Ocean currents: physical drivers in a changing world

Front Matter
Copyright
Contents
Acknowledgements
1 The restless ocean
	Chapter Outline
	Ten big questions
	Organization vs. chaos
	Measuring the ocean-Challenges and international organization
	Measuring ocean currents
		Drift measurements
		Point measurements
		Profile measurements
		Radar measurements
	Estimating ocean currents
		Hydrography
		Bottom pressure recorders
		Satellite altimeters
		Electrical cables
	Computer simulation of ocean currents
	An ocean of scales
	Summary
2 Frameworks, data, and methods
	Chapter Outline
	Essential physics and scalar conservation
		Seawater properties, the equation of state, and neutral surfaces
		Conservation of mass, salt, and heat
	Essential dynamics-With the flow and at a fixed point
		Real forces
		The effects of Earth\'s rotation
		The equations of motion-Following the flow
		Advection of momentum
		The equations of motion-At a fixed point
	Scaling arguments and approximating the equations of motion
	Ocean and climate data products
		Ocean observations (Argo)
		Ocean reanalysis (GODAS)
		Ocean analysis (EN4)
		Air-sea fluxes (COREv2)
		Atmospheric reanalysis (NCEP/NCAR)
		Tropical cyclone tracks (IBTRaCS; HURDAT)
		Sea ice (NSIDC) and icebergs (IIP; BYU/NIC)
	Numerical models of the ocean and climate
		Governing equations and approximations
		Numerical solution
		Meshes, grids, and vertical coordinates
		Resolution, processes, and parameterizations
		From bespoke to community codes
		Coupling, complexity, and climate
	Particle tracking
	Resourcing Chapters 3-1234567891012
	Exercises
	References
3 Surface drift, gyres, and the fate of plastic
	Chapter Outline
	Large scales in space and time
	The restless atmosphere
		A moist thermodynamic heat engine-Basics
		Large-scale wind patterns
	Local response to wind-Surface drift
		Wind stress
		The inertial response to a wind impulse
		Balancing forces at the surface
		Balancing forces sub-surface
		Large-scale consequences
	Basin-scale response-The great gyres
		The wind-driven circulation and vorticity
		Opposing vorticity tendencies
		Horizontal pressure gradients and sea surface slopes
	Gyre circulation and Ekman currents-The combined surface drift
	Additional influences on surface and near-surface drift
	Examples of surface drift at basin scale
		Sargassum seaweed in the Sargasso Sea
		Subsea volcanic eruptions and pumice rafts
		Tsunami debris and container spills
		The fate of plastics in the World Ocean
		References
4 Western boundary currents and drifting organisms
	Chapter Outline
	Mapping and characterizing western boundary currents
	Local force balance
		Sea surface slopes
		Horizontal density gradients
		Estimating geostrophic currents
	Basin-scale force balance
		Conservation of absolute vorticity in the interior of a subtropical gyre
		Balancing vorticity at the western boundary
		Vorticity tendencies around a subtropical gyre
		Leaving the boundary behind
	Drift through western boundary current systems-Particle trajectories, ensemble statistics, and ecological consequences
		The enigmatic first year in the life of sea turtles-Finding Nemo in NEMO
		Tracing the fate and source of the Gulf Stream
		Separation and retroflection
		Vertical shear in western boundary currents and vertical motion along trajectories
	Transports associated with western boundary currents
		Hydrographic changes along western boundary current trajectories
		Nutrient streams and wider biogeochemical contexts
		Temperature-sensitive microbial ecology
		References
5 Eastern boundary currents, upwelling, and high biological productivity
	Chapter Outline
	Mapping and characterizing EBC systems
		Eastern boundaries in the subtropics-The `Big Four upwelling systems
		The Leeuwin Current-An exception to the rule in the subtropics
		Eastern boundaries in subpolar latitudes
	Ekman dynamics in the presence of a coast
	Geostrophy in the presence of topography
	Slope currents
	Drift along and across eastern boundary current systems-3D water parcel trajectories and the ecological consequences
		The source of upwelled water, nutrients, and productivity
		Sources of the European Slope Current and downstream influences on North Sea ecosystems
		References
6 The tropical oceans, interannual climate variability, and ecosystem adaptation
	Chapter Outline
	Mapping and characterizing currents near the Equator
		The Pacific
		The Atlantic
		The Indian Ocean
	Ekman dynamics near the Equator
	Tropical variability
		Planetary waves near the Equator
		El Niño and the Southern Oscillation
		Tropical Instability Waves
	Drift in the tropics-2D water parcel trajectories and some ecological consequences
		Dispersal of coral spores and connectivity throughout the tropics
		Re-visiting pumice drift-An eruption in the tropical South Pacific
		Adaptation of sea turtles to tropical ocean currents
