Welcome to ‘Monitoring the Oceans from Space’. In this course, we will introduce you to the powerful role of satellite ‘Earth observation’ (EO) technology in monitoring our oceans, and to the beautiful and inspiring nature of the imagery and data it produces.
It is important to know what our oceans are doing and the role they play in our ecosystem as a whole. The analysis of remote-sensing data makes it possible to understand the ocean in new and exciting ways.
The data we are gathering from monitoring the oceans from space tells us about hazards, how to manage the ocean sustainably, how our climate is changing and our food supply. It’s not just scientists who are using this information but policy makers, public services, offshore industries and other businesses, all the way down to individuals who are simply curious.
Earth observation (EO) provides an unparalleled means for observing our complex planet. It is an increasingly important tool in monitoring and making decisions about climate change and the environment, and encompasses a wide range of techniques used to map, measure, and monitor an enormous variety of environmental parameters and processes on the Earth.
Using ‘remote sensing’ methods, (i.e. using electromagnetic radiation (including visible light), emitted or reflected by the Earth), the specialised instruments on board EO satellites collect a range of types of data and imagery, at a local and global scale, as they orbit around the Earth. This data enables us to make better informed decisions, over longer timeframes, than is possible by just using other forms of environmental monitoring.
This course will provide you with an overview of the different types of data, imagery and their applications and will introduce you to the fundamental techniques and methodologies of working with this data. You will also learn about the types of satellite orbits and instruments used, and you will discover which parameters of the Earth system can be probed by ‘sensing’ in different ways.
This course focuses specifically on Earth observation from space and therefore relates to satellite remote sensing rather than similar forms of remote sensing often conducted from aircraft or sometimes ground-based sensors. Throughout the course, the terms ‘Earth observation’ and ‘remote sensing’ are often used interchangeably. Also, don’t forget that the word ‘data’ in the context of satellite EO refers to optical imagery and photography, as well as to so-called ‘geospatial’ and numerical data.
Essentially, ‘geospatial data’ refers to the information extracted or inferred from measurements at a specific geographical location. A full glossary of terms used in this course is provided in Step 1.4, which you can refer back to at any time during the course.
You will also have an opportunity to directly interact with certain types of EO datasets via online tools during the course, and there is more on this in the next step.
The main topic videos are the backbone of this course, and you can re-watch them as much as you need to. For further context and more detailed explanations, you can also read the introductory text provided with each video, explore the optional ‘further reading’ links, and look in-depth at information about the data, imagery and satellites provided in each topic.
The course videos begin with Topic 1a in step 1.5. Before that, over the next few steps we have provided a bit more information about the course educators and how to get the most out of this course.
We hope you enjoy the course.
Acknowledgements
This course has been designed and produced for EUMETSAT by Imperative Space. The producers would like to thank all of the academics, experts and institutions who have contributed to and supported production of the course. This includes the universities and research centres to which our onscreen experts are affiliated.
Special thanks goes to: Plymouth Marine Laboratory, CLS (Collecte Localisation Satellites), the National Oceanographic Centre, NASA Jet Propulsion Laboratory, Pierre-Yves Cousteau, and Réserve Naturelle Marine de Cerbère Banyuls, Sir Alister Hardy Foundation for Ocean Science, and the National Marine Aquarium (Plymouth).
All NASA, ESA and CMEMS imagery and animations used throughout this course are used courtesy of NASA, ESA and CMEMS.
Week 1
Topic 1a - Why satellites?
Satellite Earth Observation is key to monitoring the health of our oceans. For more than 50 years, measurements from space have given scientists a worldwide prospective of the Earths climate and more recently, ocean topography.
The global oceans cover about 70% of the Earths surface, so the vast size and the often inhospitable nature means that we can not solely rely on in situ observations. The best way to efficiently and economically monitor this vast amount of water is to have satellites orbiting overhead watching the oceans constantly.
Now thanks to satellites we are developing operational oceanography, forecasting the ocean in 3D or 4D.
What can you retrieve from satellites?
Satellites provide long-term, continuous, and global data for key ocean parameters: sea level, ocean circulation, sea surface temperature (SST), ocean colour, sea ice, waves and winds.
Challenges and advances
The advent of ocean-observing satellites has launched a new era of marine discovery, but with this form of data monitoring also arise challenges, because satellites can only read the skin of the ocean.
Data modelling solutions can be used to simulate the evolution of ocean currents, temperature and other parameters consistent in space and time.
This allows you to infer information in the bed of the ocean from what you get from the sea surface.
Featured Educators:
Alain Ratier
Pierre Bahurel
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The Copernicus programme is one of the biggest Earth observation programmes in the world. Previously known as the Global Monitoring for Environment and Security programme (GMES), this initiative is headed by the European Commission (EC) in partnership with the European Space Agency (ESA).
Copernicus provides a unified system through which vast amounts of data are fed into a range of thematic information services designed to benefit the environment, the way we live, humanitarian needs and support effective policy making for a more sustainable future.
The data they provide is freely available to everybody, so we can make choices about what we do and how we as a society look after and use the marine environment. It serves users from businesses and public services to researchers and curious individuals.
Space Component
The Copernicus Space Component is based mostly on the fleet of dedicated Sentinels and missions from other space agencies, called Contributing Missions.
There are 6 families of Sentinels:
Sentinel-1 provides all-weather, day and night radar imagery for land and ocean services
Sentinel-2 provides high-resolution optical imagery for land services
Sentinel-3 provides high-accuracy optical, radar and altimetry data for marine and land services
Sentinel-4 and Sentinel-5 will provide data for atmospheric composition monitoring from geostationary orbit and polar orbit, respectively
Sentinel-5 Precursor will bridge the gap between Envisat and Sentinel-5
Sentinel-6 will provide radar altimetry data to measure global sea-surface height, primarily for operational oceanography and for climate studies
Service Component
The Copernicus programme provides essential information for six main domains:
Marine Environment - Services relevant for marine safety and transport, oil spill detection, water quality, weather forecasting and the polar environment.
Land Environment - Services relevant for monitoring water management, agriculture and food security, land-use change, forest monitoring, soil quality, urban planning and natural protection services.
Atmospheric Environment – Services relevant for air quality and ultraviolet radiation forecasts, greenhouse gases and climate forcing.
Emergency Management Response – Services to help mitigate the effects of manmade disasters e.g. floods, forest fires and earthquakes and contribute to humanitarian aid exercises.
Climate change is the hot topic of the moment. The oceans play a key role in the Earth’s climate system as it transports heat and carbon dioxide (a major greenhouse gas).
As a result of human activity, and greenhouse gases, the climate is warming, the ocean expands and its level rises.
Since the launch of the first weather satellite in the 1950’s, EO Satellites have proven to be vital tools for climate research. The latest addition to the network of global satellites, Sentinel 3a, is now providing even more precise measurements for observing climate change.
There are two types of data, which make up the climate data record:
Level 1 data: These are raw data, which are essential climate data measurements coming from satellites.
Level 2 data: These are datasets, where algorithms are applied on. This includes geophysical variables that people can work with e.g. Sea surface temperature and sea surface height.
Importance of consistency
The data set of all the climate data records need to be consistent over a long time period. Since nature and the environment are changing, we want to make sure not to measure changes in the satellite sensors, but rather what is happening in nature. Over a long time series small changes can make a big difference, which is why the climate data sets need to be carefully observed and monitored.
The oceans are dynamic, complex and constantly changing, so identifying the reasons for its behaviour is crucial for us to adapt to and mitigate the effects of our climate changing.
Optional Mini Task:
Visit the ESA CCI webpage to find out about the Essential Climate Variable projects that are being developed using satellite data.
Which of these projects will be most useful for understanding, monitoring, and mitigating the impacts of climate change in your location?
Currents are the central heating system of our planet and play a key role in Earth’s climate by transporting heat and moisture around the world.
The global ocean circulation can be divided into two broad systems : A wind-driven circulation that dominates in the upper few hundred meters, and a density-driven circulation in the deep ocean. The latter is called “thermohaline circulation” or THC – (thermo ~ temperature, haline ~ salty) since it is driven by variation in temperature and salinity. Both currents are shaped by the Coriolis force and the boundaries of the ocean basins.
The wind driven surface currents form large gyres. You can see these clearly in satellite data from many different sensors: Sea surface temperature (SST), sea surface salinity (SSS) and ocean colour. From altimetry measurements of sea surface height we then calculate the flow in these currents.
Except for very high latitudes the surface and deep ocean are separated by the thermocline – a layer where temperature falls rapidly with depth. This acts as a barrier to water exchange between the surface and deep ocean. Only at high latitudes in the Atlantic and Southern Ocean is it possible for surface water to become cold and dense enough to sink into the deep ocean. This has consequences for the Earth’s climate system:
Ocean heat transport: warm water flows towards the poles in the surface ocean and cold water flows back towards the equator in the deep ocean.
Carbon uptake and storage: cold water rich in CO2 sinks into the deep ocean in the high latitude North Atlantic, and remains there for hundreds of years
How does the deep water return to the surface?
Turbulence in the deep ocean helps to mix water between the thermocline and deep ocean. Thermocline water can then rise to the surface in equatorial and coastal upwelling regions at the edges of the ocean gyres. The upwelling can be seen clearly in global images of ocean colour and sea surface temperature.
Mixing between surface and deep water can easily mix in the Southern Ocean, one of the regions where stored CO2 can return to the atmosphere.
Featured Educators:
Dr Pierre Yves Le Traon
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In this video our Lead Educator Dr Mark Higgins will give us a quick introduction on Sea Level Rise.
Topic 1e - Sea level rise (part 1): overview with Dr Anny Cazenave
Altimetry has been measuring the sea levels, over all the oceans since the early 1990s.
By averaging these levels over the oceans, and looking at the variations on the whole period, one can estimate the global sea level rise with an accuracy of 0.5 mm/yr.
Sea levels across the globe are on the rise due to global climate change, and even a small, permanent increase in the global sea level could have major consequences for the Earth’s populations - particularly for those situated in coastal regions.
Sea level is one of the Essential Climate Variables, and an indicator closely monitored by the IPCC.
Optional mini task:
Explore the altimetry sea level data here. From looking at a number of different altimetry sensors on the interactive graph, how has sea level changed over recent years? How do the trends vary between different sensors and different zones?
Topic 1e - Sea level rise (part 2): altimetry in more depth
Altimetry has been measuring the sea levels, over all the oceans since the early 1990s.
By averaging these levels over the oceans, and looking at the variations on the whole period, one can estimate the global sea level rise with an accuracy of 0.5 mm/yr.
Sea levels across the globe are on the rise due to global climate change, and even a small, permanent increase in the global sea level could have major consequences for the Earth’s populations - particularly for those situated in coastal regions.
Sea level is one of the Essential Climate Variables, and an indicator closely monitored by the IPCC.
In this video our Lead Educator Dr Mark Higgins will give us a quick introduction on sea surface temperature (SST).
Topic 1f - Ocean extras - El Niño overview with Dr Bill Patzert
In this ‘ocean extras’ video, Dr Bill Patzert from NASA JPL provides an overview and added insights into the El Niño phenomenon, and the role played by satellites in monitoring and predicting its impact.
Featured educator:
Dr Bill Patzert
Topic 1f - ENSO
The El Niño Southern Oscillation (ENSO) is a coupled atmosphere-ocean phenomenon with wide reaching impacts. It can be observed through satellite sensed sea surface temperature and height.
ENSO impacts:
Droughts
Floods
Changes to marine environments, with implications for food security (agriculture, fisheries, aquaculture).
ENSO shows how interconnected the Earth system is. For example, fish catches off the coast of Peru are influenced by large scale interactions between the oceans and atmosphere over the Pacific.
ENSO is typically observed as anomalous patterns of SSH (sea surface height) and SST (sea surface temperature), but its impact on biology can also be observed by satellites. M-FR has been using ocean colour data to look at the biological response to ENSO – important from a fisheries perspective. Detecting changes in the frequency or intensity of ENSO events relies on the availability of long term, consistent data, such as that available from Copernicus and CMEMS.
Effects:
El Niño is an ocean phenomenon of the tropical Pacific. In a strong El Niño year sea surface height in the Eastern Pacific can rise by as much as 30cm, the water is much warmer than usual, and there is a dramatic drop in phytoplankton productivity off the coast of Peru. This impacts food supply of virtually all organisms in the coastal current ecosystem, and fish catches are much lower than normal. Heavy rains fill coastal deserts with lakes, and vegetation sprouts where there is usually bare soil.
El Niño is a fundamental part of Earth’s climate, and being able to predict when it will occur is important for seasonal weather prediction. The problem is how to foresee an El Niño many months or years in advance. By the time coastal temperatures rise, El Niño is already well on its way.
Along with a gradual warming of the oceans, melting of the Greenland and Antarctic ice sheets are main contributors to the sea level rise of our oceans. Satellite altimetry can help to quantify these two contributions and improve predictions of future changes in sea level.
Sea ice
For three decades satellites have been documenting the decline of Arctic summer sea ice. This shows that the ice-covered area during the summer minimum (September) has been shrinking much faster than expected from climate models.
The loss of Arctic summer ice is important for several reasons:
Open water absorbs far more of the incoming solar energy than an ice covered ocean, so the loss of ice contributes to increase global warming
The ice is a critical part of polar ecosystems, so the loss of ice will have profound impacts on Arctic life and humans who depend on Arctic living resources for their livelihoods
An opening up of the Arctic will increase ship traffic and exploration for oil and other resources in the Arctic, with its own potential problems
SAR altimeters from CryoSat and Sentinel-3 satellites can measure sea ice thickness, although only during the winter months. Melt-water on the ice surface prevents reliable measurements during the polar summer.
Land ice
While melting sea ice does not contribute to sea level rise, melting land ice in Greenland and Antarctica has a direct effect on sea level by adding water to the oceans. Recent satellite observations from Greenland and Antarctica indicate that this rate of ice loss in these areas may be increasing.
Altimeters can measure changes to the topography of ice sheets. The spatial resolution of early altimeters prevented accurate measurements from being made over the ice sheet margins, where most of the changes take place. Modern SAR altimetry (CryoSat and Sentinel-3) can measure changes also over the ice sheet margins. This has led to more accurate estimates of ice loss and the contribution this makes to global sea level rise.
Changes to the volume of ice sheets can also be calculated from satellite gravimetry (GRACE and GOCE).
Now that you have
covered the initial topics in Week 1, we hope that you are starting to become
familiar with key terms, technologies and names of satellite missions. You can
download and use the table below to explore all of the Earth observation satellite
missions that are mentioned throughout this course. You can refer back to this
table at any time, and additional links to these missions can be found in each
topic.
