocean currents

    NASA Astrophysics Data System (ADS)

    Nigmatulin, R. I.

    2012-02-01

    The problems related to the role of both natural and anthropogenic factors in global climate change are considered. The role of ocean circulation in the Earth's global thermodynamic processes is qualitatively analyzed. The balances of greenhouse gases in the atmosphere and in the ocean and the effect of anthropogenic factors are analyzed. The requirements for new-generation models of the Earth's climate are formulated.

  20. Global warming and changes in ocean circulation

    SciTech Connect

    Duffy, P.B.; Caldeira, K.C.

    1998-02-01

    This final report provides an overview of the goals and accomplishments of this project. Modeling and observational work has raised the possibility that global warming may cause changes in the circulation of the ocean. If such changes would occur they could have important climatic consequences. The first technical goal of this project was to investigate some of these possible changes in ocean circulation in a quantitative way, using a state-of -the-art numerical model of the ocean. Another goal was to develop our ocean model, a detailed three-dimensional numerical model of the ocean circulation and ocean carbon cycles. A major non-technical goal was to establish LLNL as a center of excellence in modelling the ocean circulation and carbon cycle.

  1. Absolute geostrophic currents in global tropical oceans

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Yuan, Dongliang

    2016-03-01

    A set of absolute geostrophic current (AGC) data for the period January 2004 to December 2012 are calculated using the P-vector method based on monthly gridded Argo profiles in the world tropical oceans. The AGCs agree well with altimeter geostrophic currents, Ocean Surface Current Analysis-Real time currents, and moored current-meter measurements at 10-m depth, based on which the classical Sverdrup circulation theory is evaluated. Calculations have shown that errors of wind stress calculation, AGC transport, and depth ranges of vertical integration cannot explain non-Sverdrup transport, which is mainly in the subtropical western ocean basins and equatorial currents near the Equator in each ocean basin (except the North Indian Ocean, where the circulation is dominated by monsoons). The identified non-Sverdrup transport is thereby robust and attributed to the joint effect of baroclinicity and relief of the bottom (JEBAR) and mesoscale eddy nonlinearity.

  2. Southern Ocean biological impacts on global ocean oxygen

    NASA Astrophysics Data System (ADS)

    Keller, David P.; Kriest, Iris; Koeve, Wolfgang; Oschlies, Andreas

    2016-06-01

    Southern Ocean (SO) physical and biological processes are known to have a large impact on global biogeochemistry. However, the role that SO biology plays in determining ocean oxygen concentrations is not completely understood. These dynamics are investigated here by shutting off SO biology in two marine biogeochemical models. The results suggest that SO biological processes reduce the ocean's oxygen content, mainly in the deep ocean, by 14 to 19%. However, since these processes also trap nutrients that would otherwise be transported northward to fuel productivity and subsequent organic matter export, consumption, and the accompanying oxygen consumption in midlatitude to low-latitude waters, SO biology helps to maintain higher oxygen concentrations in these subsurface waters. Thereby, SO biology can influence the size of the tropical oxygen minimum zones. As a result of ocean circulation the link between SO biological processes and remote oxygen changes operates on decadal to centennial time scales.

  3. Toward Submesocale Ocean Modelling and Observations for Global Ocean Forecast.

    NASA Astrophysics Data System (ADS)

    Drillet, Y.

    2014-12-01

    Mercator Ocean is the French oceanographic operational center involved in the development an operation of global high resolution ocean forecasting systems; it is part of the European Copernicus Marine service initiated during MyOcean project. Mercator Ocean currently delivers daily 1/12° global ocean forecast based on the NEMO model which allows for a good representation of mesoscale structures in main areas of the global ocean. Data assimilation of altimetry provides a precise initialization of the mesoscale structures while in situ observations, mainly based on the ARGO network, and satellite Sea Surface Temperature constrain water mass properties from the surface to intermediate depths. One of the main improvements scheduled in the coming years is the transitioning towards submesoscale permitting horizontal resolution (1/36°). On the basis of numerical simulations in selected areas and standard diagnostics developed to validate operational systems, we will discuss : i) The impact of the resolution increase at the basin scale. ii) Adequacy of numerical schemes, vertical resolution and physical parameterization. iii) Adequacy of currently implemented data assimilation procedures in particular with respect to new high resolution data set such as SWOT.

  4. State of Climate 2011 - Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Siegel, D. A.; Antoine, D.; Behrenfeld, M. J.; d'Andon, O. H. Fanton; Fields, E.; Franz, B. A.; Goryl, P.; Maritorena, S.; McClain, C. R.; Wang, M.; Yoder, J. A.

    2012-01-01

    Phytoplankton photosynthesis in the sun lit upper layer of the global ocean is the overwhelmingly dominant source of organic matter that fuels marine ecosystems. Phytoplankton contribute roughly half of the global (land and ocean) net primary production (NPP; gross photosynthesis minus plant respiration) and phytoplankton carbon fixation is the primary conduit through which atmospheric CO2 concentrations interact with the ocean s carbon cycle. Phytoplankton productivity depends on the availability of sunlight, macronutrients (e.g., nitrogen, phosphorous), and micronutrients (e.g., iron), and thus is sensitive to climate-driven changes in the delivery of these resources to the euphotic zone

  5. Sharing Data in the Global Ocean Observing System (Invited)

    NASA Astrophysics Data System (ADS)

    Lindstrom, E. J.; McCurdy, A.; Young, J.; Fischer, A. S.

    2010-12-01

    We examine the evolution of data sharing in the field of physical oceanography to highlight the challenges now before us. Synoptic global observation of the ocean from space and in situ platforms has significantly matured over the last two decades. In the early 1990’s the community data sharing challenges facing the World Ocean Circulation Experiment (WOCE) largely focused on the behavior of individual scientists. Satellite data sharing depended on the policy of individual agencies. Global data sets were delivered with considerable delay and with enormous personal sacrifice. In the 2000’s the requirements for global data sets and sustained observations from the likes of the U.N. Framework Convention on Climate Change have led to data sharing and cooperation at a grander level. It is more effective and certainly more efficient. The Joint WMO/IOC Technical Commission on Oceanography and Marine Meteorology (JCOMM) provided the means to organize many aspects of data collection and data dissemination globally, for the common good. In response the Committee on Earth Observing Satellites organized Virtual Constellations to enable the assembly and sharing of like kinds of satellite data (e.g., sea surface topography, ocean vector winds, and ocean color). Individuals in physical oceanography have largely adapted to the new rigors of sharing data for the common good, and as a result of this revolution new science has been enabled. Primary obstacles to sharing have shifted from the individual level to the national level. As we enter into the 2010’s the demands for ocean data continue to evolve with an expanded requirement for more real-time reporting and broader disciplinary coverage, to answer key scientific and societal questions. We are also seeing the development of more numerous national contributions to the global observing system. The drivers for the establishment of global ocean observing systems are expanding beyond climate to include biological and

  6. Improved Global Ocean Color Using Polymer Algorithm

    NASA Astrophysics Data System (ADS)

    Steinmetz, Francois; Ramon, Didier; Deschamps, ierre-Yves; Stum, Jacques

    2010-12-01

    A global ocean color product has been developed based on the use of the POLYMER algorithm to correct atmospheric scattering and sun glint and to process the data to a Level 2 ocean color product. Thanks to the use of this algorithm, the coverage and accuracy of the MERIS ocean color product have been significantly improved when compared to the standard product, therefore increasing its usefulness for global ocean monitor- ing applications like GLOBCOLOUR. We will present the latest developments of the algorithm, its first application to MODIS data and its validation against in-situ data from the MERMAID database. Examples will be shown of global NRT chlorophyll maps produced by CLS with POLYMER for operational applications like fishing or oil and gas industry, as well as its use by Scripps for a NASA study of the Beaufort and Chukchi seas.

  7. Microbial community structure at the U.S.-Joint Global Ocean Flux Study Station ALOHA: Inverse methods for estimating biochemical indicator ratios

    NASA Technical Reports Server (NTRS)

    Christian, James R.; Karl, David M.

    1994-01-01

    Modeling biogeochemical fluxes in the marine plankton requires the application of factors for extrapolation of biomass indicators measured in the field (chlorophyll a, adenosine triphosphate, bacterial counts) to biomass carbon or nitrogen. These are often inferred from culture studies and are poorly constrained for natural populations. At least squares inverse method with a simple linear model constrains the values of several common indicator ratios, giving self-consistent solutions that provide useful information about the structure of the microbial community at our North Pacific Ocean study site (Station ALOHA (A Long-term Oligotrophic Habitat Assessment)). These results indicate that the fraction of the microbial biomass that is autotrophic (pigmented) is greater in the mixed layer than at the deep chlorophyll maximum layer and that heterotrophic bacteria are a significant but not necessarily predominant component of the microbial community in the euphotic zone.

  8. Microbial community structure at the U.S. -Joint Global Ocean flux Study Station ALOHA: Inverse methods for estimating biochemical indicator ratios

    NASA Astrophysics Data System (ADS)

    Christian, James R.; Karl, David M.

    1994-07-01

    Modeling biogeochemical fluxes in the marine plankton requires the application of factors for extrapolation of biomass indicators measured in the field (chlorophyll a, adenosine triphosphate, bacterial counts) to biomass carbon or nitrogen. These are often inferred from culture studies and are poorly constrained for natural populations. A least squares inverse method with a simple linear model constrains the values of several common indicator ratios, giving self-consistent solutions that provide useful information about the structure of the microbial community at our North Pacific Ocean study site (Station ALOHA (A Long-term Oligotrophic Habitat Assessment)). These results indicate that the fraction of the microbial biomass that is autotrophic (pigmented) is greater in the mixed layer than at the deep chlorophyll maximum layer and that heterotrophic bacteria are a significant but not necessarily predominant component of the microbial community in the euphotic zone.

  9. Global Education for Ocean County College.

    ERIC Educational Resources Information Center

    Rykiel, Joan Devlin

    This paper presents a rationale for establishing a global education curriculum at Ocean County College (OCC) (New Jersey) and proposes a workable curriculum, along with suggestions for implementation. The author distinguishes between multicultural and global education--both curricula address issues of cultural diversity, human rights, and…

  10. Global Ocean Carbon and Biogeochemistry Coordination

    NASA Astrophysics Data System (ADS)

    Telszewski, Maciej; Tanhua, Toste; Palacz, Artur

    2016-04-01

    The complexity of the marine carbon cycle and its numerous connections to carbon's atmospheric and terrestrial pathways means that a wide range of approaches have to be used in order to establish it's qualitative and quantitative role in the global climate system. Ocean carbon and biogeochemistry research, observations, and modelling are conducted at national, regional, and global levels to quantify the global ocean uptake of atmospheric CO2 and to understand controls of this process, the variability of uptake and vulnerability of carbon fluxes into the ocean. These science activities require support by a sustained, international effort that provides a central communication forum and coordination services to facilitate the compatibility and comparability of results from individual efforts and development of the ocean carbon data products that can be integrated with the terrestrial, atmospheric and human dimensions components of the global carbon cycle. The International Ocean Carbon Coordination Project (IOCCP) was created in 2005 by the IOC of UNESCO and the Scientific Committee on Oceanic Research. IOCCP provides an international, program-independent forum for global coordination of ocean carbon and biogeochemistry observations and integration with global carbon cycle science programs. The IOCCP coordinates an ever-increasing set of observations-related activities in the following domains: underway observations of biogeochemical water properties, ocean interior observations, ship-based time-series observations, large-scale ocean acidification monitoring, inorganic nutrients observations, biogeochemical instruments and autonomous sensors and data and information creation. Our contribution is through the facilitation of the development of globally acceptable strategies, methodologies, practices and standards homogenizing efforts of the research community and scientific advisory groups as well as integrating the ocean biogeochemistry observations with the

  11. Decadal trends of ocean and land carbon fluxes from a regional joint ocean-atmosphere inversion

    NASA Astrophysics Data System (ADS)

    Steinkamp, K.; Gruber, N.

    2015-12-01

    From 1980 until 2010, the combined CO2 sink strengths of ocean and land increased by nearly 50% (-0.55 Pg C yr-1 decade-1), but the spatial distribution of this trend is not well known. We address this by performing a joint cyclostationary ocean-atmosphere inversion for the three decades 1980-1989, 1990-1999, and 2000-2008, using only carbon data from the ocean and atmosphere as constraints, i.e., without applying any prior information about the land fluxes. We find that in the inversion, most of the 30 year sink trend stems from the ocean (-0.44 Pg C yr-1 decade-1). The contribution of the terrestrial biosphere is commensurably smaller but has more decadal variability. First, the land sink strength intensified in the 1990s by 0.4 (±0.3) Pg C yr-1 compared to the 1980s but then weakened slightly by 0.2 (±0.4) Pg C yr-1 in the 2000s. The different land regions contributed very variedly to these global trends. While the northern extratropical land acted as an increasing carbon sink throughout the examined period primarily driven by boreal regions, the tropical land is estimated to have acted as an increasing source of CO2, with source magnitude and trend dominated by enhanced release in tropical America during the Amazon mean wet season. This pattern is largely unchanged if the oceanic inversion constraint, which is based on a stationary ocean circulation, is replaced by an estimate based on simulation results from an ocean biogeochemical general circulation model that includes year-to-year variability in the air-sea CO2 fluxes and also has a trend (-0.07 Pg C yr-1 decade-1) that is at the very low end of current estimates. However, the land/ocean partitioning of the trend contribution is adjusted accordingly. Oceanic carbon data has a major impact on carbon exchange for all tropical regions and southern Africa but also for observationally better constrained regions in North America and temperate Asia. The European trend exhibits a strong sensitivity to the choice

  12. Global View of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    2000-01-01

    together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images.

    'We can see large cracks in the ice cover, where most ice grows, ' said Kwok. 'These cracks are much longer than previously thought, some as long as 2,000 kilometers (1,200 miles),' Kwok continued. 'If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean. '

    Scientists believe this is one of the most significant breakthroughs in the last two decades of ice research. 'We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change, ' said Kwok.

    Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task.

    'This is truly a major innovation in terms of the quantities of data being processed and the novelty of the methods being used, ' said Verne Kaupp, director of the Alaska SAR Facility at the University of Alaska, Fairbanks.

    The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the Radarsat satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery project for NASA's Earth Science Enterprise, Washington, DC. The Earth Science Enterprise is dedicated to studying how natural and human-induced changes affect our global environment.

  13. Revaluating ocean warming impacts on global phytoplankton

    NASA Astrophysics Data System (ADS)

    Behrenfeld, Michael J.; O'Malley, Robert T.; Boss, Emmanuel S.; Westberry, Toby K.; Graff, Jason R.; Halsey, Kimberly H.; Milligan, Allen J.; Siegel, David A.; Brown, Matthew B.

    2016-03-01

    Global satellite observations document expansions of the low-chlorophyll central ocean gyres and an overall inverse relationship between anomalies in sea surface temperature and phytoplankton chlorophyll concentrations. These findings can provide an invaluable glimpse into potential future ocean changes, but only if the story they tell is accurately interpreted. Chlorophyll is not simply a measure of phytoplankton biomass, but also registers changes in intracellular pigmentation arising from light-driven (photoacclimation) and nutrient-driven physiological responses. Here, we show that the photoacclimation response is an important component of temporal chlorophyll variability across the global ocean. This attribution implies that contemporary relationships between chlorophyll changes and ocean warming are not indicative of proportional changes in productivity, as light-driven decreases in chlorophyll can be associated with constant or even increased photosynthesis. Extension of these results to future change, however, requires further evaluation of how the multifaceted stressors of a warmer, higher-CO2 world will impact plankton communities.

  14. Global Ocean Storage of Anthropogenic Carbon (GOSAC)

    SciTech Connect

    Orr, J C

    2002-04-02

    GOSAC was an EC-funded project (1998-2001) focused on improving the predictive capacity and accelerating development of global-scale, three-dimensional, ocean carbon-cycle models by means of standardized model evaluation and model intercomparison. Through the EC Environment and Climate Programme, GOSAC supported the participation of seven European modeling groups in the second phase of the larger international effort OCMIP (the Ocean Carbon-Cycle Model Intercomparison Project). OCMIP included model comparison and validation for both CO{sub 2} and other ocean circulation and biogeochemical tracers. Beyond the international OCMIP effort, GOSAC also supported the same EC ocean carbon cycle modeling groups to make simulations to evaluate the efficiency of purposeful sequestration of CO{sub 2} in the ocean. Such sequestration, below the thermocline has been proposed as a strategy to help mitigate the increase of CO{sub 2} in the atmosphere. Some technical and scientific highlights of GOSAC are given.

  15. Including eddies in global ocean models

    NASA Astrophysics Data System (ADS)

    Semtner, Albert J.; Chervin, Robert M.

    The ocean is a turbulent fluid that is driven by winds and by surface exchanges of heat and moisture. It is as important as the atmosphere in governing climate through heat distribution, but so little is known about the ocean that it remains a “final frontier” on the face of the Earth. Many ocean currents are truly global in extent, such as the Antarctic Circumpolar Current and the “conveyor belt” that connects the North Atlantic and North Pacific oceans by flows around the southern tips of Africa and South America. It has long been a dream of some oceanographers to supplement the very limited observational knowledge by reconstructing the currents of the world ocean from the first principles of physics on a computer. However, until very recently, the prospect of doing this was thwarted by the fact that fluctuating currents known as “mesoscale eddies” could not be explicitly included in the calculation.

  16. Ocean Observatories and Information: Building a Global Ocean Observing Network

    NASA Astrophysics Data System (ADS)

    Schofield, O.; Glenn, S. M.; Moline, M. A.; Oliver, M.; Irwin, A.; Chao, Y.; Arrott, M.

    Ocean observatories are collections of networks of sensors that are deployed to sample the ocean physics, chemistry, and biology. The goal of these networks is to overcome chronic undersampling of the oceans by providing sustained measurements in space and time. The data collected by these networks are used to address a range of basic and applied research questions, hindered by a lack of data. The ocean observatories represent collections of platforms capable of collecting data over a range of scales. The platforms include ships, satellites, radars, and a range of Lagrangian systems. Data from the individual platforms are aggregated by sophisticated cyberinfrastructure software systems, which when combined with global communications allow for two-way communication between the shoreside personnel and the networks that can be deployed anywhere in the world. This two-way communication allows the networks to be adaptively configured to improve sampling of specific processes. The maturation of these systems comes at a fortuitous time as the oceans are increasingly showing evidence of changes in the physics, chemistry, and biology over the last few decades. Understanding those changes will require the data collected by the ocean observatories.

  17. Ocean plankton. Structure and function of the global ocean microbiome.

    PubMed

    Sunagawa, Shinichi; Coelho, Luis Pedro; Chaffron, Samuel; Kultima, Jens Roat; Labadie, Karine; Salazar, Guillem; Djahanschiri, Bardya; Zeller, Georg; Mende, Daniel R; Alberti, Adriana; Cornejo-Castillo, Francisco M; Costea, Paul I; Cruaud, Corinne; d'Ovidio, Francesco; Engelen, Stefan; Ferrera, Isabel; Gasol, Josep M; Guidi, Lionel; Hildebrand, Falk; Kokoszka, Florian; Lepoivre, Cyrille; Lima-Mendez, Gipsi; Poulain, Julie; Poulos, Bonnie T; Royo-Llonch, Marta; Sarmento, Hugo; Vieira-Silva, Sara; Dimier, Céline; Picheral, Marc; Searson, Sarah; Kandels-Lewis, Stefanie; Bowler, Chris; de Vargas, Colomban; Gorsky, Gabriel; Grimsley, Nigel; Hingamp, Pascal; Iudicone, Daniele; Jaillon, Olivier; Not, Fabrice; Ogata, Hiroyuki; Pesant, Stephane; Speich, Sabrina; Stemmann, Lars; Sullivan, Matthew B; Weissenbach, Jean; Wincker, Patrick; Karsenti, Eric; Raes, Jeroen; Acinas, Silvia G; Bork, Peer

    2015-05-22

    Microbes are dominant drivers of biogeochemical processes, yet drawing a global picture of functional diversity, microbial community structure, and their ecological determinants remains a grand challenge. We analyzed 7.2 terabases of metagenomic data from 243 Tara Oceans samples from 68 locations in epipelagic and mesopelagic waters across the globe to generate an ocean microbial reference gene catalog with >40 million nonredundant, mostly novel sequences from viruses, prokaryotes, and picoeukaryotes. Using 139 prokaryote-enriched samples, containing >35,000 species, we show vertical stratification with epipelagic community composition mostly driven by temperature rather than other environmental factors or geography. We identify ocean microbial core functionality and reveal that >73% of its abundance is shared with the human gut microbiome despite the physicochemical differences between these two ecosystems. PMID:25999513

  18. Achieving Global Ocean Color Climate Data Records

    NASA Technical Reports Server (NTRS)

    Franz, Bryan

    2010-01-01

    Ocean color, or the spectral distribution of visible light upwelling from beneath the ocean surface, carries information on the composition and concentration of biological constituents within the water column. The CZCS mission in 1978 demonstrated that quantitative ocean color measurements could be. made from spaceborne sensors, given sufficient corrections for atmospheric effects and a rigorous calibration and validation program. The launch of SeaWiFS in 1997 represents the beginning of NASA's ongoing efforts to develop a continuous ocean color data record with sufficient coverage and fidelity for global change research. Achievements in establishing and maintaining the consistency of the time-series through multiple missions and varying instrument designs will be highlighted in this talk, including measurements from NASA'S MODIS instruments currently flying on the Terra and Aqua platforms, as well as the MERIS sensor flown by ESA and the OCM-2 sensor recently launched by ISRO.

  19. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP)

    SciTech Connect

    Key, Robert; Kozyr, Alexander; Sabine, Chris; Lee, K.; Wanninkhof, R.; Bullister, J.L.; Feely, R. A.; Millero, F. J.; Mordy, C.; Peng, T.-H.

    2004-01-01

    During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high-quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO{sub 2}, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb-produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1{sup o} resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.

  20. Global ocean storage of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Khatiwala, S.; Tanhua, T.; Mikaloff Fletcher, S.; Gerber, M.; Doney, S. C.; Graven, H. D.; Gruber, N.; McKinley, G. A.; Murata, A.; Ríos, A. F.; Sabine, C. L.

    2013-04-01

    The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data-based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on forward ocean models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 ± 31 PgC (±20% uncertainty). This estimate includes a broad range of

  1. Global ocean storage of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Khatiwala, S.; Tanhua, T.; Mikaloff Fletcher, S.; Gerber, M.; Doney, S. C.; Graven, H. D.; Gruber, N.; McKinley, G. A.; Murata, A.; Ríos, A. F.; Sabine, C. L.; Sarmiento, J. L.

    2012-07-01

    The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data-assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on ocean forward models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 Pg C with an uncertainty of ±20%. This estimate includes a broad range of

  2. Robust warming of the global upper ocean.

    PubMed

    Lyman, John M; Good, Simon A; Gouretski, Viktor V; Ishii, Masayoshi; Johnson, Gregory C; Palmer, Matthew D; Smith, Doug M; Willis, Josh K

    2010-05-20

    A large ( approximately 10(23) J) multi-decadal globally averaged warming signal in the upper 300 m of the world's oceans was reported roughly a decade ago and is attributed to warming associated with anthropogenic greenhouse gases. The majority of the Earth's total energy uptake during recent decades has occurred in the upper ocean, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets, the global radiation imbalance and climate models. For example, several teams have recently produced different multi-year estimates of the annually averaged global integral of upper-ocean heat content anomalies (hereafter OHCA curves) or, equivalently, the thermosteric sea-level rise. Patterns of interannual variability, in particular, differ among methods. Here we examine several sources of uncertainty that contribute to differences among OHCA curves from 1993 to 2008, focusing on the difficulties of correcting biases in expendable bathythermograph (XBT) data. XBT data constitute the majority of the in situ measurements of upper-ocean heat content from 1967 to 2002, and we find that the uncertainty due to choice of XBT bias correction dominates among-method variability in OHCA curves during our 1993-2008 study period. Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993-2008 of 0.64 W m(-2) (calculated for the Earth's entire surface area), with a 90-per-cent confidence interval of 0.53-0.75 W m(-2). PMID:20485432

  3. Global charts of ocean tide loading effects

    SciTech Connect

    Francis, O.; Mazzega, P. )

    1990-07-15

    Global ocean tide loading charts of the radial displacement, the potential divided by g (gravity acceleration), and the gravity effect have been computed using the 11 constituents M{sub 2}, S{sub 2}, N{sub 2}, K{sub 2}K{sub 1}, O{sub 1}, P{sub 1}, Q{sub 1}, M{sub f}, M{sub m}, S{sub s a} of Schwiderski's tidal model. These new charts have a resolution of 1{degree}{times}1{degree} on the continents as well as on the oceanic area. A description of Farrell's convolution method to compute the loading effects is given, and an estimate of the numerical errors leads to the conclusion that these global charts have a precision better than 2.5% independent of the accuracy of Schwiderski's maps. The current approximation of the loading effects by a proportionality relation with the local oceanic tides is also compared with Farrell's convolution method. Departures of several centimeters systematically appear, in particular over the continental shelves. The authors then show that the maps of the oceanic tides deduced from satellite altimetry could be corrected for the loading effect by an iterative computational procedure based on their algorithm of Farrell's convolution.

  4. Ocean Properties in 2007 Described by the Mercator-Ocean Global Ocean Analysis and Forecasting System

    NASA Astrophysics Data System (ADS)

    Drevillon, M.; Lellouche, J.; Greiner, E.; Verbrugge, N.; Remy, E.; Crosnier, L.

    2008-12-01

    Since the beginning of GODAE and also in the framework of the European projects MERSEA and now GMES/MyOcean, Mercator-Ocean has been designing a hierarchy of operational oceanography analysis and forecasting systems. These systems are based on numerical models of the ocean and data assimilation systems which interpolate in an optimal way all available observations of the ocean. The real time operation of these systems began in 2001, in order to produce each week realistic 3-dimensional oceanic conditions (temperature, salinity, currents) two weeks back in time and a two weeks forecast, driven at the surface by atmospheric conditions from the European Center for Medium Range Weather Forecast (ECMWF). Since April 2008, the state-of-the-art Mercator Ocean forecasting system demonstrates that the use of the ocean and sea ice model NEMO and of the data assimilation system SAM2 (Système d'Assimilation Mercator V2) can produce high quality real time analyses and forecast of the ocean at the global scale, and up to the "eddy resolving" horizontal resolution. This system currently comprises a global ocean configuration at 1/4° horizontal resolution and a North Atlantic and Mediterranean zoom at 1/12°, both having 50 levels on the vertical with a surface refinement. Both have been run and comprehensively validated over the year 2007. The realism of the description of the ocean physics, sea ice, water masses, and volume transports is assessed. Although some biases develop in regions where complex interactions take place between the different limitations of the system (mostly the Antarctic and the tropics), the results show a "qualitative jump" of the physical and statistical skills of the system. They reinforce the scientific feasibility of the future upgrade of the system into a global high resolution configuration at 1/12°.

  5. Joint variability of global runoff and global sea surface temperatures

    USGS Publications Warehouse

    McCabe, G.J.; Wolock, D.M.

    2008-01-01

    Global land surface runoff and sea surface temperatures (SST) are analyzed to identify the primary modes of variability of these hydroclimatic data for the period 1905-2002. A monthly water-balance model first is used with global monthly temperature and precipitation data to compute time series of annual gridded runoff for the analysis period. The annual runoff time series data are combined with gridded annual sea surface temperature data, and the combined dataset is subjected to a principal components analysis (PCA) to identify the primary modes of variability. The first three components from the PCA explain 29% of the total variability in the combined runoff/SST dataset. The first component explains 15% of the total variance and primarily represents long-term trends in the data. The long-term trends in SSTs are evident as warming in all of the oceans. The associated long-term trends in runoff suggest increasing flows for parts of North America, South America, Eurasia, and Australia; decreasing runoff is most notable in western Africa. The second principal component explains 9% of the total variance and reflects variability of the El Ni??o-Southern Oscillation (ENSO) and its associated influence on global annual runoff patterns. The third component explains 5% of the total variance and indicates a response of global annual runoff to variability in North Aflantic SSTs. The association between runoff and North Atlantic SSTs may explain an apparent steplike change in runoff that occurred around 1970 for a number of continental regions.

  6. Global equivalent magnetization of the oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Choi, Y.; Hamoudi, M.; Lesur, V.; Thebault, E.

    2015-11-01

    As a by-product of the construction of a new World Digital Magnetic Anomaly Map over oceanic areas, we use an original approach based on the global forward modeling of seafloor spreading magnetic anomalies and their comparison to the available marine magnetic data to derive the first map of the equivalent magnetization over the World's ocean. This map reveals consistent patterns related to the age of the oceanic lithosphere, the spreading rate at which it was formed, and the presence of mantle thermal anomalies which affects seafloor spreading and the resulting lithosphere. As for the age, the equivalent magnetization decreases significantly during the first 10-15 Myr after its formation, probably due to the alteration of crustal magnetic minerals under pervasive hydrothermal alteration, then increases regularly between 20 and 70 Ma, reflecting variations in the field strength or source effects such as the acquisition of a secondary magnetization. As for the spreading rate, the equivalent magnetization is twice as strong in areas formed at fast rate than in those formed at slow rate, with a threshold at ∼40 km/Myr, in agreement with an independent global analysis of the amplitude of Anomaly 25. This result, combined with those from the study of the anomalous skewness of marine magnetic anomalies, allows building a unified model for the magnetic structure of normal oceanic lithosphere as a function of spreading rate. Finally, specific areas affected by thermal mantle anomalies at the time of their formation exhibit peculiar equivalent magnetization signatures, such as the cold Australian-Antarctic Discordance, marked by a lower magnetization, and several hotspots, marked by a high magnetization.

  7. Is low frequency ocean sound increasing globally?

    PubMed

    Miksis-Olds, Jennifer L; Nichols, Stephen M

    2016-01-01

    Low frequency sound has increased in the Northeast Pacific Ocean over the past 60 yr [Ross (1993) Acoust. Bull. 18, 5-8; (2005) IEEE J. Ocean. Eng. 30, 257-261; Andrew, Howe, Mercer, and Dzieciuch (2002) J. Acoust. Soc. Am. 129, 642-651; McDonald, Hildebrand, and Wiggins (2006) J. Acoust. Soc. Am. 120, 711-717; Chapman and Price (2011) J. Acoust. Soc. Am. 129, EL161-EL165] and in the Indian Ocean over the past decade, [Miksis-Olds, Bradley, and Niu (2013) J. Acoust. Soc. Am. 134, 3464-3475]. More recently, Andrew, Howe, and Mercer's [(2011) J. Acoust. Soc. Am. 129, 642-651] observations in the Northeast Pacific show a level or slightly decreasing trend in low frequency noise. It remains unclear what the low frequency trends are in other regions of the world. In this work, data from the Comprehensive Nuclear-Test Ban Treaty Organization International Monitoring System was used to examine the rate and magnitude of change in low frequency sound (5-115 Hz) over the past decade in the South Atlantic and Equatorial Pacific Oceans. The dominant source observed in the South Atlantic was seismic air gun signals, while shipping and biologic sources contributed more to the acoustic environment at the Equatorial Pacific location. Sound levels over the past 5-6 yr in the Equatorial Pacific have decreased. Decreases were also observed in the ambient sound floor in the South Atlantic Ocean. Based on these observations, it does not appear that low frequency sound levels are increasing globally. PMID:26827043

  8. Coccolithophorid blooms in the global ocean

    NASA Technical Reports Server (NTRS)

    Brown, Christopher W.; Yoder, James A.

    1994-01-01

    The global distribution pattern of coccolithophrid blooms was mapped in order to ascertain the prevalence of these blooms in the world's oceans and to estimate their worldwide production of CaCO3 and dimethyl sulfide (DMS). Mapping was accomplished by classifying pixels of 5-day global composites of coastal zone color scanner imagery into bloom and nonbloom classes using a supervised, multispectral classification scheme. Surface waters with the spectral signature of coccolithophorid blooms annually covered an average of 1.4 x 10(exp 6) sq km in the world oceans from 1979 to 1985, with the subpolar latitudes accounting for 71% of this surface area. Classified blooms were most extensive in the Subartic North Atlantic. Large expanses of the bloom signal were also detected in the North Pacific, on the Argentine shelf and slope, and in numerous lower latitude marginal seas and shelf regions. The greatest spatial extent of classified blooms in subpolar oceanic regions occurred in the months from summer to early autumn, while those in lower latitude marginal seas occurred in midwinter to early spring. Though the classification scheme was effcient in separating bloom and nonbloom classes during test simulations, and biogeographical literature generally confirms the resulting distribution pattern of blooms in the subpolar regions, the cause of the bloom signal is equivocal in some geographic areas, particularly on shelf regions at lower latitudes. Standing stock estimates suggest that the presumed Emiliania huxleyi blooms act as a significant source of calcite carbon and DMS sulfur on a regional scale. On a global scale, however, the satellite-detected coccolithophorid blooms are estimated to play only a minor role in the annual production of these two compounds and their flux from the surface mixed layer.

  9. Joint spatiotemporal variability of global sea surface temperatures and global Palmer drought severity index values

    USGS Publications Warehouse

    Apipattanavis, S.; McCabe, G.J.; Rajagopalan, B.; Gangopadhyay, S.

