Looking To Earth Observation’s Future

Artist’s view of Sentinel-3. Image courtesy of ESA–Pierre Carril.

The future is very much the theme for Earth Observation (EO) in Europe this week.

One of the biggest potential impacts for the industry could come out of a meeting that took place yesterday, 7 November, in Tallinn, Estonia as part of European Space Week. It was a meeting between the European Union (EU) and the European Space Agency (ESA) to discuss the next steps for the Copernicus programme beyond 2020. This is important in terms of not only continuing the current Sentinel missions, but also expanding what is monitored. There are concerns over gaps in coverage for certain types of missions which Europe could help to fill.

As an EO SME we’re intrigued to see the outcomes of these discussions as they include a focus on how to leverage Copernicus data more actively within the private sector. According to a recent Industry Survey by the European Association of Remote Sensing Companies (EARSC), there are just over 450 EO companies operating in Europe, and 66% of these are micro companies like Pixalytics – defined by having less than ten employees. This rises to 95% of all EO European companies if you include small businesses – with between 10 and 50 employees.

Therefore, if the EU/ESA is serious about developing the entrepreneurial usage of Copernicus data, it will be the small and micro companies that will make the difference. As these companies grow, they will need high skilled employees to support them.

Looking towards the next generation of EO scientists, the UK Space Agency announced seven new outreach projects this week inspire children to get involved in space specifically and more widely, to increase interest in studying science, technology, engineering and mathematics (STEM) subjects. The seven projects are:

  1. Glasgow Science Festival: Get me into orbit!
  2. Triathlon Trust: Space to Earth view
  3. Mangorolla CIC: Space zones ‘I’m a Scientist’ and ‘I’m an Engineer’
  4. Institute for Research in Schools: MELT: Monitoring the Environment, Learning for Tomorrow
  5. The Design and Technology Association: Inspiring the next generation: design and technology in space
  6. European Space Education Resource Office-UK: James Webb Space Telescope: Design challenge
  7. Children’s Radio UK (Fun Kids): Deep Space High – UK Spaceports

There will be a total of £210,000 invested in these. We’re particularly excited to see the MELT project which will get students to use EO data to analyse what is happening at the two poles.

Each of these elements will help shape the EO industry in this country. With the UK committed to remaining within ESA, decisions on the future of the Copernicus programme will provide a strong strategic direction for both the space and EO industries in Europe. Delivering on that direction will require the next generation workforce who will come from the children studying STEM subjects now.

Both the strategic direction, and associated actions to fulfil those ambitions, are vital for future EO success.

5 Signs You Work In Earth Observation

Sentinel-2A image of UK south east coastline, acquired on 4th September 2017. Data courtesy of ESA/Copernicus.

Do you recognise yourself in any these five signs? if so, you’re definitely working in the Earth observation industry.

  1. You have a favourite satellite or instrument, or image search tool.
  2. When a satellite image appears on television, you tell everyone in the room which satellite/sensor it came from.
  3. You’ve got an irrational hatred for clouds (unless you’re working on clouds or using radar images).
  4. Anything space related happens and your family asks whether you’re involved with it, and thinks you know everyone who works at NASA or ESA.
  5. Your first reaction to seeing an interesting location isn’t that you should plan to go there. Instead, you wonder whether it would make a good satellite image.

We tick all of these signs at Pixalytics! Last week we suffered from number five when we saw a snippet from the season finale of the UK TV programme ‘Liar’. It wasn’t a programme we’d watched, but as we caught an atmospheric panning shot of the location, and only one thought when through our minds, ‘That would make a great satellite image!’

It was a stunning shot of a marshland with water interwoven between islands. Without knowing anything about the programme, we were expecting it to have been filmed in a far flung Nordic location. Following a bit of impromptu googling we were surprised to discover it was actually Tollesbury on the Essex coast in the UK. It also turns out that we were late to the party on the discovery of the programme and the location.

