so today i'm going to lecture a little bit about talk a little bit about ocean currents we know about them uh as you can see this is a funny thing that happened uh sometimes weird accidents give us information about how currents uh how they how they rotate how they how continents affect them in terms of their direction uh this is an accident that happened back in 1990 where a container ship broke apart and uh lots of nike shoes were dumped in the pacific along with rubber toys and stuff and people were picking them up along the coastlines and so you know they got an idea of how the current you know was was how this current was uh basically splitting into two directions as it hit the coast which is kind of interesting because you see that alaska current there usually we'll see the major gyres rotate in a clockwise direction in the northern hemisphere in a counterclockwise direction in the southern hemisphere but when land masses interfere that can invert and you see the alaska current there the northern pacific current alaska current moving away whenever you move water away from a coastline that's when you get upwelding and uploading is when you bring up nutrients from deeper in the ocean decomposed materials have been reworked by bacteria and that's when you get huge huge productivity and fisheries and that alaska you know alaska region is our main design nowadays our main fishery for the united and some of the states and stuff for sure i will also talk a little bit about the impact of you know how the atmosphere and the height and the oceans interact and we'll talk a little bit about el nino events today again when you enter into an el nino have all sorts of interesting uh climatic effects not the least because you trade wins a bait you cut off upwelling uh these uh lizards that live in the galapagos you know they basically honestly basically all of a sudden have to uh eat uh types of algae that is not as nutritious for what their main food sources and during normal climatic times and and they start to starve and the way they have adapted to accommodate that is they actually can resorb some of their connective tissue and shrink which is pretty weird but that's that's life is weird okay again let's go more currents lots of lazy lots of instruments just measure them and we also measure obviously from space so basically you look at the atlantic ocean to start with we have again because the trade winds are moving northeast trade winds and southeast trade winds are moving water away from the equator water tends to veer to the right of the winds in the northern hemisphere and to the left of the winds in the southern hemisphere you get the the development of these surface gyres these large subtropical gyres and water kind of piles up in the sort of in the centers of these giants but not exactly the centers because as the winds are blowing remember the earth is spinning on its axis to the east and that you know kind of whips things around so we have much more intense flow on the western basins western sides of basins and eastern sides we call that west westward intensification and water piles up in the centers of these gyres and the restoring force of course is gravity keeps things in equilibrium so we have these big gyres we can see uh in the north atlantic ocean in the south atlantic ocean uh we have again smaller like subpolar gyre you can see that you know off the coast of greenland the alaska current i showed you and similarly in the pacific ocean we'll see we have similar gyres that rotate and large giants that rotate in a clockwise direction in the northern hemisphere counterclockwise direction the southern hemisphere along the equator itself we have an equatorial current that moves the south equatorial you know the executorial currents move and towards the west and then they encounter the islands and there's a return current the counter current and moves towards the east right now the antarctica is separate from all the continents so there's this free flow around the antarctica and we have a the largest surface volume of water in the world flows around the antarctica continuously we have what's called the east wind drift and the west wind drift east wind drift driven by the polar easterlies rotate moves towards the west closer to the shoreline and then we have the west wind drift driven by the wesleys is moving in the opposite direction these counter currents are you know again nothing impedes them because you know millions of years ago south america was connected to antarctica obviously the flow is different right now nothing's impeding that flow also right now because we're in an interglacial water we'll see is flowing from the pacific ocean up into the arctic sea through the bering straits 12 000 years ago sea level was low enough that you could walk across from asia in north america and now of course that is is a free ocean is a water path so you cannot already do that okay again as i said what are veers to the right of the winds in the northern hemisphere every layer it's like a deck of cards every layer affects the layer beneath it until you get to an open ocean you get to a great depth greater than one half the wavelength and then you have any impact of the water of the wind on the deeper waters but at the surface so at the surface water is moving about 45 degrees to the right of the winds in the north hemisphere but as i said every layer is affecting the layer beneath it so the overall net direction is 90 degrees to the right if we're looking at you know where the water where the winds are impacting the water every layer is impacting the layer beneath it until we get an open ocean until we get to a water depth of greater than one half the wavelength of the waves you know most waves are propagated by the winds and we'll talk about that later when we talk about waves and tides but basically once you get down to that depth you don't have any impact the energy peters out and as i said in these big gyres the lawyers is is is basically you know being forced to the west as the earth rotates to the east and the water piles up and the restoring force you know this geostrophic flow the coriolis effect is closing this way to pile up and you know it's causing you where to come back down is gravity so it's a balance between the coriolis effect your spinning and sexist and gravity okay you can see uh here that just showing you the different temperature regions and there's you know and it's i think this is in the summer time and so we have the gulf stream that's moving up uh you know again i'll get back to the gulf stream in a minute this is uh this is this is a winter shot again the gulf stream is a really important current because it's basically moving water you know surface waters from the equator along the north american coast and then towards europe it's the gulf stream that keeps places like great britain warmer in the winter time than they would normally be there's a big transfer of heat going on here from the