    2009-01-01

    Dominant modes of individual and joint variability in global sea surface temperatures (SST) and global Palmer drought severity index (PDSI) values for the twentieth century are identified through a multivariate frequency domain singular value decomposition. This analysis indicates that a secular trend and variability related to the El Niño–Southern Oscillation (ENSO) are the dominant modes of variance shared among the global datasets. For the SST data the secular trend corresponds to a positive trend in Indian Ocean and South Atlantic SSTs, and a negative trend in North Pacific and North Atlantic SSTs. The ENSO reconstruction shows a strong signal in the tropical Pacific, North Pacific, and Indian Ocean regions. For the PDSI data, the secular trend reconstruction shows high amplitudes over central Africa including the Sahel, whereas the regions with strong ENSO amplitudes in PDSI are the southwestern and northwestern United States, South Africa, northeastern Brazil, central Africa, the Indian subcontinent, and Australia. An additional significant frequency, multidecadal variability, is identified for the Northern Hemisphere. This multidecadal frequency appears to be related to the Atlantic multidecadal oscillation (AMO). The multidecadal frequency is statistically significant in the Northern Hemisphere SST data, but is statistically nonsignificant in the PDSI data.

  10. Picophytoplankton biomass distribution in the global ocean

    NASA Astrophysics Data System (ADS)

    Buitenhuis, E. T.; Li, W. K. W.; Vaulot, D.; Lomas, M. W.; Landry, M. R.; Partensky, F.; Karl, D. M.; Ulloa, O.; Campbell, L.; Jacquet, S.; Lantoine, F.; Chavez, F.; Macias, D.; Gosselin, M.; McManus, G. B.

    2012-08-01

    The smallest marine phytoplankton, collectively termed picophytoplankton, have been routinely enumerated by flow cytometry since the late 1980s during cruises throughout most of the world ocean. We compiled a database of 40 946 data points, with separate abundance entries for Prochlorococcus, Synechococcus and picoeukaryotes. We use average conversion factors for each of the three groups to convert the abundance data to carbon biomass. After gridding with 1° spacing, the database covers 2.4% of the ocean surface area, with the best data coverage in the North Atlantic, the South Pacific and North Indian basins, and at least some data in all other basins. The average picophytoplankton biomass is 12 ± 22 μg C l-1 or 1.9 g C m-2. We estimate a total global picophytoplankton biomass of 0.53-1.32 Pg C (17-39% Prochlorococcus, 12-15% Synechococcus and 49-69% picoeukaryotes), with an intermediate/best estimate of 0.74 Pg C. Future efforts in this area of research should focus on reporting calibrated cell size and collecting data in undersampled regions. http://doi.pangaea.de/10.1594/PANGAEA.777385

  11. Picophytoplankton biomass distribution in the global ocean

    NASA Astrophysics Data System (ADS)

    Buitenhuis, E. T.; Li, W. K. W.; Vaulot, D.; Lomas, M. W.; Landry, M.; Partensky, F.; Karl, D. M.; Ulloa, O.; Campbell, L.; Jacquet, S.; Lantoine, F.; Chavez, F.; Macias, D.; Gosselin, M.; McManus, G. B.

    2012-04-01

    The smallest marine phytoplankton, collectively termed picophytoplankton, have been routinely enumerated by flow cytometry since the late 1980s, during cruises throughout most of the world ocean. We compiled a database of 40 946 data points, with separate abundance entries for Prochlorococcus, Synechococcus and picoeukaryotes. We use average conversion factors for each of the three groups to convert the abundance data to carbon biomass. After gridding with 1° spacing, the database covers 2.4% of the ocean surface area, with the best data coverage in the North Atlantic, the South Pacific and North Indian basins. The average picophytoplankton biomass is 12 ± 22 μg C l-1 or 1.9 g C m-2. We estimate a total global picophytoplankton biomass of 0.53-0.74 Pg C (17-39% Prochlorococcus, 12-15% Synechococcus and 49-69% picoeukaryotes). Future efforts in this area of research should focus on reporting calibrated cell size, and collecting data in undersampled regions.

  12. The Global S$_1$ Ocean Tide

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, G. D.

    2003-01-01

    The small S$_1$ ocean tide is caused primarily by diurnal atmospheric pressure loading. Its excitation is therefore unlike any other diurnal tide. The global character of $S-1$ is here determined by numerical modeling and by analysis of Topex/Poseidon satellite altimeter data. The two approaches yield reasonably consistent results, and large ( $ greater than $l\\cm) amplitudes in several regions are further confirmed by comparison with coastal tide gauges. Notwithstanding their excitation differences, S$-1$ and other diurnal tides are found to share several common features, such as relatively large amplitudes in the Arabian Sea, the Sea of Okhotsk, and the Gulf of Alaska. The most noticeable difference is the lack of an S$-1$ Antarctic Kelvin wave. These similarities and differences can be explained in terms of the coherences between near-diurnal oceanic normal modes and the underlying tidal forcings. While gravitational diurnal tidal forces excite primarily a 28-hour Antarctic-Pacific mode, the S$_1$ air tide excites several other near-diurnal modes, none of which has large amplitudes near Antarctica.

  13. Enhanced deep ocean ventilation and oxygenation with global warming

    NASA Astrophysics Data System (ADS)

    Froelicher, T. L.; Jaccard, S.; Dunne, J. P.; Paynter, D.; Gruber, N.

    2014-12-01

    Twenty-first century coupled climate model simulations, observations from the recent past, and theoretical arguments suggest a consistent trend towards warmer ocean temperatures and fresher polar surface oceans in response to increased radiative forcing resulting in increased upper ocean stratification and reduced ventilation and oxygenation of the deep ocean. Paleo-proxy records of the warming at the end of the last ice age, however, suggests a different outcome, namely a better ventilated and oxygenated deep ocean with global warming. Here we use a four thousand year global warming simulation from a comprehensive Earth System Model (GFDL ESM2M) to show that this conundrum is a consequence of different rates of warming and that the deep ocean is actually better ventilated and oxygenated in a future warmer equilibrated climate consistent with paleo-proxy records. The enhanced deep ocean ventilation in the Southern Ocean occurs in spite of increased positive surface buoyancy fluxes and a constancy of the Southern Hemisphere westerly winds - circumstances that would otherwise be expected to lead to a reduction in deep ocean ventilation. This ventilation recovery occurs through a global scale interaction of the Atlantic Meridional Overturning Circulation undergoing a multi-centennial recovery after an initial century of transient decrease and transports salinity-rich waters inform the subtropical surface ocean to the Southern Ocean interior on multi-century timescales. The subsequent upwelling of salinity-rich waters in the Southern Ocean strips away the freshwater cap that maintains vertical stability and increases open ocean convection and the formation of Antarctic Bottom Waters. As a result, the global ocean oxygen content and the nutrient supply from the deep ocean to the surface are higher in a warmer ocean. The implications for past and future changes in ocean heat and carbon storage will be discussed.

  14. Fifteen years of ocean observations with the global Argo array

    NASA Astrophysics Data System (ADS)

    Riser, Stephen C.; Freeland, Howard J.; Roemmich, Dean; Wijffels, Susan; Troisi, Ariel; Belbéoch, Mathieu; Gilbert, Denis; Xu, Jianping; Pouliquen, Sylvie; Thresher, Ann; Le Traon, Pierre-Yves; Maze, Guillaume; Klein, Birgit; Ravichandran, M.; Grant, Fiona; Poulain, Pierre-Marie; Suga, Toshio; Lim, Byunghwan; Sterl, Andreas; Sutton, Philip; Mork, Kjell-Arne; Vélez-Belchí, Pedro Joaquín; Ansorge, Isabelle; King, Brian; Turton, Jon; Baringer, Molly; Jayne, Steven R.

    2016-02-01

    More than 90% of the heat energy accumulation in the climate system between 1971 and the present has been in the ocean. Thus, the ocean plays a crucial role in determining the climate of the planet. Observing the oceans is problematic even under the most favourable of conditions. Historically, shipboard ocean sampling has left vast expanses, particularly in the Southern Ocean, unobserved for long periods of time. Within the past 15 years, with the advent of the global Argo array of profiling floats, it has become possible to sample the upper 2,000 m of the ocean globally and uniformly in space and time. The primary goal of Argo is to create a systematic global network of profiling floats that can be integrated with other elements of the Global Ocean Observing System. The network provides freely available temperature and salinity data from the upper 2,000 m of the ocean with global coverage. The data are available within 24 hours of collection for use in a broad range of applications that focus on examining climate-relevant variability on seasonal to decadal timescales, multidecadal climate change, improved initialization of coupled ocean-atmosphere climate models and constraining ocean analysis and forecasting systems.

  15. Monitoring ocean heat content from the current generation of global ocean observing systems

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Sallée, J.-B.; Chambers, D.; Le Traon, P.-Y.; Cabanes, C.; Gaillard, F.; Speich, S.; Hamon, M.

    2013-06-01

    Variations in the world's ocean heat storage and its associated volume changes are a key factor to gauge global warming and to assess the Earth's energy budget. It is also directly link to sea level change, which has a direct impact on coastal populations. Understanding and monitoring heat and sea level change is therefore one of the major legacies of current global ocean observing systems. In this study, we present an inter-comparison of the three of these global ocean observing systems: the ocean temperature/salinity network Argo, the gravimeter GRACE and the satellite altimeters. Their consistency is investigated at global and regional scale during the period 2005-2010 of overlapping time window of re-qualified data. These three datasets allow closing the recent global ocean sea level budget within uncertainties. However, sampling inconsistencies need to be corrected for an accurate budget at global scale. The Argo network allows estimating global ocean heat content and global sea level and reveals a positive change of 0.5 ± 0.1W m-2 and 0.5 ± 0.1 mm yr-1 over the last 8 yr (2005-2012). Regional inter-comparison of the global observing systems highlights the importance of specific ocean basins for the global estimates. Specifically, the Indonesian Archipelago appears as a key region for the global ocean variability. Both the large regional variability and the uncertainties in the current observing systems, prevent us to shed light, from the global sea level perspective, on the climatically important deep ocean changes. This emphasises, once more, the importance of continuing sustained effort in measuring the deep ocean from ship platforms and by setting up a much needed automated deep-Argo network.

  16. Modeling Nitrogen Isotopes in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Somes, C.; Schmittner, A.

    2008-12-01

    The nitrogen isotopic signal measured in marine sediments has the potential to be a valuable paleoceanographic proxy. It captures the response of different biological processes in the marine ecosystem including photosynthesis, nitrogen fixation, denitrification as well as processes within the food chain. A simple marine ecosystem model that includes the interactive cycling of nitrogen, phosphorus, and oxygen is augmented to record nitrogen isotopes in the University of Victoria Earth System Climate Model. New nitrogen isotopic tracers are employed at all trophic levels of the ecosystem. This includes the δ15N of nitrate, both classes of phytoplankton (nitrogen fixers and all other phytoplankton), zooplankton, and detritus. Despite a few shortcomings, it is shown that the nitrogen isotope model can capture the major trends observed in the modern climate. The ability to model nitrogen isotopes in a global coupled ocean- atmosphere-sea ice-ecosystem model gives us a unique opportunity to directly infer what physical and biological changes in the climate system are driving the δ15N signal on spatial and temporal scales. This is a valuable tool giving us tremendous insight on how to interpret the nitrogen isotopic signal.

  17. Distinctive climate signals in reanalysis of global ocean heat content

    NASA Astrophysics Data System (ADS)

    Balmaseda, Magdalena A.; Trenberth, Kevin E.; KäLléN, Erland

    2013-05-01

    The elusive nature of the post-2004 upper ocean warming has exposed uncertainties in the ocean's role in the Earth's energy budget and transient climate sensitivity. Here we present the time evolution of the global ocean heat content for 1958 through 2009 from a new observation-based reanalysis of the ocean. Volcanic eruptions and El Niño events are identified as sharp cooling events punctuating a long-term ocean warming trend, while heating continues during the recent upper-ocean-warming hiatus, but the heat is absorbed in the deeper ocean. In the last decade, about 30% of the warming has occurred below 700 m, contributing significantly to an acceleration of the warming trend. The warming below 700 m remains even when the Argo observing system is withdrawn although the trends are reduced. Sensitivity experiments illustrate that surface wind variability is largely responsible for the changing ocean heat vertical distribution.

  18. Global Observations in Ocean and Cryosphere

    NASA Astrophysics Data System (ADS)

    Rhein, Monika; Chambers, Don; Johnson, Gregory; Rintoul, Steve; Comiso, Joey; Vaughan, David

    2014-05-01

    Changes from direct and proxy observations in all components of the climate system are assessed In "Climate Change 2013: The Physical Science Basis", the Working Group I contribution to the Fifth IPCC report. This talk addresses the main climate-related changes observed in ocean and the cryosphere, as well as their roles in the climate system. The ocean has absorbed more than 90% of the energy increase in the climate system in the last 40 years, with warming detected even in the abyss over the last few decades. The ocean has also taken up about 30% of the carbon released by fossil fuel burning and land use change since 1750, lowering the pH of (acidifying) near-surface waters. Relatively saline near-surface ocean waters, where evaporation dominates, have become more saline, and relatively fresh regions, where precipitation dominates, have become fresher; providing indirect evidence of change in evaporation and precipitation over the oceans. Arctic Sea Ice extent has decreased much more than Antarctic sea ice extent has increased from 1979 through 2012. Ice sheets and glaciers have been losing mass at an increasing rate over recent decades. Sea level rise is driven by both, ocean warming and mass loss from ice sheets and glaciers into the ocean. The observational estimates of the various contributors to the total sea level rise account for the total from 1993-2010.

  19. Changes in ocean vertical heat transport with global warming

    NASA Astrophysics Data System (ADS)

    Zika, Jan D.; Laliberté, Frédéric; Mudryk, Lawrence R.; Sijp, Willem P.; Nurser, A. J. G.

    2015-06-01

    Heat transport between the surface and deep ocean strongly influences transient climate change. Mechanisms setting this transport are investigated using coupled climate models and by projecting ocean circulation into the temperature-depth diagram. In this diagram, a "cold cell" cools the deep ocean through the downwelling of Antarctic waters and upwelling of warmer waters and is balanced by warming due to a "warm cell," coincident with the interhemispheric overturning and previously linked to wind and haline forcing. With anthropogenic warming, the cold cell collapses while the warm cell continues to warm the deep ocean. Simulations with increasingly strong warm cells, set by their mean Southern Hemisphere winds, exhibit increasing deep-ocean warming in response to the same anthropogenic forcing. It is argued that the partition between components of the circulation which cool and warm the deep ocean in the preindustrial climate is a key determinant of ocean vertical heat transport with global warming.

  20. Recent variability of the global ocean carbon sink

    NASA Astrophysics Data System (ADS)

    Landschützer, P.; Gruber, N.; Bakker, D. C. E.; Schuster, U.

    2014-09-01

    We present a new observation-based estimate of the global oceanic carbon dioxide (CO2) sink and its temporal variation on a monthly basis from 1998 through 2011 and at a spatial resolution of 1°×1°. This sink estimate rests upon a neural network-based mapping of global surface ocean observations of the partial pressure of CO2 (pCO2) from the Surface Ocean CO2 Atlas database. The resulting pCO2 has small biases when evaluated against independent observations in the different ocean basins, but larger randomly distributed differences exist particularly in high latitudes. The seasonal climatology of our neural network-based product agrees overall well with the Takahashi et al. (2009) climatology, although our product produces a stronger seasonal cycle at high latitudes. From our global pCO2 product, we compute a mean net global ocean (excluding the Arctic Ocean and coastal regions) CO2 uptake flux of -1.42 ± 0.53 Pg C yr-1, which is in good agreement with ocean inversion-based estimates. Our data indicate a moderate level of interannual variability in the ocean carbon sink (±0.12 Pg C yr-1, 1σ) from 1998 through 2011, mostly originating from the equatorial Pacific Ocean, and associated with the El Niño-Southern Oscillation. Accounting for steady state riverine and Arctic Ocean carbon fluxes our estimate further implies a mean anthropogenic CO2 uptake of -1.99 ± 0.59 Pg C yr-1 over the analysis period. From this estimate plus the most recent estimates for fossil fuel emissions and atmospheric CO2 accumulation, we infer a mean global land sink of -2.82 ± 0.85 Pg C yr-1 over the 1998 through 2011 period with strong interannual variation.

  1. Global Earth Response to Loading by Ocean Tide Models

    NASA Technical Reports Server (NTRS)

    Estes, R. H.; Strayer, J. M.

    1979-01-01

    Mathematical and programming techniques to numerically calculate Earth response to global semidiurnal and diurnal ocean tide models were developed. Global vertical crustal deformations were evaluated for M sub 2, S sub 2, N sub 2, K sub 2, K sub 1, O sub 1, and P sub 1 ocean tide loading, while horizontal deformations were evaluated for the M sub 2 tidal load. Tidal gravity calculations were performed for M sub 2 tidal loads, and strain tensor elements were evaluated for M sub 2 loads. The M sub 2 solution used for the ocean tide included the effects of self-gravitation and crustal loading.

  2. The role of clouds and oceans in global greenhouse warming

    SciTech Connect

    Hoffert, M.I.

    1992-12-01

    During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature''. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales.

  3. Joint IAMAS/IAHS Symposium J1 on Global Monitoring and Advanced Observing Techniques in the Atmosphere and Hydrosphere

    NASA Technical Reports Server (NTRS)

    Ohring, G.; Aoki, T.; Halpern D.; Henderson-Sellers, A.; Charlock, T.; Joseph, J.; Labitzke, K.; Raschke, E.; Smith, W.

    1994-01-01

    Seventy papers were presented at the two-and-a-half-day Symposium on Global Monitoring and Advanced Observing Techniques in the Atmosphere and Hydrosphere. The symposium was jointly organized by the International Association of Meteorology and Atmospheric Sciences (IAMAS) and the International Association of Hydrological Sciences (IAHS). Global observing systems are receiving increased attention in connection with such problems as monitoring global climate change. The symposium included papers on observational requirements; measurement methodologies; descriptions of available datasets; results of analysis of observational data; plans for future observing systems, including the Global Climate Observing System (GCOS) and the Global Ocean Observing System (GOOS); and the programs and plans of the space agencies.

  4. Global observations of ocean Rossby waves

    SciTech Connect

    Chelton, D.B.; Schlax, M.G.

    1996-04-12

    Rossby waves play a critical role in the transient adjustment of ocean circulation to changes in large-scale atmospheric forcing. The TOPEX/POSEIDON satellite altimeter has detected Rossby waves throughout much of the world ocean from sea level signals with {approx_lt} 10-centimeters amplitude and {approx_lt} 500-kilometer wavelength. Outside of the tropics Rossby waves are abruptly amplified by major topographic features. Analysis of 3 years of data reveals discrepancies between observed and theoretical Rossby wave phase speeds that indicate that the standard theory for free, linear Rossby waves in an incomplete description of the observed waves. 32 refs., 5 figs.

  5. Global coupled sea ice-ocean state estimation

    NASA Astrophysics Data System (ADS)

    Fenty, Ian; Menemenlis, Dimitris; Zhang, Hong

    2015-09-01

    We study the impact of synthesizing ocean and sea ice concentration data with a global, eddying coupled sea ice-ocean configuration of the Massachusetts Institute of Technology general circulation model with the goal of reproducing the 2004 three-dimensional time-evolving ice-ocean state. This work builds on the state estimation framework developed in the Estimating the Circulation and Climate of the Ocean consortium by seeking a reconstruction of the global sea ice-ocean system that is simultaneously consistent with (1) a suite of in situ and remotely-sensed ocean and ice data and (2) the physics encoded in the numerical model. This dual consistency is successfully achieved here by adjusting only the model's initial hydrographic state and its atmospheric boundary conditions such that misfits between the model and data are minimized in a least-squares sense. We show that synthesizing both ocean and sea ice concentration data is required for the model to adequately reproduce the observed details of the sea ice annual cycle in both hemispheres. Surprisingly, only modest adjustments to our first-guess atmospheric state and ocean initial conditions are necessary to achieve model-data consistency, suggesting that atmospheric reanalysis products remain a leading source of errors for sea ice-ocean model hindcasts and reanalyses. The synthesis of sea ice data is found to ameliorate misfits in the high latitude ocean, especially with respect to upper ocean stratification, temperature, and salinity. Constraining the model to sea ice concentration modestly reduces ICESat-derived Arctic ice thickness errors by improving the temporal and spatial evolution of seasonal ice. Further increases in the accuracy of global sea ice thickness in the model likely require the direct synthesis of sea ice thickness data.

  6. Decoupling of Iron and Phosphate in the Global Ocean

    NASA Technical Reports Server (NTRS)

    Parekh, Payal

    2003-01-01

    Iron is an essential micronutrient for marine phytoplankton, limiting their growth in high nutrient, low chlorophyll regions of the ocean. I use a hierarchy of ocean circulation and biogeochemistry models to understand controls on global iron distribution. I formulate a mechanistic model of iron cycling which includes scavenging onto sinking particles and complexation with an organic ligand. The iron cycle is coupled to a phosphorus cycling model. Iron's aeolian source is prescribed. In the context of a highly idealized multi-box model scheme, the model can be brought into consistency with the relatively sparse ocean observations of iron in the oceans. This biogeochemical scheme is also implemented in a coarse resolution ocean general circulation model. This model also successfully reproduces the broad regional patterns of iron and phosphorus. In particular, the high macronutrient concentrations of the Southern Ocean result from iron limitation in the model. Due to the potential ability of iron to change the efficiency of the carbon pump in the remote Southern Ocean, I study Southern Ocean surface phosphate response to increased aeolian dust flux. My box model and GCM results suggest that a global ten fold increase in dust flux can support a phosphate drawdown of 0.25-0.5 micromolar.

  7. Global Climate Change and Ocean Education

    NASA Astrophysics Data System (ADS)

    Spitzer, W.; Anderson, J.

    2011-12-01

    The New England Aquarium, collaborating with other aquariums across the country, is leading a national effort to enable aquariums and related informal science education institutions to effectively communicate the impacts of climate change and ocean acidification on marine animals, habitats and ecosystems. Our goal is to build on visitors' emotional connection with ocean animals, connect to their deeply held values, help them understand causes and effects of climate change and motivate them to embrace effective solutions. Our objectives are to: (1) Build a national coalition of aquariums and related informal education institutions collaborating on climate change education; (2) Develop an interpretive framework for climate change and the ocean that is scientifically sound, research-based, field tested and evaluated; and (3) Build capacity of aquariums to interpret climate change via training for interpreters, interactive exhibits and activities and communities of practice for ongoing support. Centers of informal learning have the potential to bring important environmental issues to the public by presenting the facts, explaining the science, connecting with existing values and interests, and motivating concern and action. Centers that work with live animals (including aquariums, zoos, nature centers, national parks, national marine sanctuaries, etc.) are unique in that they attract large numbers of people of all ages (over 140 million in the US), have strong connections to the natural, and engage many visitors who may not come with a primary interest in science. Recent research indicates that that the public expects and trusts aquariums, zoos, and museums to communicate solutions to environmental and ocean issues, and to advance ocean conservation, and that climate change is the environmental issue of most concern to the public; Ironically, however, most people do not associate climate change with ocean health, or understand the critical role that the ocean plays in

  8. Tides of global ice-covered oceans

    NASA Astrophysics Data System (ADS)

    Wunsch, Carl

    2016-08-01

    The tides of an ice-covered ocean are examined using a Cartesian representation of the elastic and fluid equations. Although unconstrained by any observations, the ocean tides of a Neoproterozoic "snowball" Earth could have been significantly larger than they are today. Time-mean tidal-residual circulations would then have been set up that are competitive with the circulation driven by geothermal heating. In any realistic configuration, the snowball Earth would have had an ice cover that is in the thin shell limit, but by permitting the ice thickness to become large, more interesting ice tidal response can be found, ones conceivably of application to bodies in the outer Solar System or hypothetical exoplanets. Little can be said concerning a reduction in tidal dissipation necessary to avoid a crisis in the history of the lunar orbit.

  9. Oceans Abound? Tectonic Tests of Global Ocean Models for Enceladus and Mimas

    NASA Astrophysics Data System (ADS)

    Rhoden, A.; Henning, W. G.; Bland, M. T.; Tajeddine, R.; Hurford, T., Jr.

    2015-12-01

    Librations identified in Cassinidata imply that Mimas either has a global ocean or an irregular core (Tajeddine et al., 2014). A global ocean is the only model consistent with Enceladus' librations (Tajeddine et al., 2015). A global ocean can also explain gravity measurements of Enceladus as long as the overlying ice shell is thicker in the north pole than the south pole (McKinnon, 2015), although a regional sea is also possible (Iess et al., 2014). Generations of fractures at Enceladus' south pole may indicate longitudinal migration of the ice shell, which would also require a global ocean (Patthoff and Kattenhorn, 2011). Because both Mimas and Enceladus have eccentric orbits (0.0196 and 0.0047, respectively) interior models that include oceans can generate much larger tidal stresses than models without oceans. However, the enhancement in tidal stress due to oceans creates complications for both moons. Mimas' surface is ancient and heavily cratered; only about 40 tectonic features have been identified, globally (Schenk, 2011). The lack of tidal-tectonic activity on Mimas implies that either it has not experienced large tidal stresses over its surface age or that its ice shell behaves quite differently than Europa. Enceladus has a young, heavily-fractured region at the south pole, and an old, heavily-cratered region at the north pole. Are global ocean models compatible with ongoing, tidal-tectonic activity at Enceladus' south pole and the lack of activity on Mimas and at Enceladus' north pole? We consider whether global oceans are compatible with the geologic records of Mimas and Enceladus by calculating tidal stresses for 5-layer interior structure models. To explore the range of possible interior structures, we vary the ice shell thickness, the depth of the upper brittle ice layer, and the viscosities of the brittle and ductile ice layers. We find that a global ocean within Mimas generates tidal stresses comparable to those on Europa (~100 kPa) and in some cases

  10. PHC: A Global Ocean Hydrography with a High-Quality Arctic Ocean.

    NASA Astrophysics Data System (ADS)

    Steele, Michael; Morley, Rebecca; Ermold, Wendy

    2001-05-01

    A new gridded ocean climatology, the Polar Science Center Hydrographic Climatology (PHC), has been created that merges the 1998 version of the World Ocean Atlas with the new regional Arctic Ocean Atlas. The result is a global climatology for temperature and salinity that contains a good description of the Arctic Ocean and its environs. Monthly, seasonal, and annual average products have been generated. How the original datasets were prepared for merging, how the optimal interpolation procedure was performed, and characteristics of the resulting dataset are discussed, followed by a summary and discussion of future plans.

  11. Influence of the Southern Ocean on the Global deep ocean stratification

    NASA Astrophysics Data System (ADS)

    Sun, S.; Eisenman, I.; Stewart, A.

    2015-12-01

    The stratification of the deep ocean plays a key role in the climate system by influencing the ocean circulation and regulating the outgassing of CO2. Previous studies have suggested that Southern Ocean processes control the global ocean stratification below the main thermocline (i.e., below ~500m). In this study, three ocean-only simulations are carried out with the Community Earth System Model (CESM1): one control simulation forced with Pre-industrial (PI) surface conditions, a second control simulation forced with Last Glacial Maximum (LGM) surface conditions, and a test simulation forced with LGM surface conditions in southern high latitudes and PI surface conditions elsewhere. We find that the test simulation does broadly reproduce the LGM density stratification of the global ocean below 2000m, but not at intermediate depths between 500m and 1500m. We propose a mechanism whereby the stratification of the intermediate-depth waters is influenced by the differing effects on the surface buoyancy distribution of fixed versus restoring aspects of the surface buoyancy forcing. This implies the Southern Ocean exerts less influence over the global deep ocean stratification than has been previously suggested, at least when considering the difference between LGM and PI climates in CESM1.

  12. A fully-implicit model of the global ocean circulation

    NASA Astrophysics Data System (ADS)

    Weijer, Wilbert; Dijkstra, Henk A.; Öksüzoğlu, Hakan; Wubs, Fred W.; de Niet, Arie C.

    2003-12-01

    With the recent developments in the solution methods for large-dimensional nonlinear algebraic systems, fully-implicit ocean circulation models are now becoming feasible. In this paper, the formulation of such a three-dimensional global ocean model is presented. With this implicit model, the sensitivity of steady states to parameters can be investigated efficiently using continuation methods. In addition, the implicit formulation allows for much larger time steps than can be used with explicit models. To demonstrate current capabilities of the implicit global ocean model, we use a relatively low-resolution (4° horizontally and 12 levels vertically) version. For this configuration, we present: (i) an explicit calculation of the bifurcation diagram associated with hysteresis behavior of the ocean circulation and (ii) the scaling behavior of the Atlantic meridional overturning versus the magnitude of the vertical mixing coefficient of heat and salt.

  13. An International Research Strategy: Towards a Joint IGBP/IHDP/WCRP Global Carbon Cycle Project

    NASA Astrophysics Data System (ADS)

    Hibbard, K. A.

    2001-05-01

    The International Geosphere Biosphere Programme (IGBP), the International Human Dimensions Programme (IHDP) and the World Climate Research Programme (WCRP) have agreed upon a joint project that integrates the biological, ecological, social, and physical climate communities is crucial towards understanding the Earth's global carbon system. This joint science project will provide a platform to address the needs of the assessment, observing, and other scientific research communities. The aim is to address the necessary science needs while keeping in mind the policy relevance for carbon management strategies. The Joint Carbon Cycle has several fundamental drivers: first, the human-environment system is intimately linked with the biophsysical carbon cycle; second, it is clear that the terrestrial and ocean biosphere respond variably over space and time to fluctuations in atmospheric CO2, however, the patterns and processes that drive these responses in a coupled human-biophysical Earth's systems are largely unknown; and third, to predict and understand a linked human-biophysical carbon cycle, a multiple constraint approach must be utilized that integrates process studies, manipulative experiments, observations and models. Finally, an international Project is necessary to facilitate and coordinate cooperation between national and regional programmes and governments to fit the pieces of the global carbon puzzle in a coherent manner. A central problem in carbon cycle research is the synthesis of a wide variety of different measurements to provide the best possible information about the space-time distribution of carbon fluxes and stores in the human, oceanic and terrestrial biospheres. Three key strategies will be employed to address our uncertainties in global carbon sources and sinks: (1) To constrain global carbon fluxes and stores from multiple sources by integrating process studies, experiments, models, observations and case studies; (2) To incorporate institutions as

  14. Ocean Global Warming Impacts on the South America Climate

    NASA Astrophysics Data System (ADS)

    Ramos-Da-Silva, Renato

    2016-03-01

    The global Ocean-Land-Atmosphere Model (OLAM) model was used to estimate the impacts of the global oceanic warming on the climate projections for the 21st Century focusing on the South America region. This new model is able to represent simultaneously the global and regional scales using a refining grid approach for the region of interest. First, the model was run for a 31-year control period consisting on the years 1960-1990 using the monthly Sea Surface Temperature (SST) from the Atmospheric Model Intercomparison Project (AMIP) data as a driver for the ocean fluxes. Then, the model was run for the period 2010-2100 using the monthly projected SST from the Hadley Center model (HadCM3) as a driver for the oceanic changes. The model was set up with an icosahedral triangular global grid having about 250 km of grid spacing and with a refining grid resolution with the cells reaching about 32 km over the South America region. The results show an overall temperature increase mainly over the center of the Amazon basin caused by the increase of the greenhouse effect of the water vapor; a decrease on precipitation mainly over the northeast Brazil and an increase in the south and over the western Amazon region; and a major increase on the near surface wind speed. These results are similar to the global coupled models; however, OLAM has a novel type of grid that can provide the interaction between the global and regional scales simultaneously.

  15. A Global Ocean State Estimate at the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Amrhein, D. E.; Wunsch, C. I.

    2015-12-01

    Many features of Earth's climate at the Last Glacial Maximum (LGM, ca. 20,000 years ago) remain a mystery, including the role of the ocean circulation in transporting thermal energy, salinity, and other tracers. Most efforts at reconstructing the ocean state during the LGM have relied either upon integrations of general circulation models under prescribed LGM boundary conditions or the interpretation of climate proxy records without explicit physical constraints. Here we describe a global, primitive equation simulation of the LGM ocean with boundary conditions (wind, surface air temperature, and other atmospheric variables) and mixing parameters derived by a least-squares fit of an ocean general circulation model to observations of deep ocean stable isotopes and sea surface temperatures at the LGM.

  16. Marine defaunation: animal loss in the global ocean.

    PubMed

    McCauley, Douglas J; Pinsky, Malin L; Palumbi, Stephen R; Estes, James A; Joyce, Francis H; Warner, Robert R

    2015-01-16

    Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land. PMID:25593191

  17. The timescales of global surface-ocean connectivity

    NASA Astrophysics Data System (ADS)

    Jönsson, Bror F.; Watson, James R.

    2016-04-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches--each randomly located anywhere in the surface ocean--is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change--increasing temperatures, ocean acidification and changes in stratification over decadal timescales--through the advection of resilient types.

  18. Global ocean modeling on the Connection Machine

    SciTech Connect

    Smith, R.D.; Dukowicz, J.K.; Malone, R.C.

