GMES & Africa and Copernicus Marine Earth Observation
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This online training phase will provide essential overview material to read / watch, further optional material which you may choose to look at (depending on your own interests), short quizzes, and important activities such as downloading and installing software, and trying to access data. The final topic will focus on preparation for the classroom phase, where we will ask you to propose your mini project ideas. For those without specific applications in mind - don't worry - we will also provide some ideas for projects that you can work on to learn more about the data and it's applications.
Please take some time to look through the logistics information below. Here you will find all the essential steps on how to complete the online phase, so that you arrive suitably prepared for the classroom phase in Zanzibar!
We invite (and encourage) you all to use the discussion forum to introduce yourselves and share your expectations for this course (what you are hoping to learn/use Copernicus data for).
There will be further discussion forums associated with the different topics, and you are invited to post your comments and questions. The training team will be glad to answer your questions as best as we can during the course. As new users of the Copernicus data, this is also a great opportunity for us to get feedback from you about the data, access to it, and how we can improve these services to help you to best use the Copernicus marine data for your applications.
Some tips to help you get the most out of the course:
The Maputo Declaration of October 2006 lead to the EU-Africa partnership, confirming the commitment to avail European infrastructure and facilities, under the Copernicus programme to Africa, the Caribbean, and Pacific (ACP) countries. This commitment led to the launch of "GMES and Africa", which covers the entire African continent.
Objectives of GMES&Africa include long-term EU-Africa cooperation on space science and technology, enabling the two continents to jointly address and solve global challenges, and promote sustainable development under the Copernicus programme. These objectives include:
Within GMES&Africa, four consortia have been awarded grants to consolidate and develop application and services that have grown from previous African EO programmes. You can find out about the consortia here and more information on GMES&Africa can be accessed here.
This topic provides overview material on the Copernicus programme, including the role of the agencies launching and operating the satellites (EUMETSAT and ESA), and the Copernicus services who provide additional products from Copernicus (and other sources of) satellite data, models, and in situ measurements.
The schematic above summarises the major components of the Copernicus programme and those (highlighted in orange) with relevance to marine applications.
Within Copernicus, Sentinel-3 is often referred to as the 'Blue Sentinel" thanks to its suite of ocean observing instruments. The broader Copernicus Marine landscape also includes the use of Sentinel-1 and Sentinel-2 satellites, as well as several services which have a marine mandate.
The Copernicus Marine Environment Monitoring Service (CMEMS) provides products and services for marine applications, using data from the Sentinels, historic and third party missions from agencies around the world, physical and biogeochemical models, and in situ data. Other services also support the marine domain, including in particular the Emergency, Climate, and Security Services.
In this course we focus primarily on Sentinel-3 and related products provided by the marine service, as well as some marine applications of Sentinel-1 and 2 that have relevance to the aims of GMES&Africa. Below you will find additional resources from the various agencies involved in Copernicus, explaining the programme and their role in it.
Synthetic-aperture radar (SAR) is a form of side-looking radar that is typically used by airborne and remote sensing platforms to produce two-dimensional images of land and sea scapes or three-dimensional reconstructions of objects. The "synthetic" aperture refers to the technique of using the flight path of the satellite to electronically simulate a very large antenna (or aperture). In the ocean, SAR satellites can be used to monitor changes in surface roughness associated with wind and waves, as well as to detect floating objects.
SAR imagery is included in the Copernicus Programme thanks to the Sentinel-1 satellite constellation, which is operated by the European Space Agency. Unlike radiometric sensors, such OLCI and SLSTR on Sentinel-3, SAR sensors are active, not passive. Passive sensors typically rely on the sun to transmit energy to earth, and measure any reflected signals. Although this means low light conditions and/ or cloud can interfere with data collection, the strength of passive sensors is that they can measure reflected electromagnetic radiation across a number of bands within the electromagnetic spectrum. Active remote sensors, on the other hand, create their own electromagnetic energy to transmit to earth. This energy interacts with land and/or ocean surfaces - producing a backscatter of energy to be recorded by the receiver (note that the Sentinel-3 SRAL altimeter, which we will come to later, is an active sensor). Although Sentinel-1 sensors do not record across the electromagnetic spectrum in the way optical sensors such as OLCI and MSI (Sentinel-2) do, SAR sensors are able to operate day and night with little to no interference from cloud.
Sentinel-1A was launched on 3 April 2014, and Sentinel-1B was launched on 25 April 2016. Both carry a C-band synthetic-aperture radar instrument, which is an active sensor capable of collecting data in most weather, day or night. The Sentinel-1 satellites also share the same sun synchronous orbital plane - near-polar (98.18°) - with a 12-day repeat cycle at 175 orbits per cycle. This video on geographical coverage helps to illustrate what that means.
