Surface Water Deep Water CIRCULATION NOTES Turn in

Surface Water & Deep Water CIRCULATION

• NOTES – Turn in Homework -2 – Pick Up Homework – 1 – Homework 3 – Assigned Due Next Wednesday – MIDTERM • Get 2 GREEN SCANTRONS from Bookstore – – #2 pencil Exam based on Lecture Notes 40 Multi Choice Qs 5 Short Answer

• World Ocean Circulation – Traditionally divided into 2 components: • 1) Surface Water Circulation • 2) Deep Water Circulation • Actually Both Influence each other. . . • Best TERM: WORLD OCEAN Circulation • We’ll Review each separately for Simplicity Sake. . .

• World Ocean Circulation – Based on Dynamic Physical Oceanography • Describes Ocean based on: – Physical laws & conservation equations in conjunction with » Atmospheric and oceanographic observations • GOAL: – Quantify flow patterns & property distributions in the Ocean • Many PRACTICAL Applications: – Ship Routing – Search and Rescue – Marine pollutant trajectories • OUR GOAL: – Explore the Nature of Ocean Circulation – – become aware of Forces that govern. http: //www. mindfully. org/Plastic/Nike-Pacific-Dump-Ebbsmeyer. htm

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• Foundations of Physical Oceanography – Ben Franklin (1706 -1790) • US Postmaster General (reduce transit time) • Publishes First Maps of Gulf Stream • By 1800 many circulation patterns worked out by seaman • Via Trial and error • Little understanding of – Why?

• Foundations of Physical Oceanography – Many Early Scientists contributed to • Modern view of Ocean Circulations Patterns (1750 -1900) – Based on Convection Currents Model » Ben Thompson, Henry Ellis, John Buchanan, Alex Buchan » Alfred Merz, Geoarge Wust – 1958, Henry Stommel (1920 -1992) » Proposed global model of abyssal circulation. . . » Most Important Physical Oceanographer- All time

Deep flows. . Deep flows Subsurface flows. . 1958, Henry Stommel (1920 -1992) Proposed global model of abyssal circulation

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• Motion in the Ocean – Challenge Questions – The existence of the 4 Big Gyres- Where are they? • How do they arise? See next slides – What direction are their rotations Clockwise or Counterclockwise? – WHY? see next slides •

• Motion in the Ocean – The existence of the Gyres • How do they arise? V. Walfrid Ekman (1861 -1930) – Understand Ekman Transport ((Wind stress)) Friction drags layer below And so on. . . NOTE: Arrows indicate: -direction -intensity Remember: In N. Hemisphere Coriolis deflects this to Right

• Motion in the Ocean – Ekman Transport – Challenge Question? What 2 phenomena occur to the currents as you go deeper in depth layers? 1. The currents deflect Right (N. Hemisphere) 2. The currents intensity weakens NOTE: Arrows indicate: -current direction -current intensity

• CHALLENGE Question Why do the Gyres spin Clockwise or Counter Clockwise? N. Hemisphere S. Hemisphere

• CHALLENGE Question RECALL The Westerlies & The Trade Winds Provide Wind stress Under influence of Coriolis Curves currents to right Via Ekman Transport clockwise How Should this look in the S. Hemisphere? NOTE: –There is a mistake in the Text – where is it and why? S. Pacific Gyre should be counter clockwise

v • Gyres – – N. Hemisphere = Clockwise – S. Hemisphere = Counter Clockwise • What is so important about Gyres anyway? clockwise Counter clockwise Anthropogenic activity causing harm: See the Great Ocean wasteland. . . KQED http: //www. youtube. com/watch? v=g 9 f. Ebqxy. Nl 0

• WHAT CAN YOU DO? – You’re probably not Going to Stop Using all Plastics • RECYCLE • RECYLCE! • Santa Cruz one of the best County’s for RECYCLING!!! (#1 -6 or higher!) • JUST DO IT • Set an EXAMPLE for you FAMILY, Friends & – the Next Generation

• Geostrophic Flow: The Hill in the Gyre – What does geostrophic stand for? • “Earth-turning” –refers to “flow under influence of Coriolis” • EKMAN Transport Directs H 2 O to middle of Oceans (Gyres) – – Creates sloping Sea Surface (a Hill) H 2 O flows from High Pressure to Low pressure Forms geostrophic currents (gyres) A balance of: » Horiz. Press. Gradient » Coriolis force

• Geostrophic Flow: The Hill in the Gyre – Another rendition

• Geostrophic Flow: The Hill in the Gyre – Consequences. . (see TOPEX Satellite Alimeters) • Elevated Sea Surface Heights across the Oceans

• Geostrophic Flow: The Hill in the Gyre – Satellite Jason 2001 • 32 cm difference in elevation b/w Pt. A vs Pt. B

• Upwelling/Downwelling – What is upwelling? • The flow of subsurface waters to the surface – What are the two types: » Coastal » Equatorial EQUATORIAL Upwelling nutrients

• Satelite Image of Upwelling – Cooler waters in Purple

Upwelling – COASTAL Upwelling (e. g. California) • In N. California, what direction does the Coastal wind Come From? – North (Alaska) Winds. . • Surface waters are: » » blown west (via Ekman transp. ) Deep H 2 O is upwelled to fill gap Cold water upwelled

• Downwelling • What is it? • the movement of water downward in the water column – Warmer surface water migrates onto the coastline – VS Versus heading out to sea (UPWELLING)

• Serious Upwelling in N. California – Lots of biological Production f/ Nutrients (photosynthesis) • Kelp Forests marine life etc. Warmest Spot N. of Pt. Conception SATELLITE IMAGE -Cold Water (Purple)

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling – BREAK • • Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• Patterns of Surface water Circulation – Harald Sverdrop (1888 -1957) • Early theoretical Understanding • Effects of a Boundary (continent) on Ocean Circulation – His Theories allowed for calculation of surface flows » via wind stress » In his Honor created … Water transport unit the “Sverdrup” = 1 x 106 m 3 sec -1

• Patterns of Surface water Circulation – What does the Long-term averages of Surface H 2 O transport look like in terms of surface circulation?