    1993-10-01

    The authors have developed a version of the Bryan-Cox-Semtner ocean model (Bryan, 1969; Semtner, 1976; Cox, 1984) for massively parallel computers. Such models are three-dimensional, Eulerian models that use latitude and longitude as the horizontal spherical coordinates and fixed depth levels as the vertical coordinate. The incompressible Navier-Stokes equations, with a turbulent eddy viscosity, and mass continuity equation are solved, subject to the hydrostatic and Boussinesq approximations. The traditional model formulation uses a rigid-lid approximation (vertical velocity = 0 at the ocean surface) to eliminate fast surface waves. These waves would otherwise require that a very short time step be used in numerical simulations, which would greatly increase the computational cost. To solve the equations with the rigid-lid assumption, the equations of motion are split into two parts: a set of twodimensional ``barotropic`` equations describing the vertically-averaged flow, and a set of three-dimensional ``baroclinic`` equations describing temperature, salinity and deviations of the horizontal velocities from the vertically-averaged flow.

  19. Anisotropy of eddy variability in the global ocean

    NASA Astrophysics Data System (ADS)

    Stewart, K. D.; Spence, P.; Waterman, S.; Sommer, J. Le; Molines, J.-M.; Lilly, J. M.; England, M. H.

    2015-11-01

    The anisotropy of eddy variability in the global ocean is examined in geostrophic surface velocities derived from satellite observations and in the horizontal velocities of a 1/12° global ocean model. Eddy anisotropy is of oceanographic interest as it is through anisotropic velocity fluctuations that the eddy and mean-flow fields interact dynamically. This study is timely because improved observational estimates of eddy anisotropy will soon be available with Surface Water and Ocean Topography (SWOT) altimetry data. We find there to be good agreement between the characteristics and distributions of eddy anisotropy from the present satellite observations and model ocean surface. In the model, eddy anisotropy is found to have significant vertical structure and is largest close to the ocean bottom, where the anisotropy aligns with the underlying isobaths. The highly anisotropic bottom signal is almost entirely contained in the barotropic variability. Upper-ocean variability is predominantly baroclinic and the alignment is less sensitive to the underlying bathymetry. These findings offer guidance for introducing a parameterization of eddy feedbacks, based on the eddy kinetic energy and underlying bathymetry, to operate on the barotropic flow and better account for the effects of barotropic Reynolds stresses unresolved in coarse-resolution ocean models.

  20. Global ocean monitoring for the World Climate Research Programme.

    PubMed

    Revelle, R; Bretherton, F

    1986-07-01

    Oceanic research and modelling for the World Climate Research Program will utilize several recently-developed instruments and measuring techniques as well as well-tested, long-used instruments. Ocean-scanning satellites will map the component of the ocean-surface topography related to ocean currents and mesoscale eddies and to fluctuating water volumes caused by ocean warming and cooling. Other satellite instruments will measure the direction and magnitude of wind stress on the sea surface, surface water temperatures, the distribution of chlorophyll and other photosynthetic pigments, the characteristics of internal waves, and possible precipitation over the ocean. Networks of acoustic transponders will obtain a three-dimensional picture of the distribution of temperature from the surface down to mid-depth and of long-term changes in temperature at depth. Ocean research vessels will determine the distribution and fate of geochemical tracers and will also make high-precision, deep hydrographic casts. Ships of opportunity, using expendable instruments, will measure temperature, salinity and currents in the upper water layers. Drifting and anchored buoys will also measure these properties as well as those of the air above the sea surface. Tide gauges installed on islands and exposed coastal locations will measure variations in monthly and shorter-period mean sea level. These tide gauges will provide 'ground truth' for the satellite maps of sea-surface topography, and will also determine variations in ocean currents and temperature.All these instruments will be used in several major programs, the most ambitious of which is the World Ocean Circulation Experiment (WOCE) designed to obtain global measurements of major currents throughout the world ocean, greater understanding of the transformation of water masses, and the role of advective, convective, and turbulent processes in exchange of properties between surface and deep-ocean layers.A five- to ten-year experiment

  1. The positive Indian Ocean Dipole-like response in the tropical Indian Ocean to global warming

    NASA Astrophysics Data System (ADS)

    Luo, Yiyong; Lu, Jian; Liu, Fukai; Wan, Xiuquan

    2016-04-01

    Climate models project a positive Indian Ocean Dipole (pIOD)-like SST response in the tropical Indian Ocean to global warming. By employing the Community Earth System Model and applying an overriding technique to its ocean component (version 2 of the Parallel Ocean Program), this study investigates the similarities and differences of the formation mechanisms for the changes in the tropical Indian Ocean during the pIOD versus global warming. Results show that their formation processes and related seasonality are quite similar; in particular, wind-thermocline-SST feedback is the leading mechanism in producing the anomalous cooling over the eastern tropics in both cases. Some differences are also found, including the fact that the cooling effect of the vertical advection over the eastern tropical Indian Ocean is dominated by the anomalous vertical velocity during the pIOD but by the anomalous upper-ocean stratification under global warming. These findings are further examined through an analysis of the mixed layer heat budget.

  2. A global ocean reanalysis product in the China Ocean Reanalysis (CORA) project

    NASA Astrophysics Data System (ADS)

    Han, Guijun; Fu, Hongli; Zhang, Xuefeng; Li, Wei; Wu, Xinrong; Wang, Xidong; Zhang, Lianxin

    2013-11-01

    The first version of a global ocean reanalysis over multiple decades (1979-2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data assimilation scheme within the framework of 3D variational (3DVar) analysis, called multi-grid 3DVar, is implemented in 3D space for retrieving multiple-scale observational information. Assimilated oceanic observations include sea level anomalies (SLAs) from multi-altimeters, sea surface temperatures (SSTs) from remote sensing satellites, and in-situ temperature/salinity profiles. Evaluation showed that compared to the model simulation, the annual mean heat content of the global reanalysis is significantly approaching that of World Ocean Atlas 2009 (WOA09) data. The quality of the global temperature climatology was found to be comparable with the product of Simple Ocean Data Assimilation (SODA), and the major ENSO events were reconstructed. The global and Atlantic meridional overturning circulations showed some similarity as SODA, although significant differences were found to exist. The analysis of temperature and salinity in the current version has relatively larger errors at high latitudes and improvements are ongoing in an updated version. CORA was found to provide a simulation of the subsurface current in the equatorial Pacific with a correlation coefficient beyond about 0.6 compared with the Tropical Atmosphere Ocean (TAO) mooring data. The mean difference of SLAs between altimetry data and CORA was less than 0.1 m in most years.

  3. Decadal Changes in Global Ocean Annual Primary Production

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Conkright, Margarita E.; Behrenfeld, Michael J.; Ginoux, Paul; Casey, Nancy W.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence

  4. Perfluoroalkylated substances in the global tropical and subtropical surface oceans.

    PubMed

    González-Gaya, Belén; Dachs, Jordi; Roscales, Jose L; Caballero, Gemma; Jiménez, Begoña

    2014-11-18

    In this study, perfluoroalkylated substances (PFASs) were analyzed in 92 surface seawater samples taken during the Malaspina 2010 expedition which covered all the tropical and subtropical Atlantic, Pacific and Indian oceans. Nine ionic PFASs including C6-C10 perfluoroalkyl carboxylic acids (PFCAs), C4 and C6-C8 perfluoroalkyl sulfonic acids (PFSAs) and two neutral precursors perfluoroalkyl sulfonamides (PFASAs), were identified and quantified. The Atlantic Ocean presented the broader range in concentrations of total PFASs (131-10900 pg/L, median 645 pg/L, n = 45) compared to the other oceanic basins, probably due to a better spatial coverage. Total concentrations in the Pacific ranged from 344 to 2500 pg/L (median = 527 pg/L, n = 27) and in the Indian Ocean from 176 to 1976 pg/L (median = 329, n = 18). Perfluorooctanesulfonic acid (PFOS) was the most abundant compound, accounting for 33% of the total PFASs globally, followed by perfluorodecanoic acid (PFDA, 22%) and perfluorohexanoic acid (PFHxA, 12%), being the rest of the individual congeners under 10% of total PFASs, even for perfluorooctane carboxylic acid (PFOA, 6%). PFASAs accounted for less than 1% of the total PFASs concentration. This study reports the ubiquitous occurrence of PFCAs, PFSAs, and PFASAs in the global ocean, being the first attempt, to our knowledge, to show a comprehensive assessment in surface water samples collected in a single oceanic expedition covering tropical and subtropical oceans. The potential factors affecting their distribution patterns were assessed including the distance to coastal regions, oceanic subtropical gyres, currents and biogeochemical processes. Field evidence of biogeochemical controls on the occurrence of PFASs was tentatively assessed considering environmental variables (solar radiation, temperature, chlorophyll a concentrations among others), and these showed significant correlations with some PFASs, but explaining small to moderate percentages of variability

  5. Potential increasing dominance of heterotrophy in the global ocean

    NASA Astrophysics Data System (ADS)

    Kvale, K. F.; Meissner, K. J.; Keller, D. P.

    2015-07-01

    Autotrophy is largely resource-limited in the modern ocean. Paleo evidence indicates this was not necessarily the case in warmer climates, and modern observations as well as standard metabolic theory suggest continued ocean warming could shift global ecology towards heterotrophy, thereby reducing autotrophic nutrient limitation. Such a shift would entail strong nutrient recycling in the upper ocean and high rates of net primary production (NPP), yet low carbon export to the deep ocean and sediments. We demonstrate transition towards such a state in the early 22nd century as a response to business-as-usual representative concentration pathway forcing (RCP8.5) in an intermediate complexity Earth system model in three configurations; with and without an explicit calcifier phytoplankton class and calcite ballast model. In all models nutrient regeneration in the near-surface becomes an increasingly important driver of primary production. The near-linear relationship between changes in NPP and global sea surface temperature (SST) found over the 21st century becomes exponential above a 2-4{ }\\circ {{C}} global mean SST change. This transition to a more heterotrophic ocean agrees roughly with metabolic theory.

  6. Global ocean conveyor lowers extinction risk in the deep sea

    NASA Astrophysics Data System (ADS)

    Henry, Lea-Anne; Frank, Norbert; Hebbeln, Dierk; Wienberg, Claudia; Robinson, Laura; van de Flierdt, Tina; Dahl, Mikael; Douarin, Mélanie; Morrison, Cheryl L.; López Correa, Matthias; Rogers, Alex D.; Ruckelshausen, Mario; Roberts, J. Murray

    2014-06-01

    General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth's largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium-thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6 kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500 km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea.

  7. An operational global ocean forecast system and its applications

    NASA Astrophysics Data System (ADS)

    Mehra, A.; Tolman, H. L.; Rivin, I.; Rajan, B.; Spindler, T.; Garraffo, Z. D.; Kim, H.

    2012-12-01

    A global Real-Time Ocean Forecast System (RTOFS) was implemented in operations at NCEP/NWS/NOAA on 10/25/2011. This system is based on an eddy resolving 1/12 degree global HYCOM (HYbrid Coordinates Ocean Model) and is part of a larger national backbone capability of ocean modeling at NWS in strong partnership with US Navy. The forecast system is run once a day and produces a 6 day long forecast using the daily initialization fields produced at NAVOCEANO using NCODA (Navy Coupled Ocean Data Assimilation), a 3D multi-variate data assimilation methodology. As configured within RTOFS, HYCOM has a horizontal equatorial resolution of 0.08 degrees or ~9 km. The HYCOM grid is on a Mercator projection from 78.64 S to 47 N and north of this it employs an Arctic dipole patch where the poles are shifted over land to avoid a singularity at the North Pole. This gives a mid-latitude (polar) horizontal resolution of approximately 7 km (3.5 km). The coastline is fixed at 10 m isobath with open Bering Straits. This version employs 32 hybrid vertical coordinate surfaces with potential density referenced to 2000 m. Vertical coordinates can be isopycnals, often best for resolving deep water masses, levels of equal pressure (fixed depths), best for the well mixed unstratified upper ocean and sigma-levels (terrain-following), often the best choice in shallow water. The dynamic ocean model is coupled to a thermodynamic energy loan ice model and uses a non-slab mixed layer formulation. The forecast system is forced with 3-hourly momentum, radiation and precipitation fluxes from the operational Global Forecast System (GFS) fields. Results include global sea surface height and three dimensional fields of temperature, salinity, density and velocity fields used for validation and evaluation against available observations. Several downstream applications of this forecast system will also be discussed which include search and rescue operations at US Coast Guard, navigation safety information

  8. Oceanic biogeochemical controls on global dynamics of persistent organic pollutants.

    PubMed

    Dachs, Jordi; Lohmann, Rainer; Ockenden, Wendy A; Méjanelle, Laurence; Eisenreich, Steven J; Jones, Kevin C

    2002-10-15

    Understanding and quantifying the global dynamics and sinks of persistent organic pollutants (POPs) is important to assess their environmental impact and fate. Air-surface exchange processes, where temperature plays a central role in controlling volatilization and deposition, are of key importance in controlling global POP dynamics. The present study is an assessment of the role of oceanic biogeochemical processes, notably phytoplankton uptake and vertical fluxes of particles, on the global dynamics of POPs. Field measurements of atmospheric polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and furans (PCDFs) are combined with remote sensing estimations of oceanic temperature, wind speed, and chlorophyll, to model the interactions between air-water exchange, phytoplankton uptake, and export of organic matter and POPs out of the mixed surface ocean layer. Deposition is enhanced in the mid-high latitudes and is driven by sinking marine particulate matter, rather than by a cold condensation effect. However, the relative contribution of the biological pump is a function of the physical-chemical properties of POPs. It is concluded that oceanic biogeochemical processes play a critical role in controlling the global dynamics and the ultimate sink of POPs. PMID:12387392

  9. GLOBAL ENVIRONMENTAL CHANGE ISSUES IN THE WESTERN INDIAN OCEAN REGION

    EPA Science Inventory

    Mounting evidence from both instrumental and proxy records shows global climate continues to change. nalysis of near-surface temperatures over land and oceans during the past 130 years shows marked warming during the first half of this century with relatively steady temperatures ...

  10. Evaluating the deep-ocean circulation of a global ocean model using carbon isotopic ratios

    NASA Astrophysics Data System (ADS)

    Paul, André; Dutkiewicz, Stephanie; Gebbie, Jake; Losch, Martin; Marchal, Olivier

    2016-04-01

    We study the sensitivity of a global three-dimensional biotic ocean carbon-cycle model to the parameterizations of gas exchange and biological productivity as well as to deep-ocean circulation strength, and we employ the carbon isotopic ratios δ13C and Δ14C of dissolved inorganic carbon for a systematic evaluation against observations. Radiocarbon (Δ14C) in particular offers the means to assess the model skill on a time scale of 100 to 1000 years relevant to the deep-ocean circulation. The carbon isotope ratios are included as tracers in the MIT general circulation model (MITgcm). The implementation involves the fractionation processes during photosynthesis and air-sea gas exchange. We present the results of sixteen simulations combining two different parameterizations of the piston velocity, two different parameterizations of biological productivity (including the effect of iron fertilization) and four different overturning rates. These simulations were first spun up to equilibrium (more than 10,000 years of model simulation) and then continued from AD 1765 to AD 2002. For the model evaluation, we followed the OCMIP-2 (Ocean Carbon-Cycle Model Intercomparision Project phase two) protocol, comparing the results to GEOSECS (Geochemical Ocean Sections Survey) and WOCE (World Ocean Circulation Experiment) δ13C and natural Δ14C data in the world ocean. The range of deep natural Δ14C (below 1000 m) for our single model (MITgcm) was smaller than for the group of different OCMIP-2 models. Furthermore, differences between different model parameterizations were smaller than for different overturning rates. We conclude that carbon isotope ratios are a useful tool to evaluate the deep-ocean circulation. Since they are also available from deep-sea sediment records, we postulate that the simulation of carbon isotope ratios in a global ocean model will aid in estimating the deep-ocean circulation and climate during present and past.

  11. Patterns and emerging trends in global ocean health.

    PubMed

    Halpern, Benjamin S; Longo, Catherine; Lowndes, Julia S Stewart; Best, Benjamin D; Frazier, Melanie; Katona, Steven K; Kleisner, Kristin M; Rosenberg, Andrew A; Scarborough, Courtney; Selig, Elizabeth R

    2015-01-01

    International and regional policies aimed at managing ocean ecosystem health need quantitative and comprehensive indices to synthesize information from a variety of sources, consistently measure progress, and communicate with key constituencies and the public. Here we present the second annual global assessment of the Ocean Health Index, reporting current scores and annual changes since 2012, recalculated using updated methods and data based on the best available science, for 221 coastal countries and territories. The Index measures performance of ten societal goals for healthy oceans on a quantitative scale of increasing health from 0 to 100, and combines these scores into a single Index score, for each country and globally. The global Index score improved one point (from 67 to 68), while many country-level Index and goal scores had larger changes. Per-country Index scores ranged from 41-95 and, on average, improved by 0.06 points (range -8 to +12). Globally, average scores increased for individual goals by as much as 6.5 points (coastal economies) and decreased by as much as 1.2 points (natural products). Annual updates of the Index, even when not all input data have been updated, provide valuable information to scientists, policy makers, and resource managers because patterns and trends can emerge from the data that have been updated. Changes of even a few points indicate potential successes (when scores increase) that merit recognition, or concerns (when scores decrease) that may require mitigative action, with changes of more than 10-20 points representing large shifts that deserve greater attention. Goal scores showed remarkably little covariance across regions, indicating low redundancy in the Index, such that each goal delivers information about a different facet of ocean health. Together these scores provide a snapshot of global ocean health and suggest where countries have made progress and where a need for further improvement exists. PMID:25774678

  12. Patterns and Emerging Trends in Global Ocean Health

    PubMed Central

    Halpern, Benjamin S.; Longo, Catherine; Lowndes, Julia S. Stewart; Best, Benjamin D.; Frazier, Melanie; Katona, Steven K.; Kleisner, Kristin M.; Rosenberg, Andrew A.; Scarborough, Courtney; Selig, Elizabeth R.

    2015-01-01

    International and regional policies aimed at managing ocean ecosystem health need quantitative and comprehensive indices to synthesize information from a variety of sources, consistently measure progress, and communicate with key constituencies and the public. Here we present the second annual global assessment of the Ocean Health Index, reporting current scores and annual changes since 2012, recalculated using updated methods and data based on the best available science, for 221 coastal countries and territories. The Index measures performance of ten societal goals for healthy oceans on a quantitative scale of increasing health from 0 to 100, and combines these scores into a single Index score, for each country and globally. The global Index score improved one point (from 67 to 68), while many country-level Index and goal scores had larger changes. Per-country Index scores ranged from 41–95 and, on average, improved by 0.06 points (range -8 to +12). Globally, average scores increased for individual goals by as much as 6.5 points (coastal economies) and decreased by as much as 1.2 points (natural products). Annual updates of the Index, even when not all input data have been updated, provide valuable information to scientists, policy makers, and resource managers because patterns and trends can emerge from the data that have been updated. Changes of even a few points indicate potential successes (when scores increase) that merit recognition, or concerns (when scores decrease) that may require mitigative action, with changes of more than 10–20 points representing large shifts that deserve greater attention. Goal scores showed remarkably little covariance across regions, indicating low redundancy in the Index, such that each goal delivers information about a different facet of ocean health. Together these scores provide a snapshot of global ocean health and suggest where countries have made progress and where a need for further improvement exists. PMID:25774678

  13. Distribution of mesozooplankton biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; O'Brien, T. D.

    2013-02-01

    Mesozooplankton are cosmopolitan within the sunlit layers of the global ocean. They are important in the pelagic food web, having a significant feedback to primary production through their consumption of phytoplankton and microzooplankton. In many regions of the global ocean, they are also the primary contributors to vertical particle flux in the oceans. Through both they affect the biogeochemical cycling of carbon and other nutrients in the oceans. Little, however, is known about their global distribution and biomass. While global maps of mesozooplankton biomass do exist in the literature, they are usually in the form of hand-drawn maps for which the original data associated with these maps are not readily available. The dataset presented in this synthesis has been in development since the late 1990s, is an integral part of the Coastal and Oceanic Plankton Ecology, Production, and Observation Database (COPEPOD), and is now also part of a wider community effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. A total of 153 163 biomass values were collected, from a variety of sources, for mesozooplankton. Of those 2% were originally recorded as dry mass, 26% as wet mass, 5% as settled volume, and 68% as displacement volume. Using a variety of non-linear biomass conversions from the literature, the data have been converted from their original units to carbon biomass. Depth-integrated values were then used to calculate an estimate of mesozooplankton global biomass. Global epipelagic mesozooplankton biomass, to a depth of 200 m, had a mean of 5.9 μg C L-1, median of 2.7 μg C L-1 and a standard deviation of 10.6 μg C L-1. The global annual average estimate of mesozooplankton in the top 200 m, based on the median value, was 0.19 Pg C. Biomass was highest in the Northern Hemisphere, and there were slight decreases from polar oceans (40-90°) to more temperate

  14. Satellite Altimetry for a Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng

    2000-01-01

    Space-age technologies have made satellite remote sensing a powerful new tool to study the Earth on a global scale. However, the opacity of the ocean to electromagnetic sensing has limited spaceborne measurements to the properties of the surface layer of the ocean (such as sea surface temperature and color). The radar altimetric measurement of the height of the sea surface relative to the geoid, the dynamic topography of the ocean, is a very useful quantity for studying the circulation of the ocean. The ability of measuring dynamic topography from space makes satellite altimetry a uniquely useful remote sensing technique because dynamic topography reflects oceanic processes not only at the surface but at depths as well. A simple analysis shows that a one centimeter tilt in the dynamic topography is associated with a mass transport of 1-7 Sv (1Sv= 1 million tons per second) in the open ocean depending on the vertical distribution of current velocity. Such a magnitude is an appreciable fraction of the transport of the Florida Current (circa 30 Sv), for instance. TOPEX/POSEIDON has demonstrated the capability of measuring the time variation of sea level with accuracy approaching to 2 cm when the data are averaged over boxes with several hundred kilometers on each side. The data set has been used for studying ocean circulation phenomena with a wide range of scales, ranging from fast-changing barotropic variability to seasonal and interannual variability such as El Nino and La Nina. The long record of precise measurement of global sea level has also showed great promise for monitoring the variation of mean sea level, an effective indicator of global climate change. Continuation of satellite altimetry missions with capability matching or better than that of TOPEX/POSEIDON should be included as a key component of a Global Ocean Observing System. NASA and CNES have committed to continuing the measurement of TOPEX/POSEIDON with a series of follow-on missions called Jason

  15. The Mercator-Ocean Forecasting Service: a 4D vision of the Global Ocean, Serving the Ocean Services

    NASA Astrophysics Data System (ADS)

    Toumazou, V.; Baudel, S.; Vinay, G.; Nouel, L.

    2005-12-01

    Mercator-Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Meteo-France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator-Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The current high-resolution model offers a 6 km grid resolution, and the first models offering global ocean coverage has been implemented early 2004. A 1/4(°) model will be operated by the end of 2006. Objective 1- Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2- Support applications for commercial shipping and naval forces, promote sustainable stewardship of the world's oceans

  16. Evaluation of the Global Ocean Data Assimilation System at INCOIS: The Tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ravichandran, M.; Behringer, D.; Sivareddy, S.; Girishkumar, M. S.; Chacko, Neethu; Harikumar, R.

    2013-09-01

    A new version of NCEP's Global Ocean Data Assimilation System (GODAS), which is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular ocean Model version 4.0 (MOM4.0) and a three-dimensional variational (3D-VAR) data assimilation scheme, was configured and operationalized at Indian National Centre for Ocean Information Services (INCOIS). The primary objective of the GODAS at INCOIS (INCOIS-GODAS) is to provide an accurate estimate of the ocean state, which will be used to initialize a coupled model for the seasonal monsoon forecast and also to understand the variability of the ocean at different time scales. In this paper, we assess the quality of ocean analyses in the Tropical Indian Ocean (TIO) obtained from the operational INCOIS-GODAS. In addition to this, we examined the sensitivity of INCOIS-GODAS to different momentum forcing and to the assimilation of temperature and synthetic salinity based on the experiments carried out with different wind products: NCEP2 and QuikSCAT and a free run respectively. The present study reveals that the model with assimilation simulates most of the observed features of temperature, SSHA and currents with reasonably good accuracy in the TIO at both intra-seasonal and inter-annual time scales. The analysis further shows that there was a considerable improvement in the ocean current field, when the model was forced with QuikSCAT winds.

  17. An eddy-resolving model of the Global Ocean

    NASA Astrophysics Data System (ADS)

    Ibrayev, Rashit; Khabeev, Renat; Kalmykov, Vladimir; Ushakov, Konstantin

    2013-04-01

    We present results of eddy-resolving simulation of the global ocean with INM-IO general circulation model. The global grid employs tripole layout, has 0.1-degree horizontal resolution, and uses 49 vertical levels. The ocean model coupled with sea ice and atmospheric boundary layer sub-models. We address to the problem of effective implementation of the numerical code on parallel computers. The model was developed in the Institute of Numerical Mathematics (INM) and P.P.Shirshov Institute of Oceanology (IO). The global simulations were performed with atmospheric conditions based on repeat annual cycle of the normal year - CORE dataset. We present an overview from 75-year spinup. The model results are quite good when compared to observations. We discuss the results of sensitivity of AMOC to the fresh water input due to Greenland ice sheet melting.

  18. Integrated studies of uncultured microbes in the global ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Dupont, C.; Rusch, D.; Martiny, A.; Lasken, R.

    2010-12-01

    The Global Ocean Sampling (GOS) initiative at the J. Craig Venter Institute represents the most extensive metagenomic study of a single environment. Early findings highlighted the potential of shotgun metagenomics to expand our knowledge of marine microbial biodiversity and physiology. However, it also became clear that many of the abundant marine microbes remain uncultured, hindering a direct connection between phylogeny and ecophysiology. In two recent studies, a combination of single cell genomics and aggressive assembly of binned metagenomic data have resulted in the acquisition of multiple genomes for two uncultured but globally relevant organisms. Metabolic reconstructions of the whole genomes revealed unique physiological adaptations in marine Prochlorococcus to high nutrient, low Fe regions of the global ocean and illuminated the potential ecological role of the gamma-proteobacterial 16S clade SAR86. The internal reference genomes also facilitate fragment recruitment based biogeographical studies, both at the whole genome level and the protein level.

  19. Mercator-Ocean monitoring and forecasting : a 4D vision of the global ocean

    NASA Astrophysics Data System (ADS)

    Bahurel, P.; Toumazou, V.

    Mercator Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Météo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The new high-resolution model that is now on line offers 6 km grid resolution, and the first models offering global ocean coverage will be implemented in 2004. Over the next four years, Mercator Ocean also plans to establish a European Operational Oceanography Centre in Toulouse. Objective 1. Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2. Support applications for commercial shipping and

  20. Impacts of data assimilation on the global ocean carbonate system

    NASA Astrophysics Data System (ADS)

    Visinelli, L.; Masina, S.; Vichi, M.; Storto, A.; Lovato, T.

    2016-06-01

    In an ocean reanalysis, historical observations are combined with ocean and biogeochemical general circulation models to produce a reconstruction of the oceanic properties in past decades. This is one possible method to better constrain the role of the ocean carbon cycle in the determination of the air-sea CO2 flux. In this work, we investigate how the assimilation of physical variables and subsequently the combined assimilation of physical data and inorganic carbon variables - namely dissolved inorganic carbon (DIC) and alkalinity - affect the modelling of the marine carbonate system and the related air-sea CO2 fluxes. The performance of the two assimilation exercises are quantitatively assessed against the assimilated DIC and alkalinity data and the independent ocean surface pCO2 observations from global datasets. We obtain that the assimilation of physical observations has contrasting effects in different ocean basins when compared with the DIC and alkalinity data: it reduces the root-mean square error against the observed pCO2 in the Atlantic and Southern oceans, while increases the model error in the North Pacific and Indian Oceans. In both cases the corrected evaporation rates are the major factor determining the changes in concentrations. The assimilation of inorganic carbon variables on top of the physical data gives a generalized improvement in the model error of inorganic carbon variables, also improving the annual mean and spatial distribution of air-sea fluxes in agreement with other published estimates. These results indicate that data assimilation of physical and inorganic carbon data does not guarantee the improvement of the simulated pCO2 in all the oceanic regions; nevertheless, errors in pCO2 are reduced by a factor corresponding to those associated with the air-sea flux formulations.

  1. Global Hydrographic Overview of Ocean Near Surface Variability

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Gaillard, F.; Le Traon, P.

    2007-12-01

    Estimates of hydrographic variability as measured by ARGO drifters in the near surface layer of the world ocean are discussed here. A gridded global field of these hydrographic measurements is used which is disposed by the CORIOLIS Analysis System (CAS). The estimates explicitly include the description of the seasonal cycle of temperature as well as of the salinity field, depict large-scale variability patterns in the different oceanic basins and its main purpose is to provide an insight into what can be measured and resolved in the upper layer while using the CAS gridded field. Amplitudes of total variance are generally higher in the northern hemisphere compared to its southern counterpart. The distribution of standard deviations of temperature including the seasonal cycle as well as from temperature anomalies highly differs from corresponding salinity variability which can be predominantly lead back to ocean atmosphere dynamics. Large-scale and well known oceanic features such as ocean's response to NAO and PDO fluctuations and ENSO dynamics can be resolved in CAS temperatures. A substantial advance using the CAS gridded field is that its signatures in global salinity can also be discussed.

  2. Towards understanding global variability in ocean carbon-13

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Bopp, Laurent

    2008-03-01

    We include a prognostic parameterization of carbon-13 into a global ocean-biogeochemistry model to investigate the spatiotemporal variability in ocean carbon-13 between 1860 and 2000. Carbon-13 was included in all 10 existing carbon pools, with dynamic fractionations occurring during photosynthesis, gas exchange and carbonate chemistry. We find that ocean distributions of δ13CDIC at any point in time are controlled by the interplay between biological fractionation, gas exchange, and ocean mixing. In particular, the deep ocean δ13CDIC is sensitive (by > 0.5‰) to the degree of ocean ventilation. On interannual timescales, although the variability in δ13CDIC is a first order function of the atmospheric δ13CO2 and overall carbon flux, the spatial distributions are controlled by the degree to which surface waters are exposed to the atmosphere. The δ13CPOC is highly sensitive to the species of inorganic carbon assimilated during photosynthesis (by 10 to 17‰), as well as the intrinsic growth rate and in situ [CO2(aq)], suggesting that phytoplankton utilize both HCO3- and CO2(aq). The relationship between Δδ13CDIC and anthropogenic carbon (Cant) varies by ±70% regionally and circulation and biotic effects can influence estimates of Cant that are based on Δδ13CDIC.

  3. A Coupled Ocean General Circulation, Biogeochemical, and Radiative Model of the Global Oceans: Seasonal Distributions of Ocean Chlorophyll and Nutrients

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Busalacchi, Antonio (Technical Monitor)

    2000-01-01

    A coupled ocean general circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability. and the interactions among three functional phytoplankton groups (diatoms. chlorophytes, and picoplankton) and three nutrients (nitrate, ammonium, and silicate). Basin scale (greater than 1000 km) model chlorophyll results are in overall agreement with CZCS pigments in many global regions. Seasonal variability observed in the CZCS is also represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are generally in conformance although occasional departures are apparent. Model nitrate distributions agree with in situ data, including seasonal dynamics, except for the equatorial Atlantic. The overall agreement of the model with satellite and in situ data sources indicates that the model dynamics offer a reasonably realistic simulation of phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent many aspects of the great diversity of physical, biological, chemical, and radiative environments encountered in the global oceans.