equatorial waters into the higher latitude boys the equator itself the trade winds are moving water away from the equator uh to the left in the southern hemisphere to the north and the northern hemisphere you know the trade winds and so we actually get uploading at the equator and so you know we always think of the equator it's very hot and stuff but there's actually a lot of cold water upwelling there but then you know from this divergence and that uploading water you know basically is bringing up nutrients so we have a lot of productivity and a lot of cold water organisms radial area and things that are living at the equatorial waters that you might not normally expect there because again because it's so low latitude okay so whatever currents converge like the polar gyre and the sub-tropical giant in the north atlantic wherever currents converge we have down welling so where they diverge we get uploading when they converge we get down and so again you see that subpolar gi there and then you know where those two current in the subtropical variable they converge we get downloading we'll see those downloading areas are very important because they bring oxygen into the into the deeper ocean wherever the cold waters are sinking we get in so we have major sinks that occur off the coast of greenland labrador uh where cold ocean water sinking and becoming deeper water currents that carry oxygen into the oceans and as these deep water currents migrate slowly to the south call that the north atlantic deep water you see lots of in lots of different you know okay dryers and again they're rotating opposite directions in the northern and southern hemisphere and sometimes the surface currents will change direction seasonally and this is true in the indian ocean because of changes in the direction of monsoon winds along coastlines like the west coast of south america the trade winds are typically blowing water away from the coastline we get uploading that's why this is a huge fishery along the west coast of south america because all these you know nutrients are coming up into the water column because remember this is this is tropical areas so normally you know there's a thermocline that inhibits mixing but when you have you know these types of uploading zones uh developing you can you count you know trade you know we'll see the waters you know carry nutrients from the deep water up uh what happens during an el nino event is the trade winds a bait and there's no longer any upgrade and then things become a little bit ominous for organisms that try to make a living there as we'll see okay so that's one and the water when winds change direction and blow water towards the coast we get downloading you can have isolated occurrences of table mounts and things or sharp coastline it may cause an isolated upwelling event in an area that would not normally see that type of flow this is typical you know off the west coast of south america off the coast of alaska winds anything that's blowing winds away from the coastline as i mentioned before we have these two major currents going in opposite directions around the antarctica freely unimpeded okay these are the largest ocean circulation surface water circulations in on earth going opposite directions because you know because they're being driven by the westerlies and the polaristales i've done some work on sediment so one of the things i worked on with colleagues of mine oregon state years ago is we were doing sediment analyses in the wet lc uh again this is an area a lot of diatoms love that cold water diatomaceous uses and stuff and so we were working on the geochemistry of some of these organisms okay again usually you know again you can see in the north atlantic the gulf stream is the warm water current and usually it's it's actually the ghost stream is the fastest way fastest moving current surface current on earth on average about four miles an hour that doesn't seem a lot in the car but it's really fast all right and it can be as fast as five or six and as it goes up into the north it cools and broadens and slows down a little bit it's a very fast moving current because the earth is whipping around you know with it's sort of like a carnival ride you know the earth is moving on its axis to these whipping that water to the west and then because of the because of the wind directions coriolis effect and wind direction the water just whips around and so you get this really intense flows same thing with the brazil current in the southern hemisphere very fast moving current and the return currents the canary current in the northeast the northern sub-tropical gyre that you can see there these are usually very cold slow-moving currents you can also see down below you know the benguela current you know off the coast of africa you know part of that drive there whenever you're moving again because of the trade winds whenever you're moving uh water away from the coastline you get up lying so this is a big fishery in africa unfortunately a lot of the governments there can't control don't have the seaworthiness to control people sneaking in to those areas and overfishing we'll get to that later again you can see up in the northern part of the atlantic as i mentioned before these sinks all these places are cold uh saline waters are sinking carrying oxygen back to the deeper waters of the oceans and traveling as a deepwater current beneath the surface currents hugging the continental slope and we saw people famous the sargasso sea the bermuda triangle you know some of these areas are pretty infamous you know people don't know exactly what happens there maybe methane is released from the seafloor hits the engines of planes and blows them up i don't know but anyway it's a kind of notoriously uh interesting area bell stream doesn't move as a completely just linear current there's lots of eddies that occur in the current they pinch off cold water and warm water depending on which you know as you know it says they mean they're just like streams on earth you know so it's moving fast but it meanders uh people that rich people that race yachts and stuff are always looking they know when they enter the gulf stream because of the temperature increase in the water but they're also trying to figure out the direction of some of these jetty eddies within the gulf because they get a nice push in the right direction as i think i mentioned earlier in the semester ben franklin had a nephew who was a sea pilot and he and he and ben worked out you know some of the things about the gulf stream so that uh ships coming from england could avoid uh some of this current so get you know get the mail to the colonies faster and not be pushed back okay again some of these rings will travel as discreet eddies for quite a distance and so they may you know contain materials that are caught up and cut up in the ring yeah in the pacific is pretty much like the atlantic you know in the northern pacific you have this big gyre going in the clockwise direction in the southern pacific in the counter-clockwise direction so this is what we normally see you know when things are normal and we're not in a an el nino event we have you know upwelling along the west coast of south america okay we have a well-established thermocline because it's warm but there's upwelling along the coastline there so we have you know a lot of nutrients coming up in high productivity okay and then towards the west you know we have a lot of precipitation during el nino events the trade winds intensified pushing warm surface waters to the west and as winter approaches the trade winds abate and warm water start to move east off the shores of the americas and again this causes very you know large interesting atmospheric conditions climatic shifts and things we start to get heavy rainfall on the east coast because of the shift and this development of a strong climate so again there's lots of debate about you know still debating about you know how these things happen it looks like it's mostly southern oscillation of atmospheric pressure cells are not what's the size of the pacific you do get these in the you know the effect in the atlantic because the atlantic ocean is not as as huge as the pacific the effects are not as extreme so again you know this you know and the cycles of el nino events are not um easily not completely predictable i can't tell you it's going to be one every three years or five years it varies right now we're pretty much neutral but during an el nino event this is what things look like all of a sudden you have a well-established thermocline there's no migrating upwelling and people didn't realize what was going on early on or overfishing some of these areas along the you know west coast of south america and decimating the populations because they didn't realize that there was no nutrients coming up to continue the food chain developing and so when this starts to break down you know again you get a more intense self-welling so let's go it's called la nina is a more intense uploading la nina conditions as you start to return towards normal you can see the high temperature there as the water starts to warm up during an el nino event and break down during la nina again i think in the most i have to get you know if you look in your book you'll see these events of el nino and you know they're not they're not you know they don't occur they occur with enough frequency that they're going to occur in your lifetime but it's not easy to predict exactly when the next one is coming but i believe right now i'll double check if i'm wrong but i believe right now we're in el nino again there's lots of dramatic effects fires and things that have been associated drought fires you know have traveled troubles in australia in recent years uh they're associated with again these shifts and chromatic conditions that are associated with these events this is looking up the west coast united states looking normal conditions and then warming up during an el nino again the monsoon shift you know again sometimes these dryers will shift directions as i mentioned before uh the monsoon winds shift directions seasonally in the indian ocean and that shifts the surface water circulations in this region deepwater currents as i said the north atlantic deep water sinks from the northern you know up around labrador and greenland it's a very cold uh dense water body north atlantic deport nadw you can see it there it's a very dense the only water that's the only waters ocean deep ocean water current that's denser is the atlantic uh the anthropic bottom water okay that's anthonic bottom layer is the coldest densest water deepest water and as the north american as the north atlantic deep water moves towards the south it eventually catches up with the antibiotic bottom order and then migrates towards the pacific okay there are you know places where guys converge and get antibiotic intermediate water i'll show you in a minute the water that comes out of the mediterranean we'll get back to that we talk about coastal waters is uh very high in salinity and estimated so it's a higher salinity water mediterranean intermediate water okay so we have all these you know different layers of water that occur in the deep oceans and we can measure them we can we can actually determine where they are discrete bodies depending on temperature salinity oxygen content things like that so we have all the surface flow going on with all this stuff going on in the subsurface so here's a picture of the cold nothing like a bottom left leg deep where is coming towards the south and catching up with in the antarctic bottom water okay and of course the some of these warmer body waters and the highest selenium waters are above them in some places again antarctic intermediate water forms where we get convergence of gyres so it looks like this basically we have what's called thermal hairline circulation we have all this water sinking again very oxygen rich and as water travels south you know we get down into we have more sinks down around antarctica this water travels to the pacific where it gets warmed up by the east pacific rise the spreading center there and then the surface water sort of migrates back around you know again right race back asia africa back up along north america look as you know they go as the gulf stream so let me see that i have a better picture of this so it looks like this the cold water sinking and then migrating and then getting warmed up in the pacific and then traveling back as a surface current so we call this thermal haloline circulation and so my best estimates i've seen from people who study this is if you're a molecule of water and you sink in somewhere in the north atlantic you'll make it back there in the surface water takes about a thousand years or so to go through the entire cycle anyways you know it's not an area i i study but there's you know lots of experts that work on this are very concerned about it with global warming and stuff you know how they want the oceans to get too warm because part of the hunt they don't want to upset this thermal halogen circulation which uh distributes it also distributes heat within you know keeps the um things moving along and distributes heat so the northern areas don't get too cold and the southern air is too hot because if all of a sudden you can't sink water off the coast you know if it gets too warm then you're going to break down the circulation and that could be climatically and end up with some fairly dramatic yes okay just another peek at this circulation and just summaries of the different major gyres and the currents that comprise them so and a little bit more about el nino and after the exam i'll be talking about waves and tides coastal waters marginal seas shoreline processes and stuff like that and then the remainder of the course after we go through all that will be getting back into productivity and the organisms that live in the oceans all right stay safe