• Western Boundary Currents – What are they and What do they arise from? • Currents located along the western sides of Ocean basins • Arise from an intensification of Gyre circulation – In response to variations in the Coriolis effect with lattitude Where are they Below? v

• Western Boundary Currents – All fast moving & narrower then most currents – e. g. in N. Atlantic - Gulf Stream (Most Famous) • ~2. 3 m s-1 (Knots) • Transports Warm H 2 O from Gulf of Mexico to N. Atlantic Florida

• Western Boundary Currents – e. g. in N. Pacific – what Current? – Kuroshio ~ > 2. 5 m s-1 (>5 Knots) ~ 2 miles sec! • Flow is complicated, Japan archipelago wakes, eddies etc.

• Western Boundary Currents – e. g. in S. Atlantic – what Current? – Brazil Current ~ 2. 2 m s-1 (<5 Knots) • Forms Highly Productive Large Marine Ecosystem (LME) – aka Patagonian Shelf

Western Intensification • Challenge Question? – What is it - And what is it caused by? • Increase in flow rates of W. boundary currents caused by: – Coriolis effect which – Increases @ » Higher latitudes TAKE HOME Western Boundary Currents = Fast/ Narrow, b/c Coriolis What about Eastern Boundary Currents? Next slide. . CORIOLIS Force STRONGEST Stronger modest weak Latitude Gulf Stream or Kuroshio

• Eastern Boundary Currents – examples? – e. g. California Current – Slow moving (1 foot/ sec) • Bring cool water – coastal Upwelling Moderate Climate • aka Mediterranean • Also produce considerable fog

• Equatorial Counter Currents – Weak seasonal currents ~ return some (warm) flow East • May play a role in Hurricane formation. . .

• Equatorial Counter Currents – Satellite imagery, warmer temp (yellow) Hurricane Alley

• Antarctic Circumpolar Current (ACC) – Only continuous current unimpeded by land masses • Important exchange pt for Waters or all three Oceans: – Atlantic, Pacific, Indian

• Summary – Warm & Cold Surface Water Currents

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• Patterns of DEEP Water Circulation - T-S Diagrams – What are they and what are they used for? • Temp vs Salinity Diagrams: – mea. @ different pressures (depths) • Allow for the determination of diff. types of water masses & – How they are influencing mixing and current flow, their properties etc. . T-S Diagram Deep Ocean Surface Ocean

Patterns of DEEP Water Circulation - T-S Diagrams

• Patterns of Deep water Circulation – Confirming your knowledge: • What is Needed to Form Deep Water? – Cold air/H 2 O temperatures, high salinity (downward flux) – Colder/ salty water = dense » sinks – e. g. N. Atlantic • Gulf Stream transports – Warm/Salty H 2 O Greenland • S. of Greenland – Cold Air cools water » Cool/salty water sinks. . . » N. Atlantic deep water » aka (NADW)

• Patterns of Deep water Circulation • Ocean is Stratified (layered)- influenced by – Thermocline • Rapid change in temperature – Pycnocline • What is it? – Rapid change in density » (salinity & Temp) Influences the Major Water Masses. . .

NOTES: Saltier More abundant Influ deep circulation Over greater region Thought to confer greatest Shut down of NADW Abrupt climate changes Colder Most dense in World

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• Deep water Circulation – Challenge Question – Current Philosophy • What Drives Deep water Circulation? – @ Highest latitudes (downward flux – sinking) » Density changes form (Cold & salty) sinking H 2 O – @ lower Latitudes » Upward flux (upwelling) – does the WORK (pulling) upwelling

• Places where the seawater is cold enough and salty enough to form bottom water.

OUTLINE • • World Ocean Circulation Foundations of Physical Oceanography Motion in the Ocean Upwelling/Downwelling Patterns of Surface water Circulation Patterns of Deep water Circulation What Drives Deep water Circulation Global Conveyer Belt

• All this Deep Water movement – Global Conveyer Belt – – aka Thermo. Haline Circulation • What is it? – Thermo (temp) & haline (salt) dependent circulation – Heat of Earth’s oceans dissipated from circulation process. .

• Global Ocean Conveyer Belt (Thermo. Haline Circulation) – Wally Broecker’s Model – shows deep H 2 O formations + returns • Broecker et al. , 1991, Oceanography – Challenge Question? • Where are the 2 major cites for DEEP water Formation? – N. Atlantic Deep Water (NADW) – Antarctic Bottom Water (AABW) NADW AABW

• The Global Conveyer Belt aka~ http: //www. youtube. com/watch? v=3 ni. R_-Kv 4 SM FOR More Animated Effects See: http: //www. youtube. com/watch? v=L 9 zjm. C 8 In. KA http: //www. youtube. com/watch? v=MZbs. Mlr 9 WRI&feature=related

• NOTE: Global Conveyer Model: – Oversimplified representation – Schmitz Model (1995) • More accurate – Ocean Mixing = complex » Surface » Intermediate » Deep Waters all mix FINAL THOUGHTS Know the 2 Major -Cites of Deep Water formation -Why and how they would occur

• NOTES – Turn in Homework -2 – Pick Up Homework – 1 – Homework 3 – Assigned Due Next Wednesday SEE you FRIDAY (( ) brrrr)

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