  4. Global declines in oceanic nitrification rates as a consequence of ocean acidification.

    PubMed

    Beman, J Michael; Chow, Cheryl-Emiliane; King, Andrew L; Feng, Yuanyuan; Fuhrman, Jed A; Andersson, Andreas; Bates, Nicholas R; Popp, Brian N; Hutchins, David A

    2011-01-01

    Ocean acidification produced by dissolution of anthropogenic carbon dioxide (CO(2)) emissions in seawater has profound consequences for marine ecology and biogeochemistry. The oceans have absorbed one-third of CO(2) emissions over the past two centuries, altering ocean chemistry, reducing seawater pH, and affecting marine animals and phytoplankton in multiple ways. Microbially mediated ocean biogeochemical processes will be pivotal in determining how the earth system responds to global environmental change; however, how they may be altered by ocean acidification is largely unknown. We show here that microbial nitrification rates decreased in every instance when pH was experimentally reduced (by 0.05-0.14) at multiple locations in the Atlantic and Pacific Oceans. Nitrification is a central process in the nitrogen cycle that produces both the greenhouse gas nitrous oxide and oxidized forms of nitrogen used by phytoplankton and other microorganisms in the sea; at the Bermuda Atlantic Time Series and Hawaii Ocean Time-series sites, experimental acidification decreased ammonia oxidation rates by 38% and 36%. Ammonia oxidation rates were also strongly and inversely correlated with pH along a gradient produced in the oligotrophic Sargasso Sea (r(2) = 0.87, P < 0.05). Across all experiments, rates declined by 8-38% in low pH treatments, and the greatest absolute decrease occurred where rates were highest off the California coast. Collectively our results suggest that ocean acidification could reduce nitrification rates by 3-44% within the next few decades, affecting oceanic nitrous oxide production, reducing supplies of oxidized nitrogen in the upper layers of the ocean, and fundamentally altering nitrogen cycling in the sea. PMID:21173255

  5. Distribution of mesozooplankton biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; O'Brien, T. D.

    2012-09-01

    Mesozooplankton are cosmopolitan within the sunlit layers of the global ocean. They are important in the classical food web, having a significant feedback to primary production through their consumption of phytoplankton and microzooplankton. They are also the primary contributor to vertical particle flux in the oceans. Through both they affect the biogeochemical cycling of carbon and other nutrients in the oceans. Little, however, is known about their global distribution and biomass. While global maps of mesozooplankton biomass do exist in the literature they are usually in the form of hand-drawn maps and the original data associated with these maps are not readily available. The dataset presented in this synthesis has been in development since the late 1990's, is an integral part of the Coastal & Oceanic Plankton Ecology, Production, & Observation Database (COPEPOD), and is now also part of a wider community effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. A total of 153 163 biomass values were collected, from a variety of sources, for mesozooplankton. Of those 2% were originally recorded as dry mass, 26% as wet mass, 5% as settled volume, and 68% as displacement volume. Using a variety of non-linear biomass conversions from the literature, the data have been converted from their original units to carbon biomass. Depth-integrated values were then used to calculate mesozooplankton global biomass. Global mesozooplankton biomass, to a depth of 200 m, had a mean of 5.9 μg C l-1, median of 2.7 μg C l-1 and a standard deviation of 10.6 μg C l-1. The global annual average estimate of mesozooplankton, based on the median value, was 0.19 Pg C. Biomass was highest in the Northern Hemisphere, but the general trend shows a slight decrease from polar oceans to temperate regions with values increasing again in the tropics. Gridded dataset

  6. An ensemble of eddy-permitting global ocean reanalyses from the MyOcean project

    NASA Astrophysics Data System (ADS)

    Masina, Simona; Storto, Andrea; Ferry, Nicolas; Valdivieso, Maria; Haines, Keith; Balmaseda, Magdalena; Zuo, Hao; Drevillon, Marie; Parent, Laurent

    2015-07-01

    A set of four eddy-permitting global ocean reanalyses produced in the framework of the MyOcean project have been compared over the altimetry period 1993-2011. The main differences among the reanalyses used here come from the data assimilation scheme implemented to control the ocean state by inserting reprocessed observations of sea surface temperature (SST), in situ temperature and salinity profiles, sea level anomaly and sea-ice concentration. A first objective of this work includes assessing the interannual variability and trends for a series of parameters, usually considered in the community as essential ocean variables: SST, sea surface salinity, temperature and salinity averaged over meaningful layers of the water column, sea level, transports across pre-defined sections, and sea ice parameters. The eddy-permitting nature of the global reanalyses allows also to estimate eddy kinetic energy. The results show that in general there is a good consistency between the different reanalyses. An intercomparison against experiments without data assimilation was done during the MyOcean project and we conclude that data assimilation is crucial for correctly simulating some quantities such as regional trends of sea level as well as the eddy kinetic energy. A second objective is to show that the ensemble mean of reanalyses can be evaluated as one single system regarding its reliability in reproducing the climate signals, where both variability and uncertainties are assessed through the ensemble spread and signal-to-noise ratio. The main advantage of having access to several reanalyses differing in the way data assimilation is performed is that it becomes possible to assess part of the total uncertainty. Given the fact that we use very similar ocean models and atmospheric forcing, we can conclude that the spread of the ensemble of reanalyses is mainly representative of our ability to gauge uncertainty in the assimilation methods. This uncertainty changes a lot from one ocean

  7. The timescales of global surface-ocean connectivity.

    PubMed

    Jönsson, Bror F; Watson, James R

    2016-01-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches--each randomly located anywhere in the surface ocean--is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change--increasing temperatures, ocean acidification and changes in stratification over decadal timescales--through the advection of resilient types. PMID:27093522

  8. Intercomparison of Latent Heat Fluxes Over Global Oceans

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Chou, Ming-Dah

    2003-01-01

    Turbulent fluxes of momentum, moisture, and heat at the air-sea interface are essential for climate studies. Version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2) has been derived from the Special Sensor Microwave/Imager (SSM/I) radiance measurements. This dataset, covering the period July 1987-December 2000 over global oceans, has a spatial resolution of 1 deg x 1 deg lat-long and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory. The GSSTF2 bulk flux model, and retrieved daily wind stress, latent heat flux, wind speed, and surface air humidity validate well with ship observations of ten field experiments over the tropical and midlatitude oceans during 1991-99. The global distributions of 1988-2000 annual- and seasonal-mean turbulent fluxes show reasonable patterns related to the atmospheric general circulation and seasonal variations. Latent heat fluxes and related input parameters over global oceans during 1992-93 have been compared among GSSTF1 (version 1), GSSTF2, HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP/NCAR reanalysis, and one based on COADS (Comprehensive Ocean-Atmosphere Data Set). Our analyses suggest that the GSSTF2 latent heat flux, surface air humidity, surface wind, and SST are quite realistic compared to the other four flux datasets examined. However, significant differences are found among these five flux datasets. The GSSTF2, available at http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/hydrology/hd_gsstf2.O.html, is useful for climate studies.

  9. Climatological distribution of aragonite saturation state in the global oceans

    NASA Astrophysics Data System (ADS)

    Jiang, Li-Qing; Feely, Richard A.; Carter, Brendan R.; Greeley, Dana J.; Gledhill, Dwight K.; Arzayus, Krisa M.

    2015-10-01

    Aragonite saturation state (Ωarag) in surface and subsurface waters of the global oceans was calculated from up-to-date (through the year of 2012) ocean station dissolved inorganic carbon (DIC) and total alkalinity (TA) data. Surface Ωarag in the open ocean was always supersaturated (Ω > 1), ranging between 1.1 and 4.2. It was above 2.0 (2.0-4.2) between 40°N and 40°S but decreased toward higher latitude to below 1.5 in polar areas. The influences of water temperature on the TA/DIC ratio, combined with the temperature effects on inorganic carbon equilibrium and apparent solubility product (K'sp), explain the latitudinal differences in surface Ωarag. Vertically, Ωarag was highest in the surface mixed layer. Higher hydrostatic pressure, lower water temperature, and more CO2 buildup from biological activity in the absence of air-sea gas exchange helped maintain lower Ωarag in the deep ocean. Below the thermocline, aerobic decomposition of organic matter along the pathway of global thermohaline circulation played an important role in controlling Ωarag distributions. Seasonally, surface Ωarag above 30° latitudes was about 0.06 to 0.55 higher during warmer months than during colder months in the open-ocean waters of both hemispheres. Decadal changes of Ωarag in the Atlantic and Pacific Oceans showed that Ωarag in waters shallower than 100 m depth decreased by 0.10 ± 0.09 (-0.40 ± 0.37% yr-1) on average from the decade spanning 1989-1998 to the decade spanning 1998-2010.

  10. The new automatic precipitation phase distinction algorithm for OceanRAIN data over the global ocean

    NASA Astrophysics Data System (ADS)

    Burdanowitz, Jörg; Klepp, Christian; Bakan, Stephan

    2015-04-01

    The hitherto lack of surface precipitation data over the global ocean limits the capabilities to validate recent and future precipitation satellite retrievals. The first systematic ship-based surface precipitation data set OceanRAIN (Ocean Rain And Ice-phase precipitation measurement Network) aims at providing in-situ precipitation data through particle size distributions (PSDs) from optical disdrometers deployed on research vessels (RVs). From the RV Polarstern, OceanRAIN currently contains more than four years of 1-minute resolution precipitation data, which corresponds to more than 200,000 minutes of precipitation. The calculation of the precipitation rate requires to know the precipitation phase (PP) of the falling particles. We develop a novel algorithm to automatically retrieve the PP using OceanRAIN data and ancillary meteorological measurements from RVs. The main objective is to improve accuracy and efficiency of the current time-consuming manual method of discriminating liquid and solid precipitation particles. The new PP distinction algorithm is based on the relation of air temperature and relative humidity (T-rH) with respect to PP. For first-time usage over oceanic areas, the land-retrieved coefficients of this empirical relationship are adjusted to OceanRAIN data. The measured PSD supports determining the PP in certain cases where large snow aggregates exist at distinctly positive air temperatures. The classification, based on T-rH and PSD, is statistically exploited and weighed with respect to the current weather conditions to obtain an overall PP probability at 1-minute resolution. The new PP distinction algorithm agrees in more than 92% (94% excl. mixed-phase) of precipitating cases with the manually-determined PP in the RV Polarstern data. The PP distinction algorithm complements the valuable information of OceanRAIN surface precipitation over the ocean.

  11. Enceladus's measured physical libration requires a global subsurface ocean

    NASA Astrophysics Data System (ADS)

    Thomas, P. C.; Tajeddine, R.; Tiscareno, M. S.; Burns, J. A.; Joseph, J.; Loredo, T. J.; Helfenstein, P.; Porco, C.

    2016-01-01

    Several planetary satellites apparently have subsurface seas that are of great interest for, among other reasons, their possible habitability. The geologically diverse saturnian satellite Enceladus vigorously vents liquid water and vapor from fractures within a south polar depression and thus must have a liquid reservoir or active melting. However, the extent and location of any subsurface liquid region is not directly observable. We use measurements of control points across the surface of Enceladus accumulated over seven years of spacecraft observations to determine the satellite's precise rotation state, finding a forced physical libration of 0.120 ± 0.014° (2σ). This value is too large to be consistent with Enceladus's core being rigidly connected to its surface, and thus implies the presence of a global ocean rather than a localized polar sea. The maintenance of a global ocean within Enceladus is problematic according to many thermal models and so may constrain satellite properties or require a surprisingly dissipative Saturn.

  12. A daily global mesoscale ocean eddy dataset from satellite altimetry.

    PubMed

    Faghmous, James H; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin

    2015-01-01

    Mesoscale ocean eddies are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. Eddies play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean eddy dataset that contains ~45 million mesoscale features and 3.3 million eddy trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993-2014. This dataset, along with the open-source eddy identification software, extract eddies with any parameters (minimum size, lifetime, etc.), to study global eddy properties and dynamics, and to empirically estimate the impact eddies have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean eddies and other components of the Earth System. PMID:26097744

  13. A daily global mesoscale ocean eddy dataset from satellite altimetry

    PubMed Central

    Faghmous, James H.; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin

    2015-01-01

    Mesoscale ocean eddies are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. Eddies play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean eddy dataset that contains ~45 million mesoscale features and 3.3 million eddy trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993–2014. This dataset, along with the open-source eddy identification software, extract eddies with any parameters (minimum size, lifetime, etc.), to study global eddy properties and dynamics, and to empirically estimate the impact eddies have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean eddies and other components of the Earth System. PMID:26097744

  14. Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

    NASA Technical Reports Server (NTRS)

    Fu, L. -L.

    1993-01-01

    The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 43 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements...

  15. Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

    NASA Technical Reports Server (NTRS)

    Fu, L. -L.

    1993-01-01

    The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 42 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements. The verification results indicate that all the measurement objectives have been met...

  16. Eddy Permitting Simulations of Biogeochemical Cycles in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Sumata, H.; Hashioka, T.; Suzuki, T.; Yamanaka, Y.

    2008-12-01

    A 3D ecosystem-biogeochemical model simulation for the global domain is performed in order to investigate variability of oceanic ecosystem on time scales of years to decades. The model has a horizontal resolution of 1/4 times 1/6 degrees and 51 vertical levels, covering the entire domain of the world ocean. The ecosystem- biogeochemical part of the model is based on NEMURO (North Pacific Ecosystem Model Used for Regional Oceanography), and is coupled with CCSR Ocean Component Model (COCO) version 4.3 by an offline technique. The physical part of the model is driven by the inter-annual forcing by common ocean-ice reference experiments (CORE) data from 1958 to 2004, and reasonably simulates inter-annual to decadal variabilities of ocean conditions related to biogeochemical cycles. These properties of the physical model with its eddying filed enable us to reproduce the realistic distributions of nutrients and plankton productions. Comparisons with historical station data show that the model also reasonably simulates the observed variabilities of ecosystem on time scales of years to decades. In particular, the model captures the transitions of biogeochemical cycles associated with regime shifts.

  17. Global biogeography of Prochlorococcus genome diversity in the surface ocean.

    PubMed

    Kent, Alyssa G; Dupont, Chris L; Yooseph, Shibu; Martiny, Adam C

    2016-08-01

    Prochlorococcus, the smallest known photosynthetic bacterium, is abundant in the ocean's surface layer despite large variation in environmental conditions. There are several genetically divergent lineages within Prochlorococcus and superimposed on this phylogenetic diversity is extensive gene gain and loss. The environmental role in shaping the global ocean distribution of genome diversity in Prochlorococcus is largely unknown, particularly in a framework that considers the vertical and lateral mechanisms of evolution. Here we show that Prochlorococcus field populations from a global circumnavigation harbor extensive genome diversity across the surface ocean, but this diversity is not randomly distributed. We observed a significant correspondence between phylogenetic and gene content diversity, including regional differences in both phylogenetic composition and gene content that were related to environmental factors. Several gene families were strongly associated with specific regions and environmental factors, including the identification of a set of genes related to lower nutrient and temperature regions. Metagenomic assemblies of natural Prochlorococcus genomes reinforced this association by providing linkage of genes across genomic backbones. Overall, our results show that the phylogeography in Prochlorococcus taxonomy is echoed in its genome content. Thus environmental variation shapes the functional capabilities and associated ecosystem role of the globally abundant Prochlorococcus. PMID:26836261

  18. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2015-07-01

    The natural abundance of 14C in total CO2 dissolved in seawater (DIC) is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, which is the time elapsed since a body of water has been in contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with ageing, i.e. the time component of circulation, and one associated with a "preformed 14C-age". The latter quantity exists because of the slow and incomplete atmosphere-ocean equilibration of 14C particularly in high latitudes where many water masses form. In the ocean's interior, preformed 14C-age behaves like a passive tracer. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. Here, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age. Between models, the variability of preformed 14C-age can also be considerable (factor of 2), related to the combination of physical model parameters, which influence circulation dynamics or gas exchange. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation, the choice of the gas-exchange constant from within the currently accepted range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age, it could easily impair the evaluation and tuning of a model's circulation on global and regional

  19. El Nino and the Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Halpern, David

    1999-01-01

    Until a decade ago, an often-quoted expression in oceanography is that very few observations are recorded throughout the ocean. Now, the sentiment is no longer valid in the uppermost 10% of the tropical Pacific Ocean nor at the surface of the global ocean. One of the remarkable legacies of the 1985-1994 Tropical Oceans Global Atmosphere (TOGA) Program is an in situ marine meteorological and upper oceanographic measurement array throughout the equatorial Pacific to monitor the development and maintenance of El Nino episodes. The TOGA Observing System, which initially consisted of moored- and drifting-buoy arrays, a network of commercial ships, and coastal and island stations, now includes a constellation of satellites and data-assimilating models to simulate subsurface oceanographic conditions. The El Nino and La Nina tropical Pacific Ocean observing system represents the initial phase of an integrated global ocean observing system. Remarkable improvements have been made in ocean model simulation of subsurface currents, but some problems persist. For example, the simulation of the South Equatorial Current (SEC) remains an important challenge in the 2S-2N Pacific equatorial wave guide. During El Nino the SEC at the equator is reduced and sometimes the direction is reversed, becoming eastward. Both conditions allow warm water stored in the western Pacific to invade the eastern region, creating an El Nino episode. Assimilation of data is a tenet of faith to correct simulation errors caused by deficiencies in surface fluxes (especially wind stress) and parameterizations of subgrid-scale physical processes. In the first of two numerical experiments, the Pacific SEC was simulated with and without assimilation of subsurface temperature data. Along the equator, a very weak SEC occurred throughout the eastern Pacific, independent of assimilation of data. However, as displayed in the diagram, in the western Pacific there was no satisfactory agreement between the two

  20. The global Mercator Ocean analysis and forecasting high resolution system and its main future updates

    NASA Astrophysics Data System (ADS)

    Lellouche, Jean-Michel; Legalloudec, Olivier; Bourdallé-Badie, Romain; Garric, Gilles; Greiner, Eric; Drévillon, Marie; Regnier, Charly; Testut, Charles-Emmanuel; Benkiran, Mounir; Drillet, Yann

    2015-04-01

    In April 2013, Mercator Ocean has performed a major upgrade of the global 1/12° high resolution system. This system currently delivers daily services, and includes numerous improvements related to the ocean/sea-ice model and the assimilation scheme. Observations are assimilated by means of a reduced-order Kalman filter with a 3D multivariate modal decomposition of the forecast error. It includes an adaptive-error estimate and a localization algorithm. Altimeter data, satellite Sea Surface Temperature and in situ temperature and salinity vertical profiles are jointly assimilated to estimate the initial conditions for numerical ocean forecasting. A 3D-Var scheme provides a correction for the slowly-evolving large-scale biases in temperature and salinity. In April 2015, Mercator Ocean will open the Copernicus Marine Environment Monitoring Service and will be in charge of the global ocean at eddy resolving resolution. In this context, R&D activities conducted during the end of the MyOcean2 and MyOcean follow-on projects to deliver an improved version of the global system will continue throughout 2015. The main new updates we plan to integrate in the next version of the global system concern: 1) A new vertical mixing scheme k-epsilon: vertical physics has been explored with a special focus on the turbulent closure problem to improve the representation of temperature and salinity in the Mixed Layer Depth. 2) An adaptive tuning of observations errors: as the prescription of observation errors in the assimilation systems is often too approximate, some diagnostics have been developed. These diagnostics consist in the computation of the Desroziers ratio which is a function of observation errors, innovations and residuals. It helps to identify inconsistency on the specified observation errors and to tune an adaptive weight coefficient acting on the error of each assimilated observation. 3) The assimilation of sea-ice concentration observations: it is introduced in the

  1. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2014-10-01

    The natural abundance of 14C in total CO2 dissolved in seawater is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, the time elapsed since a body of water had contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with aging, i.e. the time component of circulation and one associated with a "preformed 14C-age". This latter quantity exists because of the slow and incomplete atmosphere/ocean equilibration of 14C in particular in high latitudes where many water masses form. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability, e.g. in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. In the Atlantic, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age alone. Between models the variability of age can also be considerable (factor of 2), related to the combinations of physical model parameters, which influence circulation dynamics, and gas exchange in the models. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation exercise, the choice of the gas exchange constant from within the current range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age it could easily impair the evaluation and tuning of a models circulation on global and regional scales. Based on the results of this study, we propose that considering

  2. Global Ocean Integrals and Means, with Trend Implications.

    PubMed

    Wunsch, Carl

    2016-01-01

    Understanding the ocean requires determining and explaining global integrals and equivalent average values of temperature (heat), salinity (freshwater and salt content), sea level, energy, and other properties. Attempts to determine means, integrals, and climatologies have been hindered by thinly and poorly distributed historical observations in a system in which both signals and background noise are spatially very inhomogeneous, leading to potentially large temporal bias errors that must be corrected at the 1% level or better. With the exception of the upper ocean in the current altimetric-Argo era, no clear documentation exists on the best methods for estimating means and their changes for quantities such as heat and freshwater at the levels required for anthropogenic signals. Underestimates of trends are as likely as overestimates; for example, recent inferences that multidecadal oceanic heat uptake has been greatly underestimated are plausible. For new or augmented observing systems, calculating the accuracies and precisions of global, multidecadal sampling densities for the full water column is necessary to avoid the irrecoverable loss of scientifically essential information. PMID:26331897

  3. A Web-Based Climatology of Global Ocean Winds

    NASA Astrophysics Data System (ADS)

    Risien, C. M.; Chelton, D. B.; Hodges, M. K.

    2004-12-01

    A climatology of winds over the global ocean on a 0.5° x 0.5° grid is under development based on five-years of measurements from the SeaWinds scatterometer. The SeaWinds instrument was launched on 19 June 1999 onboard the QuikSCAT satellite. SeaWinds is an active microwave radar that, using electromagnetic backscatter from the wind roughened ocean surface, measures vector winds with an accuracy equivalent to well-calibrated buoy observations. This five-year climatology is a web-based interactive atlas from which users can retrieve wind statistics, both in tabular and graphic form, for any particular region of interest. The global coverage of the scatterometer data provides valuable information about the wind statistics in the many regions of the world ocean that are sparsely sampled by ships and buoys. One of the anticipated uses of this climatology will be presented via a case study of the NOAA/HAZMAT response to a 2001 oil spill that resulted from the grounding of the tanker "Jessica" at the entrance to Puerto Baquerizo Moreno, in Wreck Bay, on San Cristóbal island, Galápagos.

  4. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    USGS Publications Warehouse

    McKay, Robert; Naish, Tim; Carter, Lionel; Riesselman, Christina; Dunbar, Robert; Sjunneskog, Charlotte; Winter, Diane; Sangiorgi, Francesca; Warren, Courtney; Pagani, Mark; Schouten, Stefan; Willmott, Veronica; Levy, Richard; DeConto, Robert; Powell, Ross D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ~3.3 Ma, followed by a coastal sea surface temperature cooling of ~2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world.

  5. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    PubMed Central

    McKay, Robert; Naish, Tim; Carter, Lionel; Riesselman, Christina; Dunbar, Robert; Sjunneskog, Charlotte; Winter, Diane; Sangiorgi, Francesca; Warren, Courtney; Pagani, Mark; Schouten, Stefan; Willmott, Veronica; Levy, Richard; DeConto, Robert; Powell, Ross D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ∼3.3 Ma, followed by a coastal sea surface temperature cooling of ∼2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world. PMID:22496594

  6. Antarctic and Southern Ocean influences on Late Pliocene global cooling.

    PubMed

    McKay, Robert; Naish, Tim; Carter, Lionel; Riesselman, Christina; Dunbar, Robert; Sjunneskog, Charlotte; Winter, Diane; Sangiorgi, Francesca; Warren, Courtney; Pagani, Mark; Schouten, Stefan; Willmott, Veronica; Levy, Richard; DeConto, Robert; Powell, Ross D

    2012-04-24

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ∼3.3 Ma, followed by a coastal sea surface temperature cooling of ∼2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world. PMID:22496594

  7. Attenuation coefficient of usable solar radiation of the global oceans

    NASA Astrophysics Data System (ADS)

    Lin, Junfang; Lee, Zhongping; Ondrusek, Michael; Kahru, Mati

    2016-05-01

    Usable solar radiation (USR) represents spectrally integrated solar energy in the spectral range of 400-560 nm, a domain where photons penetrate the most in oceanic waters and thus contribute to photosynthesis and heating at deeper depths. Through purely numerical simulations, it was found that the diffuse attenuation coefficient of downwelling USR (Kd(USR), m-1) is nearly a constant vertically in the upper water column for clear waters and most turbid waters. Subsequently an empirical model was developed to estimate Kd(USR) based on the diffuse attenuation coefficient at 490 nm (Kd(490), m-1). We here evaluate this relationship using data collected from a wide range of oceanic and coastal environments and found that the relationship between Kd(490) and Kd(USR) developed via the numerical simulation is quite robust. We further refined this relationship to extend the applicability to "clearest" natural waters. This refined relationship was then used to produce sample distribution of Kd(USR) of global oceans. As expected, extremely low Kd(USR) (˜0.02 m-1) was observed in ocean gyres, while significantly higher Kd(USR) (˜5.2 m-1) was found in very turbid coastal regions. A useful application of Kd(USR) is to easily and accurately propagate surface USR to deeper depths, potentially to significantly improve the estimation of basin scale primary production and heat fluxes in the upper water column.

  8. Subsurface Ocean Climate Data Records: Global Ocean Heat and Freshwater Content

    NASA Astrophysics Data System (ADS)

    Boyer, T.; Locarnini, R. A.; Mishonov, A. V.; Reagan, J. R.

    2015-12-01

    The ocean is the main sink of excess heat in the Earth's climate system. It absorbs more than 90% of the Top of the Atmosphere imbalance between incoming solar radiation and outgoing long-wave radiation. The ocean, covering more than 70% of the Earth's surface, is also the major component of the planet's freshwater cycle. More than 60 years of in situ subsurface temperature and salinity data have been compiled and quality controlled in World Ocean Database of the National Centers for Environmental Information. These data have been used to calculate time series of global heat and salt changes in the ocean. Salt changes can be used to calculate freshwater changes, including from melting continental glaciers. Both time series provide a measure of the changes in the Earth's climate system: from heat sequestered in the ocean, to the rise of sea level due to thermosteric and halosteric components. The time series are updated every three months and are widely used in climate related studies. Method of quality control of the data, calculation of the time series, and dissemination and use of the time series are discussed.

  9. Assimilation of GRACE-derived oceanic mass distributions with a global ocean circulation model

    NASA Astrophysics Data System (ADS)

    Saynisch, J.; Bergmann-Wolf, I.; Thomas, M.

    2015-02-01

    To study the sub-seasonal distribution and generation of ocean mass anomalies, Gravity Recovery and Climate Experiment (GRACE) observations of daily and monthly resolution are assimilated into a global ocean circulation model with an ensemble-based Kalman-Filter technique. The satellite gravimetry observations are processed to become time-variable fields of ocean mass distribution. Error budgets for the observations and the ocean model's initial state are estimated which contain the full covariance information. The consistency of the presented approach is demonstrated by increased agreement between GRACE observations and the ocean model. Furthermore, the simulations are compared with independent observations from 54 bottom pressure recorders. The assimilation improves the agreement to high-latitude recorders by up to 2 hPa. The improvements are caused by assimilation-induced changes in the atmospheric wind forcing, i.e., quantities not directly observed by GRACE. Finally, the use of the developed Kalman-Filter approach as a destriping filter to remove artificial noise contaminating the GRACE observations is presented.

  10. A Parallel Ocean Model With Adaptive Mesh Refinement Capability For Global Ocean Prediction

    SciTech Connect

    Herrnstein, A

    2005-09-08

    An ocean model with adaptive mesh refinement (AMR) capability is presented for simulating ocean circulation on decade time scales. The model closely resembles the LLNL ocean general circulation model with some components incorporated from other well known ocean models when appropriate. Spatial components are discretized using finite differences on a staggered grid where tracer and pressure variables are defined at cell centers and velocities at cell vertices (B-grid). Horizontal motion is modeled explicitly with leapfrog and Euler forward-backward time integration, and vertical motion is modeled semi-implicitly. New AMR strategies are presented for horizontal refinement on a B-grid, leapfrog time integration, and time integration of coupled systems with unequal time steps. These AMR capabilities are added to the LLNL software package SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) and validated with standard benchmark tests. The ocean model is built on top of the amended SAMRAI library. The resulting model has the capability to dynamically increase resolution in localized areas of the domain. Limited basin tests are conducted using various refinement criteria and produce convergence trends in the model solution as refinement is increased. Carbon sequestration simulations are performed on decade time scales in domains the size of the North Atlantic and the global ocean. A suggestion is given for refinement criteria in such simulations. AMR predicts maximum pH changes and increases in CO{sub 2} concentration near the injection sites that are virtually unattainable with a uniform high resolution due to extremely long run times. Fine scale details near the injection sites are achieved by AMR with shorter run times than the finest uniform resolution tested despite the need for enhanced parallel performance. The North Atlantic simulations show a reduction in passive tracer errors when AMR is applied instead of a uniform coarse resolution. No

  11. Joint IAMAS/IAHS symposium J1 on global monitoring and advanced observing techniques in the atmosphere and hydrosphere

    SciTech Connect

    Ohring, G. ); Aoki, T. ); Halpern, D. ); Henderson-Sellers, A. ); Charlock, T. ); Joseph, J. ); Labitzke, K. ); Raschke, E. ); Smith, W. )

    1994-04-01

    Seventy papers were presented at the two-and-a-half-day Symposium on Global Monitoring and Advanced Observing Techniques in the Atmosphere and Hydrosphere. The symposium was jointly organized by the International Association of Meteorology and Atmospheric Sciences (IAMAS) and the International Association of Hydrological Sciences (IAHS) and took place in Yokohama, Japan, 13-15 July 1993, as part of the IAMAS/IAHS Join Assembly. Global observing systems are receiving increased attention in connection with such problems as monitoring global climate change. The symposium included papers on observational requirements; measurement methodologies; descriptions of available datasets; results of analysis of observational data; plans for future observing systems, including the Global Climate Observing System (GCOS) and the Global Ocean Observing System (GOOS); and the programs and plans of the space agencies.

  12. A preliminary global oceanic cloud climatology from satellite albedo observations

    NASA Technical Reports Server (NTRS)

    Hughes, N. A.; Henderson-Sellers, A.

    1983-01-01

    A predictive relationship is developed between over-ocean cloud system albedo and the cloud amount present, using as a data base ERB satellite microwave readings at 0.5-0.7 micron and the USAF three-dimensional nephanalysis archive. The ERB data provided global coverage at a resolution of 2.5 x 2.5 deg during the 1974-78 period. Regression analyses were performed on the amounts and albedos for several years of data for one month in order to detect seasonal variations. A logarithmic relationship was found between the cloud system albedo and cloud amount over the oceans, with negligible seasonal variance. The analysis is noted to apply only where low surface albedos are encountered, and further work to extend the study to continental vegetated areas is indicated.

  13. The timescales of global surface-ocean connectivity

    PubMed Central

    Jönsson, Bror F.; Watson, James R.

    2016-01-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches—each randomly located anywhere in the surface ocean—is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change—increasing temperatures, ocean acidification and changes in stratification over decadal timescales—through the advection of resilient types. PMID:27093522

  14. General Bathymetric Chart of the Oceans (GEBCO) - Mapping the Global Seafloor

    NASA Astrophysics Data System (ADS)

    Weatherall, P.; Jakobsson, M.; Marks, K. M.

    2014-12-01

    For over one hundred years GEBCO (www.gebco.net) has been at the forefront of producing maps and digital data sets showing the shape of the global seafloor in the deep oceans with the first GEBCO chart series initiated in 1903 by Prince Albert I of Monaco. Today the GEBCO community consists of an international group of experts in seafloor mapping who develop a range of data sets and data products with the aim of providing the most authoritative publicly-available bathymetric data sets for the world's oceans. We are also training a new generation of seafloor mappers through the Nippon Foundation/GEBCO Training Programme. GEBCO operates under the joint auspices of the Intergovernmental Oceanographic Commission (IOC) of UNESCO and the International Hydrographic Organization (IHO). Our range of products includes: A global Digital Terrain Model (DTM) - modelling the shape of the seafloor in the form of a periodically-updated 30 arc-second interval grid A gazetteer of undersea feature names GEBCO Cook Book - information on topics related to building bathymetric grids Web services GEBCO world map GEBCO Digital Atlas - a collection of GEBCO's data sets and viewing software Recognising the importance of local expertise when building a bathymetric grid, GEBCO's latest 30 arc-second interval DTM, GEBCO_2014, (due for release in Fall 2014) has benefited from contributions from many regional mapping projects such as the International Bathymetric Charts of the Arctic Ocean (IBCAO) and Southern Ocean (IBCSO); the Baltic Sea Bathymetry Database and EMODnet for European waters. Through the Sub-Committee on Regional Undersea Mapping, GEBCO is aiming to build on and extend its collaboration with regional mapping groups to continually improve its global bathymetric model.

  15. Joint modeling of lithosphere and mantle dynamics: Evaluation of constraints from global tomography models

    NASA Astrophysics Data System (ADS)

    Wang, Xinguo; Holt, William E.; Ghosh, Attreyee

    2015-12-01

    With the advances in technology, seismological theory, and data acquisition, a number of high-resolution seismic tomography models have been published. However, discrepancies between tomography models often arise from different theoretical treatments of seismic wave propagation, different inversion strategies, and different data sets. Using a fixed velocity-to-density scaling and a fixed radial viscosity profile, we compute global mantle flow models associated with the different tomography models and test the impact of these for explaining surface geophysical observations (geoid, dynamic topography, stress, and strain rates). We use the joint modeling of lithosphere and mantle dynamics approach of Ghosh and Holt (2012) to compute the full lithosphere stresses, except that we use HC for the mantle circulation model, which accounts for the primary flow-coupling features associated with density-driven mantle flow. Our results show that the seismic tomography models of S40RTS and SAW642AN provide a better match with surface observables on a global scale than other models tested. Both of these tomography models have important similarities, including upwellings located in Pacific, Eastern Africa, Iceland, and mid-ocean ridges in the Atlantic and Indian Ocean and downwelling flows mainly located beneath the Andes, the Middle East, and central and Southeast Asia.

