Saturday, February 27, 2010
Suzee has a camera and a movable arm for taking samples. She's operated by Dries Boone, Katrien Heirman, and Lieven Naudts from Ghent University in Belgium. Dries says that controlling the ROV is a lot like playing a video game!
Here's a photo from a recent dive. Did you know that so many different things lived deep in the ocean? I didn't know that corals could survive in such cold water.
The feathery things are called crinoids, commonly referred to as sea lilies. The curly ones are brittle stars, and the bulbous pink and blue creatures are tunicates. You can also see a few sponges and soft coral.
It turns out that at least half of the deep water species in the ocean have never been described. That means they don't have names, and nobody knows anything about them. I think that's a little scary. But the cool part is that if you're a biologist, you have an excellent chance of finding a new species here. My friend Craig Smith, from the University of Hawaii (who identified all of the species in the photo for me), has personally collected hundreds of species that were totally new to science. He even has
three species named after him!
Sunday, February 21, 2010
So it shouldn't surprise you that I'm not the only one blogging. This blog is primarily meant to be educational and is part of the LEEFS program at Columbia University. But if you want to learn more about some of the projects going on here and get some different perspectives, here is the list of blogs being kept:
This is kept by Kim Roe, a graduate student working on the cruise.
Buzz Campbell writes this one, and he's been working out here in Antarctica for a long time.
Martin Truffer - he's from Alaska and knows all about snow and ice.
This is kept by Terry Haran and Ted Scambos (the guy with the AMIGOS) at the National Snow and Ice Data Center
This is the National Geographic blog. I bet they'll have some great photos there!
This blog is kept by the team running the Remotely Operated Vehicle (ROV). They're from Gent University in Belgium. And you can follow the ROV on twitter @ROV_Suzee (yes, they named the ROV Suzee).
This is kept by Craig Smith and Laura Grange, who work on marine ecosystems at the University of Hawaii.
More marine ecosystems, this time by Maria Vernet and Mattias Cape of Scripps Institution of Oceanography.
And don't forget, I'm also on twitter @Ms_T_at_Sea. I meant to post this list a while ago, but I forgot to. Sorry about that! But please check out these blogs and let me know what you think. FYI, the photo is one of the NBP that I took from the zodiac a few days ago.
Friday, February 19, 2010
We have two zodiacs, and each went out for three trips. There was a trip to retrieve a time-lapse camera for the National Geographic team, there were trips to gather kelp for the biologists, there were trips to gather water for chemical analysis, and there was my trip to listen to some glaciers. We used the hydrophones again, this time to listen to glaciers instead of sea ice.
The moment we put the hydrophones in the water, Ross, our marine technician and zodiac pilot saw that the iceberg that we were listening to was going to flip over. It did, and I have a great video that I'll post once I'm back on shore. I listened to that iceberg and one other before it was time to return to the ship.
On the way back to the ship, we saw a leopard seal on some ice. Leopard seals are known to eat people, but they generally don't bother you if you're in a zodiac. So we approached, carefully and quietly, and got to circle around him before we went back to the ship. You can identify a leopard seal by it's silhouette: there's a medium head, a skinny neck, and a big body. They're the only seals with necks, and they also have leopard-like spots on their undersides - but you usually don't want to get close enough to see those!
Wednesday, February 17, 2010
Now that you know how to run a CTD and how it works, what about the data it collects? This figure is more or less what I see on my screen while the CTD is in the water.
There are four x-axes: fluorometer (remember, that records the microscopic plants), salinity, temperature, and oxygen. Having all four on one graph means that I can keep track of lots of different variables at once.
What do you notice about this graph? I notice that below 40m, temperature and oxygen vary inversely - when one gets bigger, the other gets smaller. I also notice that at around 140m, it gets warmer very suddenly. I can also see that the maximum fluorescence is at 15m, so I bet the biologists will want a sample of the water there.
This graph only shows the top 200m, but the CTD actually went down to 600 m at this location. It's in a place called Hughes Bay on the western side of the Antarctic Peninsula. And there's something special about this cast, something that makes it different from all the other casts. Can you guess what it is?
Tuesday, February 16, 2010
Last week, three people left the ship by helicopter for nearby James Ross Island. On the flight home, the weather worsened and they had to land on the island. Greg Balco, the geologist I've told you about before, Doug Fox, our science writer, and Barry James, the helicopter pilot, had to spend the night on the ice. It took a few days for the weather to improve, so they ended up staying on the ice for four days and three nights.
They're all back on the ship now and they're fine. Every time one of us takes a flight by helicopter, we have a survival bag. Those bags add a lot of weight, which means we can't take as much equipment as we would sometimes like. But those bags are the reason that everyone made it through. They had tents, stoves, food, and sleeping bags, as well as a survival manual. All three of the people on the ice have a lot of camping experience and their personal bags contained spare clothing and flashlights, even though they completely expected to be back on the ship the same night.
Greg, Doug, and Barry each ate one freeze-dried meal per day. They had fuel and a stove for melting water. In the Antarctic, water can be a big problem. You can't melt snow in your mouth for water because it takes too much energy, and your body needs that energy to keep itself warm. They all stayed calm and kept in contact with the ship via a satellite phone, and they cut blocks of ice to build a shelter to keep some of the wind and snow off the tents.