Sentinel-1 operates in four acquisition modes, which give different spatial resolution and revisit times, relevant for different applications. The image below and the link here from ESA provide more detailed information on this.
Sentinel-1 acquisition modes. Image credit: ESA.
The revisit rate of Sentinel-1 is highly dependent on the mode being used and the Sentinel-1 satellite sensors tend to be turned on to collect data over the most relevant areas e.g. areas with active volcanoes, rapidly changing landscapes, and areas with high population densities. This prioritisation is due to the size of the data that is collected. For marine applications such as sea state observation, oil spill monitoring and ship detection, the most useful data is likely to be the Extra Wide (EW) or interferometric wide swath mode (IW). The EW mode is active mostly over European seas, Arctic and Southern Ocean areas, to support sea ice and surveillance applications. For African users, the data available will mostly be from IW mode. Strip map mode available in extraordinary events such as disasters. Wave Mode (WM) is available globally and is used to provide inputs to wave and numerical weather prediction models. The modes are summarised in the table below.
|Wave Mode (WM)||Interferometric Wide Swath (IW)||Extra-Wide Swath (EW)||Stripmap (SM)|
|Purpose||Gathering wave spectra from the open ocean||Coastal imaging: vessel monitoring, oil spill tracking||Coastal imaging: vessel monitoring, oil spill tracking||High resolution targeted acquisitions|
|Geographical availability||Global open ocean||Coastal globally||Coastal Europe, sea-ice areas, polar zones, specific maritime regions||Small islands and in exceptional cases only (e.g. emergency support)|
How Sentinel-1 sees our Oceans:
The Sentinel-1 mission provides critical EO data for three applications related to marine monitoring, namely: oil spill detection and pollution identification (illegal discharges of oil are visible in SAR imagery as characteristic dark features); sea-ice and iceberg monitoring (covers safety of shipping / offshore operations, climate monitoring, and polar species habitat monitoring); and wind / wave information (vital for maritime safety and rescue operations, measurements can be extracted directly from SAR surface roughness).
However, the Sentinel-1 mission also allows for a range of other applications in the marine context, including observing or monitoring of vessels. For example, in this scene acquired by Sentinel-1, you can see a number of small bright spots against a black background. These are boats on the surface of the ocean, just outside of Zanzibar port. The grey patches are land and islands.
For more information on Sentinel-1 and SAR for marine applications, please consult the resources below.
Sentinel-2 is an Earth observation mission developed and operated by ESA under the Copernicus Programme. Like the Sentinel-1 and Sentinel-3 missions, the Sentinel-2 mission is also a constellation with two satellites (A and B). The Multi-Spectral Instrument (MSI) aboard Sentinel-2 is passive, exploits the sunlight reflected from the surface of the Earth. Optical data is acquired along the orbital path at high spatial resolution (10 m, 20 m and 60 m) over land and adjoining coastal waters.
Primarily, Sentinel-2 is a terrestrial focussed mission with priorities around land and agricultural monitoring, land cover classification, and emergency management and security. Consequently, its sensors are not ideally designed for marine applications; having rather few, wide bands and low signal to noise ratio. However, it has proved to be very useful in monitoring the coastal environment for applications such as detecting blooms of Cyanobacteria algae and assessing water quality.
As a primarily terrestrial mission, coverage is focussed on continental land surfaces (including inland waters) between latitudes 56° south and 84° north, which includes adjacent coastal waters up to 20 km from the shore. Sentinel-2 coverage also extends to all EU islands and islands greater than 100 km2, and covers the Mediterranean Sea and closed seas like the Caspian.
Additionally, if member states (or Copernicus) makes a request for coverage to include areas not listed above, the Sentinel-2 observation scenario is able to adapt and respond. Examples of coverage being extended include Pitcairn island, when the British government requested continuous Sentinel-2 coverage.
Depending on geographical location, the Sentinel-2 constellation will revisit every 2 to 5 days, with highest revisit times at the higher latitudes, as with all the other polar orbiting Sentinels (when they are collecting data).
Multi-Spectral Instrument Spatial and Spectral Resolution:
The Sentinel-2 MSI samples across 13 spectral bands which range from the Visible (VNIR) and Near Infra-Red (NIR) to the Short Wave Infra-Red (SWIR). Four of these bands are at 10 m spatial resolution, six bands are at 20 m and three bands are at 60 m spatial resolution. It's important to also note that spatial resolution is dependent on the spectral band:
From a marine perspective, the effective resolution of the satellite, e.g. the resolution at which the signal is reliably detectable above the noise, depends on the application in question.