  16. Sea level ECV quality assessment via global ocean model assimilation

    NASA Astrophysics Data System (ADS)

    Scharffenberg, Martin; Köhl, Armin; Stammer, Detlef

    2015-04-01

    In the ocean modeling community satellite data, especially SSH fields, are assimilated on a regular basis. SSH fields are very important in this context because of their dynamical relevance for constraining the ocean's flow field. However, assimilating SSH data into an ocean model does not only improve the quality of model but in addition, can also help testing the quality and the consistency of the input data as well. In our work we aim to quantify improvements in Sea Level (SL) data through the ESA - Climate Change Initiative (cci) effort and we aim to test the consistency of the Essential Climate Variable (ECV) of Sea Level (SL_ECV) with other ECVs through the assimilation process and to investigate where remaining inconsistencies exist and why. For this purpose the GECCO2 assimilation approach assimilates SSH jointly with in situ data over the ocean. The dynamically consistent ocean state estimation adjusts only uncertain model parameters to bring the model into consistency with ocean observations. Improvements in data products can be investigated by studying the residuals between the different data products and the constrained model. PHASE 1: With this approach we could demonstrate, that in many regions the SL_ECV has been improved from version V0 (AVISO product) to version V1 (SL_cci product). However, there are regions where SL_ECV_V1 is further away from the model "truth". In that sense it is important to understand that the model assimilated SL_ECV_V0 (origianl AVISO product) and therefore has tried to adapt to the SL_ECV_V0. Therefore, inconsistencies existed when comparing the synthesis results to the updated version SL_ECV_V1! These deviations between the model "truth" and the improved data product (SL_ECV_V1) increased mostly in low energetic areas. PHASE 2: Two GECCO2-assimilation-runs (5 additional iterations) have been performed to date: 1) assimilating the original AVISO SL-product (V0) and 2) assimilating the updated-improved sea level estimate

  17. Signature of ocean warming in global fisheries catch.

    PubMed

    Cheung, William W L; Watson, Reg; Pauly, Daniel

    2013-05-16

    Marine fishes and invertebrates respond to ocean warming through distribution shifts, generally to higher latitudes and deeper waters. Consequently, fisheries should be affected by 'tropicalization' of catch (increasing dominance of warm-water species). However, a signature of such climate-change effects on global fisheries catch has so far not been detected. Here we report such an index, the mean temperature of the catch (MTC), that is calculated from the average inferred temperature preference of exploited species weighted by their annual catch. Our results show that, after accounting for the effects of fishing and large-scale oceanographic variability, global MTC increased at a rate of 0.19 degrees Celsius per decade between 1970 and 2006, and non-tropical MTC increased at a rate of 0.23 degrees Celsius per decade. In tropical areas, MTC increased initially because of the reduction in the proportion of subtropical species catches, but subsequently stabilized as scope for further tropicalization of communities became limited. Changes in MTC in 52 large marine ecosystems, covering the majority of the world's coastal and shelf areas, are significantly and positively related to regional changes in sea surface temperature. This study shows that ocean warming has already affected global fisheries in the past four decades, highlighting the immediate need to develop adaptation plans to minimize the effect of such warming on the economy and food security of coastal communities, particularly in tropical regions. PMID:23676754

  18. Effects of Drake Passage on a strongly eddying global ocean

    NASA Astrophysics Data System (ADS)

    Viebahn, Jan; von der Heydt, Anna S.; Dijkstra, Henk A.

    2015-04-01

    During the past 65 Million (Ma) years, Earth's climate has undergone a major change from warm 'greenhouse' to colder 'icehouse' conditions with extensive ice sheets in the polar regions of both hemispheres. The Eocene-Oligocene (~34 Ma) and Oligocene-Miocene (~23 Ma) boundaries reflect major transitions in Cenozoic global climate change. Proposed mechanisms of these transitions include reorganization of ocean circulation due to critical gateway opening/deepening, changes in atmospheric CO2-concentration, and feedback mechanisms related to land-ice formation. Drake Passage (DP) is an intensively studied gateway because it plays a central role in closing the transport pathways of heat and chemicals in the ocean. The climate response to a closed DP has been explored with a variety of general circulation models, however, all of these models employ low model-grid resolutions such that the effects of subgrid-scale fluctuations ('eddies') are parameterized. We present results of the first high-resolution (0.1° horizontally) realistic global ocean model simulation with a closed DP in which the eddy field is largely resolved. The simulation extends over more than 200 years such that the strong transient adjustment process is passed and a near-equilibrium ocean state is reached. The effects of DP are diagnosed by comparing with both an open DP high-resolution control simulation (of same length) and corresponding low-resolution simulations. By focussing on the heat/tracer transports we demonstrate that the results are twofold: Considering spatially integrated transports the overall response to a closed DP is well captured by low-resolution simulations. However, looking at the actual spatial distributions drastic differences appear between far-scattered high-resolution and laminar-uniform low-resolution fields. We conclude that sparse and highly localized tracer proxy observations have to be interpreted carefully with the help of high-resolution model simulations.

  19. Global contamination by persistent organochlorines in the ocean

    SciTech Connect

    Iwata, H.; Tanabe, S.; Tatsukawa, R.

    1995-12-31

    Global pollution by persistent organochlorines (POCs) such as polychlorinated biphenyls (PCBs) and DDTs has become a matter of great concern in the public with an increase of recent scientific knowledge. Nevertheless, a world-wide survey has not been systematically carried out, which makes it difficult to clarify the dynamics and fate of POCs on a global scale. In this presentation, an attempt to monitor POCs in the world oceans will be introduced and the geographical distribution, composition, and temporal trend of POCs will be discussed on the basis of recent researches. This discussion led by the ocean surveys can be summarized as follows -- POCs not only DDTs but also PCBs, chlordane compounds and hexachlorocyclohexanes (HCHs) usage tended to shift or expand from the mid- to low-latitude areas during the last decades, the compounds released in the tropics were more efficiently dispersed rather than those in colder regions and then latitudinally redistributed, perhaps depending on their physico-chemical properties and climatic parameters. For example, it was found that HCHs transported through the atmosphere were prominently accumulated in higher latitude ocean, while DDTs are likely less-volatile and readily removed from the atmosphere even in the lower latitudes with high temperature. Furthermore, POCs in the sediment collected from the cold seas suggested that the aerial inputs into the seas were still continuing significantly, and the accumulation rates of OCs into sediments were smaller than the atmospheric inputs, indicating that the residues in water bodies were unlikely to decrease rapidly in near future. Although these schematic features have been conceptually presented from the field surveys, studies regarding the factors controlling POCs dynamics, the quantitative estimates to understand the fate, and the short-/longterm fluctuations particularly in open oceans are not adequate or still lacking.

  20. The global land and ocean mean energy balance

    NASA Astrophysics Data System (ADS)

    Wild, Martin; Folini, Doris

    2016-04-01

    land, and 16 and 100 Wm-2 over oceans, for sensible and latent heat fluxes, respectively. Estimated uncertainties are on the order of 10 and 5 Wm-2 for most surface and TOA fluxes, respectively. Combining these surface budgets with satellite-determined TOA budgets (CERES-EBAF) results in an atmospheric solar absorption of 77 and 82 Wm-2 and a net atmospheric thermal emission of -165 and -190 Wm-2 over land and oceans, respectively. We further revisit the global mean energy balance by combining the area weighed land and ocean mean budgets. This study is published in: Wild, M., Folini, D., Hakuba, M., Schär, C., Seneviratne, S.I., Kato, S., Rutan, D., Ammann, C., Wood, E.F., and König-Langlo, G., 2015: The energy balance over land and oceans: An assessment based on direct observations and CMIP5 climate models. Clim. Dyn., Dyn., 44, 3393-3429, doi: 10.1007/s00382-014-2430-z.

  1. Marine sources of bromoform in the global open ocean - global patterns and emissions

    NASA Astrophysics Data System (ADS)

    Stemmler, I.; Hense, I.; Quack, B.

    2014-11-01

    Bromoform (CHBr3) is one important precursor of atmospheric reactive bromine species that are involved in ozone depletion in the troposphere and stratosphere. In the open ocean bromoform production is linked to phytoplankton that contains the enzyme bromoperoxidase. Coastal sources of bromoform are higher than open ocean sources. However, open ocean emissions are important, because the transfer of tracers into higher altitude in the air, i.e. into the ozone layer, strongly depends on the location of emissions. For example, emissions in the tropics are more rapidly transported into the upper atmosphere than emissions from higher latitudes. Global spatio-temporal features of bromoform emissions are poorly constrained. Here, a global three-dimensional ocean biogeochemistry model (MPIOM-HAMOCC) is used to simulate bromoform cycling in the ocean and emissions into the atmosphere using recently published data of global atmospheric concentrations (Ziska et al., 2013) as upper boundary conditions. In general, simulated surface concentrations of CHBr3 match the observations well. Simulated global annual emissions based on monthly mean model output are lower than previous estimates, including the estimate by Ziska et al. (2013), because the gas-exchange reverses when less bromoform is produced in non-blooming seasons. This is the case for higher latitudes, i.e. the polar regions and northern North Atlantic. Further model experiments show that future model studies may need to distinguish different bromoform producing phytoplankton species and reveal that the transport of CHBr3 from the coast considerably alters open ocean bromoform concentrations, in particular in the northern sub-polar and polar regions.

  2. Marine sources of bromoform in the global open ocean - global patterns and emissions

    NASA Astrophysics Data System (ADS)

    Stemmler, I.; Hense, I.; Quack, B.

    2015-03-01

    Bromoform (CHBr3) is one important precursor of atmospheric reactive bromine species that are involved in ozone depletion in the troposphere and stratosphere. In the open ocean bromoform production is linked to phytoplankton that contains the enzyme bromoperoxidase. Coastal sources of bromoform are higher than open ocean sources. However, open ocean emissions are important because the transfer of tracers into higher altitude in the air, i.e. into the ozone layer, strongly depends on the location of emissions. For example, emissions in the tropics are more rapidly transported into the upper atmosphere than emissions from higher latitudes. Global spatio-temporal features of bromoform emissions are poorly constrained. Here, a global three-dimensional ocean biogeochemistry model (MPIOM-HAMOCC) is used to simulate bromoform cycling in the ocean and emissions into the atmosphere using recently published data of global atmospheric concentrations (Ziska et al., 2013) as upper boundary conditions. Our simulated surface concentrations of CHBr3 match the observations well. Simulated global annual emissions based on monthly mean model output are lower than previous estimates, including the estimate by Ziska et al. (2013), because the gas exchange reverses when less bromoform is produced in non-blooming seasons. This is the case for higher latitudes, i.e. the polar regions and northern North Atlantic. Further model experiments show that future model studies may need to distinguish different bromoform-producing phytoplankton species and reveal that the transport of CHBr3 from the coast considerably alters open ocean bromoform concentrations, in particular in the northern sub-polar and polar regions.

  3. Nonlinear Dependence of Global Warming Prediction on Ocean State

    NASA Astrophysics Data System (ADS)

    Liang, M.; Lin, L.; Tung, K. K.; Yung, Y. L.; Sun, S.

    2010-12-01

    Global temperature has increased by 0.8 C since the pre-industrial era, and is likely to increase further if greenhouse gas emission continues unchecked. Various mitigation efforts are being negotiated among nations to keep the increase under 2 C, beyond which the outcome is believed to be catastrophic. Such policy efforts are currently based on predictions by the state-of-the-art coupled atmosphere ocean models (AOGCM). Caution is advised for their use for the purpose of short-term (less than a century) climate prediction as the predicted warming and spatial patterns vary depending on the initial state of the ocean, even in an ensemble mean. The range of uncertainty in such predictions by Intergovernmental Panel on Climate Change (IPCC) models may be underreported when models were run with their oceans at various stages of adjustment with their atmospheres. By comparing a very long run (> 1000 years) of the coupled Goddard Institute for Space Studies (GISS) model with what was reported to IPCC Fourth Assessment Report (AR4), we show that the fully adjusted model transient climate sensitivity should be 30% higher for the same model, and the 2 C warming should occur sooner than previously predicted. Using model archives we further argue that this may be a common problem for the IPCC AR4 models, since few, if any, of the models has a fully adjusted ocean. For all models, multi-decadal climate predictions to 2050 are highly dependent on the initial ocean state (and so are unreliable). Such dependence cannot be removed simply by subtracting the climate drift from control runs.

  4. The Mercator-Ocean forecasting service: a 4D vision of the global ocean, serving the ocean services.

    NASA Astrophysics Data System (ADS)

    Hernandez, F.

    2006-12-01

    Mercator Ocean is a public consortium formed in Toulouse in early 2002 by the six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Meo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. More than three thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator-Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The current high-resolution model offers a 6 km grid resolution, and the first models offering global ocean coverage has been implemented early 2004. A ¼° model is operated since October 2005. The services offered by Mercator-Ocean consist in a real-time general description of the physical state of the ocean (3D currents, temperature, salinity ). This is exactly in line with the so called Marine Core Service initiative developed by the operational oceanography community within the programs funded by the European Commission and the European Space Agency (Marcoast, Mersea, BOSS4GMES projects ). The downstream activities are now in

  5. Global ocean circulation and equator-pole heat transport as a function of ocean GCM resolution

    SciTech Connect

    Covey, C.

    1994-06-01

    To determine whether resolution of smaller scales is necessary to simulate large-scale ocean climate correctly, I examine results from a global ocean GCM run with horizontal grid spacings spanning a range from coarse resolutions traditionally used in climate modeling to nearly the highest resolution attained with today`s computers. The experiments include four cases employing 4{degrees}, 2{degrees}, 1{degrees} and 1/2{degrees} spacing in latitude and longitude, which were run with minimal differences among them, i.e., in a controlled experiment. Two additional cases-1/2{degrees} spacing with a more scale-selective sub-gridscale mixing of heat and momentum, and approximate 1/4{degrees} spacing-are also included. The 1/4{degrees} run resolves most of the observed mesoscale eddy energy in the ocean. Several artificial constraints on the model tend to minimize differences among the different resolution cases. Nevertheless, for quantities of interest to global climate studies,the simulations show significant changes as resolution increases.

  6. Global ocean carbon uptake: magnitude, variability and trends

    NASA Astrophysics Data System (ADS)

    Wanninkhof, R.; Park, G.-H.; Takahashi, T.; Sweeney, C.; Feely, R.; Nojiri, Y.; Gruber, N.; Doney, S. C.; McKinley, G. A.; Lenton, A.; Le Quéré, C.; Heinze, C.; Schwinger, J.; Graven, H.; Khatiwala, S.

    2013-03-01

    The globally integrated sea-air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is -2.0 Pg C yr-1. The interannual variability in the sea-air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr-1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from -0.13 (Pg C yr-1) decade-1 to -0.50 (Pg C yr-1) decade-1 for the two decades under investigation. The OBGCMs and the data-based sea-air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.

  7. Global atmospheric and ocean modeling on the connection machine

    SciTech Connect

    Atlas, S.R.

    1993-12-01

    This paper describes the high-level architecture of two parallel global climate models: an atmospheric model based on the Geophysical Fluid Dynamics Laboratory (GFDL) SKYHI model, and an ocean model descended from the Bryan-Cox-Semtner ocean general circulation model. These parallel models are being developed as part of a long-term research collaboration between Los Alamos National Laboratory (LANL) and the GFDL. The goal of this collaboration is to develop parallel global climate models which are modular in structure, portable across a wide variety of machine architectures and programming paradigms, and provide an appropriate starting point for a fully coupled model. Several design considerations have emerged as central to achieving these goals. These include the expression of the models in terms of mathematical primitives such as stencil operators, to facilitate performance optimization on different computational platforms; the isolation of communication from computation to allow flexible implementation of a single code under message-passing or data parallel programming paradigms; and judicious memory management to achieve modularity without memory explosion costs.

  8. Global abundance of planktonic heterotrophic protists in the deep ocean.

    PubMed

    Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon

    2015-03-01

    The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml(-1) in mesopelagic waters down to 11±1 cells ml(-1) in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml(-1). The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web. PMID:25290506

  9. Freshwater and heat transports from global ocean synthesis

    NASA Astrophysics Data System (ADS)

    Valdivieso, M.; Haines, K.; Zuo, H.; Lea, D.

    2014-01-01

    An eddy-permitting ¼° global ocean reanalysis based on the Operational Met Office FOAM data assimilation system has been run for 1989-2010 forced by ERA-Interim meteorology. Freshwater and heat transports are compared with published estimates globally and in each basin, with special focus on the Atlantic. The meridional transports agree with observations within errors at most locations, but where eddies are active the transports by the mean flow are nearly always in better agreement than the total transports. Eddy transports are down gradient and are enhanced relative to a free run. They may oppose or reinforce mean transports and provide 40-50% of the total transport near midlatitude fronts, where eddies with time scales <1 month provide up to 15%. Basin-scale freshwater convergences are calculated with the Arctic/Atlantic, Indian, and Pacific oceans north of 32°S, all implying net evaporation of 0.33 ± 0.04 Sv, 0.65 ± 0.07 Sv, and 0.09 ± 0.04 Sv, respectively, within the uncertainty of observations in the Atlantic and Pacific. The Indian is more evaporative and the Southern Ocean has more precipitation (1.07 Sv). Air-sea fluxes are modified by assimilation influencing turbulent heat fluxes and evaporation. Generally, surface and assimilation fluxes together match the meridional transports, indicating that the reanalysis is close to a steady state. Atlantic overturning and gyre transports are assessed with overturning freshwater transports southward at all latitudes. At 26°N eddy transports are negligible, overturning transport is 0.67 ± 0.19 Sv southward and gyre transport is 0.44 ± 0.17 Sv northward, with divergence between 26°N and the Bering Strait of 0.13 ± 0.23 Sv over 2004-2010.

  10. Paradox lost: silicon 32 and the global ocean silica cycle

    NASA Astrophysics Data System (ADS)

    Craig, H.; Somayajulu, B. L. K.; Turekian, K. K.

    2000-02-01

    The 32Si Paradox is that the GEOSECS measurements of 32Si specific activity in silica collected on ferric hydroxide-coated fibers are essentially uniform throughout the deep water of the global oceans [Somayajulu et al., Earth Planet. Sci. Lett. 85 (1987) 329-342; 107 (1991) 197-216]. Peng, Maier-Reimer, and Broecker have argued that 32Si specific activities in Indian and Pacific deep water should be 3-5 times lower than in the deep Atlantic, because the dissolved SiO 2 concentrations are higher than in the Atlantic by this factor, and because cosmogenic 32Si should be essentially confined to the ocean basins in which it falls due to its short half-life relative to mixing times for water interchange between the oceans. Thus these authors proposed that the entire GEOSECS 32Si data set "may be flawed". The resolution of the 32Si Paradox is straightforward. Silica collected on the acrilan fibers is a two-phase mixture of biogenic particulate SiO 2 (opaline tests of diatoms and radiolaria) and silica scavenged chemically from dissolved SiO 2 in ocean water. Particulate silica is the high-activity component in this mixture, and dissolved SiO 2 is the low-activity end-member. Thus the mixing trajectories on 'Cornucopia plots' of specific activity vs. reciprocal SiO 2 recovered weights overlap in specific-activity range, regardless of the different concentrations and specific activities of dissolved silica in the deep waters. The specific activities of dissolved SiO 2 in the Pacific, Indian, and Atlantic oceans, as deciphered from the two-component total activity data, are ˜0, 2.6, and 4.5 dpm/kg SiO 2. The atmospheric production rate of 32Si has been calculated and is found to be 0.72 atoms/m 2 s. This value is much lower than in previous calculations, which were based on the Lal and Peters plots of stratospheric fallout that incorrectly use geomagnetic latitude for scaling the fallout patterns. Correcting these curves to scale by geographic latitude, which controls the

  11. Madden Julian Oscillation impacts on global ocean surface waves

    NASA Astrophysics Data System (ADS)

    Marshall, Andrew G.; Hendon, Harry H.; Durrant, Tom H.; Hemer, Mark A.

    2015-12-01

    We assess the impact of the tropical Madden Julian Oscillation (MJO) on global ocean wind waves using 30 years of wave data from a wave model hindcast that is forced with high resolution surface winds from the NCEP-CFSR reanalysis. We concentrate on the boreal winter season when the MJO has its greatest amplitude and is potentially a source of predictable wave impacts at intra-seasonal lead times. Statistically significant anomalies in significant wave height (Hs), peak wave period (Tp) and zonal wave energy flux (CgE) are found to covary with the intra-seasonal variation of surface zonal wind induced by the MJO as it traverses eastward from the western tropical Indian Ocean to the eastern tropical Pacific. Tp varies generally out of phase with Hs over the life cycle of the MJO, indicating that these MJO-wave anomalies are locally wind-generated rather than remotely generated by ocean swell. Pronounced Hs anomalies develop on the northwest shelf of Australia, where the MJO is known to influence sea level and surface temperatures, and in the western Caribbean Sea and Guatemalan-Panama Seas with enhanced wave anomalies apparent in the vicinity of the Tehuantepec and Papagayo gaps. Significant wave anomalies are also detected in the North Pacific and North Atlantic oceans in connection with the MJO teleconnection to the extratropics via atmospheric wave propagation. The impact in the north Atlantic stems from induction of the high phase of the North Atlantic Oscillation (NAO) about 1 week after MJO convection traverses the Indian Ocean, and the low phase of the NAO about one week after suppressed convection traverses the Indian Ocean. Strong positive Hs anomalies maximize on the Northern European coast in the positive NAO phase and vice versa for the negative NAO phase. The MJO also influences the occurrence of daily low (below the 5th percentile) and high (above the 95th percentile) wave conditions across the tropics and in the North Pacific and North Atlantic

  12. Atmospheric response to Indian Ocean Dipole forcing: changes of Southeast China winter precipitation under global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Sielmann, Frank; Fraedrich, Klaus; Zhi, Xiefei

    2016-05-01

    To investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the subsequent winter precipitation in Southeast China (SEC), observed fields of monthly precipitation, sea surface temperature (SST) and atmospheric circulation are subjected to a running and a maximum correlation analysis. The results show a significant change of the relevance of IOD for the early modulation of SEC winter precipitation in the 1980s. After 1980, positive correlations suggest prolonged atmospheric responses to IOD forcing, which are linked to an abnormal moisture supply initiated in autumn and extended into the subsequent winter. Under global warming two modulating factors are relevant: (1) an increase of the static stability has been observed suppressing vertical heat and momentum transports; (2) a positive (mid-level) cloud-radiation feedback jointly with the associated latent heating (apparent moisture sink Q2) explains the prolongation of positive as well as negative SST anomalies by conserving the heating (apparent heat source Q1) in the coupled atmosphere-ocean system. During the positive IOD events in fall (after 1980) the dipole heating anomalies in the middle and lower troposphere over the tropical Indian Ocean are prolonged to winter by a positive mid-level cloud-radiative feedback with latent heat release. Subsequently, thermal adaptation leads to an anticyclonic anomaly over Eastern India overlying the anomalous cooling SST of the tropical Eastern Indian Ocean enhancing the moisture flow from the tropical Indian Ocean through the Bay of Bengal into South China, following the northwestern boundary of the anticyclonic circulation anomaly over east India, thereby favoring abundant precipitation in SEC.

  13. Assimilation of SeaWiFS Ocean Chlorophyll Data into a Three-Dimensional Global Ocean Model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.

    2005-01-01

    Assimilation of satellite ocean color data is a relatively new phenomenon in ocean sciences. However, with routine observations from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), launched in late 1997, and now with new data from the Moderate Resolution Imaging Spectroradometer (MODIS) Aqua, there is increasing interest in ocean color data assimilation. Here SeaWiFS chlorophyll data were assimilated with an established thre-dimentional global ocean model. The assimilation improved estimates of hlorophyll and primary production relative to a free-run (no assimilation) model. This represents the first attempt at ocean color data assimilation using NASA satellites in a global model. The results suggest the potential of assimilation of satellite ocean chlorophyll data for improving models.

  14. Designing Scatterometer Constellations for Sampling Global Ocean Vector Winds

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Chelton, D. B.; Stoffelen, A.; Schlax, M.

    2012-12-01

    The rapid temporal variations in ocean vector winds make it impossible to obtain synoptic global snapshots of winds and wind stress from a single spaceborne sensor. Even when multiple sensors are present, the peculiarities of the resulting space-time sampling pattern require that significant smoothing in space and time be performed to limit spatially and temporally inhomogeneous error characteristics in the merged data. Based on the collected common experience in its member states, the World Meteorological Organization collects requirements for spatio-temporal sampling in meteorological applications such as global and regional Numerical Weather Prediction, nowcasting, and climate. An additional concern, when constructing data sets from sun-synchronous missions, is that undersampling of diurnal and sub-diurnal variability may result in aliasing of the climate data record. Indeed, examination of climatologies constructed from different satellite missions, such as NASA's QuikSCAT and EUMETSAT's ASCAT scatterometers, show systematic differences that cannot be explained as being due solely to unresolved incoherent diurnal and sub-diurnal variability. Some of these differences, especially in the tropics, are probably explained by systematic diurnal and sub-diurnal variations. Other differences may be due to the difficulty of cross-calibrating sun-synchronous satellites with different local times. Forthcoming satellite missions may offer the possibility of overcoming or mitigating the space-time sampling and calibration challenges using multiple coordinated platforms. In the next decade, there is an expectation that ocean vector winds will be measured simultaneously by multiple satellites from the European community, India, China, and the United States. The coordination and suitable merging of the data from these satellites to produce a climate data record will be a challenge to the ocean vector winds community. In this presentation, we use climatologies constructed from

  15. Modeling selective pressures on phytoplankton in the global ocean.

    PubMed

    Bragg, Jason G; Dutkiewicz, Stephanie; Jahn, Oliver; Follows, Michael J; Chisholm, Sallie W

    2010-01-01

    Our view of marine microbes is transforming, as culture-independent methods facilitate rapid characterization of microbial diversity. It is difficult to assimilate this information into our understanding of marine microbe ecology and evolution, because their distributions, traits, and genomes are shaped by forces that are complex and dynamic. Here we incorporate diverse forces--physical, biogeochemical, ecological, and mutational--into a global ocean model to study selective pressures on a simple trait in a widely distributed lineage of picophytoplankton: the nitrogen use abilities of Synechococcus and Prochlorococcus cyanobacteria. Some Prochlorococcus ecotypes have lost the ability to use nitrate, whereas their close relatives, marine Synechococcus, typically retain it. We impose mutations for the loss of nitrogen use abilities in modeled picophytoplankton, and ask: in which parts of the ocean are mutants most disadvantaged by losing the ability to use nitrate, and in which parts are they least disadvantaged? Our model predicts that this selective disadvantage is smallest for picophytoplankton that live in tropical regions where Prochlorococcus are abundant in the real ocean. Conversely, the selective disadvantage of losing the ability to use nitrate is larger for modeled picophytoplankton that live at higher latitudes, where Synechococcus are abundant. In regions where we expect Prochlorococcus and Synechococcus populations to cycle seasonally in the real ocean, we find that model ecotypes with seasonal population dynamics similar to Prochlorococcus are less disadvantaged by losing the ability to use nitrate than model ecotypes with seasonal population dynamics similar to Synechococcus. The model predictions for the selective advantage associated with nitrate use are broadly consistent with the distribution of this ability among marine picocyanobacteria, and at finer scales, can provide insights into interactions between temporally varying ocean processes and

  16. Near-Real Time Monthly Global Temperature and Salinity Gridded Data from New Ocean Exploration by Argo Floats

    NASA Astrophysics Data System (ADS)

    Chu, P. C.; Sun, L.; Fan, C.

    2010-12-01

    New ocean exploration by Argo floats provides sufficient spatial and temporal coverage for sampling the global ocean temperature and salinity. Currently, there are 3193 Argo floats all over the world oceans. Combined with traditionally sampled data, they are included into the Global Temperature and Salinity Profile Program (GTSPP). To fully understanding the variability in ocean thermohaline structure and then its effects on climate variability needs a sufficient resolution in space and, especially, in time, gridded ocean temperature and salinity (T, S) dataset. We analyzed observational profiles (from Argo and traditional technologies) from the GTSPP and produced a T-S data set to meet the above need. GTSPP is a joint programme of the International Oceanographic Data and Information Exchange committee (IODE) and the Joint Commission on Oceanography and Marine Meteorology (JCOMM). IODE and JCOMM are technical committees of the Intergovernmental Oceanographic Commission and the World Meteorological Organization. The quality control procedures used in GTSPP were developed by the Marine Environmental Data Service (MEDS), now the Integrated Science Data Management (ISDM), of Canada. The GTSPP handles all temperature and salinity profile data. This includes observations collected using water samplers, continuous profiling instruments such as Argo, CTDs, thermistor chain data and observations acquired using thermosalinographs. These data will reach data processing centres of the Program through the real-time channels of the IGOSS program or in delayed mode through the IODE system. Real-time data in GTSPP are acquired from the Global Telecommunications System in the bathythermal (BATHY) and temperature, salinity & current (TESAC) codes forms supported by the WMO. Delayed mode data are contributed directly by member states of IOC. Any variable (temperature, salinity, or velocity) can be decomposed into generalized Fourier series using the recently developed optimal

  17. Climate Models from the Joint Global Change Research Institute

    DOE Data Explorer

    Staff at the Joint Institute develop and use models to simulate the economic and physical impacts of global change policy options. The GCAM, for example, gives analysts insight into how regional and national economies might respond to climate change mitigation policies including carbon taxes, carbon trading, and accelerated deployment of energy technology. Three available models are Phoenix, GCAM, and EPIC. Phoenix is a global, dynamic recursive, computable general equilibrium model that is solved in five-year time steps from 2005 through 2100 and divides the world into twenty-four regions. Each region includes twenty-six industrial sectors. Particular attention is paid to energy production in Phoenix. There are nine electricity-generating technologies (coal, natural gas, oil, biomass, nuclear, hydro, wind, solar, and geothermal) and four additional energy commodities: crude oil, refined oil products, coal, and natural gas. Phoenix is designed to answer economic questions related to international climate and energy policy and international trade. Phoenix replaces the Second Generation Model (SGM) that was formerly used for general equilibrium analysis at JGCRI. GCAM is the Global Change Assessment Model, a partial equilibrium model of the world with 14 regions. GCAM operates in 5 year time steps from 1990 to 2095 and is designed to examine long-term changes in the coupled energy, agriculture/land-use, and climate system. GCAM includes a 151-region agriculture land-use module and a reduced form carbon cycle and climate module in addition to its incorporation of demographics, resources, energy production and consumption. The model has been used extensively in a number of assessment and modeling activities such as the Energy Modeling Forum (EMF), the U.S. Climate Change Technology Program, and the U.S. Climate Change Science Program and IPCC assessment reports. GCAM is now freely available as a community model. The Environmental Policy Integrated Climate (EPIC) Model

  18. Does Ocean Color Data Assimilation Improve Estimates of Global Ocean Inorganic Carbon?

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2012-01-01

    Ocean color data assimilation has been shown to dramatically improve chlorophyll abundances and distributions globally and regionally in the oceans. Chlorophyll is a proxy for phytoplankton biomass (which is explicitly defined in a model), and is related to the inorganic carbon cycle through the interactions of the organic carbon (particulate and dissolved) and through primary production where inorganic carbon is directly taken out of the system. Does ocean color data assimilation, whose effects on estimates of chlorophyll are demonstrable, trickle through the simulated ocean carbon system to produce improved estimates of inorganic carbon? Our emphasis here is dissolved inorganic carbon, pC02, and the air-sea flux. We use a sequential data assimilation method that assimilates chlorophyll directly and indirectly changes nutrient concentrations in a multi-variate approach. The results are decidedly mixed. Dissolved organic carbon estimates from the assimilation model are not meaningfully different from free-run, or unassimilated results, and comparisons with in situ data are similar. pC02 estimates are generally worse after data assimilation, with global estimates diverging 6.4% from in situ data, while free-run estimates are only 4.7% higher. Basin correlations are, however, slightly improved: r increase from 0.78 to 0.79, and slope closer to unity at 0.94 compared to 0.86. In contrast, air-sea flux of C02 is noticeably improved after data assimilation. Global differences decline from -0.635 mol/m2/y (stronger model sink from the atmosphere) to -0.202 mol/m2/y. Basin correlations are slightly improved from r=O.77 to r=0.78, with slope closer to unity (from 0.93 to 0.99). The Equatorial Atlantic appears as a slight sink in the free-run, but is correctly represented as a moderate source in the assimilation model. However, the assimilation model shows the Antarctic to be a source, rather than a modest sink and the North Indian basin is represented incorrectly as a sink

  19. Approach to equilibrium in accelerated global oceanic models

    SciTech Connect

    Danabasoglu, G.; McWilliams, J.C.; Large, W.G.

    1996-05-01

    The approach to equilibrium of a coarse-resolution, seasonally forced, global oceanic general circulation model is investigated, considering the effects of a widely used acceleration technique that distorts the dynamics by using unequal time steps in the governing equations. A measure of the equilibration time for any solution property is defined as the time it takes to go 90% of the way from its present value to its equilibrium value. This measure becomes approximately time invariant only after sufficiently long integration. It indicates that the total kinetic energy and most mass transport rates attain equilibrium within about 90 and 40 calendar years, respectively. The upper-ocean potential temperature and salinity equilibrium times are about 480 and 380 calender years, following 150- and 20-year initial adjustments, respectively. In the abyssal ocean, potential temperature and salinity equilibration take about 4500 and 3900 calender years, respectively. These longer equilibration times are due to the slow diffusion of tracers both along and across the isopycnal surfaces in stably stratified regions, and these times vary with the associated diffusivities. An analysis of synchronous (i.e., not accelerated) integrations shows that there is a complex interplay between convective, advective, and diffusive timescales. Because of the distortion by acceleration of the seasonal cycle, the solutions display some significant adjustments upon switching to synchronous integration. However, the proper seasonal cycle is recovered within five years. Provided that a sufficient equilibrium state has been achieved with acceleration, the model must be integrated synchronously for only about 15 years thereafter to closely approach synchronous equilibrium. 16 refs., 11 figs., 1 tab.

  20. Role of the Polar Oceans in Global Climate

    NASA Technical Reports Server (NTRS)

    Rothrock, D. A.

    2003-01-01

    The project focused on ice-ocean model development and in particular on the assimilation of ice motion data and ice concentration data into both regional and global models. Many of the resulting publications below deal with improvements made in the physics treated by the model and the procedures for assimilating data. Several papers examine how the ability of the model to simulate the past behavior of the ice cover, especially to represent the ice thickness and ice deformation, is improved by data assimilation. A second aspect of the work involved interpretation of modeled behavior. Resulting papers treat the decline of arctic ice thickness over the last thirty years, and how that decline was caused by a slight warming of the near-surface atmosphere, and also how large variation in ice thickness are due to changes in wind patterns associated with a well- known oscillation of the atmospheric circulation. The research resulted in over 20 published papers on these topics.