Sentinel-2A image of Mersea Island and surrounding area, acquired on 4th September 2017. Data courtesy of ESA/Copernicus.

The image on the right shows Mersea Island, which has brown saltmarshes above it within the adjacent inlets of the Blackwater Estuary. To the left of the island is the village of Tollesbury and the Tollesbury marina, which is located within the saltmarshes. This area is the largest of the saltmarshes of Essex, but only the fifth largest of the UK. They play a key role in flood protection and can reduce the height of damaging waves in storm surge conditions by 20%. However, they are disappearing due to sea erosion that’s caused a sixty percent reduction in the last 20 years.

The image itself is a zoomed in pseudo-true-colour composite at 10 m spatial resolution using data acquired by Sentinel-2A on the 4th September 2017 – a surprisingly cloud free day for the UK. The full Sentinel-2 image can be seen at the top of the blog.

As often happens when we look in detail at satellite images, something catches our eye. This time it was the three bluish looking strips just above Mersea island. These are the 82,944 solar panels which make up Langenhoe Solar Farm, and have the capacity to generate 21.15 MW of solar power.

So how many of you recognise our signs of working in Earth observation? Any you think we’ve missed? Get in touch, let us know!

Inspiring the Next Generation of EO Scientists

Artist's rendition of a satellite - 3dsculptor/123RF Stock Photo

Artist’s rendition of a satellite – 3dsculptor/123RF Stock Photo

Last week, whilst Europe’s Earth Observation (EO) community was focussed on the successful launch of Sentinel-5P, over in America Tuesday 10th October was Earth Observation Day!

This annual event is co-ordinated by AmericaView, a non-profit organisation, whose aim to advance the widespread use of remote sensing data and technology through education and outreach, workforce development, applied research, and technology transfer to the public and private sectors.

Earth Observation Day is a Science, Technology, Engineering, and Mathematics (STEM) event celebrating the Landsat mission and its forty-five year archive of imagery. Using satellite imagery provides valuable experience for children in maths and sciences, together with introducing subjects such as land cover, food production, hydrology, habitats, local climate and spatial thinking. The AmericaView website contains a wealth of EO materials available for teachers to use, from fun puzzles and games through to a variety of remote sensing tutorials. Even more impressive is that the event links schools to local scientists in remote sensing and geospatial technologies. These scientists provide support to teachers including giving talks, helping design lessons or being available to answer student’s questions.

This is a fantastic event by AmericaView, supporting by wonderful resources and remote sensing specialists. We first wrote about this three years ago, and thought the UK would benefit from something similar. We still do. The UK Space Agency recently had an opportunity for organisations interested in providing education and outreach activities to support EO, satellite launch programme or the James Webb Space Telescope. It will be interesting to see what the successful candidates come up with.

At Pixalytics we’re passionate about educating and inspiring the next generation of EO scientists. For example, we regularly support the Remote Sensing and Photogrammetry Society’s Wavelength conference for students and early career scientists; and sponsored the Best Early-Career Researcher prize at this year’s GISRUK Conference. We’re also involved with two exciting events at Plymouth’s Marine Biological Association, a Young Marine Biologists (YMB) Summit for 12-18 year olds at the end of this month and their 2018 Postgraduate conference.

Why is this important?
The space industry, and the EO sector, is continuing to grow. According to Euroconsult’s ‘Satellites to Be Built & Launched by 2026 – I know this is another of the expensive reports we highlighted recently – there will be around 3,000 satellites with a mass above 50 kg launched in the next decade – of which around half are anticipated as being used for EO or communication purposes. This almost doubles the number of satellites launched in the last ten years and doesn’t include the increasing number of nano and cubesats going up.

Alongside the number of satellites, technological developments mean that the amount of EO data available is increasing almost exponentially. For example, earlier this month World View successfully completed multi-day flight of its Stratollite™ service, which uses high-altitude balloons coupled with the ability to steer within stratospheric winds. They can carry a variety of sensors, a mega-pixel camera was on the recent flight, offering an alternative vehicle for collecting EO data.

