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]