  1. Wet deposition of persistent organic pollutants to the global oceans.

    PubMed

    Jurado, Elena; Jaward, Foday; Lohmann, Rainer; Jones, Kevin C; Simó, Rafel; Dachs, Jordi

    2005-04-15

    Wet deposition fluxes of polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and furans to the Atlantic Ocean have been estimated by combining meteorological satellite data and measured atmospheric field concentrations. They are then compared to other atmospheric depositional mechanisms on a global scale. Additional features not treated in traditional studies are addressed such as contaminant adsorption onto raindrops and enhancement of dry gaseous diffusive fluxes due to rain-induced turbulence. Wet deposition estimates show a high spatial and seasonal variability, with maxima located in the Intertropical Convergence Zone (ITCZ) and in low-temperature regions. Seasonal variability reflects the northward shift of ITCZ in July. Average wet deposition fluxes estimated for the Atlantic Ocean in this study are 110 and 45 ng m(-2) yr(-1) for sigmaPCB and sigmaPCDD/Fs, respectively. Furthermore, the total wet deposition to the Atlantic results in 4100 kg yr(-1) (sigmaPCB) and 2500 kg yr(-1) (sigmaPCDD/Fs). Model validation shows good agreement with available coastal data measurements of wet deposition fluxes. When compared to other atmospheric depositional mechanisms and during precipitation events, wet deposition is found to be dominant. However, when raining events and non-raining time periods are integrated, air-water diffusive exchange fluxes acquire an important role, which can be dominant in some regions and for some POPs. PMID:15884331

  2. Effects of Drake Passage on a strongly eddying global ocean

    NASA Astrophysics Data System (ADS)

    Viebahn, Jan P.; Heydt, Anna S.; Le Bars, Dewi; Dijkstra, Henk A.

    2016-05-01

    The climate impact of ocean gateway openings during the Eocene-Oligocene transition is still under debate. Previous model studies employed grid resolutions at which the impact of mesoscale eddies has to be parameterized. We present results of a state-of-the-art eddy-resolving global ocean model with a closed Drake Passage and compare with results of the same model at noneddying resolution. An analysis of the pathways of heat by decomposing the meridional heat transport into eddy, horizontal, and overturning circulation components indicates that the model behavior on the large scale is qualitatively similar at both resolutions. Closing Drake Passage induces (i) sea surface warming around Antarctica due to equatorward expansion of the subpolar gyres, (ii) the collapse of the overturning circulation related to North Atlantic Deep Water formation leading to surface cooling in the North Atlantic, and (iii) significant equatorward eddy heat transport near Antarctica. However, quantitative details significantly depend on the chosen resolution. The warming around Antarctica is substantially larger for the noneddying configuration (˜5.5°C) than for the eddying configuration (˜2.5°C). This is a consequence of the subpolar mean flow which partitions differently into gyres and circumpolar current at different resolutions. We conclude that for a deciphering of the different mechanisms active in Eocene-Oligocene climate change detailed analyses of the pathways of heat in the different climate subsystems are crucial in order to clearly identify the physical processes actually at work.

  3. Simulating the global distribution of nitrogen isotopes in the ocean

    NASA Astrophysics Data System (ADS)

    Somes, Christopher J.; Schmittner, Andreas; Galbraith, Eric D.; Lehmann, Moritz F.; Altabet, Mark A.; Montoya, Joseph P.; Letelier, Ricardo M.; Mix, Alan C.; Bourbonnais, Annie; Eby, Michael

    2010-12-01

    We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth system climate model designed for millennial timescale simulations. The model includes prognostic tracers for the two stable nitrogen isotopes, 14N and 15N, in the nitrate (NO3-), phytoplankton, zooplankton, and detritus variables of the marine ecosystem model. The isotope effects of algal NO3- uptake, nitrogen fixation, water column denitrification, and zooplankton excretion are considered as well as the removal of NO3- by sedimentary denitrification. A global database of δ15NO3- observations is compiled from previous studies and compared to the model results on a regional basis where sufficient observations exist. The model is able to qualitatively and quantitatively reproduce many of the observed patterns such as high subsurface values in water column denitrification zones and the meridional and vertical gradients in the Southern Ocean. The observed pronounced subsurface minimum in the Atlantic is underestimated by the model presumably owing to too little simulated nitrogen fixation there. Sensitivity experiments reveal that algal NO3- uptake, nitrogen fixation, and water column denitrification have the strongest effects on the simulated distribution of nitrogen isotopes, whereas the effect from zooplankton excretion is weaker. Both water column and sedimentary denitrification also have important indirect effects on the nitrogen isotope distribution by reducing the fixed nitrogen inventory, which creates an ecological niche for nitrogen fixers and, thus, stimulates additional N2 fixation in the model. Important model deficiencies are identified, and strategies for future improvement and possibilities for model application are outlined.

  4. Multidecadal climate variability of global lands and oceans

    USGS Publications Warehouse

    McCabe, G.J.; Palecki, M.A.

    2006-01-01

    Principal components analysis (PCA) and singular value decomposition (SVD) are used to identify the primary modes of decadal and multidecadal variability in annual global Palmer Drought Severity Index (PDSI) values and sea-surface temperature (SSTs). The PDSI and SST data for 1925-2003 were detrended and smoothed (with a 10-year moving average) to isolate the decadal and multidecadal variability. The first two principal components (PCs) of the PDSI PCA explained almost 38% of the decadal and multidecadal variance in the detrended and smoothed global annual PDSI data. The first two PCs of detrended and smoothed global annual SSTs explained nearly 56% of the decadal variability in global SSTs. The PDSI PCs and the SST PCs are directly correlated in a pairwise fashion. The first PDSI and SST PCs reflect variability of the detrended and smoothed annual Pacific Decadal Oscillation (PDO), as well as detrended and smoothed annual Indian Ocean SSTs. The second set of PCs is strongly associated with the Atlantic Multidecadal Oscillation (AMO). The SVD analysis of the cross-covariance of the PDSI and SST data confirmed the close link between the PDSI and SST modes of decadal and multidecadal variation and provided a verification of the PCA results. These findings indicate that the major modes of multidecadal variations in SSTs and land-surface climate conditions are highly interrelated through a small number of spatially complex but slowly varying teleconnections. Therefore, these relations may be adaptable to providing improved baseline conditions for seasonal climate forecasting. Published in 2006 by John Wiley & Sons, Ltd.

  5. GLOBEC: Global Ocean Ecosystems Dynamics: A component of the US Global Change Research Program

    NASA Technical Reports Server (NTRS)

    1991-01-01

    GLOBEC (GLOBal ocean ECosystems dynamics) is a research initiative proposed by the oceanographic and fisheries communities to address the question of how changes in global environment are expected to affect the abundance and production of animals in the sea. The approach to this problem is to develop a fundamental understanding of the mechanisms that determine both the abundance of key marine animal populations and their variances in space and time. The assumption is that the physical environment is a major contributor to patterns of abundance and production of marine animals, in large part because the planktonic life stages typical of most marine animals are intrinsically at the mercy of the fluid motions of the medium in which they live. Consequently, the authors reason that a logical approach to predicting the potential impact of a globally changing environment is to understand how the physical environment, both directly and indirectly, contributes to animal abundance and its variability in marine ecosystems. The plans for this coordinated study of of the potential impact of global change on ocean ecosystems dynamics are discussed.

  6. Global ocean carbon uptake: magnitude, variability and trends

    NASA Astrophysics Data System (ADS)

    Wanninkhof, R.; Park, G.-H.; Takahashi, T.; Sweeney, C.; Feely, R.; Nojiri, Y.; Gruber, N.; Doney, S. C.; McKinley, G. A.; Lenton, A.; Le Quéré, C.; Heinze, C.; Schwinger, J.; Graven, H.; Khatiwala, S.

    2012-08-01

    Estimates of the anthropogenic global-integrated sea-air carbon dioxide (CO2) flux from 1990 to 2009, based on different models and measurements, range from -1.4 to -2.6 Pg C yr-1. The median values of anthropogenic CO2 for each method show better agreement and are: -1.9 for Pg C yr-1 for numerical ocean general circulation hind cast models (OGCMs) with parameterized biogeochemistry; -2.1 Pg C yr-1 for atmospheric inverse models; -1.9 Pg C yr-1 for global atmospheric constraints based on O2 / N2 ratios for 1990-2000; and -2.4 Pg C yr-1 for oceanic inverse models. An updated estimate of this anthropogenic CO2 flux based on a climatology of sea-air partial pressure of CO2 differences (ΔpCO2) (Takahashi et al., 2009) and a bulk formulation of gas transfer with wind speed for year 2000 is -2.0 Pg C yr-1. Using this ΔpCO2 climatology and empirical relationships of pCO2 with sea-surface temperature (SST) anomalies (Park et al., 2010a), the interannual variability of the contemporary CO2 flux is estimated to be 0.20 Pg C yr-1 (1σ) from 1990 through 2009. This is similar to the variability estimated by the OGCMs of 0.16 Pg C yr-1 but smaller than the interannual variability from atmospheric inverse estimates of 0.40 Pg C yr-1. The variability is largely driven by large-scale climate re-organizations. The decadal trends for different methods range from -0.13 (Pg C yr-1) decade-1 to -0.50 (Pg C yr-1) decade-1. The OGCMs and the data based sea-air CO2 flux estimates show smaller uptakes and appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. It is not clear if this large difference in trend is a methodological issue or a real natural feedback.

  7. Iron Resources and Oceanic Nutrients: Advancement of Global Environment Simulations

    NASA Astrophysics Data System (ADS)

    Debaar, H. J.

    2002-12-01

    The concept of a single factor limiting plankton blooms, is presently giving way to co-limitation by light, and the nutrients N, P, Si and Fe. Primary production, export into the deep sea, and CO2 uptake from the atmosphere together form the 'biological pump' in Ocean Biogeochemical Climate Models (OBCM's). Thus far OBCM's assume just one limiting nutrient (P) and one universal phytoplankton species, for C budgets and CO2 exchange. New realistic OBCM's are being developed for budgeting and exchanges of both CO2 and DMS, implementing (i) co-limitation by 4 nutrients of 5 major taxonomic classes of phytoplankton, (ii) DMS(P) pathways, (iii) global iron cycling, (iv) chemical forms of iron and (v) iron supply into surface waters. The new OBCM's will predict realistic climate scenario's, notably climatic feedbacks on oceanic biogeochemistry. IRONAGES is a European consortium of twelve institutes and is coordinated by Royal NIOZ. Input from below of iron from anoxic sediments of coastal margins has been assessed (March 2002) along a 2-D vertical section from Europe into the centre of the north Atlantic. Input from above of Fe(II) dissolved in rainwater from Sahara dust blown over the central Atlantic will be quantified at sea (October 2002), and related to observed plankton production. Different chemical forms of iron are being assessed and a certification excercise for Fe in seawater also under aegis of SCOR Working Group 109 is being completed (December 2002). For two major DMS-producing algal groups Phaeocystis sp. and Emiliania huxleyi the life cycle, Fe limitation, export production, CO2 uptake and DMS emissions have been synthesized from existing literature and laboratory experiments. This is being fed into ecosystem modeling, as well as into DMS(P) pathway modeling. Also know-how has been synthesized for three other major classes (diatoms, N2-fixing Trichodesmium and nano-pico-plankton) and fed into the ecosystem modeling. Pathways of DMS(P) in blooms are being

  8. Ocean topography mapping, improvement of the marine geoid, and global permanent ocean circulation studies from TOPEX/Poseidon altimeter data

    NASA Technical Reports Server (NTRS)

    Marsh, James G.; Lerch, F. J.; Koblinsky, C. J.; Nerem, R. S.; Klosko, S. M.; Williamson, R. G.

    1991-01-01

    The TOPEX/POSEIDON altimeter measurements will be the first global observations of the sea surface with accuracy sufficient to make quantitative determinations of the ocean's general circulation and its variations. These measurements are an important step to understanding global change in the ocean and its impact on the climate. Our investigation will focus on the examination of features in the sea surface elevation at the largest spatial and temporal scales. TOPEX/POSEIDON altimeter measurements will be used in conjunction with observations from past satellite-altimeter missions, such as NASA's GEOS-3 and Seasat, the U.S. Navy's Geosat and SALT, and the European Remote Sensing satellite in order to address the following issues: (1) Improve models of the marine geoid, especially at wavelengths needed to understand the basin-scale ocean dynamic topograpy. (2) Measure directly from the altimeter data the expression of the mean global ocean circulation in the sea surface at the largest scales through a simultaneous solution for gravity, orbital, and oceanographic parameters. (3) Examine the sea surface measurements for changes in global ocean mass or volume, interannual variations in the basin-scale ocean circulation, and annual changes in the heating and cooling of the upper ocean.

  9. The oceanic cycle and global atmospheric budget of carbonyl sulfide

    SciTech Connect

    Weiss, P.S.

    1994-12-31

    A significant portion of stratospheric air chemistry is influenced by the existence of carbonyl sulfide (COS). This ubiquitous sulfur gas represents a major source of sulfur to the stratosphere where it is converted to sulfuric acid aerosol particles. Stratospheric aerosols are climatically important because they scatter incoming solar radiation back to space and are able to increase the catalytic destruction of ozone through gas phase reactions on particle surfaces. COS is primarily formed at the surface of the earth, in both marine and terrestrial environments, and is strongly linked to natural biological processes. However, many gaps in the understanding of the global COS cycle still exist, which has led to a global atmospheric budget that is out of balance by a factor of two or more, and a lack of understanding of how human activity has affected the cycling of this gas. The goal of this study was to focus on COS in the marine environment by investigating production/destruction mechanisms and recalculating the ocean-atmosphere flux.

  10. Comparison of retrospective analyses of the global ocean heat content

    NASA Astrophysics Data System (ADS)

    Chepurin, Gennady A.; Carton, James A.

    1999-07-01

    In this study, we compare seven retrospective analyses of basin- to global-scale upper ocean temperature. The analyses span a minimum of 10 years during the 50-year period since World War II. Three of the analyses (WOA-94, WHITE, BMRC) are based on objective analysis and thus, do not rely on a numerical forecast model. The remaining four (NCEP, WAJSOWICZ, ROSATI, SODA) are based on data assimilation in which the numerical forecast is provided by some form of the Geophysical Fluid Dynamics Laboratory Modular Ocean Model driven by historical winds. The comparison presented here is limited to heat content in the upper 250 m, information that is available for all analyses. The results are presented in three frequency bands: seasonal, interannual (periods of 1-5 years), and decadal (periods of 5-25 years). At seasonal frequencies, all of the analyses are quite similar. Otherwise, the differences among analyses are limited to the regions of the western boundary currents, and some regions in the Southern Hemisphere. At interannual frequencies, significant differences appear between the objective analyses and the data assimilation analyses. Along the equator in the Pacific, where variability is dominated by El Niño, the objective analyses have somewhat noisier fields, as well as reduced variance prior to 1980 due to lack of observations. Still, the correlation among analyses generally exceeds 80% in this region. Along the equator in the Atlantic, the correlation is lower (30-60%) although inspection of the time series shows that the same biennial progression of warm and cool events appears in all analyses since 1980. In the midlatitude Pacific agreement among objective analyses and data assimilation analyses is good. The analysis of Rosati et al. [Rosati, A., Gudgel, R., Miyakoda, K., 1995. Decadal analysis produced from an ocean assimilation system. Mon. Weather Rev., 123, 2, 206.] differs somewhat from the others apparently because in this analysis, the forecast model

  11. 75 FR 48731 - Notice of Availability for Public Comment on the Draft Joint Subcommittee on Ocean Science and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-11

    ... From the Federal Register Online via the Government Publishing Office NATIONAL SCIENCE FOUNDATION Notice of Availability for Public Comment on the Draft Joint Subcommittee on Ocean Science and Technology--Interagency Ocean Observation Committee Public-Private Use Policy AGENCY: National Science Foundation....

  12. Millennial-scale projection of oceanic oxygen change due to global warming

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akitomo; Abe-Ouchi, Ayako; Shigemitsu, Masahito; Oka, Akira; Takahashi, Kunio; Ohgaito, Rumi; Yamanaka, Yasuhiro

    2016-04-01

    Global warming is expected to globally decrease ocean oxygen concentrations by sea surface warming and ocean circulation change. Oxygen reduction is expected to persist for a thousand years or more, even after atmospheric carbon dioxide stops rising. However, long-term changes in ocean oxygen and circulation are still unclear. Here we simulate multimillennium changes in ocean circulation and oxygen under doubling and quadrupling of atmospheric carbon dioxide, using GCM (MIROC) and an offline biogeochemical model. In the first 500 years, global oxygen concentration decreases, consistent with previous studies. Thereafter, however, the oxygen concentration in the deep ocean globally recovers and overshoots at the end of the simulations, despite surface oxygen decrease and weaker AMOC. This is because, after the initial cessation, the recovery and overshooting of deep ocean convection in the Weddell Sea enhance ventilation and supply oxygen-rich surface waters to deep ocean. Another contributor to deep ocean oxygenation is seawater warming, which reduces the export production and shifts the organic matter remineralization to the upper water column. Our results indicate that the change in ocean circulation in the Southern Ocean potentially drives millennial-scale oxygenation in deep ocean, which is opposite to the centennial-scale global oxygen reduction and general expectation.

  13. Global Oceanic Basalt Geochemistry From EarthChem Databases

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.; Sarbas, B.; Jochum, K. P.; Stracke, A.

    2004-12-01

    For the past 21 years, global trace element systematics in oceanic basalts have been systematically developed, using mass spectrometry, by the MPI geochemistry department in Mainz, starting with Ba-Rb-Cs, and continuing with K-U-Th, Nb-U-Th, Pb-Ce, Pr-Mo, Nb-Ta, Sn-REE, Sb-REE, and Y-Ho relations. These were complemented by other groups, contributing e.g. Sr-REE relationships and more refined Nb-Ta systematics. Goal of these investigations was to establish relative trace element compatibilities during mantle melting, the corresponding enrichment and depletion patterns in MORB, OIB, subduction-related volcanics and the continental crust, and the relationships to Bulk Silicate Earth abundances through comparisons with element abundances in meteorites and in the continental crust (see e.g. [1]). Most of these studies were initially based on extremely limited data sets, often fewer than 100 analyses, because routine analytical techniques such as XRF and INAA were inadequate, either in sensitivity or accuracy or both, for many of the elements of interest. The advent of ICPMS technology has increased the volume of available, useable data enormously. The most recent development of laser source ICPMS is accelerating the acquisition of comprehensive trace element data even more dramatically. Although the general quality of recent trace element analyses has improved significantly, there remain large differences in reliability between published data because of varying analytical uncertainties and sample alteration. Thus, quality assurance remains an enormous task. In any case, now and in the foreseeable future, it will be impossible to assess global geochemical data without the use of comprehensive databases. Such databases are now available under http://www.earthchem.org/, comprising http://beta.petdb.ciesin.columbia.edu/; http://georoc.mpch-mainz.gwdg.de/, and http://navdat.geo.ku.edu/ . Unfortunately, the use of such databases is not without pitfalls. Often, appropriate

  14. Decadal Ocean Heat Content Westward Shift in the Indian Ocean during the Global Surface Warming and Hiatus

    NASA Astrophysics Data System (ADS)

    Wu, X.; Yan, X. H.; Li, Y.

    2015-12-01

    Understanding the ocean's role in Earth's energy budget is fundamental to evaluate climate variability and change, including the rate of global warming and the recent 18-years' so-called Global Surface Warming Hiatus (GSWH). Previous studies have shown that basin-wide warming in the Atlantic Ocean triggers the intensification of trade wind and wind-driven circulation since late 1990s, resulting in Global Surface Warming Hiatus (GSWH). A recent work revealed that missing heat in the Pacific during the GSWH was transported to the Indian Ocean by the Indonesia throughflow. It brings the Indian Ocean to the platform of the GSWH study and suggests that the global ocean is at play in the GSWH and in the ocean heat content (OHC) westwards shifting. The westwards shifting of the OHC was detected from in-situ data and model/in-situ reanalysis data. The shifting has a period of about 30 years, and takes about 60 years to travel from the eastern Pacific to the western Atlantic. Heat was distributed to deeper layers after the warm OHC passed the southern tip of the Africa continent. This may shed light on the understanding of the physical mechanisms for the multi-decadal climate variability.

  15. Oceanic Observations

    NASA Technical Reports Server (NTRS)

    Busalacchi, Antonio J.

    1997-01-01

    For many years, merchant ships and the naval fleets of various countries have been the major source of data over and in the open ocean. Oceanographic research experiments and process studies in the field have also contributed to the climatological data bases for the global ocean, but, for the most part, these have been limited in duration and extent. However, over the last 10 years under the auspices of the World Climate Research Program and the International Geosphere Biosphere Program the role of the oceans in global and climate change has taken on increased significance. This has created a need for a considerably improved understanding of the seasonal, interannual, decadal and longer time-scale variability of the physical and biogeochemical attributes of the global ocean. As a result, over the past 10 years several major international field programs have been implemented and have had a tremendous impact on the number of in situ observations obtained for the global ocean. The Tropical Ocean Global Atmosphere (TOGA) program, the World Ocean Circulation Experiment (WOCE), and the Joint Global Ocean Flux Study (JGOFS) were designed with observational, modelling, and process study components aimed at analyzing different aspects of the ocean's role in the coupled climate system. In parallel with the field programs, continuous space-based observations of sea surface temperature, sea surface topography, and sea surface winds spanning nearly a decade or longer have become a reality. During this same time period, numerical ocean models and computational power have advanced to the point where the oceanographic observations, both in situ and remotely sensed, can be assimilated into numerical ocean models in order to provide a four-dimensional (x-y-z-t) depiction of the evolving state of the global ocean.

  16. Global thermohaline circulation and ocean-atmosphere coupling

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli

    1997-09-01

    A global ocean general circulation model (GCM) with idealized geometry (two basins of equal size, Marotzke and Willebrand, 1991) is coupled to an energy balance atmospheric model with nonlinear parameterizations of meridional atmospheric transports of heat and moisture. With the coupled model that prescribes the atmospheric heat and moisture transports, the North Atlantic meridional mass overturning rates at equilibrium increases as the global hydrological cycle strength increases. Furthermore, the equilibrium overturning rate is primarily controlled by the hydrological cycle of the Southern Hemisphere, whereas the Northern Hemispheric hydrological cycle has little impact. The transition of the thermohaline circulation from the conveyor belt to the southern sinking state is controlled by two factors, the hydrological cycle in Northern Hemisphere, and the ratio of hydrological cycle strengths between the Northern Hemisphere and the Southern Hemisphere. Increasing either of them destabilizes the thermohaline circulation. The large-scale dynamics of the North Atlantic overturning is mainly interhemispheric, with the bulk of the overturning rising in the Southern Hemisphere. Multiple intermediate states exist that are only quantitatively different, under very small salinity perturbations. The coupled feedbacks between the thermohaline circulation and the atmospheric heat and moisture transports are demonstrated to exist in the coupled model, and all of them are positive. In addition, it is identified that the coupled feedbacks associated with the atmospheric transports in the Southern Hemisphere are also positive. Two different flux adjustments are used in the coupled model, with one adjusting the atmospheric transports efficiencies, the other adjusting the surface fluxes. Different flux adjustments influence the coupled feedback intensities, and hence the stability of the thermohaline circulation. (Copies available exclusively from MIT Libraries, Rm. 14

  17. The Ocean as a Global Reservoir of Antibiotic Resistance Genes

    PubMed Central

    Hatosy, Stephen M.

    2015-01-01

    Recent studies of natural environments have revealed vast genetic reservoirs of antibiotic resistance (AR) genes. Soil bacteria and human pathogens share AR genes, and AR genes have been discovered in a variety of habitats. However, there is little knowledge about the presence and diversity of AR genes in marine environments and which organisms host AR genes. To address this, we identified the diversity of genes conferring resistance to ampicillin, tetracycline, nitrofurantoin, and sulfadimethoxine in diverse marine environments using functional metagenomics (the cloning and screening of random DNA fragments). Marine environments were host to a diversity of AR-conferring genes. Antibiotic-resistant clones were found at all sites, with 28% of the genes identified as known AR genes (encoding beta-lactamases, bicyclomycin resistance pumps, etc.). However, the majority of AR genes were not previously classified as such but had products similar to proteins such as transport pumps, oxidoreductases, and hydrolases. Furthermore, 44% of the genes conferring antibiotic resistance were found in abundant marine taxa (e.g., Pelagibacter, Prochlorococcus, and Vibrio). Therefore, we uncovered a previously unknown diversity of genes that conferred an AR phenotype among marine environments, which makes the ocean a global reservoir of both clinically relevant and potentially novel AR genes. PMID:26296734

  18. A Multiyear Dataset of SSM/I-Derived Global Ocean Surface Turbulent Fluxes

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Shie, Chung-Lin; Atlas, Robert M.; Ardizzone, Joe; Nelkin, Eric; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The surface turbulent fluxes of momentum, latent heat, and sensible heat over global oceans are essential to weather, climate and ocean problems. Evaporation is a key component of the hydrological cycle and the surface heat budget, while the wind stress is the major forcing for driving the oceanic circulation. The global air-sea fluxes of momentum, latent and sensible heat, radiation, and freshwater (precipitation-evaporation) are the forcing for driving oceanic circulation and, hence, are essential for understanding the general circulation of global oceans. The global air-sea fluxes are required for driving ocean models and validating coupled ocean-atmosphere global models. We have produced a 7.5-year (July 1987-December 1994) dataset of daily surface turbulent fluxes over the global oceans from the Special Sensor microwave/Imager (SSM/I) data. Daily turbulent fluxes were derived from daily data of SSM/I surface winds and specific humidity, National Centers for Environmental Prediction (NCEP) sea surface temperatures, and European Centre for Medium-Range Weather Forecasts (ECMWF) air-sea temperature differences, using a stability-dependent bulk scheme. The retrieved instantaneous surface air humidity (with a 25-km resolution) validated well with that of the collocated radiosonde observations over the global oceans. Furthermore, the retrieved daily wind stresses and latent heat fluxes were found to agree well with that of the in situ measurements (IMET buoy, RV Moana Wave, and RV Wecoma) in the western Pacific warm pool during the TOGA COARE intensive observing period (November 1992-February 1993). The global distributions of 1988-94 seasonal-mean turbulent fluxes will be presented. In addition, the global distributions of 1990-93 annual-means turbulent fluxes and input variables will be compared with those of UWM/COADS covering the same period. The latter is based on the COADS (comprehensive ocean-atmosphere data set) and is recognized to be one of the best

  19. XBT effects on the global ocean observation system in the early 21st century

    NASA Astrophysics Data System (ADS)

    Chang, You-Soon; Zhang, Shaoqing

    2016-04-01

    During the early 21st century, we have experienced a transition period of global ocean observing system from expendable bathythermograph (XBT) to Argo. There has been decreasing of XBT observations, but significant increasing of Argo profiles in the global ocean. However, evaluation of the XBT observation system during this period has little been presented. Here, this study investigates the XBT effects on the global ocean observing system by using GFDL data assimilation model. After Argo period, the amount of heat content correction by XBT assimilation is significantly weaken especially in the upper ocean, but it remains in the deeper oceans below 700 m depth within a dynamic model system. This study also confirms that although XBT only provides temperature observations mostly in the upper 700 m of the northern hemisphere, it can affects both temperature and salinity fields of data assimilation system especially in the deep and southern oceans.

  20. On Verifying Currents and Other Features in the Hawaiian Islands Region Using Fully Coupled Ocean/Atmosphere Mesoscale Prediction System Compared to Global Ocean Model and Ocean Observations

    NASA Astrophysics Data System (ADS)

    Jessen, P. G.; Chen, S.

    2014-12-01

    This poster introduces and evaluates features concerning the Hawaii, USA region using the U.S. Navy's fully Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS-OS™) coupled to the Navy Coastal Ocean Model (NCOM). It also outlines some challenges in verifying ocean currents in the open ocean. The system is evaluated using in situ ocean data and initial forcing fields from the operational global Hybrid Coordinate Ocean Model (HYCOM). Verification shows difficulties in modelling downstream currents off the Hawaiian islands (Hawaii's wake). Comparing HYCOM to NCOM current fields show some displacement of small features such as eddies. Generally, there is fair agreement from HYCOM to NCOM in salinity and temperature fields. There is good agreement in SSH fields.

  1. Global oceanic emission of ammonia: Constraints from seawater and atmospheric observations

    NASA Astrophysics Data System (ADS)

    Paulot, F.; Jacob, D. J.; Johnson, M. T.; Bell, T. G.; Baker, A. R.; Keene, W. C.; Lima, I. D.; Doney, S. C.; Stock, C. A.

    2015-08-01

    Current global inventories of ammonia emissions identify the ocean as the largest natural source. This source depends on seawater pH, temperature, and the concentration of total seawater ammonia (NHx(sw)), which reflects a balance between remineralization of organic matter, uptake by plankton, and nitrification. Here we compare [NHx(sw)] from two global ocean biogeochemical models (BEC and COBALT) against extensive ocean observations. Simulated [NHx(sw)] are generally biased high. Improved simulation can be achieved in COBALT by increasing the plankton affinity for NHx within observed ranges. The resulting global ocean emissions is 2.5 TgN a-1, much lower than current literature values (7-23 TgN a-1), including the widely used Global Emissions InitiAtive (GEIA) inventory (8 TgN a-1). Such a weak ocean source implies that continental sources contribute more than half of atmospheric NHx over most of the ocean in the Northern Hemisphere. Ammonia emitted from oceanic sources is insufficient to neutralize sulfate aerosol acidity, consistent with observations. There is evidence over the Equatorial Pacific for a missing source of atmospheric ammonia that could be due to photolysis of marine organic nitrogen at the ocean surface or in the atmosphere. Accommodating this possible missing source yields a global ocean emission of ammonia in the range 2-5 TgN a-1, comparable in magnitude to other natural sources from open fires and soils.

  2. Global-Local Finite Element Analysis of Bonded Single-Lap Joints

    NASA Technical Reports Server (NTRS)

    Kilic, Bahattin; Madenci, Erdogan; Ambur, Damodar R.

    2004-01-01

    Adhesively bonded lap joints involve dissimilar material junctions and sharp changes in geometry, possibly leading to premature failure. Although the finite element method is well suited to model the bonded lap joints, traditional finite elements are incapable of correctly resolving the stress state at junctions of dissimilar materials because of the unbounded nature of the stresses. In order to facilitate the use of bonded lap joints in future structures, this study presents a finite element technique utilizing a global (special) element coupled with traditional elements. The global element includes the singular behavior at the junction of dissimilar materials with or without traction-free surfaces.

  3. Assimilation of TOPEX/POSEIDON Altimeter Data into a Global Ocean Circulation Model: Are the Results Any Good?

    NASA Technical Reports Server (NTRS)

    Fukumori, I.; Fu, L. L.; Chao, Y.

    1998-01-01

    The feasibility of assimilating satellite altimetry data into a global ocean general ocean general circulation model is studied. Three years of TOPEX/POSEIDON data is analyzed using a global, three-dimensional, nonlinear primitive equation model.

  4. Are Global In-Situ Ocean Observations Fit-for-purpose? Applying the Framework for Ocean Observing in the Atlantic.

    NASA Astrophysics Data System (ADS)

    Visbeck, M.; Fischer, A. S.; Le Traon, P. Y.; Mowlem, M. C.; Speich, S.; Larkin, K.

    2015-12-01

    There are an increasing number of global, regional and local processes that are in need of integrated ocean information. In the sciences ocean information is needed to support physical ocean and climate studies for example within the World Climate Research Programme and its CLIVAR project, biogeochemical issues as articulated by the GCP, IMBER and SOLAS projects of ICSU-SCOR and Future Earth. This knowledge gets assessed in the area of climate by the IPCC and biodiversity by the IPBES processes. The recently released first World Ocean Assessment focuses more on ecosystem services and there is an expectation that the Sustainable Development Goals and in particular Goal 14 on the Ocean and Seas will generate new demands for integrated ocean observing from Climate to Fish and from Ocean Resources to Safe Navigation and on a healthy, productive and enjoyable ocean in more general terms. In recognition of those increasing needs for integrated ocean information we have recently launched the Horizon 2020 AtlantOS project to promote the transition from a loosely-coordinated set of existing ocean observing activities to a more integrated, more efficient, more sustainable and fit-for-purpose Atlantic Ocean Observing System. AtlantOS takes advantage of the Framework for Ocean observing that provided strategic guidance for the design of the project and its outcome. AtlantOS will advance the requirements and systems design, improving the readiness of observing networks and data systems, and engaging stakeholders around the Atlantic. AtlantOS will bring Atlantic nations together to strengthen their complementary contributions to and benefits from the internationally coordinated Global Ocean Observing System (GOOS) and the Blue Planet Initiative of the Global Earth Observation System of Systems (GEOSS). AtlantOS will fill gaps of the in-situ observing system networks and will ensure that their data are readily accessible and useable. AtlantOS will demonstrate the utility of

  5. MERCATOR-Ocean monitoring and forecasting : a 4D vision of the global ocean. Data policy and applications.

    NASA Astrophysics Data System (ADS)

    Toumazou, V.; Nouel, L.; Sureau, J.; Greiner, E.; Landes, V.; Dombrowsky, E.; Charon, I.

    2003-12-01

    Mercator Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Météo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The new high-resolution model that is now on line offers 6 km grid resolution, and the first models offering global ocean coverage will be implemented late 2003. Over the next four years, Mercator Ocean also plans to establish a European Operational Oceanography Centre in Toulouse. Objective 1. Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2. Support applications for commercial shipping

  6. Building the Global Community: Joint Statement on the Role of Community Colleges in International Education

    ERIC Educational Resources Information Center

    American Association of Community Colleges (NJ1), 2006

    2006-01-01

    This joint statement by the American Association of Community Colleges and the Association of Community College Trustees describes the economic, cultural, and social value of global education in community colleges. Through bullet points, the statement describes how community colleges, including their Boards and CEOs, can promote global competency.…

  7. TARA OCEANS: A Global Analysis of Oceanic Plankton Ecosystems (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Karsenti, Eric

    2013-03-01

    Eric Karsenti of EMBL delivers the closing keynote on "TARA OCEANS: A Global Analysis of Oceanic Plankton Ecosystems" at the 8th Annual Genomics of Energy & Environment Meeting on March 28, 2013 in Walnut Creek, Calif.

  8. Keeping the lights on for global ocean salinity observation

    NASA Astrophysics Data System (ADS)

    Durack, Paul J.; Lee, Tong; Vinogradova, Nadya T.; Stammer, Detlef

    2016-03-01

    Insights about climate are being uncovered thanks to improved capacities to observe ocean salinity, an essential climate variable. However, cracks are beginning to appear in the ocean observing system that require prompt attention if we are to maintain the existing, hard-won capacity into the near future.

  9. Keeping the lights on for global ocean salinity observation

    DOE PAGESBeta

    Durack, Paul J.; Lee, Tong; Vinogradova, Nadya T.; Stammer, Detlef

    2016-02-24

    Here, insights about climate are being uncovered thanks to improved capacities to observe ocean salinity, an essential climate variable. However, cracks are beginning to appear in the ocean observing system that require prompt attention if we are to maintain the existing, hard-won capacity into the near future.

  10. Validation of GLORYS ocean bottom pressure using global high resolution GRACE mascon solutions

    NASA Astrophysics Data System (ADS)

    Boy, Jean-Paul; Rowlands, David; Luthcke, Scott; Sabaka, Terence; Lemoine, Frank; Ferry, Nicolas; Parent, Laurent

    2010-05-01

    We present the comparison of oceanic mass variations deduced from GLORYS1V1 (GLobal Ocean ReanalYses and Simulations) eddy-resolving ocean model and derived from a global high resolution GRACE (Gravity Recovery And Climate Experiment) mascon solution (Rowlands et al., 2010), for the period 2003-2008. Compared to the classical spherical harmonic solutions, the mascon (mass concentration) technique allows the retrieval of mass variations at the Earth's surface with higher temporal and spatial sampling (2 degrees and 10 days). The forward modeling of hydrology using GLDAS (Global Land Data Assimilation System) also reduces the leakage of continental hydrology into the oceans, demonstrating that the global mascon solution developed at NASA Goddard Space Flight Center (Rowlands et al., 2010) is optimal for studying global oceanic circulation. GLORYS1V1 is the first implementation of the global eddy-resolving (1/4 degree) ocean reanalysis performed by Mecator-Océan, covering the ARGO period (2002-2008). The model assimilate sea-surface height variations from radar altimetry (AVISO), sea-surface temperature (Reynolds) and in-situ temperature and salinity measurements (CORIOLIS).We also show the comparison, in terms of ocean bottom pressure variations, with the 1/4 degree operational (PSY3) models. In addition, we compare and validate both GLORYS and GRACE estimated bottom pressure variations to an independent datasets of bottom pressure records.

  11. Strong coupling among Antarctic ice shelves, ocean circulation and sea ice in a global sea-ice - ocean circulation model

    NASA Astrophysics Data System (ADS)

    Sergienko, Olga

    2016-04-01

    The thermodynamic effects of Antarctic ice shelf interaction with ocean circulation are investigated using a global, high-resolution, isopycnal ocean-circulation model coupled to a sea-ice model. The model uses NASA MERRA Reanalysis from 1992 to 2011 as atmospheric forcing. The simulated long-period variability of ice-shelf melting/freezing rates differ across geographic locations. The ice shelves in Antarctic Peninsula, Amundsen and Bellingshausen sea embayments and the Amery Ice Shelf experience an increase in melting starting from 2005. This increase in melting is due to an increase in the subsurface (100-500 m) ocean heat content in the embayments of these ice shelves, which is caused by an increase in sea-ice concentration after 2005, and consequent reduction of the heat loss to the atmosphere. Our simulations provide a strong evidence for a coupling between ocean circulation, sea ice and ice shelves.

  12. Role of Indian Ocean SST variability on the recent global warming hiatus

    NASA Astrophysics Data System (ADS)

    Arora, Anika; Rao, Suryachandra A.; Chattopadhyay, R.; Goswami, Tanmoy; George, Gibies; Sabeerali, C. T.

    2016-08-01

    Previous studies have shown a slowdown in the warming rate of the annual mean global surface temperature in the recent decade and it is referred to as the hiatus in global warming. Some recent studies have suggested that the hiatus in global warming is possibly due to strong cooling in the tropical Pacific. This study investigates the possible role of the Indian Ocean warming on the tropical Pacific cooling. Despite the continued rise in sea surface temperature (SST) over the tropical Indian Ocean, SST over the tropical Pacific has shown a cooling trend in the recent decade (2002 - 2012). It is well known fact that the Indian Ocean and the Pacific Ocean are strongly coupled to each other and the Indian Ocean basin wide warming is triggered by El Niño on interannual time scale. However, in the recent decade, this relationship is weakening. The recent Indian Ocean warming is triggering a Matsuno-Gill type response in the atmosphere by generating anomalous cyclonic circulations on either side of equator over the tropical Indian Ocean and anomalous easterlies along the tropical Pacific Ocean. These anomalous easterlies result in Ekman divergence in the equatorial Pacific and produce upwelling Kelvin waves, cools the tropical Pacific and therefore indirectly contributes to the hiatus in global warming.

  13. Trends and drivers in global surface ocean pH over the past three decades

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Gruber, N.; Landschützer, P.; Olsen, A.; Tjiputra, J.

    2014-11-01

    We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a global mean rate of decrease of -0.0018 ± 0.0004 yr-1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In two-thirds of the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean carbon chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes deviations from such equilibrium may reflect changes in the trend of surface ocean fCO2, most notably in the equatorial Pacific Ocean, or changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

  14. Consistency of the current global ocean observing systems from an Argo perspective

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Sallée, J.-B.; Chambers, D.; Le Traon, P.-Y.; Cabanes, C.; Gaillard, F.; Speich, S.; Hamon, M.

    2014-06-01

    Variations in the world's ocean heat storage and its associated volume changes are a key factor to gauge global warming and to assess the earth's energy and sea level budget. Estimating global ocean heat content (GOHC) and global steric sea level (GSSL) with temperature/salinity data from the Argo network reveals a positive change of 0.5 ± 0.1 W m-2 (applied to the surface area of the ocean) and 0.5 ± 0.1 mm year-1 during the years 2005 to 2012, averaged between 60° S and 60° N and the 10-1500 m depth layer. In this study, we present an intercomparison of three global ocean observing systems: the Argo network, satellite gravimetry from GRACE and satellite altimetry. Their consistency is investigated from an Argo perspective at global and regional scales during the period 2005-2010. Although we can close the recent global ocean sea level budget within uncertainties, sampling inconsistencies need to be corrected for an accurate global budget due to systematic biases in GOHC and GSSL in the Tropical Ocean. Our findings show that the area around the Tropical Asian Archipelago (TAA) is important to closing the global sea level budget on interannual to decadal timescales, pointing out that the steric estimate from Argo is biased low, as the current mapping methods are insufficient to recover the steric signal in the TAA region. Both the large regional variability and the uncertainties in the current observing system prevent us from extracting indirect information regarding deep-ocean changes. This emphasizes the importance of continuing sustained effort in measuring the deep ocean from ship platforms and by beginning a much needed automated deep-Argo network.

  15. Global warming: Growing feedback from ocean carbon to climate

    NASA Astrophysics Data System (ADS)

    Joos, Fortunat

    2015-06-01

    The finding that feedbacks between the ocean's carbon cycle and climate may become larger than terrestrial carbon-climate feedbacks has implications for the socio-economic effects of today's fossil-fuel emissions.

  16. Visualization and analysis of eddies in a global ocean simulation

    SciTech Connect

    Williams, Sean J; Hecht, Matthew W; Petersen, Mark; Strelitz, Richard; Maltrud, Mathew E; Ahrens, James P; Hlawitschka, Mario; Hamann, Bernd

    2010-10-15

    Eddies at a scale of approximately one hundred kilometers have been shown to be surprisingly important to understanding large-scale transport of heat and nutrients in the ocean. Due to difficulties in observing the ocean directly, the behavior of eddies below the surface is not very well understood. To fill this gap, we employ a high-resolution simulation of the ocean developed at Los Alamos National Laboratory. Using large-scale parallel visualization and analysis tools, we produce three-dimensional images of ocean eddies, and also generate a census of eddy distribution and shape averaged over multiple simulation time steps, resulting in a world map of eddy characteristics. As expected from observational studies, our census reveals a higher concentration of eddies at the mid-latitudes than the equator. Our analysis further shows that mid-latitude eddies are thicker, within a range of 1000-2000m, while equatorial eddies are less than 100m thick.

  17. Ocean Sciences Best Student Papers for 1988 Joint AGU/ASLO Meeting

    NASA Astrophysics Data System (ADS)

    The Ocean Sciences Section has selected four students to receive Best Student Paper Awards for the 1988 Joint AGU and American Society for Limnology and Oceanography (ASLO) Meeting held last January in New Orleans.Brad M. Bebout received a Best Student Paper Award for his paper “The Use of Agricultural Waste (Corn Slash) to Support Microzone-Associated Nitrogen Fixation by Marine Microorganisms.” Bebout is an M.S. candidate in marine sciences at the University of North Carolina at Chapel Hill. His thesis is on “The Role of Marine Fungi in Food Selection and Nutrition of the Salt Marsh Periwinkle Littorina irrorata Say (Gastropoda).” He received his B.A. in biology from the University of California, Santa Cruz.

  18. Global Bathymetric Prediction For Ocean Modeling and Marine Geophysics

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Smith, Walter H. F.; Sichoix, Lydie; Frey, Herbert V. (Technical Monitor)

    2001-01-01

    We proposed to construct a complete bathymetric map of the oceans at a 3-10 km resolution by combining all of the available depth soundings collected over the past 30 years with high resolution marine gravity information provided by the Geosat, ERS-1/2, and Topex/Poseidon altimeters. Detailed bathymetry is essential for understanding physical oceanography and marine geophysics. Currents and tides are controlled by the overall shapes of the ocean basins as well as the smaller sharp ocean ridges and seamounts. Because erosion rates are low in the deep oceans, detailed bathymetry reveals the mantle convection patterns, the plate boundaries, the cooling/subsidence of the oceanic lithosphere, the oceanic plateaus, and the distribution of off-ridge volcanoes. We proposed to: (1) Accumulate all available depth soundings collected over the past 30 years; (2) Use the short wavelength (< 160 km) satellite gravity information to interpolate between sparse ship soundings; (3) Improve the resolution of the marine gravity field using enhanced estimates along repeat altimeter profiles together with the dense altimeter measurements; (4) Refine/improve bathymetric predictions using the improved resolution gravity field and also by investigating computer-intensive methods for bathymetric prediction such as inverse theory; and (5) Produce a 'Globe of the Earth' similar to the globe of Venus prepared by the NASA Magellan investigation. This will also include the best available digital land data.

  19. Sensitivity of global ocean heat content from reanalyses to the atmospheric reanalysis forcing: A comparative study

    NASA Astrophysics Data System (ADS)

    Storto, Andrea; Yang, Chunxue; Masina, Simona

    2016-05-01

    The global ocean heat content evolution is a key component of the Earth's energy budget and can be consistently determined by ocean reanalyses that assimilate hydrographic profiles. This work investigates the impact of the atmospheric reanalysis forcing through a multiforcing ensemble ocean reanalysis, where the ensemble members are forced by five state-of-the-art atmospheric reanalyses during the meteorological satellite era (1979-2013). Data assimilation leads the ensemble to converge toward robust estimates of ocean warming rates and significantly reduces the spread (1.48 ± 0.18 W/m2, per unit area of the World Ocean); hence, the impact of the atmospheric forcing appears only marginal for the global heat content estimates in both upper and deeper oceans. A sensitivity assessment performed through realistic perturbation of the main sources of uncertainty in ocean reanalyses highlights that bias correction and preprocessing of in situ observations represent the most crucial component of the reanalysis, whose perturbation accounts for up to 60% of the ocean heat content anomaly variability in the pre-Argo period. Although these results may depend on the single reanalysis system used, they reveal useful information for the ocean observation community and for the optimal generation of perturbations in ocean ensemble systems.

  20. Integrated earth system studies. Joint research efforts of global change

    SciTech Connect

    Rosswall, T.; Ojima, D.S.

    1995-06-01

    The physical, chemical and biological studies which have documented the changes to the Earth system and investigated the critical processes which couple the biosphere and the geosphere have increased our understanding of the natural variation in the Earth`s dynamics and of how human activities have modified these processes. This effort has been fundamental in furthering our understanding of what controls the Earth`s energy budget, global biogeochemistry including atmospheric composition of radiatively active gases and the hydrological cycle. This research has necessitated unprecedented international collaboration among various scientific disciplines and led to the development of major research programs like the World Climate Research Programme, the International Geosphere-Biosphere Programme, and the Human Dimensions of Global Environmental Change Programme. Through the Intergovernmental Panel on Climate Change a continuous assessment is carried out and provides the much needed bridge between science and policy making manifested in the development of a Framework Convention of Climate Change. The challenge now facing the global change science community is to maintain the interest in elucidating the functioning of the global system when political interest may move elsewhere. To understand the functioning of the Earth system is a daunting scientific challenge and a necessity for the necessary stewardship of planet Earth.

  1. CLIVAR-GSOP/GODAE Ocean Synthesis Inter-Comparison of Global Air-Sea Fluxes From Ocean and Coupled Reanalyses

    NASA Astrophysics Data System (ADS)

    Valdivieso, Maria

    2014-05-01

    The GODAE OceanView and CLIVAR-GSOP ocean synthesis program has been assessing the degree of consistency between global air-sea flux data sets obtained from ocean or coupled reanalyses (Valdivieso et al., 2014). So far, fifteen global air-sea heat flux products obtained from ocean or coupled reanalyses have been examined: seven are from low-resolution ocean reanalyses (BOM PEODAS, ECMWF ORAS4, JMA/MRI MOVEG2, JMA/MRI MOVECORE, Hamburg Univ. GECCO2, JPL ECCOv4, and NCEP GODAS), five are from eddy-permitting ocean reanalyses developed as part of the EU GMES MyOcean program (Mercator GLORYS2v1, Reading Univ. UR025.3, UR025.4, UKMO GloSea5, and CMCC C-GLORS), and the remaining three are couple reanalyses based on coupled climate models (JMA/MRI MOVE-C, GFDL ECDA and NCEP CFSR). The global heat closure in the products over the period 1993-2009 spanned by all data sets is presented in comparison with observational and atmospheric reanalysis estimates. Then, global maps of ensemble spread in the seasonal cycle, and of the Signal to Noise Ratio of interannual flux variability over the 17-yr common period are shown to illustrate the consistency between the products. We have also studied regional variability in the products, particularly at the OceanSITES project locations (such as, for instance, the TAO/TRITON and PIRATA arrays in the Tropical Pacific and Atlantic, respectively). Comparisons are being made with other products such as OAFlux latent and sensible heat fluxes (Yu et al., 2008) combined with ISCCP satellite-based radiation (Zhang et al., 2004), the ship-based NOC2.0 product (Berry and Kent, 2009), the Large and Yeager (2009) hybrid flux dataset CORE.2, and two atmospheric reanalysis products, the ECMWF ERA-Interim reanalysis (referred to as ERAi, Dee et al., 2011) and the NCEP/DOE reanalysis R2 (referred to as NCEP-R2, Kanamitsu et al., 2002). Preliminary comparisons with the observational flux products from OceanSITES are also underway. References Berry, D

  2. Ocean Front Detection from MERIS and OLCI Ocean Colour Data Applied to Marine Conservation and Global Oceanography

    NASA Astrophysics Data System (ADS)

    Miller, Peter I.

    2015-12-01

    Ocean front detection and aggregation techniques were recently applied to 300m resolution Medium Resolution Imaging Spectrometer (MERIS) satellite ocean colour data for the first time, to describe frequently occurring shelf-sea fronts near to the Scottish coast (Miller et al., in press). This resolution enabled the location of smaller frontal zones and those in close proximity to a convoluted coastline, and was used to identify zones of ecological importance that could assist the process of defining marine protected areas. Frequent front zones are associated with higher abundance of plankton, certain pelagic fish and megafauna. This paper anticipates the improved insights into submesoscale sediment and plankton dynamics that will result from application of these techniques to the Ocean and Land Colour Instrument (OLCI) on Sentinel-3a and 3b. Looking to the global scale, we show global chlorophyll-a fronts, eddies and other structures detected from the ESA Ocean Colour Climate Change Initiative daily 4 km resolution merged dataset derived from MERIS, SeaWiFS and MODIS data. This emphasises the importance of the Sentinel missions to improving study of both physical and biological ocean processes.

  3. A joint method to retrieve directional ocean wave spectra from SAR and wave spectrometer data

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan

    2015-11-01

    This paper proposes a joint method to simultaneously retrieve wave spectra at different scales from spaceborne Synthetic Aperture Radar (SAR) and wave spectrometer data. The method combines the output from the two different sensors to overcome retrieval limitations that occur in some sea states. The wave spectrometer sensitivity coefficient is estimated using an effective significant wave height (SWH), which is an average of SAR-derived and wave spectrometer-derived SWH. This averaging extends the area of the sea surface sampled by the nadir beam of the wave spectrometer to improve the accuracy of the estimated sensitivity coefficient in inhomogeneous sea states. Wave spectra are then retrieved from SAR data using wave spectrometer-derived spectra as first guess spectra to complement the short waves lost in SAR data retrieval. In addition, the problem of 180° ambiguity in retrieved spectra is overcome using SAR imaginary cross spectra. Simulated data were used to validate the joint method. The simulations demonstrated that retrieved wave parameters, including SWH, peak wave length (PWL), and peak wave direction (PWD), agree well with reference parameters. Collocated data from ENVISAT advanced SAR (ASAR), the airborne wave spectrometer STORM, the PHAROS buoy, and the European Centre for Medium-Range Weather Forecasting (ECMWF) were then used to verify the proposed method. Wave parameters retrieved from STORM and two ASAR images were compared to buoy and ECMWF wave data. Most of the retrieved parameters were comparable to reference parameters. The results of this study show that the proposed joint retrieval method could be a valuable complement to traditional methods used to retrieve directional ocean wave spectra, particularly in inhomogeneous sea states.

  4. A joint method to retrieve directional ocean wave spectra from SAR and wave spectrometer data

    NASA Astrophysics Data System (ADS)

    Ren, Lin; Yang, Jingsong; Zheng, Gang; Wang, Juan

    2016-07-01

    This paper proposes a joint method to simultaneously retrieve wave spectra at different scales from spaceborne Synthetic Aperture Radar (SAR) and wave spectrometer data. The method combines the output from the two different sensors to overcome retrieval limitations that occur in some sea states. The wave spectrometer sensitivity coefficient is estimated using an effective significant wave height (SWH), which is an average of SAR-derived and wave spectrometer-derived SWH. This averaging extends the area of the sea surface sampled by the nadir beam of the wave spectrometer to improve the accuracy of the estimated sensitivity coefficient in inhomogeneous sea states. Wave spectra are then retrieved from SAR data using wave spectrometer-derived spectra as first guess spectra to complement the short waves lost in SAR data retrieval. In addition, the problem of 180° ambiguity in retrieved spectra is overcome using SAR imaginary cross spectra. Simulated data were used to validate the joint method. The simulations demonstrated that retrieved wave parameters, including SWH, peak wave length (PWL), and peak wave direction (PWD), agree well with reference parameters. Collocated data from ENVISAT advanced SAR (ASAR), the airborne wave spectrometer STORM, the PHAROS buoy, and the European Centre for Medium-Range Weather Forecasting (ECMWF) were then used to verify the proposed method. Wave parameters retrieved from STORM and two ASAR images were compared to buoy and ECMWF wave data. Most of the retrieved parameters were comparable to reference parameters. The results of this study show that the proposed joint retrieval method could be a valuable complement to traditional methods used to retrieve directional ocean wave spectra, particularly in inhomogeneous sea states.

  5. Penetration of UV-visible solar radiation in the global oceans: Insights from ocean color remote sensing

    NASA Astrophysics Data System (ADS)

    Lee, Zhongping; Hu, Chuanmin; Shang, Shaoling; Du, Keping; Lewis, Marlon; Arnone, Robert; Brewin, Robert

    2013-09-01

    Penetration of solar radiation in the ocean is determined by the attenuation coefficient (Kd(λ)). Following radiative transfer theory, Kd is a function of angular distribution of incident light and water's absorption and backscattering coefficients. Because these optical products are now generated routinely from satellite measurements, it is logical to evolve the empirical Kd to a semianalytical Kd that is not only spectrally flexible, but also the sun-angle effect is accounted for explicitly. Here, the semianalytical model developed in Lee et al. (2005b) is revised to account for the shift of phase function between molecular and particulate scattering from the short to long wavelengths. Further, using field data collected independently from oligotrophic ocean to coastal waters covering >99% of the Kd range for the global oceans, the semianalytically derived Kd was evaluated and found to agree with measured data within ˜7-26%. The updated processing system was applied to MODIS measurements to reveal the penetration of UVA-visible radiation in the global oceans, where an empirical procedure to correct Raman effect was also included. The results indicated that the penetration of the blue-green radiation for most oceanic waters is ˜30-40% deeper than the commonly used euphotic zone depth; and confirmed that at a depth of 50-70 m there is still ˜10% of the surface UVA radiation (at 360 nm) in most oligotrophic waters. The results suggest a necessity to modify or expand the light attenuation product from satellite ocean-color measurements in order to be more applicable for studies of ocean physics and biogeochemistry.

  6. Pliocene three-dimensional global ocean temperature reconstruction

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.; Foley, K.M.

    2009-01-01

    The thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water temperature estimates from 27 locations produced using Mg/Ca paleothermometry based upon the ostracod genus Krithe. Deep water temperature estimates are skewed toward the Atlantic Basin (63% of the locations) and represent depths from 1000m to 4500 m. This reconstruction, meant to serve as a validation data set as well as an initialization for coupled numerical climate models, assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic Bottom Water (AABW) production (relative to present day) as well as possible changes in the depth of intermediate waters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.

  7. Pliocene three-dimensional global ocean temperature reconstruction

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.; Foley, K.M.

    2009-01-01

    A snapshot of the thermal structure of the mid-Piacenzian ocean is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water tempera-5 ture estimates produced using Mg/Ca paleothermometry. This reconstruction assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic Ocean during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic BottomWater (AABW) production (relative to present day) as well as possible changes in the depth of intermediate wa15 ters. The reconstructed mid-Piacenzian three-dimensional ocean was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.

  8. New features of global climatology revealed by satellite-derived oceanic rainfall maps

    NASA Technical Reports Server (NTRS)

    Rao, M. S. V.; Theon, J. S.

    1977-01-01

    Quantitative rainfall maps over the oceanic areas of the globe were derived from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) data. Analysis of satellite derived oceanic rainfall maps reveal certain distinctive characteristics of global patterns for the years 1973-74. The main ones are (1) the forking of the Intertropical Convergence Zone in the Pacific, (2) a previously unrecognized rain area in the South Atlantic, (3) the bimodal behavior of rainbelts in the Indian Ocean and (4) the large interannual variability in oceanic rainfall. These features are discussed.

  9. The polar oceans and their role in shaping the global environment

    SciTech Connect

    Johannessen, O.M.; Muench, R.D.; Overland, J.E.

    1994-12-31

    This book is a comprehensive treatment of major advances made in the past decade in understanding of the interactions between polar oceans and the local atmosphere and ocean system. Included are 38 papers discussing the circulation, dynamics and convective processes occurring in the polar oceans; its carbon cycle chemistry and biology; the paleooceanography and paleoclimate of the polar regions; the interaction between the polar ocean and the global climate, and a variety of strategies for detection of climate change in polar regions, predominantly Arctic.

  10. Oceanic Carbon Dioxide Uptake in a Model of Century-Scale Global Warming

    PubMed

    Sarmiento; Le Quéré C

    1996-11-22

    In a model of ocean-atmosphere interaction that excluded biological processes, the oceanic uptake of atmospheric carbon dioxide (CO2) was substantially reduced in scenarios involving global warming relative to control scenarios. The primary reason for the reduced uptake was the weakening or collapse of the ocean thermohaline circulation. Such a large reduction in this ocean uptake would have a major impact on the future growth rate of atmospheric CO2. Model simulations that include a simple representation of biological processes show a potentially large offsetting effect resulting from the downward flux of biogenic carbon. However, the magnitude of the offset is difficult to quantify with present knowledge. PMID:8910268

  11. Global Upper Ocean Salinity Change in the Recent Years 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Ren, L.; Hackert, E. C.; Arkin, P. A.; Busalacchi, A. J.

    2011-12-01

    Recent satellite missions, such as Aquarius and the European Soil Moisture/Ocean Salinity (SMOS) are designed to observe sea surface salinity on a global scale with an accuracy of 0.2 PSU on a monthly basis . It is envisioned that these satellites will provide an unprecedented view of SSS leading to a better estimate of the global salinity budget. However, until enough data become available from these satellites, in situ observations are utilized to make large scale estimates of the salinity trend. Data from Argo floats indicate that mean salinity in the upper 700 m of the global ocean has increased from 2006 to 2010. Such a salinity change implies a net freshwater loss from the ocean to the atmosphere. Oceanic precipitation observations are extremely limited, but large scale data sets have been developed using estimates derived from both satellite observations and atmospheric data assimilation systems. In this presentation, precipitation products including GPCP, CMAP, MERRA and NCEP-CFSR are used to investigate the freshwater changes. The global ocean average of the precipitation shows a decrease during the time period of 2006 to 2010, consistent with the salinity change. We will describe the spatial patterns of these changes in both salinity and precipitation during this time period, and compare the areal integrals with the other components of the spatially averaged oceanic freshwater budget. In addition, we will put the upper layer salinity and precipitation trends into context by comparing these observations with longer time series of oceanic/atmospheric reanalysis data.

  12. How well do global ocean biogeochemistry models simulate dissolved iron distributions?

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Aumont, Olivier; DeAth, Ros; Dunne, John P.; Dutkiewicz, Stephanie; Galbraith, Eric; Misumi, Kazuhiro; Moore, J. Keith; Ridgwell, Andy; Sherman, Elliot; Stock, Charles; Vichi, Marcello; Völker, Christoph; Yool, Andrew

    2016-02-01

    Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.

  13. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Buitenhuis, E. T.; Moriarty, R.; Alvain, S.; Aumont, O.; Bopp, L.; Chollet, S.; Enright, C.; Franklin, D. J.; Geider, R. J.; Harrison, S. P.; Hirst, A.; Larsen, S.; Legendre, L.; Platt, T.; Prentice, I. C.; Rivkin, R. B.; Sathyendranath, S.; Stephens, N.; Vogt, M.; Sailley, S.; Vallina, S. M.

    2015-07-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs); six types of phytoplankton, three types of zooplankton, and heterotrophic bacteria. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing zooplankton, and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean High Nutrient Low Chlorophyll (HNLC) region during summer. When model simulations do not represent crustacean macrozooplankton grazing, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there was no iron deposition from dust. When model simulations included the developments of the zooplankton component, the simulation of phytoplankton biomass improved and the high chlorophyll summer bias in the Southern Ocean HNLC region largely disappeared. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  14. The role of clouds and oceans in global greenhouse warming. Part 1, Progress report

    SciTech Connect

    Hoffert, M.I.

    1992-12-01

    During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, ``Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature``. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales.

  15. Global Observations and Understanding of the General Circulation of the Oceans

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The workshop was organized to: (1) assess the ability to obtain ocean data on a global scale that could profoundly change our understanding of the circulation; (2) identify the primary and secondary elements needed to conduct a World Ocean Circulation Experiment (WOCE); (3) if the ability is achievable, to determine what the U.S. role in such an experiment should be; and (4) outline the steps necessary to assure that an appropriate program is conducted. The consensus of the workshop was that a World Ocean Circulation Experiment appears feasible, worthwhile, and timely. Participants did agree that such a program should have the overall goal of understanding the general circulation of the global ocean well enough to be able to predict ocean response and feedback to long-term changes in the atmosphere. The overall goal, specific objectives, and recommendations for next steps in planning such an experiment are included.

  16. How well-connected is the surface of the global ocean?

    NASA Astrophysics Data System (ADS)

    Froyland, Gary; Stuart, Robyn M.; van Sebille, Erik

    2014-09-01

    The Ekman dynamics of the ocean surface circulation is known to contain attracting regions such as the great oceanic gyres and the associated garbage patches. Less well-known are the extents of the basins of attractions of these regions and how strongly attracting they are. Understanding the shape and extent of the basins of attraction sheds light on the question of the strength of connectivity of different regions of the ocean, which helps in understanding the flow of buoyant material like plastic litter. Using short flow time trajectory data from a global ocean model, we create a Markov chain model of the surface ocean dynamics. The surface ocean is not a conservative dynamical system as water in the ocean follows three-dimensional pathways, with upwelling and downwelling in certain regions. Using our Markov chain model, we easily compute net surface upwelling and downwelling, and verify that it matches observed patterns of upwelling and downwelling in the real ocean. We analyze the Markov chain to determine multiple attracting regions. Finally, using an eigenvector approach, we (i) identify the five major ocean garbage patches, (ii) partition the ocean into basins of attraction for each of the garbage patches, and (iii) partition the ocean into regions that demonstrate transient dynamics modulo the attracting garbage patches.

  17. How well-connected is the surface of the global ocean?

    PubMed

    Froyland, Gary; Stuart, Robyn M; van Sebille, Erik

    2014-09-01

    The Ekman dynamics of the ocean surface circulation is known to contain attracting regions such as the great oceanic gyres and the associated garbage patches. Less well-known are the extents of the basins of attractions of these regions and how strongly attracting they are. Understanding the shape and extent of the basins of attraction sheds light on the question of the strength of connectivity of different regions of the ocean, which helps in understanding the flow of buoyant material like plastic litter. Using short flow time trajectory data from a global ocean model, we create a Markov chain model of the surface ocean dynamics. The surface ocean is not a conservative dynamical system as water in the ocean follows three-dimensional pathways, with upwelling and downwelling in certain regions. Using our Markov chain model, we easily compute net surface upwelling and downwelling, and verify that it matches observed patterns of upwelling and downwelling in the real ocean. We analyze the Markov chain to determine multiple attracting regions. Finally, using an eigenvector approach, we (i) identify the five major ocean garbage patches, (ii) partition the ocean into basins of attraction for each of the garbage patches, and (iii) partition the ocean into regions that demonstrate transient dynamics modulo the attracting garbage patches. PMID:25273206

  18. Trends and drivers in global surface ocean pH over the past 3 decades

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Gruber, N.; Landschützer, P.; Olsen, A.; Tjiputra, J.

    2015-03-01

    We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr-1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO2 chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean fCO2 is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

  19. Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae).

    PubMed

    Jackson, Jennifer A; Steel, Debbie J; Beerli, P; Congdon, Bradley C; Olavarría, Carlos; Leslie, Matthew S; Pomilla, Cristina; Rosenbaum, Howard; Baker, C Scott

    2014-07-01

    Humpback whales (Megaptera novaeangliae) annually undertake the longest migrations between seasonal feeding and breeding grounds of any mammal. Despite this dispersal potential, discontinuous seasonal distributions and migratory patterns suggest that humpbacks form discrete regional populations within each ocean. To better understand the worldwide population history of humpbacks, and the interplay of this species with the oceanic environment through geological time, we assembled mitochondrial DNA control region sequences representing approximately 2700 individuals (465 bp, 219 haplotypes) and eight nuclear intronic sequences representing approximately 70 individuals (3700 bp, 140 alleles) from the North Pacific, North Atlantic and Southern Hemisphere. Bayesian divergence time reconstructions date the origin of humpback mtDNA lineages to the Pleistocene (880 ka, 95% posterior intervals 550-1320 ka) and estimate radiation of current Northern Hemisphere lineages between 50 and 200 ka, indicating colonization of the northern oceans prior to the Last Glacial Maximum. Coalescent analyses reveal restricted gene flow between ocean basins, with long-term migration rates (individual migrants per generation) of less than 3.3 for mtDNA and less than 2 for nuclear genomic DNA. Genetic evidence suggests that humpbacks in the North Pacific, North Atlantic and Southern Hemisphere are on independent evolutionary trajectories, supporting taxonomic revision of M. novaeangliae to three subspecies. PMID:24850919

  20. The Global Ocean Data Analysis Project version 2 (GLODAPv2) - an internally consistent data product for the world ocean

    NASA Astrophysics Data System (ADS)

    Olsen, Are; Key, Robert M.; van Heuven, Steven; Lauvset, Siv K.; Velo, Anton; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; Jutterström, Sara; Steinfeldt, Reiner; Jeansson, Emil; Ishii, Masao; Pérez, Fiz F.; Suzuki, Toru

    2016-08-01

    Version 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. The data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. This compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg-1 in dissolved inorganic carbon, 6 µmol kg-1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracers.The original data and their documentation and doi codes are available at the Carbon Dioxide Information Analysis Center (oceans/GLODAPv2/" target="_blank">http://cdiac.ornl.gov/oceans/GLODAPv2/). This site also provides access to the calibrated data product, which is provided as a single global file or four regional ones - the Arctic, Atlantic, Indian, and Pacific oceans - under the doi:10.3334/CDIAC

  1. Accuracy assessment of the global ionospheric model over the Southern Ocean based on dynamic observation

    NASA Astrophysics Data System (ADS)

    Luo, xiaowen

    2016-04-01

    The global ionospheric model based on the reference stations of the Global Navigation Satellite System (GNSS) of the International GNSS Services is presently the most commonly used products of the global ionosphere. It is very important to comprehensively analyze and evaluate the accuracy and reliability of the model for the reasonable use of this kind of ionospheric product. This work is different to the traditional performance evaluation of the global ionosphere model based on observation data of ground-based static reference stations. The preliminary evaluation and analysis of the the global ionospheric model was conducted with the dynamic observation data across different latitudes over the southern oceans. The validation results showed that the accuracy of the global ionospheric model over the southern oceans is about 5 TECu, which deviates from the measured ionospheric TEC by about -0.6 TECu.