Therefore, we need a future EO workforce who are excited, and inspired, by the possibilities and who will take this data and do fantastic things with it.

To find that workforce we need to shout about our exciting industry and make sure everyone knows about the career opportunities available.

No Paraskevidekatriaphobia For Sentinel-5P!

Sentinel-5P carries the state-of-the-art Tropomi instrument. Image courtesy of ESA/ATG medialab.

On Friday the latest of the Sentinel satellites, Sentinel-5P, is due to be launched at 09.27 GMT from Plesetsk Cosmodrome in Russia.

Friday is the 13th October, and within parts of the western world this is considered to be an unlucky date – although in Italy its Friday 17th which is unlucky and in some Spanish speaking countries it is Tuesday the 13th. Fear of Friday 13th is known as paraskevidekatriaphobia, although evidently it isn’t something Sentinel-5P worries about!

Sentinel-5 Precursor, to give the full title, is dedicated to monitoring our atmosphere. It will create maps of the various trace gases such as nitrogen dioxide, ozone, formaldehyde, sulphur dioxide, methane and carbon monoxide alongside aerosols in our atmosphere. The mission will also support the monitoring of air pollution over cities, volcanic ash, stratospheric ozone and surface UV radiation.

An internal view of the Copernicus Sentinel-5P satellite. Image courtesy of ESA/ATG medialab.

The satellite itself is a hexagonal structure as can be seen in the image to the right. It has three solar wings which will be deployed once the polar sun-synchronous 824 km low earth orbit has been achieved. Sentinel-5P will be orbiting three and half minutes behind NOAA’s Suomi-NPP satellite which carries the Visible/Infrared Imager and Radiometer Suite (VIIRS). This synergy will allow the high resolution cloud mask from VIIRS to be used within the calculations for methane from Sentinel-5P.

Within the hexagonal body the main scientific instrument is the Tropospheric Monitoring Instrument (Tropomi). This is a push-broom imaging spectrometer covering a spectral range from ultraviolet and visible (270–495 nm), near infrared (675–775 nm) and shortwave infrared (2305–2385 nm). The spatial resolution of the instrument will be 7 km x 3.5 km. However, one of the exciting elements of this instrument is that it will have a swath width of 2600 km meaning it can map almost the entire planet every day. It will have full daily surface coverage of radiance and reflectance measurements for latitudes > 7° and < -7°, and better than 95 % coverage for other latitudes.

The key role of Sentinel-5P is to reduce the data gap between the end of the Envisat mission in May 2012 and the launch of Sentinel-5 in 2020. Sentinel-5, and Sentinel-4, will be instruments onboard meteorological satellites operated by Eumetsat and both will be used to monitor the atmosphere.

The timing of Sentinel-5 is interesting for those of within the UK given that almost three quarters of the funding from Copernicus comes from the European Union. By this time Brexit will have occurred and it is currently unclear how that will impact on our future involvement in this programme. This also applies to the work announced at the end of last month to look at an expansion of the Sentinel missions. Invitations to tender (ITT) are due to be issued in the near future, and given our previous blogs on potential limitations and issues, it will be interesting to see which UK companies bid, and whether they will be successful.

Sentinel-5P will help improve our understanding of the processes within the atmosphere which affect our climate, the air we breathe and ultimately the health of everyone on the planet.

Can You See The Great Wall of China From Space?

Area north of Beijing, China, showing the Great Wall of China running through the centre. Image acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

Dating back over two thousand three hundred years, the Great Wall of China winds its way from east to west across the northern part of the country. The current remains were built during Ming Dynasty and have a length of 8 851.8 km according to 2009 work by the Chinese State Administration of Cultural Heritage and National Bureau of Surveying and Mapping Agency. However, if you take into account the different parts of the wall built by other dynasties, its length is almost twenty two thousand kilometres.

The average height of the wall is between six and seven metres, and its width is between four to five metres. This width would allow five horses, or ten men, to walk side by side. The sheer size of the structure has led people to believe that it could be seen from space. This was first described by William Stukeley in 1754, when he wrote in reference to Hadrian’s Wall that ‘This mighty wall of four score miles in length is only exceeded by the Chinese Wall, which makes a considerable figure upon the terrestrial globe, and may be discerned at the Moon.’

Despite Stukeley’s personal opinion not having any scientific basis, it has been repeated many times since. By the time humans began to go into space, it was considered a fact. Unfortunately, astronauts such as Buzz Aldrin, Chris Hatfield and even China’s first astronaut, Yang Liwei, have all confirmed that the Great Wall is not visible from space by the naked eye. Even Pixalytics has got a little involved in this debate. Two years ago we wrote a blog saying that we couldn’t see the wall on Landsat imagery as the spatial resolution was not small enough to be able to distinguish it from its surroundings.

Anyone who is familiar with the QI television series on the BBC will know that they occasionally ask the same question in different shows and give different answers when new information comes to light. This time it’s our turn!

Last week Sam was a speaker at the TEDx One Step Beyond event at the National Space Centre in Leicester – you’ll hear more of that in a week or two. However, in exploring some imagery for the event we looked for the Great Wall of China within Sentinel-2 imagery. And guess what? We found it! In the image at the top, the Great Wall can be seen cutting down the centre from the top left.

Screenshot of SNAP showing area north of Beijing, China. Data acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

It was difficult to spot. The first challenge was getting a cloud free image of northern China, and we only found one covering our area of interest north of Beijing! Despite Sentinel-2 having 10 m spatial resolution for its visible wavelengths, as noted above, the wall is generally narrower. This means it is difficult to see the actual wall itself, but it is possible to see its path on the image. This ability to see very small things from space by their influence on their surroundings is similar to how we are able to spot microscopic phytoplankton blooms. The image on the right is a screenshot from Sentinel Application Platform tool (SNAP) which shows the original Sentinel-2 image of China on the top left and the zoomed section identifying the wall.

So whilst the Great Wall of China might not be visible from space with the naked eye, it is visible from our artificial eyes in the skies, like Sentinel-2.

Brexit: Science & Space

Artist's rendition of a satellite - paulfleet/123RF Stock Photo

Artist’s rendition of a satellite – paulfleet/123RF Stock Photo

Brexit currently dominates UK politics. Whilst it’s clear the UK is leaving the European Union (EU) in March 2019, the practical impact, and consequences, are still a confused fog hanging over everything. The UK Government Department for Exiting the European Union has been issuing position papers to set out how it sees the UK’s future arrangements with the EU.

Last week, the ‘Collaboration in science and innovation: a future partnership paper’ was issued. Given our company’s focus we were eager to see what was planned. Unfortunately, like a lot of the UK Government pronouncements on Brexit, it is high on rhetoric, but low on any helpful, or new, information or clarity.

It begins with a positive, but perhaps rather obvious, statement, stating that one of the UK’s core objectives is to ‘seek agreement to continue to collaborate with European partners on major science, research and technology initiatives.’

Future Partnership with EU Principles
Key aspects of the UK’s ambition for the future partnership include:

  • Science & Innovation collaboration is not only maintained, but strengthened.
  • With its strong research community, the UK wants an ambitious agreement for continued research co-operation.
  • Government wants the UK to be a hub for international talent in research, and to welcome the brightest and best people from around the world.

The principles are followed by four particular areas the UK wants to discuss with the EU. Interestingly, it specifically outlines how non-EU countries currently participate in each of these areas, which are Research & Innovation Framework Programmes, Space Programmes, Nuclear R&D and Defence R&D.

Research & Innovation Framework Programmes
Horizon 2020 is highlighted as the UK ranks top across the EU in terms of contracts and participants in it. The Government confirms its commitment to underwriting any projects submitted whilst the UK is still an EU member.

Support for this programme is good, however with an end date of 2020 it is going to be equally important to be a strong partner of whatever research funding programme that is going to follow.

Space Programmes
As we have described before the European Space Agency is not an EU institution, and so is not impacted by Brexit – a fact reinforced by the paper. Three key EU, rather than ESA, led space programmes are highlighted:

  • Galileo Navigation and Positioning System – Issues here surround both the use of the system and its ongoing development. UK firms have been key suppliers for this work including Surrey Satellite Technology Ltd (SSTL), Qinetiq, CGI, Airbus and Scisys.
  • Copernicus – The Copernicus Earth Observation data is freely available to anyone in the world. The key element here is about being at the table to influence the direction. Although, the paper does refer to existing precedents for third party participation.
  • Space Surveillance and Tracking – this is a new programme.

The paper states that given the unique nature of space programmes, the ‘EU and UK should discuss all options for future cooperation including new arrangements.’

What Is Not Said
There are a lot of positive and welcome words here, but also a huge amount unsaid, for example:

  • Interconnectivity: Science and innovation happens when researchers work together, so the UK’s approach to the movement of people is fundamental. Will the brightest and best be allowed to come and work here, and will they want to?
  • Education: Education is fundamental to this area, yet it does not merit a single mention in the paper. New researchers and early career scientists benefit hugely from programmes such as Erasmus, will our involvement in these continue?
  • Financial Contribution: How much is the UK willing to pay to be part of science and innovation programmes? The paper notes any financial contribution will have to be weighed against other spending priorities. Not exactly hugely encouraging.
  • Contractual Issues: Part of the issue with Galileo is that the contracts specifically exclude non-EU countries from involvement.. Whilst, it is possible to see that the UK could negotiate use of Galileo, continued involvement as a supplier may be more difficult.

Conclusion
The UK wants dialogue with the EU on far-reaching science and innovation agreement. This ambition is to be applauded, but we are a very long way away from that point. We hope both parties are able to work together to get there.

Algae Starting To Bloom

Algal Blooms in Lake Erie, around Monroe, acquired by Sentinel-2 on 3rd August 2017. Data Courtesy of ESA/Copernicus.

Algae have been making the headlines in the last few weeks, which is definitely a rarely used phrase!

Firstly, the Lake Erie freshwater algal bloom has begun in the western end of the lake near Toledo. This is something that is becoming an almost annual event and last year it interrupted the water supply for a few days for around 400,000 residents in the local area.

An algae bloom refers to a high concentration of micro algae, known as phytoplankton, in a body of water. Blooms can grow quickly in nutrient rich waters and potentially have toxic effects. Although a lot of algae is harmless, the toxic varieties can cause rashes, nausea or skin irritation if you were to swim in it, it can also contaminate drinking water and can enter the food chain through shellfish as they filter large quantities of water.

Lake Erie is fourth largest of the great lakes on the US/Canadian border by surface area, measuring around 25,700 square km, although it’s also the shallowest and at 484 cubic km has the smallest water volume. Due to its southern position it is the warmest of the great lakes, something which may be factor in creation of nutrient rich waters. The National Oceanic and Atmospheric Administration produce both an annual forecast and a twice weekly Harmful Algal Bloom Bulletin during the bloom season which lasts until late September. The forecast reflects the expected biomass of the bloom, but not its toxicity, and this year’s forecast was 7.5 on a scale to 10, the largest recent blooms in 2011 and 2015 both hit the top of the scale. Interestingly, this year NOAA will start incorporating Sentinel-3 data into the programme.

Western end of Lake Erie acquired by Sentinel-2 on 3rd August 2017. Data

Despite the phytoplankton within algae blooms being only 1,000th of a millimetre in size, the large numbers enable them to be seen from space. The image to the left is a Sentinel-2 image, acquired on the 3rd August, of the western side of the lake where you can see the green swirls of the algal bloom, although there are also interesting aircraft contrails visible in the image. The image at the start of the top of the blog is zoomed in to the city of Monroe and the Detroit River flow into the lake and the algal bloom is more prominent.