Week 2
Topic 2a (part 1) - Weather prediction - overview
Welcome to Week 2 of the course where we will explore ‘Oceans, Weather and Climate Impacts’. What happens in the ocean has a fundamental impact on the weather conditions we experience on land. In our first video of the week we look at how satellite data and other observations are assimilated into numerical models used in weather forecasting.
Predicting the weather through satellite data works in two ways: Expert forecasters interpret the images retrieved from the satellites, and numerical weather-prediction models assimilate the observations.
Most satellite observations go directly into numerical weather-prediction models. The quality of data going into weather forecasting models and the computer models themselves, have improved drastically over the years.
The data used for these models include vertical distribution of temperature and humidity, cloud distributions, land and sea surface temperature, location of volcanic ash, and wind speeds directions.
The next evolution for weather forecasting models is to incorporate and work more with probabilities of where a storm might go. Knowing far in advance that a storm is coming, and being able to prepare (by e.g. locking down transport systems and moving people away from the area) really helps reduce the risk to people and their infrastructure.
Please note that at 3:02 of the video Dr Mark Higgins accidentally says 800 metres, the correct distance is 800 kilometres away. We apologise for any confusion this may have caused.
Topic 2a (part 2) - Sea surface temperature and weather prediction
Here we speak to Dr Christoforos Tsamalis from the Met Office about his research in support of forecasting applications and climate monitoring.
In order to obtain accurate weather forecasting models you need sea surface temperature measurements, especially when forecasting storms and cyclones. Using satellite observations to measure sea surface temperature provides you with a global picture.
There are two types of satellite instruments that provide information about sea surface temperature:
Instruments working in the infrared spectrum
Instruments working in the microwave spectrum (not affected by clouds)
The Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) system then merges the information from different satellites together with in situ observations to create a high resolution analysis of the current sea surface temperature for the global ocean.
Topic 2b (part 1) - Sea surface temperature and tropical storms
Tropical storms are a major threat in many countries. The ocean plays a major role in tropical storm generation, their frequency, duration and intensity against a backdrop of a warming world.
The addition of ocean observing satellites enables better forecasting of their trajectories and intensity.
Sentinel 3 and its cutting-edge sensors are opening new avenues for monitoring our oceans. It is important to have a good understanding of the accuracy and the uncertainty of these observations, so scientists compare in-situ data coming from drifting buoys and other satellite data.
Combining datasets of sea surface temperature measurements from different satellites over time gives a valuable insight into the temperature changes of the ocean. The intensity of a tropical storm is directly influenced by the rise in sea surface temperature. This means changes in the temperature of the ocean have direct effects on the intensity of tropical storms.
Optional mini task:
To view active storms download the Living Earth mobile app (only compatible with Apple devices) and use the storm symbol on the bottom tool bar to see where active storms are currently located. Alternatively view the US National Hurricane Center.Where are the current storms that you can see? How strong are they?
Topic 2b (part 2) - Altimetry in tropical storm predictions
The ocean plays a major role in tropical storm generation, their frequency, duration and intensity against a backdrop of a warming world.
We are increasing the amount of water in the oceans, but we are also heating the ocean, which means water will expand leading the water column to rise.
In the Atlantic and Northeast Pacific, hurricanes form as a result of warm air and warm seawater interacting.
Altimeter data can tell us something about the heat content in the water column, which in turn helps predict the intensity of hurricanes and where they might go.
A storm surge is an unexpectedly high water level brought on by high winds pushing water towards the coast and low atmospheric pressure causing sea level to rise.
In low-lying areas surges that occur on high tide may cause extensive flooding and destruction. Being among the most devastating of natural disasters, storm surges pose a huge threat to low lying coasts and river deltas around the world.
Surge modelling and forecasting
Altimetry measurements of sea surface height (SSH) can be used to validate numerical models used to estimate flood risk from cyclonic weather systems.
Scatterometers, altimeters and synthetic aperture radar (SAR) can also be used to measure wind speeds, both in the coastal zone and in the open ocean where no in-situ measurements are available.
The intensity of a storm is measured by monitoring sea surface temperature (SST).
Optional mini task:
Storm surges are often associated with hurricanes. Visit the US National Hurricane Center website on storm surges to see how models have been used to estimate inundation from storm surges for recent hurricanes. Under ‘Notable Surge Events’ you can view model runs. Which recent storm do you think caused the worst coastal inundation?
Satellite altimeters, which are used to measure sea surface currents, are also able to measure significant wave height. The introduction of altimeter observation with wave forecasting programmes has increased the accuracy of wave forecasting.
Wave models, give a first guess of the wave height measured, but satellite data will then provide necessary information for eliminating uncertainties in significant wave height models.
Over the past 25 years of measuring wave height, the highest significant wave height was observed during winter storms in the North Atlantic. This wave was 20m high during the Quirin storm in February 2011. Also known as Rogue waves, these waves can be extremely dangerous to ships on high sea.
