WEBVTT FILE 1 00:00:23.680 --> 00:00:28.780 [Susan Lozier] And it seems a little odd in a way because salt is really a molecule 2 00:00:28.780 --> 00:00:34.630 in the ocean water, but collectively, that salinity plays a role in the ocean 3 00:00:34.630 --> 00:00:38.080 circulation. [Narrator] It's these differences in salinity that 4 00:00:38.080 --> 00:00:43.090 play a role in the processes that affect weather, climate, sea life, and the whole 5 00:00:43.090 --> 00:00:48.910 ocean system itself. And not all oceans have the same salinity. In fact, the North 6 00:00:48.910 --> 00:00:54.880 Atlantic Ocean tends to be the saltiest, much more than the Pacific. [Susan Lozier] The salt in 7 00:00:54.880 --> 00:00:59.680 the ocean affects its density, just like the temperature affects its density, and 8 00:00:59.680 --> 00:01:05.379 the density, meaning the amount mass per volume, is going to then impact where the 9 00:01:05.379 --> 00:01:10.810 water goes as it circulates throughout the globe. [Jeff Halverson] Differences in temperature and 10 00:01:10.810 --> 00:01:15.430 salt content of the water cause some areas of water to sink in some areas of 11 00:01:15.430 --> 00:01:19.270 water to rise. And so we tend to see the sinking water at the poles, the water 12 00:01:19.270 --> 00:01:22.570 rising back up at the equator, and if you connect the two together, what you have 13 00:01:22.570 --> 00:01:26.590 is an overturning that is deep in the ocean. It's like a big conveyor belt that 14 00:01:26.590 --> 00:01:31.240 operates in the ocean. [Narrator] This overturning moves warm water from the tropics toward 15 00:01:31.240 --> 00:01:36.490 the poles, and cold water from the poles toward the tropics. In this way the 16 00:01:36.490 --> 00:01:41.500 overturning regulates Earth's climate. [Susan Lozier] And the atmosphere and the ocean, both being 17 00:01:41.500 --> 00:01:45.340 fluids of the Earth, really work together. We consider them sort of equal partners 18 00:01:45.340 --> 00:01:50.200 in the redistribution of this heat on the planet. So when those warm waters are 19 00:01:50.200 --> 00:01:53.740 returning, as they're moving up to the higher and higher latitudes then, they're 20 00:01:53.740 --> 00:01:58.140 releasing that heat to the atmosphere. Then the winds blow over the ocean, they 21 00:01:58.140 --> 00:02:03.120 pick up that heat and those winds over the Atlantic Ocean are moving from the 22 00:02:03.120 --> 00:02:08.280 North American continent to the European continent. [Jeff Halverson] It takes perhaps a thousand 23 00:02:08.280 --> 00:02:12.510 years for the water to cycle through the deep ocean. So we say the oceans have a 24 00:02:12.510 --> 00:02:17.040 memory. They're like a tape recorder. Things that happen now will still be 25 00:02:17.040 --> 00:02:20.460 manifest hundreds of years in the future as that cold water moves through this 26 00:02:20.460 --> 00:02:25.680 giant circulation. [Susan Lozier] So if there's any change to that overturning circulation, that 27 00:02:25.680 --> 00:02:29.250 means that Northern Europe and the British Isles would be robbed of that 28 00:02:29.250 --> 00:02:33.900 heat due to those waters that are returning to the high latitudes. 29 00:02:33.900 --> 00:02:39.300 [Narrator] The oceans are vast, covering 70 percent of our planet, and so it is no surprise that we 30 00:02:39.300 --> 00:02:43.980 still know only a little about this system, and how it will respond to change, 31 00:02:43.980 --> 00:02:49.170 and furthermore, create change. [Jeff Halverson] Climate change on earth is complicated by the 32 00:02:49.170 --> 00:02:53.850 fact that the ocean moves much more slowly than the atmosphere. So you have 33 00:02:53.850 --> 00:02:56.280 warming in the atmosphere, warming in the ocean, but they're occurring at different 34 00:02:56.280 --> 00:03:00.930 speeds. So they're out of sync, and that makes predicting what's going to 35 00:03:00.930 --> 00:03:04.560 happen in the next hundred or two years very, very difficult. [Susan Lozier] Now what we might expect 36 00:03:04.560 --> 00:03:08.489 happens, in a very simplistic sense, is that as the ocean warms, there's going to 37 00:03:08.489 --> 00:03:11.880 be more evaporation. And that more evaporation would would mean that oceans 38 00:03:11.880 --> 00:03:16.580 become saltier. But really it's not just that simple because there's also 39 00:03:16.580 --> 00:03:20.790 evaporation, precipitation, and the ice as well, and that's all wrapped up in the 40 00:03:20.790 --> 00:03:25.810 study of the hydrologic cycle. [Narrator] People have been measuring salinity for 41 00:03:25.810 --> 00:03:30.280 centuries, but ships and buoys alone cannot match the perspective from space. 42 00:03:30.280 --> 00:03:36.760 In fact, a whole quarter of the oceans--larger than the size of Africa-- have no 43 00:03:36.760 --> 00:03:41.560 salinity data at all. [Susan Lozier] Up until now when we've been trying to how 44 00:03:41.560 --> 00:03:45.990 density changes impact ocean circulation, we've really just had half the picture. 45 00:03:45.990 --> 00:03:51.430 [Narrator] When the Aquarius satellite is launched, scientists, for the first time, can look 46 00:03:51.430 --> 00:03:56.350 at salinity of the surface of the ocean from 400 miles above the earth. [Susan Lozier] But now 47 00:03:56.350 --> 00:03:59.620 with the Aquarius mission, we'll be able to complete the other half. We'll be able 48 00:03:59.620 --> 00:04:03.880 to look at the salinity information. And so salinity, combined with temperature, 49 00:04:03.880 --> 00:04:07.690 will give us the information about the density field. [Narrator] In the first two months of 50 00:04:07.690 --> 00:04:11.920 Aquarius' launch, the satellite will gather more salinity data than in the 51 00:04:11.920 --> 00:04:17.620 last 125 years. This mission will help scientists better understand how 52 00:04:17.620 --> 00:04:22.990 salinity and ocean circulation are tied to global climate and how both systems 53 00:04:22.990 --> 00:04:26.500 are changing throughout time. 54 00:04:26.500 --> 00:04:35.300 [natural sound, waves, bubbles]