Creator: Ambarin Sadaf Ahmed (Grade 6)
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Ocean and its layersOceans cover about 70% of Earth’s surface—they're huge and deep! Imagine the ocean as one big box, like the one in the picture on the left. The top layer of the ocean is called the mixed layer. This layer usually goes down about 100–200 meters. It gets its name because wind mixes the water here, and sunlight can reach almost all the way to the bottom of this layer. It is also where thousands and thousands of tiny organisms called phytoplankton live and use sunlight to photosynthesize. These phytoplankton provide food for much of the marine ecosystem.
Right below the mixed layer is a thin boundary layer, which separates the surface from the dark, cold deep layer. On average, the deep layer is about 3.8 km deep (however, there are places which are way deeper) — the deepest part of the ocean is deeper than the height of Mount Everest. The deep ocean is the largest habitat in the planet. Can you name any of the creatures that live in this dark, deep, cold habitat? |
The deep layer of the ocean can be further divided into thinner layers based on how dense, or heavy, the water is. Unlike the surface, where wind helps move water around, it's much harder to move water in the deep layer. Differences in the temperature and salt content of the water affect the density of the water and help move ocean currents in the deep layers.
Why does this matter?
The movement of deep ocean water is very important because it helps control Earth’s climate. Scientists have studied this for many years and describe it like a conveyor belt that moves water around the globe. You can watch a video about this here: The Atlantic Meridional Overturning Circulation (AMOC).
Interestingly, the surface and deep layers are connected: When tiny organisms living near the surface die, they sink through the deep ocean and settle at the bottom. This has been happening for a very long time — for millions of years. So, the layers of mud and tiny particles (called sediments) at the ocean floor are more than just home to some amazing deep-sea creatures. They also hold clues about the ocean’s history. Scientists can study these sediments, including the preserved remains (called “microfossils”) of the tiny creatures that lived in ancient ocean environments, to learn what the ocean was like thousands of years ago — such as how warm or cold it was, and whether the water was more or less acidic than it is now. All this information helps us understand Earth’s climate in the past, how it’s changing now, and what might happen in the future.
The movement of deep ocean water is very important because it helps control Earth’s climate. Scientists have studied this for many years and describe it like a conveyor belt that moves water around the globe. You can watch a video about this here: The Atlantic Meridional Overturning Circulation (AMOC).
Interestingly, the surface and deep layers are connected: When tiny organisms living near the surface die, they sink through the deep ocean and settle at the bottom. This has been happening for a very long time — for millions of years. So, the layers of mud and tiny particles (called sediments) at the ocean floor are more than just home to some amazing deep-sea creatures. They also hold clues about the ocean’s history. Scientists can study these sediments, including the preserved remains (called “microfossils”) of the tiny creatures that lived in ancient ocean environments, to learn what the ocean was like thousands of years ago — such as how warm or cold it was, and whether the water was more or less acidic than it is now. All this information helps us understand Earth’s climate in the past, how it’s changing now, and what might happen in the future.
Oceanographers are scientists who study the chemistry, biology, geology, and physics of the oceans — how ocean water moves, what it carries, and how it helps sustain life and ecosystems while interacting with Earth’s climate over time. During this research trip, our team of oceanographers will connect with students and educators on Zoom to give them a sneak peek into how we study the ocean. We’ll show you the instruments we use, the labs we work in aboard our research ship, and answer your questions.
Ship-to-Shore Dates: June 9, 10, 11, 12, 13, 16, 18, and 19
We’re excited to share what it’s like to be an oceanographer!
Ship-to-Shore Dates: June 9, 10, 11, 12, 13, 16, 18, and 19
We’re excited to share what it’s like to be an oceanographer!
Lesson Plans for Educators
Frequently Asked Questions (FAQ)
How does your research help with climate change?
One of the ways we understand how our climate is changing is by looking at changes in climate throughout Earth's history. We do this by using something called "proxies" - a chemical measurement we can make in the modern day that reflects some geologic process in the past! Neodymium (Nd) is one of the key focuses of this research cruise and is often used as a proxy for water masses and ocean circulation throughout Earth's history. But we can only use proxies like Nd to reconstruct that past if we understand how these elements behave in the ocean: where do they come from, are they removed, and what other processes might impact them?
We use our understanding of how different Earth processes relate to each other to inform the models we use to project changes in our climate. By studying the past, we can better understand our present and what we think might happen in the future.