We can measure changes in sea level using altimeter data. Since we started making these measurements, global average sea levels have risen by 8cm.
Although there is variability on a year-to-year basis, the overarching trend is very clear, and is consistent between lots of different altimeters. This gives scientists great confidence in these observations.
The rise in sea level presents challenges for communities living in the coastal regions. The rise in sea level is not consistent over the globe, due to changes in gravity, current dynamics, and heating effects.
In addition to this, the characteristics of the coast in different locations will effect how the impacts of sea level rise manifest. Areas that are already low lying, such as some islands, will be affected even by a small rise in sea level.
Satellite data give us an opportunity to see a global picture of these changes and allows governments to plan how to react.
Optional mini task
Visit this Google Earth based tool to view how different extremes of sea level rise might affect different areas around the world. Share what you find out in the comments.
Welcome to week 3 of the course! This week we will look at how our oceans are moving and the importance of using satellite data when managing risks from ocean hazards. We can use information on currents to explain the way things move in the ocean; from plastic pollution to ice, oil spills, and algal blooms.
Ocean currents influence how efficient shipping is, and knowing where these currents are, allows the shipping industry to optimise routes for efficiency. Pollution, such as from oil spills, is also transported by ocean currents. To manage the clean up of these events, information on ocean currents can be used to predict where pollution will make landfall, or determine where it came from.
Ocean plastics are a big issue at present, and we are just learning about how extensive their presence in the oceans is. Ocean currents will influence where ocean plastics are transported and where they accumulate. This is key information when planning to clean up regions of the ocean. Ocean currents also connect ecosystems, transporting larvae of different species from one place to another. This information is important to properly conserve and manage the ocean ecosystem and the resources it supplies.
Ocean currents can be complex, and are driven by different factors including wind, gravity (in the case of tides), density, and rotation (in the case of the global thermohaline circulation and geostrophic currents).
Satellite altimeters, which measure the height of the sea surface, can be used to detect and characterise ocean currents. This data can then be used to support data assimilation into ocean models.
Optional mini task:
You can explore models of ocean currents further using this interactive map - Click on ‘ earth’ at the bottom left corner and select ‘ocean’ as the mode and ‘currents’ as the animation. You can see the different strengths and patterns of the currents. Share your observations below.
Featured Educators:
Dr Ben Loveday
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Topic 3a (part 2) - Argo floats and in-situ sensors
In this video, we hear from Vinca Rosmurduc from CLS about the role of ‘Argo Floats’ and other in situ sensors which monitor ocean parameters and track animals. These sensors relay their data via satellite and also complements data obtained from satellite sensors.
Featured Educator
Dr Vinca Rosmorduc
Topic 3b - Ocean salinity
In this video, Dr Chris Banks tells us about ocean salinity and its impacts on the water cycle, ocean currents and the global climate.
Everyone knows the ocean is salty, but how salty it is varies depending on where you measure it. Input from rivers and rain can alter the oceans salinity, by adding fresh water.
Salinity is an important variable for understanding the global, density driven, ocean circulation, known as the ‘Thermohaline” circulation. However it is a very new variable for satellite remote sensing, with the first sensor (SMOS) being launched in 2009. This is an innovative satellite, using 69 radiometers to produce salinity measurements globally.
It is hoped that this fascinating new data will be assimilated in to global ocean models to improve simulation of physical ocean dynamics. As well as measuring salinity, SMOS can also measure soil moisture and sea ice thickness – a true multitasking satellite!
Featured Educators:
Dr Chris Banks
View featured satellites on the satellite tracking app
In this video our Lead
Educator Dr Mark Higgins will give us a quick introduction on sea, wind and ice
Topic 3c - Ice and icebergs
The way icebergs move is very complicated, so predicting where they might be is challenging. Thanks to satellites, we are able to detect them and provide risk maps for boats and navigation.
Icebergs can be detected by radar altimetry, the radar wave coming back earlier when bouncing off an iceberg. A second sight is then often made using SAR imagery, where surface roughness shows the icebergs in the image.
Human analysts then pick out the patterns and interpret the signal of altimetry. With the radar image satellite data they are able to qualify whether the spots are icebergs, boats or something else.
Data on icebergs is used in round-the-world sail races like the “Vendée Globe”, with a major impact on skippers’ safety, as areas with icebergs are deemed forbidden by the race organisation.
Satellite data are used to provide decision support for oil spill response during accidents that release large volumes of oil into the sea.
The data are used in two ways: optical and SAR data from satellites and aircrafts provide information on; the location, extent and thickness of surface oil. While other sensors provide wind, wave and current measurements that can be used as input into numerical models to predict how the spill will evolve. This is used, for example, by the European Maritime Safety Agency (EMSA), to provide an oil spill monitoring service that alerts the authorities when an oil slick indicates a breach of regulations to prevent oil pollution.
