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Ocean Colour from Space

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Introduction to Earth Observation

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[Optional: slide introducing presenters]

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What is a satellite?

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What is a satellite?

    • Definition: something in orbit around the Earth (or another planet!)
    • Fun Fact! The Earth itself is a natural satellite, orbiting the Sun
    • Thousands of man made satellite orbit the Earth
    • Give a bird's eye view of the Earth

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What is Earth Observation?

'Earthrise' - Apollo 8 Mission, 1968

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What is Earth Observation?

    • Earth Observation involves collecting information about the Earth from space.

    • Earth Observation satellites carry giant cameras, radars, and even lasers!

    • Applications of Earth Observation:
      • weather forecasting
      • disaster response
      • tracking wildlife
      • measuring land-use change
      • research.

'Earthrise' - Apollo 8 Mission, 1968

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Where on Earth..?

1.

Eiffel Tower,

A quick quiz

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Where on Earth..?

1.

Eiffel Tower,

Eiffel Tower, Paris

Image from very high-resolution WorldView-2 Satellite

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2.

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2.

Antarctica

This is actually a mosaic image made up of lots of smaller satellite images, because Antarctica is so big!

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3.

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3.

Mount Everest

Image from very high-resolution GeoEye-1 Satellite

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4.

Bonus: Can you identify some man-made and natural features?

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4.

London, UK

Image from the Sentinel-2 satellite (10m resolution)

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5.

What do you think the bright orange feature is?

Can you identify any other interesting features?

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5.

La Palma, Canary Islands

During an eruption of the Cumbre Vieja volcano!

This is an infrared image, meaning it can detect the lava flow due to its heat causing it to appear very bright.

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6.

What is the main feature you can see in this image?

Where do you think this could be?

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6.

Hurricane Katrina, Gulf of Mexico

This is a satellite image of hurricane Katrina in 2005 in the Gulf of Mexico, starting to move across the southern states of the USA.

Sometimes cloud and weather can block satellite images, but in some cases, like this one, you want to track the cloud and weather in order to warn those that may be affected.

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Ocean Colour from Space

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Why are the oceans important to study?

The ocean is the foundation of all life on Earth, and our planet ecosystems depends on the health of the ocean to support and sustain it.

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Take two minutes to brainstorm what you already know, thinking about the following questions:

1. How much of planet Earth is Ocean?

2. What role do the oceans play in regulating our climate and why is this important?

3. Who/what is the ocean important for, maybe think about what lives in the oceans and who uses the oceans?

Oceans from Space

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Oceans from Space

Photo: Google Earth

As you may have figured out, oceans cover 70% of Earth's surface and hold 97% of the water on Earth. That is why Earth is often called the ‘blue planet’.

We don’t often view Earth from the perspective of the Pacific Ocean, but it really highlights just how much of our Earth is ocean.

The Blue Planet

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Breathe... Now breathe again... Now thank the ocean!

Did you know the oceans produce 50% of the oxygen we breath, so for every two breaths, we have the oceans to thank!

The oceans help to regulate the Earth's climate by absorbing and storing atmospheric carbon in the deep ocean. This happens through: (1) the biological pump, where the inhabitants within the ocean transfer carbon from the surface to the sea bed and; (2) through the physical pump, where ocean circulation transfers carbon to the depths.

The oxygen we breath and Earth's climate regulation

Oceans from Space

Photo: ESA

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The oceans are home to many plants and animals.

The ocean ecosystem is highly sensitive to change.

Habitats and biodiversity

Oceans from Space

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Oceans from Space

    • Jobs
    • Transportation
    • Shipping
    • Oil and gas (energy)

The economy

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Oceans from Space

The ocean provides food for both humans and animals.

~3 billion people rely on seafood as their primary source of protein!

However, 85% of marine fish stocks are now fully exploited or overfished.

Food Source

Photo: Commercial and Sport Fishing

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As climate change threatens planet Earth, we need to find alternative renewable energy sources.

The power of the oceans, through the waves, tides or winds, can generate renewable energy.change.

Renewable Energy

Oceans from Space

Photo: Power Engineering International

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How can satellites help us study the ocean?

Oceans from Space

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Satellites cannot see the ocean floor, so just how can they help us map how deep the ocean is? The surface of the ocean/sea surface height, changes with the topography (the height and location of ocean landforms) of the ocean floor and can be measured using a type of satellite sensor called radar altimetry. Sea surface height can be used to infer sea level rise caused by climate change.

How deep is the ocean?

Oceans from Space

Photo: NOAA

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The oceans are so vast and most of its inhabitants are highly mobile and spend large amounts of time below the surface, meaning it is very challenging to study wildlife. Scientists are using very high resolution images of Earth to spy on whales, walrus, seals, penguins, albatross and even krill from space!