		The Sargassum Crisis in the Atlantic
	Tropical ocean circulation and climate variability
		Recent ENSO variability and associated teleconnections
		Variable Atlantic hurricane seasons
		Western Indian Ocean warming and the South Asian Monsoon
		References
7 From the northern subpolar oceans to the Arctic and its retreating sea ice
	Chapter Outline
	The northern cryosphere
		Sea ice
		Glacial ice
	The atmosphere at mid and high latitudes
		The jet stream
		The stratospheric polar vortex (SPV)
		The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO)
		Greenland tip jets and intense air-sea interaction
	Water masses of subpolar and high latitudes
		Mode waters
		Intermediate waters
		Dense waters
	Ocean circulation at subpolar and high latitudes
		The subpolar North Atlantic and water mass transformation
		The Greenland-Iceland-Norwegian Seas
		The Arctic
		The deep circulation
	Variability and long-term change
		Variability and recent events across the subpolar North Atlantic
		Greenland mass imbalance and peripheral seas
		The changing Arctic
		References
8 From the Southern Ocean to Antarctica and its changing ice shelves
	Chapter Outline
	The southern cryosphere
		Sea ice
		Glacial ice
	The atmosphere at southern high latitudes
		Mid-latitude atmospheric circulation and the Roaring Forties
		High latitude atmospheric circulation and the Southern Polar Vortex
		Katabatic winds
		The Southern Annular Mode
		Air-sea exchanges of heat and freshwater
	Water masses of the Southern Ocean and around Antarctica
		Mode Waters and Intermediate Waters
		Dense water preconditioning around Antarctica
		Abyssal and Deep Waters
	Surface and deep-reaching currents
		Ekman currents in the Southern Ocean
		The Antarctic Circumpolar Current (ACC)
		Fronts, jets, and eddies
		The subpolar gyres
		Coastal and slope currents around Antarctica
	Meridional overturning cells and sensitivity of the 3D circulation to wind forcing
		The upper limb and CDW upwelling
		The lower limb and AABW export
		Sensitivity of the 3D circulation to wind forcing
	Modelling the Southern Ocean-A brief history and the status quo
	Applied contexts
		Microplastics reaching the Southern Ocean and consequences for seabirds
		Plastics reaching Antarctic waters
		Ecological pathways to Antarctica
		Natural and artificial iron fertilization
		Heat and carbon uptake in the Southern Ocean
		Interaction of warming ocean with Antarctic ice shelves and global sea level rise
9 Processes and flows in marginal seas
	Chapter Outline
	Processes in marginal seas
		Turbulence and mixing
		Tides
		Seasonal stratification
		Tidal mixing fronts and residual circulation
		Runoff and freshwater
		Exchanges
		Summary of processes
	Deep or isolated marginal seas
		The Mediterranean and Black Seas
		Red Sea and Persian Gulf
		Japan and Okhotsk Seas
		The Indonesian Seas
		Caribbean Sea and Gulf of Mexico
	Shelf seas
		Northwest European shelf
		China Seas
		Sunda and Sahul shelves
		Northeast US and east Canadian seaboard
		Patagonian shelf
		High-latitude shelf seas
	Freshwater influences
		Equatorial Atlantic
		East Asia
		Northwest Europe
	Biological productivity and pollution in marginal seas
		Primary productivity in shelf seas and at shelf breaks
		Microplastic drift through coastal and shelf seas
		References
10 Ocean boundaries, connectivity, and inter-ocean exchanges
	Chapter Outline
	Defining an ocean basin
	Surface connectivity
	Upper-ocean connectivity and inter-ocean exchanges
	Fronts as demarcation lines
	Coherent structures and marine biogeography
	Re-defining an ocean basin
	References
11 The global circulation and transformation of water masses
	Chapter Outline
	Piecing together a global circulation
		The near-surface circulation
		The sub-surface circulation
		The 3D global circulation
	Meridional overturning cells, forcing, and energetics
		Pole-to-pole overturning - The holistic perspective
		Boundary forcing - The thermohaline perspective
		Pushing and pulling the MOC - The energetics perspective
	Global trajectories and pathways of water parcels
	Re-thinking circulation in property space
		Surface density fluxes
		Diapycnal density fluxes
		The surface water mass transformation rate
		Interior water mass transformation
	Linking the circulation and transformation of water masses
		Surface-forced overturning
		The global thermohaline circulation in temperature and salinity space
		References
12 Ocean currents, heat transport, and climate
	Chapter Outline
	Meridional heat transport by the AMOC and north European warmth
	Variability of the large-scale ocean circulation and regional climate
	Tracing the global overturning in changing property distributions
	Abrupt climate change in the past-A warning for the future
	References
Epilogue: Looking ahead
	Unfolding changes in ocean currents
	Emerging technologies
	Opportunities and solutions
	References
Index