Oil spill detection
The main satellite sensor for oil spill detection is Synthetic Aperture Radar (SAR). It has a sufficiently high resolution to reveal relatively small areas of surface oil, and can ‘see’ through clouds.
How does it work?
Oil spill detection works at wind speeds between 3 and 10-12 m/s.
Oil appears darker than water in SAR images because it calms the wind-ripples that make the sea surface appear bright in SAR images when wind speeds exceed 3 m/s.
Above 10-12 m/s the oil is increasing mixed into the water and disappears.
Satellite data for oil spill detection are used in different ways:
In support of oil spill response during major accidents (e.g. Deepwater Horizon oil spill)
Routine monitoring of shipping lanes, ports and off-shore installations to check on compliance with discharge limits (e.g. EMSA Clean Sea Net)
In environmental impact assessments: either to assess the impact of new infrastructure (ports, oil refineries, off-shore installations) or to assess the impact of large scale accidents.
In this video our lead
educator Dr Mark Higgins will give us a quick introduction on ocean colour.
Topic 3e (part 1) - Ocean water quality
Harmful Algal Blooms and coastal pollution can impact aquaculture, tourism and human health. The colour of the ocean is directly linked to the components of ocean waters that determine water quality.
We intuitively understand what might be in water just by looking at its colour. This is something that’s long been investigated by those working on the sea, e.g. fishermen.
Blue ocean water usually contains very little beyond sea water itself, whilst brown waters may be full of sediments and dissolved substances from rivers, or the sea bed. Green water is full of life, in particular, tiny phytoplankton, the sea-dwelling equivalent of plants. These plants provide food for almost the entire marine food web, but they can also produce toxins, or cause anoxia when they form Harmful Algal Blooms.
Ocean colour can be measured from space, and in situ using radiometers. Sentinel 3a has a radiometer on board, the Ocean and Land Colour Instrument (OLCI), which is now measuring the ocean colour for scientists to use to understand water quality.
Optional Mini Task:
You can learn more about Harmful Algal Blooms and how ocean colour validation is conducted by completing this LearnEO tutorial using ocean colour data and the BILKO software. BILKO can be downloaded here
A CTD device is a package of electronic instruments that measures conductivity, temperature, and depth. Scientists use these devices to measure water quality and better understand species distribution and abundance in the ocean.
CTD’s are attached to a much larger metal frame called a rosette, which holds water-sampling bottles that are used to collect water at different depths and other sensors measuring physical and chemical properties in the ocean.
The data gathered from these devices is then used for algorithm development to understand long time series and extract big patterns of how the natural environment varies from weeks to months to years.
Making the most of this data requires validation, where scientists make measurements from boats, coincident in time with the satellite flying overhead and capturing it’s images. Using validation to ensure the accuracy of data products is crucial if we are to give advice to aquaculture farmers, fishermen or tourists wishing to swim at beaches.
Welcome to week 4 -
focussing on the Living Oceans. In this week, we will explore the role of
phytoplankton in the oceans and how it can be measured with satellites. And we
will look at a range of ways in which satellites can be used to monitor
biodiversity.
In this first video,
Dr Helen Czerski and Dr Hayley Evers-King provide a special introduction to
‘Ocean Colour’ as a key ocean parameter which can be measured from space. They
also discuss in this video how measurements from satellites complement observations
made by oceanographers in-situ to help monitor and manage biodiversity.
Featured Educators:
Dr Helen Czerski
Dr Hayley Evers-King
Topic 4a - Phytoplankton and climate
The story of oceans and climate would not be complete until we explore the impact of weather and climate on marine life. We also need to understand how ocean life, notably phytoplankton might modulate oceanic weather and climate, through their role in the global carbon cycle, and on the ocean heat budget.
One way that phytoplankton influence the oceans is through heating. Photosynthesis is quite inefficient, so much of the light absorbed by phytoplankton cells is released as heat.
Phytoplankton are also affected by climate. Changes in the heat content and distribution within the Earth system can change ocean circulation. This can alter the access phytoplankton have to light and nutrients. Warmer or colder temperatures may favour some species over others, and similarly may change the dynamics between predators and their prey (often phytoplankton).
Long-term ocean colour records, and ocean biogeochemical models can be used to understand these changes.
Carbon is a fundamental building block of life. As such carbon is a common component in most ecosystem and climate models.
To know if these models are correct, and to understand what drives the carbon cycle, we need data to help us understand ocean carbon content. Satellite ocean colour data offer suitable spatial and temporal scales to capture this by measuring reflected light. The challenge is to understand what links carbon with variability in the ocean colour signal. This can be tricky.
Burning any carbon-based fuel releases carbon dioxide into the atmosphere, a main contributor to the current climate change we are experiencing. The biological pump pulls carbon dioxide down in to the ocean, through the actions of phytoplankton, such as photosynthesis. We can get estimates of phytoplankton production from ocean colour derived chlorophyll a concentrations. However, the ratio of carbon to chlorophyll varies depending on the size of the phytoplankton cells, the species present and their physiological variability.
There are also other types of carbon in the oceans, from different sources. Near the coast, rivers will contribute sediments and dissolved matter, containing carbon. These will vary according to different factors to those which influence phytoplankton, so separating the ocean colour signal to quantify these different pools is important for understanding the overall dynamics of the ocean carbon cycle.
Topic 4c (part 1) - Ocean colour and sustainable fisheries
Ocean colour is intricately connected to the biology of our oceans.
Ocean colour provides information on primary production relevant to fisheries and marine ecology, which can be used as input into ecosystem models, and help to develop advisories for marine management and aquaculture.
The applications of ocean colour data for managing, for example, fisheries have been found very useful. The timing of phytoplankton blooms can have a direct impact on e.g. larvae survival in fish. Knowing where these nutrient rich areas are in the ocean is fundamental for ensuring their sustainable management.
Fishermen use information from satellite data to achieve catch targets more efficiently and minimise the search time for fish. When fish are vulnerable (when they lay eggs) fishermen are advised to stop fishing during this time, to help the survival of the fish.
So understanding what ocean colour says about the marine ecosystem and monitoring seasonal shifts, allows scientists to make predictions from early in the year to months in advance.
In this second video on the relationship between ocean colour monitoring and fisheries, Dr Thomas Jackson explains how satellite measurements play a crucial role in developing accurate models for predicting changes in ecosystems and fish stocks.
Ocean colour provides information on primary production relevant to fisheries and marine ecology, which can be used as input into ecosystem models, and help to develop Earth system models used to predict future climate change and support climate change adaptation.
Ecosystem models rely on ocean colour. These models and observations can show consistent features or areas where you have strong gradients in temperature or nutrients in the ocean. Along these so-called fronts you get blooms of phytoplankton, which support large amounts of higher life like zooplankton or fish.
These habitats are constantly shifting around, but models are able to capture this shift and allow scientists to make predictions from earlier in the year to changes in the future.
Topic 4d - Sir Alister Foundation for Ocean Sciences (SAHFOS)
The Sir Alister Hardy Foundation for Ocean Science (SAHFOS) is an international charity that operates the Continuous Plankton Recorder (CPR) Survey.
The CPR is a robust and reliable device designed to capture plankton samples whilst being towed around the oceans from ships of opportunity e.g. merchant ships, ferries and other vessels.
The sampling instrument is used to give a rapid metric for the abundance of zooplankton in the water column (tiny organisms like e.g. Dinoflagellates and Foraminifera), which is then used to inform longer more intensive analysis about the health of our oceans.
The original CPR platforms have been augmented with a range of modern day sensors like water sampling devices, as well as optical and acoustic sensors.
The in-situ environmental measurements gathered from these recorders can then complement other ocean observation networks and provide validation data for remotely sensed earth observation programmes.
Satellite technology is not just about imagery. Satellites also provide ways of monitoring things that are moving around the oceans – ships, data buoys, even animals.
By fitting them with tags, scientists can see where animals travel. The tags can have miniature instruments added to provide data on their environment as well. This can be a new source for satellite validation, and is particularly useful in inhospitable regions where it is dangerous for scientists to work.
Combining the information that these tagged animals gather with satellite data can provide more information about both the animals behaviour and the validity of the satellite data products. This sort of information can be used to manage our impacts on these animals, deciding where we should or shouldn’t fish, or where we should protect areas for their benefit and conservation.
A diverse range of important ecosystems can be monitored using satellite imagery. Whilst imagery may not be able to identify individual animals from space, it can tell us something about large communities of organisms that live in the ocean.
Methods have been developed to characterise phytoplankton by their size, or function (how they contribute to certain ocean biogeochemical processes for example). These methods are based on the way different traits or species interact with light, which makes up the ocean colour signal.
Other approaches have been developed to map species that form important habitats such as coral reefs, seagrasses and mangroves. These habitats provide many important functions for both us and the ocean.
Coral reefs are important biodiversity hotspots, and their calcium carbonate structures are an important store of carbon.
Seagrasses provide another environment in which many species live and breed, and also contribute to photosynthesis. Mangroves exist at the interface between land and sea. They are often nurseries for fish, and provide direct services for coastal communities, acting as barriers to large waves.
Ocean Extras: Models and future missions for phytoplankton and biodiversity
In this extra video, Dr Michelle Gierach from NASA JPL outlines how models can be used to assess phytoplankton biodiversity, and how future satellite missions will lead to better monitoring of coral health, biodiversity and potentially even phytoplankton species.
Featured educator:
Dr Michelle Gierach
Oceans MOOC Feedback Session - Week 4
Week 5
Topic 5a - Policy
Welcome to week 5 of the course, the final week! ‘Oceans and Us’ will look at how Earth observation helps us to set international policy and investigate socio-economic issues surrounding the use of our marine ecosystem and its resources. In this first video Dr Pierre Bahurel and others reflect on how monitoring the oceans from space can influence policy decisions on climate change and other areas.
Satellite sensors provide data that can inform the development of environmental policies and help to implement them by monitoring changes to the environment and providing potential evidence of when regulations are breached.
Tagged animals and satellite monitoring gives fishermen the necessary information on where they can’t fish in certain areas (to reduce ‘by-catch’, for example).
The information, which satellite sensors can provide, hugely supports the investigations of socio-economic issues surrounding the use of marine resources.
In an ever-changing world, with more and more people moving to the coast and exploiting marine resources, governments need to make decisions about what sectors a marine environment can support sustainably over time. This also means weighing out where we can benefit most from either conserving or using valuable resources.
The job for socio-economists is to understand how the marine environment is changing,what kind of sectors it can support (e.g. Aquaculture) and what that means to communities.
By combining satellite data with tools for mapping socioeconomic parameters we gain useful insight for planning solutions on how to use the environment in a more holistic way. This helps making decisions on whether an area is suitable for e.g. tourism, aquaculture or offshore oil platforms.
Satellite data offers a chance for the public, as well as scientists to get a bird’s eye view of the world. This has inspired new projects where the public collect data and help scientists working with Earth Observation to better understand the marine environment; including surfing to measure the temperature of coastal waters and identifying kelp forests in satellite images.
Remote sensing, especially sea surface temperature readings from satellites, are an essential part of conservation today, however these satellites and SST data only reads the skin of the ocean. When it comes to what is happening beneath the surface in situ measurements can be done by gathering data from public observation projects and crowd sourcing.
Project Hermes: The first global effort to measure ocean temperatures worldwide at the scale of the ecosystem. A community of divers worldwide source data revealing temperatures of the ocean, and other parameters important to understanding the underwater world.
PML Surfer Project: A project, which gathers SST measurements with surfers as the vehicle, rather than a boat or buoy. The coastal zone is a difficult area to measure, as these zones are high with life so sensors often get covered in algae or seaweed. Scientists use data gathered by surfers to create maps and time series, which provides them with information on distribution measurements along the coast.
Once you have a sufficient number of people taking measurements you can start to improve SST retrieval algorithms in those areas, especially with the improvements of satellite resolution, as we are starting to see with modern satellites.
Featured Educators:
Pierre Yves Cousteau
Dr Thomas Jackson
Topic 5d - Energy
Satellite data can be used to identify energy potential in ocean locations suitable for renewable energy.
Strong currents, high surface waves and internal waves are all potential hazards to offshore installations, whether oil rigs, offshore wind farms or wave-energy installations.
Putting equipment out at sea to gather data can be very expensive, so satellite data measurements are extremely valuable when choosing where you want to put your investment.
Satellite data collected over many years can provide information that is of value when selecting a suitable site, developing technical specifications, and carrying out environmental impact assessments for new infrastructure projects.
Sentinel-1a is carrying instruments that produce SAR images of the sea surface showing a multitude of resources, which are of interest to the renewable energy sector.
Featured Educators
Dr Christine Gommenginger
View featured satellites on the satellite tracking app
In this video we take a look at the future of Earth Observation.
We hear from our featured educators Dr Mauro Facchini and Pierre Yves Cousteau about new satellites and synergy between sensors, including sensors that take advantage of reflected signals from navigation satellites to measure wind, surface waves and sea level.
Ocean Extras: Monitoring our own impact on sea level rise
In this first of two extra videos for this final week of the course, Dr Josh Willis from NASA JPL provides his thoughts and insights on the role of satellite data in assessing the ‘footprint’ of human activity on changes in the oceans.
Don’t forget to also watch the course round-up video in the final step of the course.
Featured educator:
Dr Joshua Willis
Ocean Extras: The people managing ocean monitoring satellites at EUMETSAT
In this second of two extra videos for this final week of the course, we hear from some of the people responsible for operating and managing satellites and data from the EUMETSAT satellite control rooms.
Featured Educators
Kevin Marston
Sean Burns
Final course round-up
We have now come to
the end of ‘Monitoring the Oceans from Space’, congratulations on completing
the course and thank you for your participation over the last five weeks.
We hope you have
enjoyed this course, and gained a useful insight into the science, techniques
and applications of using Earth observation from space to monitor our oceans,
and our interaction with it. We hope that this will help you in your further
work, interests and decisions, and we wish you the very best for the future.
This course has been
designed and produced for EUMETSAT by Imperative Space. The producers would
like to thank all of the academics, experts and institutions who have
contributed to and supported production of the course. This includes the
universities and research centres to which our onscreen experts are affiliated.
Special thanks goes
to: Plymouth Marine Laboratory, CLS (Collecte Localisation Satellites), the
National Oceanographic Centre, NASA Jet Propulsion Laboratory, Pierre-Yves
Cousteau, and Réserve Naturelle Marine de Cerbère Banyuls, Sir Alister Hardy
Foundation for Ocean Science, and the National Marine Aquarium (Plymouth).
All NASA, ESA and
CMEMS imagery and animations used throughout this course are used courtesy of
NASA, ESA and CMEMS.