Wildlife from Space

Oceans from Space

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Climate change and warming oceans are causing coral bleaching (the process in which corals release the symbiotic algae living in their tissues). To map the effects of climate change on coral reefs, optical satellites are being used to detect beaching. Scientists are also using SST measurements to forecast potential hotspots for bleaching.

Mapping Coral Reefs and Coral Bleaching

Oceans from Space

Photo: ESA

Learn more:

https://www.allencoralatlas.org/

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Ocean surface currents, primarily driven by winds, form part of the wider global ocean circulation. They help to move heat around the world, which is an important part of the oceans role in regulating the world's climate.As with mapping the sea floor, changes in sea surface height (measured using radar altimetry) can be used to map ocean surface currents.

Ocean Circulation/Ocean Surface Currents

Oceans from Space

Photo: NASA/Goddard Space Flight Center Scientific Visualization Studio

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Mapping SST is important, as heat exchange from the ocean drives global weather and climate and ocean warming can effect animal behaviour and cause coral bleaching.

SST and SSS are also important drivers for global ocean circulation.

Satellites using long wave microwave and infrared wavelengths, can help to measure SST and SSS.

Sea Surface Temperature (SST) and Sea Surface Salinity (SSS)

Oceans from Space

Photo: Olivier et al. (2020) https://doi.org/10.1029/2020JC016641

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Light reflected from the Earth's surface in the visible wavelengths of the electromagnetic spectrum can tell us information about ocean colour. This in turn can be used to estimate chlorophyll concentrations (the pigment in phytoplankton responsible for photosynthesis) and so inform us of harmful algal blooms, and can be used to understand other ocean constituents such as suspended sediments.

Ocean Colour

Oceans from Space

Photo: NOAA

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What is Plankton?

Oceans from Space

    • Phytoplankton are tiny microorganisms that live in the surface layer of the ocean.
    • Like plants, they use sunlight and carbon dioxide to photosynthesis and grow.

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Why is it Important?

Oceans from Space

Plankton is a Primary Producer

    • produce food through photosynthesis
    • Basis of the marine food web
    • All marine life depends on phytoplankton !

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How Can We See Plankton from Space?

Oceans from Space

What is colour?

    • White light is a mixture of many different colours.
    • White light can be separated in to a spectrum using a prism

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How Can We See Plankton from Space?

Oceans from Space

Refraction & Dispersion

    • Light travels at different speeds in different materials! This change in speed when entering a new material is called refraction.
    • Most importantly each colour of light is refracted a different amount due to each colour having its own frequency.
    • This effect allows us to seperate the white light into its constituent colours, this process is called dispersion.

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How Can We See Plankton from Space?

Oceans from Space

    • The change in speed when light enters a new material is called refraction.
    • The amount a light wave oscillates is its frequency.
    • White light is separated into its constituent colours, using dispersion.

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How Can We See Plankton from Space?

Oceans from Space

    • When light hits a surface some of it is absorbed and some of it is reflected.
    • Why is the ocean blue?

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How Can We See Plankton from Space?

Oceans from Space

    • When light hits a surface some of it is absorbed and some of it is reflected.
    • The ocean is blue as it reflects blue light very well, while it absorbs the other colour frequencies!
    • However, it is not always the SAME colour of blue.

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How Can We See Plankton from Space?

Oceans from Space

    • Shallow water appears lighter, the light interactes with fewer water molecules and absorbs less colours. Some light is also reflected by the ocean bed!
    • Deeper water is the opposite, more light is absorbed so it appears darker.

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How Can We See Plankton from Space?

Oceans from Space

    • The ocean can appear green, red or other colours as light bounces of other particles!
    • We can use our knowledge of how light interacts with water to identify blooms of phytoplankton in our oceans.
    • Phytoplankton contains chlorophyll, a green pigment, allowing it to show up clearly as green light is reflected .

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How Can We See Plankton from Space?

Oceans from Space

    • Shallow water appears lighter, the light interactes with fewer water molecules and absorbs less colours. Some light is also reflected by the ocean bed!
    • Deeper water is the opposite, more light is absorbed so it appears darker.

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Activity 1: Blooms from Space

Oceans from Space

Follow link to StoryMap and explore the map showing phytoplankton algae blooms and answer the following questions:

    • How large are the blooms? (hint: use map scale)
    • Where can you see these blooms occuring?
    • Are some of the blooms different colours?
    • What might be confused as a bloom? (hint: coasts)

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Activity 2: Plankton The Basis of Life

Oceans from Space

Watch the video and answer the following questions:

    • What are the different plankton species, how can we tell them apart?
    • what is a red tide?
    • How have phytoplankton benefitted global ecosystems, on land and in the ocean?

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Oceans from Space

What have we learnt today?

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Oceans from Space

As you watch the next video, think about these questions:

1. What threats do the scientists mention?

2. What do the scientists say might happen to the oceans and life on Earth as a result of these threats?

3. What do the scientists say we can do to change the future of our oceans?

Our actions are putting the heath of the oceans at risk

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Oceans from Space