For more information on Sentinel-2 for marine applications, please consult this link from ESA.
The Sentinel-3 constellation contains the primary satellites within the Copernicus programme for providing data on the oceans. The Sentinel-3A and B spacecraft are operated by EUMETSAT, and the instruments on-board provide the data that forms the Copernicus Marine Data Stream (CMDS).
We will first cover 3 key types of measurement that are made by satellites that monitor the oceans, and in particular form the basis of data and derived products you will find in the Copernicus Marine Data Service from EUMETSAT:
Following this you will also find information about the historical context of these satellites, and the instruments on board.
Within this topic we will look at the format of the Sentinel-3 marine data files, and the processing that takes place to get this data from the measurements made by the satellite instrumentation down to a usable product.
Please begin by watching the videos below as an introduction to the data products available from the CMDS for each of the main instrument packages.
Within this topic we will introduce you to several ways you can access the Sentinel-3 data available through the EUMETSAT Copernicus Marine Data Stream (CMDS). Which method you choose will depend on a number of factors including:
Get a quick look at recent coverage from the Sentinel 3 instruments, download image files, and make animations.
Download service offers all the recently acquired Sentinel-3 marine and atmospheric products through a rolling dataset that (at a maximum) spans 12 months.
A separate instance of CODA exists for reprocessed data at codarep.eumetsat.int
Data Centre Long-Term Archive
Ordering application that enables users to browse and select products, from EUMETSAT’s long-term archive, including the Copernicus Sentinel-3 marine and atmospheric products.
EUMETCast is a multi-service push dissemination system based on multicast technology. The multicast stream is transported to the user via satellite or terrestrial networks.
WEkEO is one of the Copernicus Data Information and Access Services (DIAS), and is coordinated by EUMETSAT, ECMWF and Mercator Ocean. It is currently open for beta testing. You can find out more information here: https://www.wekeo.eu/
The Copernicus Marine Environmental Monitoring Service (CMEMS) provides operational information on the oceans, building on the success of the MyOcean projects funded through the European Union framework programmes. The service is designed to meet the needs of users, providing data and information to inform and support European Maritime policy.
Observational products from the marine service are delivered by thematic assembly centres (TACs) under different topics including Ocean colour, sea ice, SST, sea level, wind and waves. These products typically include combinations of satellite data from the Sentinels and other sources, and/or in situ data, and are available as reprocessed (historical time series) and/or near real-time (NRT).
Products derived from models (for monitoring or forecasting) are provided by the monitoring and forecasting centres (MFCs). Models assimilate data from the TACs to provide historic (reanalysis), current (analysis), and future (forecast) products.
You can find our more information about the CMEMS producers here.
Working with marine satellite data often involves using large numbers of (often) individually large data files, of varying formats. The applications for this data are also broad, and range from exploratory, research led purposes, to routine and operational analysis for more commercial applications. As such, there are many different tools available to work with marine satellite data. Here we provide a (non-exhaustive) list and discussion of some of the more commonly used tools by the marine remote sensing community. Choosing which tool to use will be very dependent on the type of application you are working on. Key things you should consider include:
Do you know explicitly what you want to do with the data? Or do you want to explore and investigate?
Do you need to repeat your application regularly?
Do you need to be able to share the processes you go through with others? If so, what is their experience?
Below you can complete some basic tutorials using software developed specifically to work with the sort of data available from the Sentinel-1, 2 and 3 satellites.
You can also read about other types of software available, the programming languages commonly used across the remote sensing community, and discuss the advantages and disadvantages of these.
To complete this section you should read all content, install Acolite, install SNAP and complete the tutorials with the data you downloaded in the previous section, install python and/or post about your choice of programming language.
During the classroom phase of this training course, you will be given to opportunity to work with data from Sentinel-1, 2 and 3 and the Copernicus services in ways aligned with your own research interests and planned future uses of the data. Members of the training team will be present to help with questions about the data and software, and provide feedback for you.
We would like you to suggest a small project that you would like to work on during these few days. At the end of the course you will be asked to present a short summary on what you have done, your experiences working with the data and future plans. You are free to work together with other participants if this suits you. We have provided some ideas below for those of you who are new to the use of marine satellite data.
We will discuss the concepts of the satellite data value chain during the classroom phase, however, towards the aims of GMES&Africa and Earth Observation service development, you may wish to consider the following:
To complete this section, please post in the discussion forum below about your ideas for a mini project. You should state: your region and topic of interest, and the particular type(s) of data you would like to work with.
If you need some inspiration, you can look at the mini project ideas page below, and/or some recent case studies using Copernicus data: