DOCSLIB.ORG

Summertime Increases in Upper-Ocean Stratification And

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Summertime Increases in Upper-Ocean Stratification And Summertime increases in upper-ocean stratification and mixed-layer depth Jean-Baptiste Sallée, Violaine Pellichero, Camille Akhoudas, Etienne Pauthenet, Lucie Vignes, Sunke Schmidtko, Alberto Naveira Garabato, Peter Sutherland, Mikael Kuusela To cite this version: Jean-Baptiste Sallée, Violaine Pellichero, Camille Akhoudas, Etienne Pauthenet, Lucie Vignes, et al.. Summertime increases in upper-ocean stratification and mixed-layer depth. Nature, Nature Publishing Group, 2021, 591 (7851), pp.592-598. 10.1038/s41586-021-03303-x. hal-03184114 HAL Id: hal-03184114 https://hal.archives-ouvertes.fr/hal-03184114 Submitted on 1 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Article Summertime increases in upper-ocean stratification and mixed-layer depth https://doi.org/10.1038/s41586-021-03303-x Jean-Baptiste Sallée1 ✉, Violaine Pellichero2,3, Camille Akhoudas1, Etienne Pauthenet1, Lucie Vignes1, Sunke Schmidtko4, Alberto Naveira Garabato5, Peter Sutherland6 & Received: 8 December 2019 Mikael Kuusela7 Accepted: 26 January 2021 Published online: 24 March 2021 The surface mixed layer of the world ocean regulates global climate by controlling Check for updates heat and carbon exchange between the atmosphere and the oceanic interior1–3. The mixed layer also shapes marine ecosystems by hosting most of the ocean’s primary production4 and providing the conduit for oxygenation of deep oceanic layers. Despite these important climatic and life-supporting roles, possible changes in the mixed layer during an era of global climate change remain uncertain. Here we use oceanographic observations to show that from 1970 to 2018 the density contrast across the base of the mixed layer increased and that the mixed layer itself became deeper. Using a physically based defnition of upper-ocean stability that follows diferent dynamical regimes across the global ocean, we fnd that the summertime density contrast increased by 8.9 ± 2.7 per cent per decade (10−6–10−5 per second squared per decade, depending on region), more than six times greater than previous estimates. Whereas prior work has suggested that a thinner mixed layer should accompany a more stratifed upper ocean5–7, we fnd instead that the summertime mixed layer deepened by 2.9 ± 0.5 per cent per decade, or several metres per decade (typically 5–10 metres per decade, depending on region). A detailed mechanistic interpretation is challenging, but the concurrent stratifcation and deepening of the mixed layer are related to an increase in stability associated with surface warming and high-latitude surface freshening8,9, accompanied by a wind-driven intensifcation of upper-ocean turbulence10,11. Our fndings are based on a complex dataset with incomplete coverage of a vast area. Although our results are robust within a wide range of sensitivity analyses, important uncertainties remain, such as those related to sparse coverage in the early years of the 1970–2018 period. Nonetheless, our work calls for reconsideration of the drivers of ongoing shifts in marine primary production, and reveals stark changes in the world’s upper ocean over the past fve decades. The fundamental vertical structure of the world ocean consists of three will expectedly weaken surface-to-depth exchanges as enhanced den- main layers: the surface mixed layer, which continually exchanges sity gradients decouple surface and subsurface waters, act to shoal heat, freshwater, carbon and other climatically important gases with the surface mixed layer, and result in reduced air–sea gas transfer, the atmosphere; the pycnocline, characterized by its pronounced deep-ocean ventilation and biological productivity3,13–15. Detecting stratification—that is, an enhanced density contrast between shallower and understanding physical changes in the ocean’s surface and pyc- and deeper layers, which inhibits cross-layer vertical mixing; and the nocline layers is thus essential to determine the role of the ocean in deep ocean, which is largely isolated from the atmosphere (Fig. 1; climate, and predict climate change and its ecosystem impacts. The some regions have an additional layer between the mixed layer and latest Special Report on Ocean and Cryosphere in a Changing Climate the pycnocline, which is termed ‘barrier layer’ and is associated with from the Intergovernmental Panel on Climate Change (IPCC)16 clearly an enhanced vertical salinity gradient12). Changes in the surface and identifies this aspect of oceanic evolution as highly policy-relevant. pycnocline layers can have widespread consequences for climate, as Changes in the surface mixed-layer depth and pycnocline stratifica- they may alter the rates at which exchanges occur between the surface tion feature prominently in the report’s summary for policymakers, and the deep ocean. For example, increased pycnocline stratification and in multiple contexts including ocean de-oxygenation, nutrient 1Sorbonne Université, CNRS/IRD/MNHN, LOCEAN, IPSL, Paris, France. 2Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia. 3CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia. 4GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. 5Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton, UK. 6Ifremer, Université Brest, CNRS, IRD, Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM, Brest, France. 7Department of Statistics and Data Science, Carnegie Mellon University, Pittsburgh, PA, USA. ✉e-mail: [email protected] 592 | Nature | Vol 591 | 25 March 2021 Buoyancy uxes Winds (heat and freshwater) 50-year deepening of the summer Surface mixed-layer at a rate of ~2.9% dec–1 Seasonal mixed layer 50-year strengthening of the pycnocline easonal pycn S ocl –1 500 m ine stratication at a rate of ~8.9% dec 2,000 m Deep ocean 4,000 m South Equator North Fig. 1 | The three-layer structure of the world ocean. Schematic of an between surface and deep waters. The deep ocean is largely insulated from the idealized meridional section across the world ocean illustrating the ocean’s atmosphere, but climate signals propagate from and to the deep ocean three-layer structure. The upper seasonal mixed layer is stirred by a range of through mixing across the seasonal pycnocline and/or through direct contact turbulent processes driven by wind and buoyancy forcings (see Methods with the mixed layer as seasonal pycnocline stratification is eroded in winter. section ‘Dynamical forcing of changes in mixed-layer depth’). The seasonal Here, we present 50-year trends in both mixed-layer depth and pycnocline pycnocline emerges from the density contrast (that is, stratification) between stratification, with impacts on upper-ocean structure and deep-ocean surface and deep waters, and acts as a barrier that reduces communication ventilation. supply to living organisms in the mixed layer, and the global energy estimates. Data selection is based on a rigorously tested data-mapping budget. procedure21,23–25, temporal and spatial decorrelation scales used in the Despite its far-reaching climatic effects, the variability in the regression model are estimated from the data26, and uncertainties mixed-layer depth and pycnocline strength have not been examined in a associated with each individual observation are propagated through systematic fashion from observations. A few studies have documented the model to produce standard error maps for the climatology and the changes in upper-ocean stratification, but they have done so by focus- associated trends (see Methods for details). Because of the large sea- ing on mixed-layer depth variations at specific locations17 or on changes sonal cycle that characterizes the upper ocean, all our results are pre- in stratification averaged over a fixed depth range (generally 0–200 m, sented by season, where ‘summer’ (‘winter’) refers to August–October 0–1,000 m or 0–2,000 m) that conflates the distinct dynamical regimes in the Northern (Southern) Hemisphere and to January–March in the of the mixed layer, pycnocline and deep ocean1,8,9,18,19. For instance, Southern (Northern) Hemisphere. The fields referred to hereafter as stratification over 0–200 m, which has been widely used in past studies, ‘climatological fields’ are seasonal means estimated for year 2000, entirely misses pycnocline changes in regions where the mixed layer is computed from the monthly weighted local linear regression (see Meth- deeper than 200 m (typically at high latitudes in the Southern Ocean ods). In regions where salinity-driven barrier layers are present between and North Atlantic) and can underestimate pycnocline changes where the mixed layer and the pycnocline (mostly in the tropics12), the vari- the mixed layer is shallower than 200 m (such as in the tropics and the able referred to as ‘pycnocline strength’—that is, the density gradient subtropical ocean), especially when the mixed-layer depth also evolves at the base of the density-defined mixed layer (see Methods)—is actu- in time (see Methods, Extended
Load more

Recommended publications
  • World Ocean Thermocline Weakening and Isothermal Layer Warming
    applied sciences Article World Ocean Thermocline Weakening and Isothermal Layer Warming Peter C. Chu * and Chenwu Fan Naval Ocean Analysis and Prediction Laboratory, Department of Oceanography, Naval Postgraduate School, Monterey, CA 93943, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-831-656-3688 Received: 30 September 2020; Accepted: 13 November 2020; Published: 19 November 2020 Abstract: This paper identifies world thermocline weakening and provides an improved estimate of upper ocean warming through replacement of the upper layer with the fixed depth range by the isothermal layer, because the upper ocean isothermal layer (as a whole) exchanges heat with the atmosphere and the deep layer. Thermocline gradient, heat flux across the air–ocean interface, and horizontal heat advection determine the heat stored in the isothermal layer. Among the three processes, the effect of the thermocline gradient clearly shows up when we use the isothermal layer heat content, but it is otherwise when we use the heat content with the fixed depth ranges such as 0–300 m, 0–400 m, 0–700 m, 0–750 m, and 0–2000 m. A strong thermocline gradient exhibits the downward heat transfer from the isothermal layer (non-polar regions), makes the isothermal layer thin, and causes less heat to be stored in it. On the other hand, a weak thermocline gradient makes the isothermal layer thick, and causes more heat to be stored in it. In addition, the uncertainty in estimating upper ocean heat content and warming trends using uncertain fixed depth ranges (0–300 m, 0–400 m, 0–700 m, 0–750 m, or 0–2000 m) will be eliminated by using the isothermal layer.
    [Show full text]
  • Downloaded from the Coriolis Global Data Center in France (Ftp://Ftp.Ifremer.Fr)
    remote sensing Article Impact of Enhanced Wave-Induced Mixing on the Ocean Upper Mixed Layer during Typhoon Nepartak in a Regional Model of the Northwest Pacific Ocean Chengcheng Yu 1 , Yongzeng Yang 2,3,4, Xunqiang Yin 2,3,4,*, Meng Sun 2,3,4 and Yongfang Shi 2,3,4 1 Ocean College, Zhejiang University, Zhoushan 316000, China; [email protected] 2 First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China; yangyz@fio.org.cn (Y.Y.); sunm@fio.org.cn (M.S.); shiyf@fio.org.cn (Y.S.) 3 Laboratory for Regional Oceanography and Numerical Modeling, Pilot National Laboratory for Marine Science and Technology, Qingdao 266071, China 4 Key Laboratory of Marine Science and Numerical Modeling (MASNUM), Ministry of Natural Resources, Qingdao 266061, China * Correspondence: yinxq@fio.org.cn Received: 30 July 2020; Accepted: 27 August 2020; Published: 30 August 2020 Abstract: To investigate the effect of wave-induced mixing on the upper ocean structure, especially under typhoon conditions, an ocean-wave coupled model is used in this study. Two physical processes, wave-induced turbulence mixing and wave transport flux residue, are introduced. We select tropical cyclone (TC) Nepartak in the Northwest Pacific ocean as a TC example. The results show that during the TC period, the wave-induced turbulence mixing effectively increases the cooling area and cooling amplitude of the sea surface temperature (SST). The wave transport flux residue plays a positive role in reproducing the distribution of the SST cooling area. From the intercomparisons among experiments, it is also found that the wave-induced turbulence mixing has an important effect on the formation of mixed layer depth (MLD).
    [Show full text]
  • Influences of the Ocean Surface Mixed Layer and Thermohaline Stratification on Arctic Sea Ice in the Central Canada Basin J
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, C10018, doi:10.1029/2009JC005660, 2010 Influences of the ocean surface mixed layer and thermohaline stratification on Arctic Sea ice in the central Canada Basin J. M. Toole,1 M.‐L. Timmermans,2 D. K. Perovich,3 R. A. Krishfield,1 A. Proshutinsky,1 and J. A. Richter‐Menge3 Received 22 July 2009; revised 19 April 2010; accepted 1 June 2010; published 8 October 2010. [1] Variations in the Arctic central Canada Basin mixed layer properties are documented based on a subset of nearly 6500 temperature and salinity profiles acquired by Ice‐ Tethered Profilers during the period summer 2004 to summer 2009 and analyzed in conjunction with sea ice observations from ice mass balance buoys and atmosphere‐ocean heat flux estimates. The July–August mean mixed layer depth based on the Ice‐Tethered Profiler data averaged 16 m (an overestimate due to the Ice‐Tethered Profiler sampling characteristics and present analysis procedures), while the average winter mixed layer depth was only 24 m, with individual observations rarely exceeding 40 m. Guidance interpreting the observations is provided by a 1‐D ocean mixed layer model. The analysis focuses attention on the very strong density stratification at the base of the mixed layer in the Canada Basin that greatly impedes surface layer deepening and thus limits the flux of deep ocean heat to the surface that could influence sea ice growth/ decay. The observations additionally suggest that efficient lateral mixed layer restratification processes are active in the Arctic, also impeding mixed layer deepening. Citation: Toole, J.
    [Show full text]
  • Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S
    Journal of Geophysical Research: Oceans RESEARCH ARTICLE Coastal Upwelling Revisited: Ekman, Bakun, and Improved 10.1029/2018JC014187 Upwelling Indices for the U.S. West Coast Key Points: Michael G. Jacox1,2 , Christopher A. Edwards3 , Elliott L. Hazen1 , and Steven J. Bograd1 • New upwelling indices are presented – for the U.S. West Coast (31 47°N) to 1NOAA Southwest Fisheries Science Center, Monterey, CA, USA, 2NOAA Earth System Research Laboratory, Boulder, CO, address shortcomings in historical 3 indices USA, University of California, Santa Cruz, CA, USA • The Coastal Upwelling Transport Index (CUTI) estimates vertical volume transport (i.e., Abstract Coastal upwelling is responsible for thriving marine ecosystems and fisheries that are upwelling/downwelling) disproportionately productive relative to their surface area, particularly in the world’s major eastern • The Biologically Effective Upwelling ’ Transport Index (BEUTI) estimates boundary upwelling systems. Along oceanic eastern boundaries, equatorward wind stress and the Earth s vertical nitrate flux rotation combine to drive a near-surface layer of water offshore, a process called Ekman transport. Similarly, positive wind stress curl drives divergence in the surface Ekman layer and consequently upwelling from Supporting Information: below, a process known as Ekman suction. In both cases, displaced water is replaced by upwelling of relatively • Supporting Information S1 nutrient-rich water from below, which stimulates the growth of microscopic phytoplankton that form the base of the marine food web. Ekman theory is foundational and underlies the calculation of upwelling indices Correspondence to: such as the “Bakun Index” that are ubiquitous in eastern boundary upwelling system studies. While generally M. G. Jacox, fi [email protected] valuable rst-order descriptions, these indices and their underlying theory provide an incomplete picture of coastal upwelling.
    [Show full text]
  • Ocean 423 Vertical Circulation 1 When We Are Thinking About How The
    Ocean 423 Vertical circulation 1 When we are thinking about how the density, temperature and salinity structure is set in the ocean, there are different processes at work depending on where in the water column we are looking. If we are considering the thermocline, then we notice first that north-south distribution of the surface density/temperature/ salinity across the subtropical gyre can be mapped into their structure in the vertical. This suggests that vertical structure originates at the surface. To figure this out, we can look any one particular isopycnal layer, and see that at some point north and south it intersects the sea surface. Poleward of that point, the layer below the mixed layer is a slightly denser layer. Following stratigraphy, we call the point where an isopycnal layer intersects the sea-surface its outcrop. isopycnal outcrop w < 0 (downwelling), v < 0 z w(0)=we z=0 y z=-H(y) vG mixed layer, winter L.I. V. P. permanent thermocline = const Let’s imagine a water parcel starting somewhere at the surface in the northern half of the subtropical gyre. We ignore the Ekman layer, except for the Ekman pumping it produces, which we specify as a boundary condition on vertical velocity at the ocean surface. The geostrophic velocity is southward everywhere (including the mixed layer) in this part of the ocean because of the downward Ekman pumping. Imagine water parcels flowing southward in the mixed layer Ocean 423 Vertical circulation 2 (and no heating or cooling). A water parcel, when it encounters lighter water to the south will tend to follow its own isopycnal down out of the mixed layer.
    [Show full text]
  • Implementation of an Ocean Mixed Layer Model in IFS
    622 Implementation of an ocean mixed layer model in IFS Y. Takaya12, F. Vitart1, G. Balsamo1, M. Balmaseda1, M. Leutbecher1, F. Molteni1 Research Department 1European Centre for Medium-Range Weather Forecasts, Reading, UK 2Japan Meteorological Agency, Tokyo, Japan March 2010 Series: ECMWF Technical Memoranda A full list of ECMWF Publications can be found on our web site under: http://www.ecmwf.int/publications/ Contact: [email protected] c Copyright 2010 European Centre for Medium-Range Weather Forecasts Shinfield Park, Reading, RG2 9AX, England Literary and scientific copyrights belong to ECMWF and are reserved in all countries. This publication is not to be reprinted or translated in whole or in part without the written permission of the Director. Appropriate non-commercial use will normally be granted under the condition that reference is made to ECMWF. The information within this publication is given in good faith and considered to be true, but ECMWF accepts no liability for error, omission and for loss or damage arising from its use. Implementation of an ocean mixed layer model Abstract An ocean mixed layer model has been implemented in the ECMWF Integrated Forecasting System (IFS) in order to have a better representation of the atmosphere-upper ocean coupled processes in the ECMWF medium-range forecasts. The ocean mixed layer model uses a non-local K profile parameterization (KPP; Large et al. 1994). This model is a one-dimensional column model with high vertical resolution near the surface to simulate the diurnal thermal variations in the upper ocean. Its simplified dynamics makes it cheaper than a full ocean general circulation model and its implementation in IFS allows the atmosphere- ocean coupled model to run much more efficiently than using a coupler.
    [Show full text]
  • Characterizing Transport Between the Surface Mixed Layer and the Ocean Interior with a Forward and Adjoint Global Ocean Transport Model
    APRIL 2005 P R I M E A U 545 Characterizing Transport between the Surface Mixed Layer and the Ocean Interior with a Forward and Adjoint Global Ocean Transport Model FRANÇOIS PRIMEAU Department of Earth System Science, University of California, Irvine, Irvine, California (Manuscript received 1 July 2003, in final form 7 September 2004) ABSTRACT The theory of first-passage time distribution functions and its extension to last-passage time distribution functions are applied to the problem of tracking the movement of water masses to and from the surface mixed layer in a global ocean general circulation model. The first-passage time distribution function is used to determine in a probabilistic sense when and where a fluid element will make its first contact with the surface as a function of its position in the ocean interior. The last-passage time distribution is used to determine when and where a fluid element made its last contact with the surface. A computationally efficient method is presented for recursively computing the first few moments of the first- and last-passage time distributions by directly inverting the forward and adjoint transport operator. This approach allows integrated transport information to be obtained directly from the differential form of the transport operator without the need to perform lengthy multitracer time integration of the transport equations. The method, which relies on the stationarity of the transport operator, is applied to the time-averaged transport operator obtained from a three-dimensional global ocean simulation performed with an OGCM. With this approach, the author (i) computes surface maps showing the fraction of the total ocean volume per unit area that ventilates at each point on the surface of the ocean, (ii) partitions interior water masses based on their formation region at the surface, and (iii) computes the three-dimensional spatial distribution of the mean and standard deviation of the age distribution of water.
    [Show full text]
  • Lecture 4: OCEANS (Outline)
    LectureLecture 44 :: OCEANSOCEANS (Outline)(Outline) Basic Structures and Dynamics Ekman transport Geostrophic currents Surface Ocean Circulation Subtropicl gyre Boundary current Deep Ocean Circulation Thermohaline conveyor belt ESS200A Prof. Jin -Yi Yu BasicBasic OceanOcean StructuresStructures Warm up by sunlight! Upper Ocean (~100 m) Shallow, warm upper layer where light is abundant and where most marine life can be found. Deep Ocean Cold, dark, deep ocean where plenty supplies of nutrients and carbon exist. ESS200A No sunlight! Prof. Jin -Yi Yu BasicBasic OceanOcean CurrentCurrent SystemsSystems Upper Ocean surface circulation Deep Ocean deep ocean circulation ESS200A (from “Is The Temperature Rising?”) Prof. Jin -Yi Yu TheThe StateState ofof OceansOceans Temperature warm on the upper ocean, cold in the deeper ocean. Salinity variations determined by evaporation, precipitation, sea-ice formation and melt, and river runoff. Density small in the upper ocean, large in the deeper ocean. ESS200A Prof. Jin -Yi Yu PotentialPotential TemperatureTemperature Potential temperature is very close to temperature in the ocean. The average temperature of the world ocean is about 3.6°C. ESS200A (from Global Physical Climatology ) Prof. Jin -Yi Yu SalinitySalinity E < P Sea-ice formation and melting E > P Salinity is the mass of dissolved salts in a kilogram of seawater. Unit: ‰ (part per thousand; per mil). The average salinity of the world ocean is 34.7‰. Four major factors that affect salinity: evaporation, precipitation, inflow of river water, and sea-ice formation and melting. (from Global Physical Climatology ) ESS200A Prof. Jin -Yi Yu Low density due to absorption of solar energy near the surface. DensityDensity Seawater is almost incompressible, so the density of seawater is always very close to 1000 kg/m 3.
    [Show full text]
  • NOAA Atlas NESDIS 81 WORLD OCEAN ATLAS 2018 Volume 1
    NOAA Atlas NESDIS 81 WORLD OCEAN ATLAS 2018 Volume 1: Temperature Silver Spring, MD July 2019 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Environmental Satellite, Data, and Information Service National Centers for Environmental Information NOAA National Centers for Environmental Information Additional copies of this publication, as well as information about NCEI data holdings and services, are available upon request directly from NCEI. NOAA/NESDIS National Centers for Environmental Information SSMC3, 4th floor 1315 East-West Highway Silver Spring, MD 20910-3282 Telephone: (301) 713-3277 E-mail: [email protected] WEB: http://www.nodc.noaa.gov/ For updates on the data, documentation, and additional information about the WOA18 please refer to: http://www.nodc.noaa.gov/OC5/indprod.html This document should be cited as: Locarnini, R.A., A.V. Mishonov, O.K. Baranova, T.P. Boyer, M.M. Zweng, H.E. Garcia, J.R. Reagan, D. Seidov, K.W. Weathers, C.R. Paver, and I.V. Smolyar (2019). World Ocean Atlas 2018, Volume 1: Temperature. A. Mishonov, Technical Editor. NOAA Atlas NESDIS 81, 52pp. This document is available on line at http://www.nodc.noaa.gov/OC5/indprod.html . NOAA Atlas NESDIS 81 WORLD OCEAN ATLAS 2018 Volume 1: Temperature Ricardo A. Locarnini, Alexey V. Mishonov, Olga K. Baranova, Timothy P. Boyer, Melissa M. Zweng, Hernan E. Garcia, James R. Reagan, Dan Seidov, Katharine W. Weathers, Christopher R. Paver, Igor V. Smolyar Technical Editor: Alexey Mishonov Ocean Climate Laboratory National Centers for Environmental Information Silver Spring, Maryland July 2019 U.S. DEPARTMENT OF COMMERCE Wilbur L.
    [Show full text]
  • Oxygen, Apparent Oxygen Utilization, and Dissolved Oxygen Saturation
    NOAA Atlas NESDIS 83 WORLD OCEAN ATLAS 2018 Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Dissolved Oxygen Saturation Silver Spring, MD July 2019 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Environmental Satellite, Data, and Information Service National Centers for Environmental Information NOAA National Centers for Environmental Information Additional copies of this publication, as well as information about NCEI data holdings and services, are available upon request directly from NCEI. NOAA/NESDIS National Centers for Environmental Information SSMC3, 4th floor 1315 East-West Highway Silver Spring, MD 20910-3282 Telephone: (301) 713-3277 E-mail: [email protected] WEB: http://www.nodc.noaa.gov/ For updates on the data, documentation, and additional information about the WOA18 please refer to: http://www.nodc.noaa.gov/OC5/indprod.html This document should be cited as: Garcia H. E., K.W. Weathers, C.R. Paver, I. Smolyar, T.P. Boyer, R.A. Locarnini, M.M. Zweng, A.V. Mishonov, O.K. Baranova, D. Seidov, and J.R. Reagan (2019). World Ocean Atlas 2018, Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Dissolved Oxygen Saturation. A. Mishonov Technical Editor. NOAA Atlas NESDIS 83, 38pp. This document is available on-line at https://www.nodc.noaa.gov/OC5/woa18/pubwoa18.html NOAA Atlas NESDIS 83 WORLD OCEAN ATLAS 2018 Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Dissolved Oxygen Saturation Hernan E. Garcia, Katharine W. Weathers, Chris R. Paver, Igor Smolyar, Timothy P. Boyer, Ricardo A. Locarnini, Melissa M. Zweng, Alexey V. Mishonov, Olga K. Baranova, Dan Seidov, James R.
    [Show full text]
  • Three-Dimensional Model-Observation Intercomparison
    Dynamics of Atmospheres and Oceans 76 (2016) 283–305 Contents lists available at ScienceDirect Dynamics of Atmospheres and Oceans journal homepage: www.elsevier.com/locate/dynatmoce Three-dimensional model-observation comparison in the Loop Current region a,∗ a b K.C. Rosburg , K.A. Donohue , E.P. Chassignet a Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA b Center for Ocean-Atmosphere Prediction Studies, Florida State University, Tallahassee, FL, USA a r t i c l e i n f o a b s t r a c t Article history: Accurate high-resolution ocean models are required for hurricane and oil spill pathway pre- Received 9 October 2015 dictions, and to enhance the dynamical understanding of circulation dynamics. Output from Received in revised form 4 May 2016 ◦ the 1/25 data-assimilating Gulf of Mexico HYbrid Coordinate Ocean Model (HYCOM31.0) Accepted 4 May 2016 is compared to daily full water column observations from a moored array, with a focus on Available online 6 May 2016 Loop Current path variability and upper-deep layer coupling during eddy separation. Array- mean correlation was 0.93 for sea surface height, and 0.93, 0.63, and 0.75 in the thermocline Keywords: for temperature, zonal, and meridional velocity, respectively. Peaks in modeled eddy kinetic Evaluation energy were consistent with observations during Loop Current eddy separation, but with Modelling modeled deep eddy kinetic energy at half the observed amplitude. Modeled and observed Ocean currents LC meander phase speeds agreed within 8% and 2% of each other within the 100 – 40 and 40 Mesoscale eddies Baroclinic instability – 20 day bands, respectively.
    [Show full text]
  • Arabian Sea Mixed Layer Deepening During the Monsoon: Observations and Dynamics
    Arabian Sea Mixed Layer Deepening during the Monsoon: Observations and Dynamics by Albert S. Fischer S.B., Physics (1994) Massachusetts Institute of Technology Submitted to the Massachusetts Institute of Technology / Woods Hole Oceanographic Institution Joint Program in Physical Oceanography in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY and the WOODS HOLE OCEANOGRAPHIC INSTITUTION September 1997 © Albert S. Fischer 1997. All rights reserved. The author hereby grants MIT and WHOI permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part. Signature of Author ........./...................................................... Joint Program in Physical Oceanography Massachusetts Institute of Technology Woods Hole Oceanographic Institution 18 June 1997 C ertified by ............=.... ..... .. ..................................................................................... Robert A. Weller Senior Scientist Thesis Supervisor A ccepted by ....................... ......... ... ...... Accepted -............... ........................ ........... by.............Paola Malanotte-Rizzoli Chairman, Joint Committee for Physical Oceanography A , i Massachusetts Institute of Technology a IA ' ,-TIM1"" Woods Hole Oceanographic Institution oil~~~E Arabian Sea Mixed Layer deepening during the Monsoon: Observations and Dynamics by Albert S. Fischer Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution Abstract The unusual twice-yearly cycle of mixed layer deepening and cooling driven by the mon- soon is analyzed using a recently collected (1994-95) dataset of concurrent local air-sea fluxes and upper ocean dynamics from the Arabian Sea. The winter northeast monsoon has moderate wind forcing and a strongly destabilizing surface buoyancy flux, driven by large radiative and latent heat losses at the sea surface.
    [Show full text]