We use our understanding of how different Earth processes relate to each other to inform the models we use to project changes in our climate. By studying the past, we can better understand our present and what we think might happen in the future.
How do you collect and analyze water samples from thousands of meters deep?
Some of the deepest water we're collecting on this cruise is 3600 m deep (that's about the length of 33 American Football fields)! At that depth, we can't swim down and simply collect the seawater in a bottle.
We use a special instrument called a CTD (which stands for Conductivity, Temperature, and Depth) that measures the salinity and temperature of the water. We lower it on a wire and get readings sent back to the ship. Attached to this instrument are 24 special bottles called Niskin Bottles, which are open as we send the CTD down. Sending the CTD to 3600 m can take over an hour!
Once we have a profile of what the salinity and temperature is like, we decide which depths we want to sample seawater from. Then, we bring the CTD back up to each of those depths and "fire" the bottle to close it. Once all the bottles have been closed, we bring the CTD onto the deck of the ship and the scientists collect samples of the water depths they want to study.
We use a special instrument called a CTD (which stands for Conductivity, Temperature, and Depth) that measures the salinity and temperature of the water. We lower it on a wire and get readings sent back to the ship. Attached to this instrument are 24 special bottles called Niskin Bottles, which are open as we send the CTD down. Sending the CTD to 3600 m can take over an hour!
Once we have a profile of what the salinity and temperature is like, we decide which depths we want to sample seawater from. Then, we bring the CTD back up to each of those depths and "fire" the bottle to close it. Once all the bottles have been closed, we bring the CTD onto the deck of the ship and the scientists collect samples of the water depths they want to study.
How do you use sediment to learn about what the ocean was like thousands of years ago?
There are multiple ways we can look at sediment to learn about what the ocean was like thousands of years ago, but on this cruise, we have people looking at microfossils within the sediment. These are super tiny creatures the size of a grain of sand called foraminifera that either live in the sediment (called benthic foraminifera) or live in the water column (planktonic foraminifera). These creatures build a shell out of a material called calcium carbonate, which is the same material seashells and coral are made of. They build these shells by taking calcium and carbonate dissolved in seawater and combine them into a hard shell. But while they build these shells, other elements dissolved in seawater (like magnesium or lithium) can enter the shell structure. Changes in the seawater can affect how much of these other elements enter the shell.
When these creatures die, they get buried in the sediment. Then, scientists can look at the chemistry of the foraminifera shells across thousands-of-years’ worth of sediment layers to learn about those changes the seawater chemistry.
When these creatures die, they get buried in the sediment. Then, scientists can look at the chemistry of the foraminifera shells across thousands-of-years’ worth of sediment layers to learn about those changes the seawater chemistry.
How do you make sure your samples aren't contaminated?
We are studying trace amounts of metals (like iron) in a big metal ship! Fortunately, there are ways to make sure our samples don't get contaminated. One of the ways we do this is by making something called a "clean bubble" on the ship. We put up plastic sheets to make a tent like room and filter the air that is pumped into the space. We affectionately call it "The Bubble" because it looks like a bubble in the middle of the main lab.
Anyone who works in The Bubble must change their shoes to special clean Crocs and wear clean clothes that won't shed fibers into the samples. We make sure to clean our sampling equipment with super clean water before using it and we store all our samples in pre-cleaned containers to ship back to our labs on land for analysis.
Anyone who works in The Bubble must change their shoes to special clean Crocs and wear clean clothes that won't shed fibers into the samples. We make sure to clean our sampling equipment with super clean water before using it and we store all our samples in pre-cleaned containers to ship back to our labs on land for analysis.
Have you ever encountered any dangerous situations at sea?
One of the challenges of doing research at sea is making sure the ship, crew, and scientists are all safe. The Captain has been working with the crew and scientists to make sure we avoid situations that could be dangerous (such as extreme weather or sea ice). Things like sea ice can sometime interfere with our ability to collect samples, so we must stay flexible as the expedition progresses. But safety is a top priority!
To make sure we're ready for any possible situation, we do safety drills about once a week, so we know what to do and where to go in case of an emergency. Since we're in the North Atlantic, we're keeping a close eye on both stormy weather and sea ice, and making sure everyone on the ship feels prepared for any possible situation.
To make sure we're ready for any possible situation, we do safety drills about once a week, so we know what to do and where to go in case of an emergency. Since we're in the North Atlantic, we're keeping a close eye on both stormy weather and sea ice, and making sure everyone on the ship feels prepared for any possible situation.