World Ocean Thermocline Weakening and Isothermal Layer Warming
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Basic Concepts in Oceanography
Chapter 1 XA0101461 BASIC CONCEPTS IN OCEANOGRAPHY L.F. SMALL College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, United States of America Abstract Basic concepts in oceanography include major wind patterns that drive ocean currents, and the effects that the earth's rotation, positions of land masses, and temperature and salinity have on oceanic circulation and hence global distribution of radioactivity. Special attention is given to coastal and near-coastal processes such as upwelling, tidal effects, and small-scale processes, as radionuclide distributions are currently most associated with coastal regions. 1.1. INTRODUCTION Introductory information on ocean currents, on ocean and coastal processes, and on major systems that drive the ocean currents are important to an understanding of the temporal and spatial distributions of radionuclides in the world ocean. 1.2. GLOBAL PROCESSES 1.2.1 Global Wind Patterns and Ocean Currents The wind systems that drive aerosols and atmospheric radioactivity around the globe eventually deposit a lot of those materials in the oceans or in rivers. The winds also are largely responsible for driving the surface circulation of the world ocean, and thus help redistribute materials over the ocean's surface. The major wind systems are the Trade Winds in equatorial latitudes, and the Westerly Wind Systems that drive circulation in the north and south temperate and sub-polar regions (Fig. 1). It is no surprise that major circulations of surface currents have basically the same patterns as the winds that drive them (Fig. 2). Note that the Trade Wind System drives an Equatorial Current-Countercurrent system, for example. -
Methane Cold Seeps As Biological Oases in the High‐
LIMNOLOGY and Limnol. Oceanogr. 00, 2017, 00–00 VC 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. OCEANOGRAPHY on behalf of Association for the Sciences of Limnology and Oceanography doi: 10.1002/lno.10732 Methane cold seeps as biological oases in the high-Arctic deep sea Emmelie K. L. A˚ strom€ ,1* Michael L. Carroll,1,2 William G. Ambrose, Jr.,1,2,3,4 Arunima Sen,1 Anna Silyakova,1 JoLynn Carroll1,2 1CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT The Arctic University of Norway, Tromsø, Norway 2Akvaplan-niva, FRAM – High North Research Centre for Climate and the Environment, Tromsø, Norway 3Division of Polar Programs, National Science Foundation, Arlington, Virginia 4Department of Biology, Bates College, Lewiston, Maine Abstract Cold seeps can support unique faunal communities via chemosynthetic interactions fueled by seabed emissions of hydrocarbons. Additionally, cold seeps can enhance habitat complexity at the deep seafloor through the accretion of methane derived authigenic carbonates (MDAC). We examined infaunal and mega- faunal community structure at high-Arctic cold seeps through analyses of benthic samples and seafloor pho- tographs from pockmarks exhibiting highly elevated methane concentrations in sediments and the water column at Vestnesa Ridge (VR), Svalbard (798 N). Infaunal biomass and abundance were five times higher, species richness was 2.5 times higher and diversity was 1.5 times higher at methane-rich Vestnesa compared to a nearby control region. Seabed photos reveal different faunal associations inside, at the edge, and outside Vestnesa pockmarks. Brittle stars were the most common megafauna occurring on the soft bottom plains out- side pockmarks. -
Influences of the Choice of Climatology on Ocean Heat
388 JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY VOLUME 32 Influences of the Choice of Climatology on Ocean Heat Content Estimation LIJING CHENG AND JIANG ZHU International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China (Manuscript received 30 August 2014, in final form 9 October 2014) ABSTRACT The choice of climatology is an essential step in calculating the key climate indicators, such as historical ocean heat content (OHC) change. The anomaly field is required during the calculation and is obtained by subtracting the climatology from the absolute field. The climatology represents the ocean spatial variability and seasonal circle. This study found a considerable weaker long-term trend when historical climatologies (constructed by using historical observations within a long time period, i.e., 45 yr) were used rather than Argo- period climatologies (i.e., constructed by using observations during the Argo period, i.e., since 2004). The change of the locations of the observations (horizontal sampling) during the past 50 yr is responsible for this divergence, because the ship-based system pre-2000 has insufficient sampling of the global ocean, for instance, in the Southern Hemisphere, whereas this area began to achieve full sampling in this century by the Argo system. The horizontal sampling change leads to the change of the reference time (and reference OHC) when the historical-period climatology is used, which weakens the long-term OHC trend. Therefore, Argo-period climatologies should be used to accurately assess the long-term trend of the climate indicators, such as OHC. 1. Introduction methodology. -
A Numerical Study of the Long- and Short-Term Temperature Variability and Thermal Circulation in the North Sea
JANUARY 2003 LUYTEN ET AL. 37 A Numerical Study of the Long- and Short-Term Temperature Variability and Thermal Circulation in the North Sea PATRICK J. LUYTEN Management Unit of the Mathematical Models, Brussels, Belgium JOHN E. JONES AND ROGER PROCTOR Proudman Oceanographic Laboratory, Bidston, United Kingdom (Manuscript received 3 January 2001, in ®nal form 4 April 2002) ABSTRACT A three-dimensional numerical study is presented of the seasonal, semimonthly, and tidal-inertial cycles of temperature and density-driven circulation within the North Sea. The simulations are conducted using realistic forcing data and are compared with the 1989 data of the North Sea Project. Sensitivity experiments are performed to test the physical and numerical impact of the heat ¯ux parameterizations, turbulence scheme, and advective transport. Parameterizations of the surface ¯uxes with the Monin±Obukhov similarity theory provide a relaxation mechanism and can partially explain the previously obtained overestimate of the depth mean temperatures in summer. Temperature strati®cation and thermocline depth are reasonably predicted using a variant of the Mellor±Yamada turbulence closure with limiting conditions for turbulence variables. The results question the common view to adopt a tuned background scheme for internal wave mixing. Two mechanisms are discussed that describe the feedback of the turbulence scheme on the surface forcing and the baroclinic circulation, generated at the tidal mixing fronts. First, an increased vertical mixing increases the depth mean temperature in summer through the surface heat ¯ux, with a restoring mechanism acting during autumn. Second, the magnitude and horizontal shear of the density ¯ow are reduced in response to a higher mixing rate. -
Coastal and Marine Ecological Classification Standard (2012)
FGDC-STD-018-2012 Coastal and Marine Ecological Classification Standard Marine and Coastal Spatial Data Subcommittee Federal Geographic Data Committee June, 2012 Federal Geographic Data Committee FGDC-STD-018-2012 Coastal and Marine Ecological Classification Standard, June 2012 ______________________________________________________________________________________ CONTENTS PAGE 1. Introduction ..................................................................................................................... 1 1.1 Objectives ................................................................................................................ 1 1.2 Need ......................................................................................................................... 2 1.3 Scope ........................................................................................................................ 2 1.4 Application ............................................................................................................... 3 1.5 Relationship to Previous FGDC Standards .............................................................. 4 1.6 Development Procedures ......................................................................................... 5 1.7 Guiding Principles ................................................................................................... 7 1.7.1 Build a Scientifically Sound Ecological Classification .................................... 7 1.7.2 Meet the Needs of a Wide Range of Users ...................................................... -
Grade 3 Unit 2 Overview Open Ocean Habitats Introduction
G3 U2 OVR GRADE 3 UNIT 2 OVERVIEW Open Ocean Habitats Introduction The open ocean has always played a vital role in the culture, subsistence, and economic well-being of Hawai‘i’s inhabitants. The Hawaiian Islands lie in the Pacifi c Ocean, a body of water covering more than one-third of the Earth’s surface. In the following four lessons, students learn about open ocean habitats, from the ocean’s lighter surface to the darker bottom fl oor thousands of feet below the surface. Although organisms are scarce in the deep sea, there is a large diversity of organisms in addition to bottom fi sh such as polycheate worms, crustaceans, and bivalve mollusks. They come to realize that few things in the open ocean have adapted to cope with the increased pressure from the weight of the water column at that depth, in complete darkness and frigid temperatures. Students fi nd out, through instruction, presentations, and website research, that the vast open ocean is divided into zones. The pelagic zone consists of the open ocean habitat that begins at the edge of the continental shelf and extends from the surface to the ocean bottom. This zone is further sub-divided into the photic (sunlight) and disphotic (twilight) zones where most ocean organisms live. Below these two sub-zones is the aphotic (darkness) zone. In this unit, students learn about each of the ocean zones, and identify and note animals living in each zone. They also research and keep records of the evolutionary physical features and functions that animals they study have acquired to survive in harsh open ocean habitats. -
CP-2019-161 Lessons from a High CO2 World: an Ocean View from ~3 Million Years Ago Reply to Editor
CP-2019-161 Lessons from a high CO2 world: an ocean view from ~3 million years ago Reply to Editor This document addresses the concerns of the Editor on our revised manuscript. We also include the “tracked changes” manuscript text. No changes have been made to the Supplement text. We thank the Editor for the remaining comments, which are addressed here and shown as tracked changes in the document below: Upon final reading of the manuscript I noticed 2 areas, that I feel need addressing before the manuscript can be published. These are minor and the second I think is a result of some changes you made to the manuscript in the most recent submission. 1. Please reference the underlying SST data in Figure 2. At present, the figure caption only makes reference to the the PlioVAR sites. Thank you for flagging this, we had omitted to cite our source data. The PlioVAR sites have been overlaid on the World Ocean Atlas (2018) mean annual SSTs. We have cited this source in the caption. We also felt that we should highlight that the compiled information on sites and proxies is included in the Supplement file and in the Pangaea archive. Our caption has been edited accordingly: Figure 2: Locations of sites used in the synthesis, overlain on mean annual SST data from the World Ocean Atlas 2018 (Locarnini et al., 2018). A full list of the data sources and K proxies applied per site are available in Table S3 (U 37’) and Table S4 (Mg/Ca), and can be accessed at https://pliovar.github.io/km5c.html. -
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). -
Shear Dispersion in the Thermocline and the Saline Intrusion$
Continental Shelf Research ] (]]]]) ]]]–]]] Contents lists available at SciVerse ScienceDirect Continental Shelf Research journal homepage: www.elsevier.com/locate/csr Research papers Shear dispersion in the thermocline and the saline intrusion$ Hsien-Wang Ou a,n, Xiaorui Guan b, Dake Chen c,d a Division of Ocean and Climate Physics, Lamont-Doherty Earth Observatory, Columbia University, 61 Rt. 9W, Palisades, NY 10964, United States b Consultancy Division, Fugro GEOS, 6100 Hillcroft, Houston, TX 77081, United States c Lamont-Doherty Earth Observatory, Columbia University, United States d State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, China article info abstract Article history: Over the mid-Atlantic shelf of the North America, there is a pronounced shoreward intrusion of the Received 11 March 2011 saltier slope water along the seasonal thermocline, whose genesis remains unexplained. Taking note of Received in revised form the observed broad-band baroclinic motion, we postulate that it may propel the saline intrusion via the 15 March 2012 shear dispersion. Through an analytical model, we first examine the shear-induced isopycnal diffusivity Accepted 19 March 2012 (‘‘shear diffusivity’’ for short) associated with the monochromatic forcing, which underscores its varied even anti-diffusive short-term behavior and the ineffectiveness of the internal tides in driving the shear Keywords: dispersion. We then derive the spectral representation of the long-term ‘‘canonical’’ shear diffusivity, Saline intrusion which is found to be the baroclinic power band-passed by a diffusivity window in the log-frequency Shear dispersion space. Since the baroclinic power spectrum typically plateaus in the low-frequency band spanned by Lateral diffusion the diffusivity window, canonical shear diffusivity is simply 1/8 of this low-frequency plateau — Isopycnal diffusivity Tracer dispersion independent of the uncertain diapycnal diffusivity. -
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. -
Introduction to Oceanography
Introduction to Oceanography Introduction to Oceanography Lecture 14: Tides, Biological Productivity Memorial Day holiday Monday no lab meetings Go to any other lab section this week (and let the TA know!) Bay of Fundy -- low tide, Photo by Dylan Kereluk, . Creative Commons A 2.0 Generic, Mudskipper (Periophthalmus modestus) at low tide, photo by OpenCage, Wikimedia Commons, Creative http://commons.wikimedia.org/wiki/File:Bay_of_Fundy_-_Tide_Out.jpg Commons A S-A 2.5, http://commons.wikimedia.org/wiki/File:Periophthalmus_modestus.jpg Tides Earth-Moon-Sun System Planet-length waves Cyclic, repeating rise & fall of sea level • Earth-Sun Distance – Most regular phenomenon in the oceans 150,000,000 km Daily tidal variation has great effects on life in & around the ocean (Lab 8) • Earth-Moon Distance 385,000 km Caused by gravity and Much closer to Earth, but between Earth, Moon & much less massive Sun, their orbits around • Earth Obliquity = 23.5 each other, and the degrees Earth’s daily spin – Seasons Photos by Samuel Wantman, Creative Commons A S-A 3.0, http://en.wikipedia.org/ wiki/File:Bay_of_Fundy_Low_Tide.jpg and Figure by Homonculus 2/Geologician, Wikimedia Commons, http://en.wikipedia.org/wiki/ Creative Commons A 3.0, http://en.wikipedia.org/wiki/ File:Bay_of_Fundy_High_Tide.jpg File:Lunar_perturbation.jpg Tides are caused by the gravity of the Moon and Sun acting on Scaled image of Earth-Moon distance, Nickshanks, Wikimedia Commons, Creative Commons A 2.5 Earth and its ocean. Pluto-Charon mutual orbit, Zhatt, Wikimedia Commons, Public -
Exploration of the Deep Gulf of Mexico Slope Using DSV Alvin: Site Selection and Geologic Character
Exploration of the Deep Gulf of Mexico Slope Using DSV Alvin: Site Selection and Geologic Character Harry H. Roberts1, Chuck R. Fisher2, Jim M. Brooks3, Bernie Bernard3, Robert S. Carney4, Erik Cordes5, William Shedd6, Jesse Hunt, Jr.6, Samantha Joye7, Ian R. MacDonald8, 9 and Cheryl Morrison 1Coastal Studies Institute, Louisiana State University, Baton Rouge, Louisiana 70803 2Department of Biology, Penn State University, University Park, Pennsylvania 16802-5301 3TDI Brooks International, Inc., 1902 Pinon Dr., College Station, Texas 77845 4Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, Louisiana 70803 5Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Ave., Cambridge, Massachusetts 02138 6Minerals Management Service, Office of Resource Evaluation, New Orleans, Louisiana 70123-2394 7Department of Geology, University of Georgia, Athens, Georgia 30602 8Department of Physical and Environmental Sciences, Texas A&M – Corpus Christi, Corpus Christi, Texas 78412 9U.S. Geological Survey, 11649 Leetown Rd., Keameysville, West Virginia 25430 ABSTRACT The Gulf of Mexico is well known for its hydrocarbon seeps, associated chemosyn- thetic communities, and gas hydrates. However, most direct observations and samplings of seep sites have been concentrated above water depths of approximately 3000 ft (1000 m) because of the scarcity of deep diving manned submersibles. In the summer of 2006, Minerals Management Service (MMS) and National Oceanic and Atmospheric Admini- stration (NOAA) supported 24 days of DSV Alvin dives on the deep continental slope. Site selection for these dives was accomplished through surface reflectivity analysis of the MMS slope-wide 3D seismic database followed by a photo reconnaissance cruise. From 80 potential sites, 20 were studied by photo reconnaissance from which 10 sites were selected for Alvin dives.