  2. Joint CO2 and CH4 accountability for global warming

    PubMed Central

    Smith, Kirk R.; Desai, Manish A.; Rogers, Jamesine V.; Houghton, Richard A.

    2013-01-01

    We propose a transparent climate debt index incorporating both methane (CH4) and carbon dioxide (CO2) emissions. We develop national historic emissions databases for both greenhouse gases to 2005, justifying 1950 as the starting point for global perspectives. We include CO2 emissions from fossil sources [CO2(f)], as well as, in a separate analysis, land use change and forestry. We calculate the CO2(f) and CH4 remaining in the atmosphere in 2005 from 205 countries using the Intergovernmental Panel on Climate Change’s Fourth Assessment Report impulse response functions. We use these calculations to estimate the fraction of remaining global emissions due to each country, which is applied to total radiative forcing in 2005 to determine the combined climate debt from both greenhouse gases in units of milliwatts per square meter per country or microwatts per square meter per person, a metric we term international natural debt (IND). Australia becomes the most indebted large country per capita because of high CH4 emissions, overtaking the United States, which is highest for CO2(f). The differences between the INDs of developing and developed countries decline but remain large. We use IND to assess the relative reduction in IND from choosing between CO2(f) and CH4`control measures and to contrast the imposed versus experienced health impacts from climate change. Based on 2005 emissions, the same hypothetical impact on world 2050 IND could be achieved by decreasing CH4 emissions by 46% as stopping CO2 emissions entirely, but with substantial differences among countries, implying differential optimal strategies. Adding CH4 shifts the basic narrative about differential international accountability for climate change. PMID:23847202

  3. Joint CO2 and CH4 accountability for global warming.

    PubMed

    Smith, Kirk R; Desai, Manish A; Rogers, Jamesine V; Houghton, Richard A

    2013-07-30

    We propose a transparent climate debt index incorporating both methane (CH4) and carbon dioxide (CO2) emissions. We develop national historic emissions databases for both greenhouse gases to 2005, justifying 1950 as the starting point for global perspectives. We include CO2 emissions from fossil sources [CO2(f)], as well as, in a separate analysis, land use change and forestry. We calculate the CO2(f) and CH4 remaining in the atmosphere in 2005 from 205 countries using the Intergovernmental Panel on Climate Change's Fourth Assessment Report impulse response functions. We use these calculations to estimate the fraction of remaining global emissions due to each country, which is applied to total radiative forcing in 2005 to determine the combined climate debt from both greenhouse gases in units of milliwatts per square meter per country or microwatts per square meter per person, a metric we term international natural debt (IND). Australia becomes the most indebted large country per capita because of high CH4 emissions, overtaking the United States, which is highest for CO2(f). The differences between the INDs of developing and developed countries decline but remain large. We use IND to assess the relative reduction in IND from choosing between CO2(f) and CH4`control measures and to contrast the imposed versus experienced health impacts from climate change. Based on 2005 emissions, the same hypothetical impact on world 2050 IND could be achieved by decreasing CH4 emissions by 46% as stopping CO2 emissions entirely, but with substantial differences among countries, implying differential optimal strategies. Adding CH4 shifts the basic narrative about differential international accountability for climate change. PMID:23847202

  4. Seismic performance and global ductility of RC frames rehabilitated with retrofitted joints by CFRP laminates

    NASA Astrophysics Data System (ADS)

    Fakharifar, M.; Sharbatdar, M. K.; Lin, Z.; Dalvand, A.; Sivandi-Pour, A.; Chen, G.

    2014-03-01

    This paper presents a new FRP retrofitting scheme to strengthen local beam-column joints in reinforced concrete (RC) frames. The new retrofitting scheme was proposed following a preliminary study of four different existing retrofitting schemes. A numerical simulation was conducted to evaluate the effectiveness of FRP-strengthened reinforced concrete frames by bridging behavior of local joints to the whole structure. Local confinement effects due to varying retrofitting schemes in the joints were simulated in the frame model. The seismic behavior factor was used to evaluate the seismic performance of the strengthened RC frames. The results demonstrated that the new proposed retrofitting scheme was robust and promising, and finite element analysis appropriately captured the strength and global ductility of the frame due to upgrading of the local joints.

  5. Seasonal Distributions of Global Ocean Chlorophyll and Nutrients: Analysis with a Coupled Ocean General Circulation Biogeochemical, and Radiative Model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.

    1999-01-01

    A coupled general ocean circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. The model is driven by climatological meteorological conditions, cloud cover, and sea surface temperature. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability, and the interactions among three functional phytoplankton groups (diatoms, chorophytes, and picoplankton) and three nutrient groups (nitrate, ammonium, and silicate). Phytoplankton groups are initialized as homogeneous fields horizontally and vertically, and allowed to distribute themselves according to the prevailing conditions. Basin-scale model chlorophyll results are in very good agreement with CZCS pigments in virtually every global region. Seasonal variability observed in the CZCS is also well represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are also in good conformance, although occasional departures are apparent. Agreement of nitrate distributions with in situ data is even better, including seasonal dynamics, except for the equatorial Atlantic. The good agreement of the model with satellite and in situ data sources indicates that the model dynamics realistically simulate phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization, and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent the great diversity of physical, biological

  6. Assessment of Global Oceanic Net Freshwater Flux Products Using Argo Salinity Observations

    NASA Astrophysics Data System (ADS)

    Ren, L.; Arkin, P. A.; Hackert, E. C.; Busalacchi, A. J.

    2012-12-01

    The annual mean global upper ocean salt budget is investigated using the Argo profiling float data from 2006 to 2011, which provides a way to estimate the annual mean oceanic evaporation and precipitation (E-P) from the ocean salinity. Employing this "ocean rain gauge" concept, E-P estimated from the salt budget is compared with the various satellite based oceanic precipitation and evaporation observational products. In this study, twelve sets of E-P from the evaporation and precipitation products including the precipitation datasets GPCP, CMAP and TRMM and the evaporation datasets OAFlux, GSSTF2b, IFREMER and RSS are compared to the E-P estimated from the salinity. We will describe the spatial patterns of the various E-P products derived from the satellite based data sets and compare these patterns to those derived from the oceanic salinity on the annual mean time scale. We will also examine time series of near-global integrated E-P derived from satellite products and compare them to time series based on oceanic salinity observations as well as continental discharge. This intercomparison of independently derived estimates of fresh water flux at the ocean surface will improve our understanding of errors in remotely sensed estimates of evaporation and precipitation.

  7. Global Ocean Circulation Modeling with an Isopycnic Coordinate Model. Final Report for May 1, 1998 - April 30, 2002

    SciTech Connect

    Bleck, R.

    2004-05-19

    The overall aim of this project was to continue development of a global version of the Miami Isopycnic Coordinate Ocean Model (MICOM) with the intent of turning it into a full-fledged oceanic component of an earth system model.

  8. Total Human-Caused Global Ocean Heat Uptake Nearly Doubles During Recent Surface Warming Hiatus

    NASA Astrophysics Data System (ADS)

    Gleckler, P. J.; Durack, P. J.; Stouffer, R. J.; Johnson, G. C.; Forest, C. E.

    2015-12-01

    Formal detection and attribution studies have used observations and climate models to identify an anthropogenic warming signature in the upper (0­-700 m) ocean. Recently, as a result of the so-called surface warming hiatus, there has been considerable interest in global ocean heat content (OHC) changes in the deeper ocean, including natural and anthropogenically forced changes evidenced in observational, modelling, and data re-analysis studies. We rely on OHC change estimates from a diverse collection of measurement systems including data from the 19th Century Challenger expedition, a multi-decadal record of ship-based in-situ mostly upper ocean measurements, the more recent near-global Argo floats profiling to intermediate (2000m) depths, and full-depth repeated transoceanic sections. By diagnosing simulated global OHC changes in historically-forced climate models in three depth layers, we show that the current generation of climate models is broadly consistent with multi-decadal estimates of upper, intermediate (700­-2000m) and deep (2000m - ­bottom) global OHC changes as well as with Argo-based estimates over the most recent period. Our results suggest that nearly half of the 1860-­present human-caused increases in global ocean heat content may have occurred since 1998.

  9. Digital Global Map of Potential Ocean Paleoshorelines on Mars

    NASA Astrophysics Data System (ADS)

    Parker, T. J.; Calef, F. J.

    2012-05-01

    Our objective is to compile a global shoreline map, in the form of GIS shapefiles. This map will be used to investigate deviations from horizontal that might indicate neotectonic changes such as mass accumulations and crustal deformations over time.

  10. Constraints on the transient climate response from observed global temperature and ocean heat uptake

    NASA Astrophysics Data System (ADS)

    Knutti, Reto; Tomassini, Lorenzo

    2008-05-01

    Projections of future transient global temperature increase in climate models for a known forcing depend on the strength of the atmospheric feedbacks and the rate of transient ocean heat uptake. A Bayesian framework and an intermediate complexity climate model are used to calculate a probability density function (PDF) of the transient climate response (TCR), constrained by observations of global surface warming and ocean heat uptake. The PDF constrained by observations is wider than the TCR range of current climate models, and has a slightly lower mean. Uncertainties in the observed ocean warming are shown to potentially affect the TCR. It is proposed, however, that even if models were found to overestimate ocean heat uptake, correcting that bias would lead to revisions in surface temperature projections over the twenty-first century that are smaller than the uncertainties introduced by poorly quantified atmospheric feedbacks.

  11. Oceanic primary production: 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll

    SciTech Connect

    Antione, D.; Andre, J.M.; Morel, A.

    1996-03-01

    The purpose of this study was to assess the oceanic seasonal evolution and spatial distribution of photosynthetic carbon fixation. Computation of primary production from the upper ocean chlorophyll-like pigment concentrations were made from monthly global maps from the coastal zone color scanner data archive. Relative contributions of various oceans and zonal belts were identified. Depending on the ratio used for active pigments to total pigments, the calculated global annual production ranges from 36.5 and 45.6 G tons (metric) carbon per year. These values are among the highest estimates proposed to date; although the absolute values may be somewhat questionable, the relative contribution of the various zonal belts and oceans are considered to have a high degree of accuracy. 33 refs., 4 figs., 2 tabs.

  12. Global patterns of changes in underwater sound transmission caused by ocean acidification

    NASA Astrophysics Data System (ADS)

    Ilyina, T.; Zeebe, R. E.; Brewer, P. G.

    2009-04-01

    Oceanic uptake of man-made CO2 leads to a decrease in the ocean pH and carbonate saturation state. This processes, known as ocean acidification is expected to have adverse effects on a variety of marine organisms. A surprising consequence of ocean acidification, which has gone widely unrecognized, is its effect on underwater sound transmission. Low-frequency sound absorption in the ocean occurs due to chemical relaxation of the pH-dependent boric acid-borate ion reaction. As ocean pH drops, sound absorption in the audible range decreases. The decreased sound absorption will amplify ambient noise levels, and enhance long distance sound transmission, although its exact environmental impact is uncertain. Changes in the underwater sound absorption will affect the operation of scientific, commercial, and naval applications that are based on ocean acoustics, with yet unknown consequences for marine life. We project these changes using a global biogeochemical model (HAMOCC), which is forced by the anthropogenic CO2 emissions during the years 1800-2300. Based on model projections, we quantify when and where in the ocean these ocean chemistry induced perturbations in sound absorption will occur.

  13. Cycling of DDT in the global environment 1950-2002: World ocean returns the pollutant

    NASA Astrophysics Data System (ADS)

    Stemmler, Irene; Lammel, Gerhard

    2009-12-01

    The global distribution and fate of the insecticide DDT was modeled for the first time using a spatially resolved global multicompartment chemistry-transport model comprising a 3D coupled atmosphere and ocean GCM, coupled to 2D vegetation surfaces and top soils. DDT enters the model environment as a pesticide in agriculture only. Final sinks of DDT in the total environment are degradation in air (hydroxyl radical reaction), on vegetation surfaces, in ocean sediments and soils. The process resolution of the ocean compartment, i.e., either a fixed or variable size and sinking velocity of suspended particles, has almost no effect on the large-scale cycling and fate of DDT. The residence times in various ocean basins were declining but varied regionally. The global ocean absorbed until 1977 and since then has been losing DDT, while large sea areas are still accumulating the pollutant. The main sink is volatilization to the atmosphere. In 1990, the year when emissions ceased, 292 kt of DDT were deposited to the global ocean, 301 kt were volatilized, and 41 kt were exported from the surface layer to the deeper levels. The sea region that has been representing the most significant (secondary) DDT source is the western N Atlantic (Gulf stream and N Atlantic Drift regions). It has been a source since approximately 1970. Also large parts of the tropical ocean and the southern mid-latitude ocean have turned net volatilizational (i.e., volatilization flux > deposition flux) during the 1980s. Despite the emissions migrating southward as a consequence of substance ban in mid latitudes, the geographic distribution of the contaminant (and, hence, environmental exposure) has been migrating steadily northward since the 1960s.

  14. Assessment of Global Forecast Ocean Assimilation Model (FOAM) using new satellite SST data

    NASA Astrophysics Data System (ADS)

    Ascione Kenov, Isabella; Sykes, Peter; Fiedler, Emma; McConnell, Niall; Ryan, Andrew; Maksymczuk, Jan

    2016-04-01

    There is an increased demand for accurate ocean weather information for applications in the field of marine safety and navigation, water quality, offshore commercial operations, monitoring of oil spills and pollutants, among others. The Met Office, UK, provides ocean forecasts to customers from governmental, commercial and ecological sectors using the Global Forecast Ocean Assimilation Model (FOAM), an operational modelling system which covers the global ocean and runs daily, using the NEMO (Nucleus for European Modelling of the Ocean) ocean model with horizontal resolution of 1/4° and 75 vertical levels. The system assimilates salinity and temperature profiles, sea surface temperature (SST), sea surface height (SSH), and sea ice concentration observations on a daily basis. In this study, the FOAM system is updated to assimilate Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) SST data. Model results from one month trials are assessed against observations using verification tools which provide a quantitative description of model performance and error, based on statistical metrics, including mean error, root mean square error (RMSE), correlation coefficient, and Taylor diagrams. A series of hindcast experiments is used to run the FOAM system with AMSR2 and SEVIRI SST data, using a control run for comparison. Results show that all trials perform well on the global ocean and that largest SST mean errors were found in the Southern hemisphere. The geographic distribution of the model error for SST and temperature profiles are discussed using statistical metrics evaluated over sub-regions of the global ocean.

  15. A Global, Multi-Resolution Approach to Regional Ocean Modeling

    SciTech Connect

    Du, Qiang

    2013-11-08

    In this collaborative research project between Pennsylvania State University, Colorado State University and Florida State University, we mainly focused on developing multi-resolution algorithms which are suitable to regional ocean modeling. We developed hybrid implicit and explicit adaptive multirate time integration method to solve systems of time-dependent equations that present two signi cantly di erent scales. We studied the e ects of spatial simplicial meshes on the stability and the conditioning of fully discrete approximations. We also studies adaptive nite element method (AFEM) based upon the Centroidal Voronoi Tessellation (CVT) and superconvergent gradient recovery. Some of these techniques are now being used by geoscientists(such as those at LANL).

  16. Sources of global warming of the upper ocean on decadal period scales

    USGS Publications Warehouse

    White, Warren B.; Dettinger, M.D.; Cayan, D.R.

    2003-01-01

    Recent studies find global climate variability in the upper ocean and lower atmosphere during the twentieth century dominated by quasi-biennial, interannual, quasi-decadal and interdecadal signals. The quasi-decadal signal in upper ocean temperature undergoes global warming/cooling of ???0.1??C, similar to that occuring with the interannual signal (i.e., El Nin??o-Southern Oscillation), both signals dominated by global warming/cooling in the tropics. From the National Centers for Environmental Prediction troposphere reanalysis and Scripps Institution of Oceanography upper ocean temperature reanalysis we examine the quasi-decadal global tropical diabetic heat storage (DHS) budget from 1975 to 2000. We find the anomalous DHS warming tendency of 0.3-0.9 W m-2 driven principally by a downward global tropical latent-plus-sensible heat flux anomaly into the ocean, overwhelming the tendency by weaker upward shortwave-minus-longwave heat flux anomaly to drive an anomalous DHS cooling tendency. During the peak quasi-decadal warming the estimated dissipation of DHS anomaly of 0.2-0.5 W m-2 into the deep ocean and a similar loss to the overlying atmosphere through air-sea heat flux anomaly are balanced by a decrease in the net poleward Ekman heat advection out of the tropics of 0.4-0.7 W m-2. This scenario is nearly the opposite of that accounting for global tropical warming during the El Nin??o. These diagnostics confirm that even though the global quasi-decadal signal is phase-locked to the 11-year signal in the Sun's surface radiative forcing of ???0.1 W m-2, the anomalous global tropical DHS tendency cannot be driven by it directly.

  17. Remote sensing of oceanic biology in relation to global climate change

    SciTech Connect

    Aiken, J.; Moore, G.F.; Holligan, P.M. )

    1992-10-01

    The oceans have a fundamental role in the global climate system because of their capacity to store and transport heat and absorb and emit trace gases which affect the earth's radiation budget. Although good progress has been made with issues such as carbon and sulfur cycling, feedback responses related to the impact of climate change on biological systems, and links between plankton ecology and climate, there is a lack of information on the distributions of biological properties on a global scale. This article reviews the potential contribution of ocean color measurements for biological studies within the context of climate change. The remote sensing of oceanic phytoplankton from satellites measuring radiance at visible and near infrared wavelenghts has produced a wealth of new information on biomass distributions and has provided a basis for new approaches to estimation of global marine primary productivity.

  18. Atmospheric and oceanographic research review, 1978. [global weather, ocean/air interactions, and climate

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Research activities related to global weather, ocean/air interactions, and climate are reported. The global weather research is aimed at improving the assimilation of satellite-derived data in weather forecast models, developing analysis/forecast models that can more fully utilize satellite data, and developing new measures of forecast skill to properly assess the impact of satellite data on weather forecasting. The oceanographic research goal is to understand and model the processes that determine the general circulation of the oceans, focusing on those processes that affect sea surface temperature and oceanic heat storage, which are the oceanographic variables with the greatest influence on climate. The climate research objective is to support the development and effective utilization of space-acquired data systems in climate forecast models and to conduct sensitivity studies to determine the affect of lower boundary conditions on climate and predictability studies to determine which global climate features can be modeled either deterministically or statistically.

  19. The role of clouds and oceans in global greenhouse warming. Final report

    SciTech Connect

    Hoffert, M.I.

    1996-10-01

    This research focuses on assessing connections between anthropogenic greenhouse gas emissions and global climatic change. it has been supported since the early 1990s in part by the DOE ``Quantitative Links`` Program (QLP). A three-year effort was originally proposed to the QLP to investigate effects f global cloudiness on global climate and its implications for cloud feedback; and to continue the development and application of climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by clouds and oceans. It is well-known that cloud and ocean processes are major sources of uncertainty in the ability to predict climatic change from humankind`s greenhouse gas and aerosol emissions. And it has always been the objective to develop timely and useful analytical tools for addressing real world policy issues stemming from anthropogenic climate change.

  20. Freshwater and its role in the Arctic Marine System: Sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans

    NASA Astrophysics Data System (ADS)

    Carmack, E. C.; Yamamoto-Kawai, M.; Haine, T. W. N.; Bacon, S.; Bluhm, B. A.; Lique, C.; Melling, H.; Polyakov, I. V.; Straneo, F.; Timmermans, M.-L.; Williams, W. J.

    2016-03-01

    The Arctic Ocean is a fundamental node in the global hydrological cycle and the ocean's thermohaline circulation. We here assess the system's key functions and processes: (1) the delivery of fresh and low-salinity waters to the Arctic Ocean by river inflow, net precipitation, distillation during the freeze/thaw cycle, and Pacific Ocean inflows; (2) the disposition (e.g., sources, pathways, and storage) of freshwater components within the Arctic Ocean; and (3) the release and export of freshwater components into the bordering convective domains of the North Atlantic. We then examine physical, chemical, or biological processes which are influenced or constrained by the local quantities and geochemical qualities of freshwater; these include stratification and vertical mixing, ocean heat flux, nutrient supply, primary production, ocean acidification, and biogeochemical cycling. Internal to the Arctic the joint effects of sea ice decline and hydrological cycle intensification have strengthened coupling between the ocean and the atmosphere (e.g., wind and ice drift stresses, solar radiation, and heat and moisture exchange), the bordering drainage basins (e.g., river discharge, sediment transport, and erosion), and terrestrial ecosystems (e.g., Arctic greening, dissolved and particulate carbon loading, and altered phenology of biotic components). External to the Arctic freshwater export acts as both a constraint to and a necessary ingredient for deep convection in the bordering subarctic gyres and thus affects the global thermohaline circulation. Geochemical fingerprints attained within the Arctic Ocean are likewise exported into the neighboring subarctic systems and beyond. Finally, we discuss observed and modeled functions and changes in this system on seasonal, annual, and decadal time scales and discuss mechanisms that link the marine system to atmospheric, terrestrial, and cryospheric systems.

  1. The joint impact of ocean circulation and plate tectonics on the glacial South Pacific carbon pool

    NASA Astrophysics Data System (ADS)

    Ronge, T.; Tiedemann, R.; Lamy, F.; Köhler, P.; Alloway, B.; De Pol-Holz, R.; Pahnke, K.; Southon, J. R.

    2015-12-01

    To understand the whereabouts of CO2 during glacials and its pathways during deglacial transitions is one of the main priorities in paleoclimate research. The opposing patterns of atmospheric CO2 and Δ14C suggest that the bulk of CO2 was released from an old and therefore 14C-depleted carbon reservoir. As the modern deep ocean, below ~2000 m, stores up to 60-times more carbon than the entire atmosphere, it is considered to be a major driver of the atmospheric CO2 pattern, storing CO2 during glacials, releasing it during deglacial transitions. We use a South Pacific transect of sediment cores, covering the Antarctic Intermediate Water (AAIW), the Upper Circumpolar Deep Water (UCDW) and the Lower Circumpolar Deep Water (LCDW), to reconstruct the spatio-temporal evolution of oceanic Δ14C over the last 30,000 years. During the last glacial, we find significantly 14C-depleted waters between 2000 and 4300 m water depth, indicating a strong stratification and the storage of carbon in these water masses. However, two sediment cores from 2500 m and 3600 m water depth reveal an extreme glacial atmosphere-to-deep-water Δ14C offset of up to -1000‰ and ventilation ages (deep-water to atmosphere 14C-age difference) of ~8000 years. Such old water masses are expected to be anoxic, yet there is no evidence of anoxia in the glacial S-Pacific. Recent studies showed an increase of Mid Ocean Ridge (MOR) volcanism during glacials due to the low stand of global sea level. For this reason, we hypothesize that the admixture of 14C-dead carbon via tectonic activity along MORs might have contributed to these extremely low radiocarbon values. With a simple 1-box model, we calculated if the admixture of hydrothermal CO2 has the potential to lower the deep Pacific Δ14C signal. We show that if the oceanic turnover time is at least 2700 years, an increased hydrothermal flux of 1.2 μmol kg-1 yr-1 has the potential to reproduce the extreme radiocarbon values observed in our records.

  2. Global representation of tropical cyclone-induced short-term ocean thermal changes using Argo data

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Zhu, J.; Sriver, R. L.

    2015-09-01

    Argo floats are used to examine tropical cyclone (TC) induced ocean thermal changes on the global scale by comparing temperature profiles before and after TC passage. We present a footprint method that analyzes cross-track thermal responses along all storm tracks during the period 2004-2012. We combine the results into composite representations of the vertical structure of the average thermal response for two different categories: tropical storms/tropical depressions (TS/TD) and hurricanes. The two footprint composites are functions of three variables: cross-track distance, water depth and time relative to TC passage. We find that this footprint strategy captures the major features of the upper-ocean thermal response to TCs on timescales up to 20 days when compared against previous case study results using in situ measurements. On the global scale, TCs are responsible for 1.87 PW (11.05 W m-2) of heat transfer annually from the global ocean to the atmosphere during storm passage (0-3 days). Of this total, 1.05 ± 0.20 PW (4.80 ± 0.85 W m-2) is caused by TS/TD and 0.82 ± 0.21 PW (6.25 ± 1.5 W m-2) is caused by hurricanes. Our findings indicate that ocean heat loss by TCs may be a substantial missing piece of the global ocean heat budget. Changes in ocean heat content (OHC) after storm passage are estimated by analyzing the temperature anomalies during wake recovery following storm events (4-20 days after storm passage) relative to pre-storm conditions. Results indicate the global ocean experiences a 0.75 ± 0.25 PW (5.98 ± 2.1 W m-2) heat gain annually for hurricanes. In contrast, under TS/TD conditions, the ocean experiences 0.41 ± 0.21 PW (1.90 ± 0.96 W m-2) ocean heat loss, suggesting the overall oceanic thermal response is particularly sensitive to the intensity of the event. The ocean heat uptake caused by all storms during the restorative stage is 0.34 PW.

  3. Low-frequency variability of sea level as related to the heat balance of global oceans

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, P.; Patzert, W.

    1991-01-01

    The TOPEX/POSEIDON mission will determine global changes of sea level with unprecedented accuracy. Our main objective is the use TOPEX/POSEIDON data, concurrent in situ ocean measurements, and other satellite observations to document and diagnose physical processes by which heat is exchanged with the atmosphere, stored in the ocean, or transported by ocean circulation. During the prelaunch period, our objectives are to advise the project on an improved method of retrieving sea level data and prepare for the application of TOPEX/POSEIDON data by developing a diagnostic model using in situ measurements and altimeter observations from Geosat and the European Remote Sensing satellite.

  4. Insights into global diatom distribution and diversity in the world’s ocean

    PubMed Central

    Malviya, Shruti; Scalco, Eleonora; Audic, Stéphane; Vincent, Flora; Veluchamy, Alaguraj; Poulain, Julie; Wincker, Patrick; Iudicone, Daniele; de Vargas, Colomban; Bittner, Lucie; Zingone, Adriana; Bowler, Chris

    2016-01-01

    Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron. We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered. PMID:26929361

  5. Insights into global diatom distribution and diversity in the world's ocean.

    PubMed

    Malviya, Shruti; Scalco, Eleonora; Audic, Stéphane; Vincent, Flora; Veluchamy, Alaguraj; Poulain, Julie; Wincker, Patrick; Iudicone, Daniele; de Vargas, Colomban; Bittner, Lucie; Zingone, Adriana; Bowler, Chris

    2016-03-15

    Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered. PMID:26929361

  6. The complementary role of SMOS sea surface salinity observations for estimating global ocean salinity state

    NASA Astrophysics Data System (ADS)

    Lu, Zeting; Cheng, Lijing; Zhu, Jiang; Lin, Renping

    2016-06-01

    Salinity is a key ocean state property, changes in which reveal the variation of the water cycle and the ocean thermohaline circulation. However, prior to this century, in situ salinity observations were extremely sparse, which decreased the reliability of simulations of ocean general circulation by ocean and climate models. In 2009, sea surface salinity (SSS) observations covered the global ocean via the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission, and several versions of global SSS products were subsequently released. How can these data benefit model performance? Previous studies found contradictory results. In this work, we assimilated SMOS-SSS data into the LASG/IAP Climate system Ocean Model (LICOM) using the Ensemble Optimum Interpolation (EnOI) assimilation scheme. To assess and quantify the contribution of SMOS-SSS data to model performance, several tests were conducted. The results indicate that the CECOS/CATDS 2010.V02 SMOS-SSS product can significantly improve model simulations of sea surface/subsurface salinity fields. This study provides the basis for the future assimilation of SMOS-SSS data for short-range climate forecasting.

  7. Joint distributions of partial and global maxima of a Brownian bridge

    NASA Astrophysics Data System (ADS)

    Bénichou, Olivier; Krapivsky, P. L.; Mejía-Monasterio, Carlos; Oshanin, Gleb

    2016-08-01

    We analyze the joint distributions and temporal correlations between the partial maximum m and the global maximum M achieved by a Brownian bridge on the subinterval [0,{t}1] and on the entire interval [0,t], respectively. We determine three probability distribution functions: the joint distribution P(m,M) of both maxima; the distribution P(m) of the partial maximum; and the distribution {{\\Pi }}(G) of the gap between the maxima, G=M-m. We present exact results for the moments of these distributions and quantify the temporal correlations between m and M by calculating the Pearson correlation coefficient.

  8. Global-Local Finite Element Analysis for Thermo-Mechanical Stresses in Bonded Joints

    NASA Technical Reports Server (NTRS)

    Shkarayev, S.; Madenci, Erdogan; Camarda, C. J.

    1997-01-01

    An analysis of adhesively bonded joints using conventional finite elements does not capture the singular behavior of the stress field in regions where two or three dissimilar materials form a junction with or without free edges. However, these regions are characteristic of the bonded joints and are prone to failure initiation. This study presents a method to capture the singular stress field arising from the geometric and material discontinuities in bonded composites. It is achieved by coupling the local (conventional) elements with global (special) elements whose interpolation functions are constructed from the asymptotic solution.

  9. A global seasonal surface ocean climatology of phytoplankton types based on CHEMTAX analysis of HPLC pigments

    NASA Astrophysics Data System (ADS)

    Swan, Chantal M.; Vogt, Meike; Gruber, Nicolas; Laufkoetter, Charlotte

    2016-03-01

    Much advancement has been made in recent years in field data assimilation, remote sensing and ecosystem modeling, yet our global view of phytoplankton biogeography beyond chlorophyll biomass is still a cursory taxonomic picture with vast areas of the open ocean requiring field validations. High performance liquid chromatography (HPLC) pigment data combined with inverse methods offer an advantage over many other phytoplankton quantification measures by way of providing an immediate perspective of the whole phytoplankton community in a sample as a function of chlorophyll biomass. Historically, such chemotaxonomic analysis has been conducted mainly at local spatial and temporal scales in the ocean. Here, we apply a widely tested inverse approach, CHEMTAX, to a global climatology of pigment observations from HPLC. This study marks the first systematic and objective global application of CHEMTAX, yielding a seasonal climatology comprised of ~1500 1°×1° global grid points of the major phytoplankton pigment types in the ocean characterizing cyanobacteria, haptophytes, chlorophytes, cryptophytes, dinoflagellates, and diatoms, with results validated against prior regional studies where possible. Key findings from this new global view of specific phytoplankton abundances from pigments are a) the large global proportion of marine haptophytes (comprising 32±5% of total chlorophyll), whose biogeochemical functional roles are relatively unknown, and b) the contrasting spatial scales of complexity in global community structure that can be explained in part by regional oceanographic conditions. The results are publically accessible via

  10. Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming.

    PubMed

    Vallina, S M; Simó, R; Manizza, M

    2007-10-01

    The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds over the ocean, a positive relationship between DMS and the SRD supports the occurrence of a negative feedback between the oceanic biosphere and climate, as postulated 20 years ago. Such a natural feedback might partly counteract anthropogenic global warming through a shoaling of the mixed layer depth (MLD) and a consequent increase of the SRD and DMS concentrations and emission. By applying two globally derived DMS diagnostic models to global fields of MLD and chlorophyll simulated with an Ocean General Circulation Model coupled to a biogeochemistry model for a 50% increase of atmospheric CO(2) and an unperturbed control run, we have estimated the response of the DMS-producing pelagic ocean to global warming. Our results show a net global increase in surface DMS concentrations, especially in summer. This increase, however, is so weak (globally 1.2%) that it can hardly be relevant as compared with the radiative forcing of the increase of greenhouse gases. This contrasts with the seasonal variability of DMS (1000-2000% summer-to-winter ratio). We suggest that the "plankton-DMS-clouds-earth albedo feedback" hypothesis is less strong a long-term thermostatic system than a seasonal mechanism that contributes to regulate the solar radiation doses reaching the earth's biosphere. PMID:17901211