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and it seems a little odd in a way

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because salt is really a molecule in the

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ocean water

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but collectively that salinity plays a

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role in the ocean circulation

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it's these differences in salinity that

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play a role in the processes that affect

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weather climate sea life and the whole

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ocean system itself and not all oceans

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have the same salinity in fact the north

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atlantic ocean tends to be the saltiest

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much more than the pacific

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the salt in the ocean affects its

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density just like the temperature

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affects its density and the density

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meaning the amount of mass per volume

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is going to then impact where the water

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goes as it circulates throughout the

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globe

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differences in temperature and salt

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content of the water cause some areas of

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water to sink and some areas of water to

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rise and so we tend to see the sinking

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water at the poles the water rising back

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up the equator and if you connect the

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two together what you have is an

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overturning that's deep in the ocean

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it's like a big conveyor belt that

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operates in the ocean

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this overturning moves warm water from

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the tropics toward the poles and cold

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water from the poles toward the tropics

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in this way the overturning regulates

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earth's

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climate and the atmosphere in the ocean

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both being fluids of the earth really

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work together we consider them sort of

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equal partners in the redistribution of

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this heat on the planet

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so when those warm waters are returning

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as they're moving up to the higher and

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higher latitudes then they're releasing

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that heat to the atmosphere then the

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winds blow over the ocean they pick up

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that heat and those winds

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over the atlantic ocean are moving from

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the north american continent to the

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european continent

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it takes perhaps a thousand years for

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the water to cycle through the deep

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oceans so he said the oceans have a

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memory

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they're like a tape recorder things that

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happen now will still be manifest

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hundreds of year in the future as that

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cold water moves through this giant

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circulation

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so if there's any change to that

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overturning circulation that means that

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northern europe and the british isles

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would be robbed of that heat

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due to those waters that are returning

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to the high latitudes the oceans are

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vast covering 70 percent of our planet

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and so it is no surprise that we still

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know only a little about this system and

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how it will respond to change and

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furthermore create change

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climate change on earth is complicated

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by the fact that the ocean

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moves much more slowly than the

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atmosphere so you have warming in the

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atmosphere warming in the ocean but

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they're occurring at different speeds so

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they're out of sync and that's that

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makes predicting what's going to happen

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the next 102 years very very difficult

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now what we might expect happens in a

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very simplistic sense is that as the

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ocean warms there's going to be more

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evaporation and that more evaporation

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would mean that the oceans become

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saltier but really it's not just that

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simple because there's also evaporation

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precipitation

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and the ice as well and that's all

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wrapped up in the study of the

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hydrologic cycle

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people have been measuring salinity for

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centuries but ships and buoys alone

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cannot match the perspective from space

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fact a whole quarter of the oceans

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larger than the size of africa have no

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salinity data at all

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up until now when we've been trying to

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understand how density changes impact

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ocean circulation we've really just had

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half the picture

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00:03:51,350 --> 00:03:48,959
when the aquarius satellite is launched

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scientists for the first time can look

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at salinity of the surface of the ocean

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from 400 miles above the earth but now

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with the aquarius mission we'll be able

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to complete that other half we'll be

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able to look at the salinity information

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and so salinity combined with

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temperature will give us the information

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about the density field in the first two

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months of aquarius's launch the

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satellite will gather more salinity data

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than in the last 125 years

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this mission will help scientists better

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understand how salinity and ocean

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circulation are tied to global climate