Thursday, February 11, 2010
Here's a map showing salinity from -60° (that's me!) to 70° (further north than New York, which is at 40°) in the western Atlantic Ocean. The average salinity in the ocean is 35. The units of salinity are a little complicated - some people use what's called the practical salinity unit, or psu, and some people use per mil (0/00‰), which is like percent except that it's a fraction out of one thousand instead of one hundred.
For now, just concentrate on the colors in the map. Red and yellow represent the high salinities and blue and purple represent low salinities. The big mass of green is NADW. The blue is AABW, and the purple is AAIW. The red area near 30° of latitude is water that flows out from the Mediterranean Sea.
Saltier water is denser, but temperature has a bigger effect on density than salinity does. AABW isn't the saltiest, but it's the coldest and the densest. NADW comes next: it's not as cold, but it's very salty. AAIW is near the same temperature as NADW, but it isn't as salty so it's less dense. The water from the Mediterranean Sea is very salty but also very warm, so it's the least dense of all.
Question: Besides temperature and salinity, what else do you think might make water masses different?
Sunday, February 7, 2010
One of our goals down here is to understand how glaciers work. We're studying them lots of different ways. We put AMIGOS on them, we put GPS stations on them, we take ice cores, we take sediment cores, we look at satellite pictures - you get the idea. But Erin wants to try something else: listening to them.
Some of you may remember that I use sound to measure ocean currents. That's called active acoustics because I send out a sound and listen for the return. This is passive acoustics, where I put a special kind of microphone, called a hydrophone, into the water and listen.
What am I listening for? When ice melts, it makes sounds. It can sound like crackling or popping. When big chunks of ice fall off glaciers (called calving) it can sound like fireworks, at least in the air. Erin and other scientists think that they could use passive acoustic systems to monitor glacial melt rates in areas that are too hard to reach with other instruments.
To test that idea, we are making measurements of sound near any ice we can reach. Our goal right now is to gather preliminary data and also to test the instruments.
Yesterday, we got to go out on the ice again. The biologists took an ice core to look for algae and we used the hole that remained to put the hydrophones in to the water. Clockwise from the left, you can see Yuribia Muñoz, Kim Roe, me, and Laura Grange. We got some good data and identified some problems with one of the hydrophones. It isn't heavy enough, so it's hard to get it through the hole in the ice. Once it's in the water it doesn't fully straighten the wire it's attached to, so we can't be sure exactly how deep it is. We also had some interference on both hydrophones from noises that the ship makes.
It's really important to work out those kinds of problems, even if they sound small and unimportant compared to the complicated equations we use to turn sound from the water into usable data. Scientists need to be able to solve practical problems as well as intellectual ones. Did any of you at DLMS have similar problems with your science fair projects?
Saturday, February 6, 2010
The ocean is mostly stable. The ocean is heated by the sun, so the water on top is warmer than the water in the bottom. If you remember what you learned about convection in sixth grade, you know that you only get all of that motion when heat is added to the bottom of a fluid. When it's added at the top, you get layers of lighter (less dense) water over layers of heavier (more dense) water.
Still, the oceans circulate. One reason is that the tropics get more heat than the poles do. Since it's warm near the equator and colder everywhere else, heat has to circulate. Some of that circulation is done by the atmosphere, but some is done by the ocean.
Water sinks in the ocean in two areas: the North Atlantic and the Southern Ocean around Antarctica. The water that sinks in the North Atlantic is called North Atlantic Deep Water (NADW) and is very salty. Some of the water that sinks in the Southern Ocean goes down to around 1000m and is called Antarctic Intermediate Water (AAIW). The really cold water from the Southern Ocean sinks all the way down to the sea floor and is called Antarctic Bottom Water (AABW).
NADW is around 2° to 4° C (35.6° to 39.2° F). That sounds pretty cold to me! But AABW is colder: -2° to 0° C (28.4° to 32° F). Based on these different temperatures, we can see how far they travel.
Everywhere the map shows red is NADW, and the blue is AABW. Now you can see why processes in Antarctica are so important: water that forms here spreads all over the world.
Wednesday, February 3, 2010
Topic: The speed of ocean currents in Antarctica
Question: How does the depth of the water affect its speed?
Hypothesis: Shallow water moves faster than deep water.
Background Information: Lowered acoustic Doppler current profilers (LADCPs) use sound energy to measure the speed and direction of ocean currents. Water in the ocean can be moved by wind, tides, and differences in pressure due to temperature or salt content.
Procedure: Use LADCP data to compare the depth of water (the independent variable) with the speed of the water (the dependent variable).
Results: I was able to collect data from 38 stations all around the Antarctica Peninsula. On average, the fastest water was at the surface as predicted (figure 1).
Discussion: Average speed does not tell the whole story. The maximum speed that was found in any location occurred at 60 m (figure 2), and the minimum was found at 175 m (figure 3). There is a lot of variability in water speeds, especially at depths above 100m. Below that, the speed changes very little but does not stay exactly steady.
These figures show average, maximum, and minimum water speeds. Please note the different scales.
Conclusions: On average, the fastest water is at the surface. However, there is variability between stations and there can be high speeds below the surface. Speed generally decreases with depth, but there are exceptions. Differences in tides, wind, and ice conditions might also effect water speed.