Landsat 8 acquired this image of the northwest coast of Norway on the 23rd July 2017,. Image courtesy of NASA/NASA Earth Observatory.

It’s not just Lake Erie where algal blooms have been spotted recently:

  • The Chautauqua Lake and Findley Lake, which are both just south of Lake Erie, have reported algal blooms this month.
  • NASA’s Landsat 8 satellite captured the image on the right, a bloom off the northwest coast of Norway on the 23rd July. It is noted that blooms at this latitude are in part due to the sunlight of long summer days.
  • The MODIS instrument onboard NASA’s Aqua satellite acquired the stunning image below of the Caspian Sea on the 3rd August.

Image of the Caspian Sea, acquired on 3rd August 2017, by MODIS on NASA’s Aqua satellite. Image Courtesy of NASA/NASA Earth Observatory.

Finally as reported by the BBC, an article in Nature this week proposes that it was a takeover by ocean algae 650 million years ago which essentially kick started life on Earth as we know it.

So remember, they may be small, but algae can pack a punch!

Supporting Soil Fertility From Space

Sentinel-2 pseudo-true colour composite from 2016 with a Kompsat-3 Normalized Difference Vegetation Index (NDVI) product from 2015 inset. Sentinel data courtesy of ESA/Copernicus.

Last Tuesday I was at the academic launch event for the Tru-Nject project at Cranfield University. Despite the event’s title, it was in fact an end of project meeting. Pixalytics has been involved in the project since July 2015, when we agreed to source and process high resolution satellite Earth Observation (EO) imagery for them.

The Tru-Nject project is funded via Innovate UK. It’s official title is ‘Tru-Nject: Proximal soil sensing based variable rate application of subsurface fertiliser injection in vegetable/ combinable crops’. The focus is on modelling soil fertility within fields, to enable fertiliser to be applied in varying amounts using point-source injection technology which reduces the nitrogen loss to the atmosphere when compared with spreading fertiliser on the soil surface.

To do this the project created soil fertility maps from a combination of EO products, physical sampling and proximal soil sensing – where approximately 15 000 georeferenced hyperspectral spectra are collected using an instrument connected to a tractor. These fertility maps are then interpreted by an agronomist, who decides on the relative application of fertiliser.

Initial results have shown that applying increased fertiliser to areas of low fertility improves overall yield when compared to applying an equal amount of fertiliser everywhere, or applying more fertiliser to high yield areas.

Pixalytics involvement in the work focussed on acquiring and processing, historical, and new, sub 5 metre optical satellite imagery for two fields, near Hull and York. We have primarily acquired data from the Kompsat satellites operated by the Korea Aerospace Research Institute (KARI), supplemented with WorldView data from DigitalGlobe. Once we’d acquired the imagery, we processed it to:

  • remove the effects of the atmosphere, termed atmospheric correction, and then
  • converted them to maps of vegetation greenness

The new imagery needed to coincide with a particular stage of crop growth, which meant the satellite data acquisition period was narrow. This led to a pleasant surprise for Dave George, Tru-Nject Project Manager, who said, “I never believed I’d get to tell a satellite what to do.’ To ensure that we collected data on specific days we did task the Kompsat satellites each year.

Whilst we were quite successful with the tasking the combination of this being the UK, and the fact that the fields were relatively small, meant that some of the images were partly affected by cloud. Where this occurred we gap-filled with Copernicus Sentinel-2 data, it has coarser spatial resolution (15m), but more regular acquisitions.

In addition, we also needed to undertake vicarious adjustment to ensure that we produced consistent products over time whilst the data came from different sensors with different specifications. As we cannot go to the satellite to measure its calibration, vicarious adjustment is a technique which uses ground measurements and algorithms to not only cross-calibrate the data, but also adjusts for errors in the atmospheric correction.

An example of the work is at the top, which shows a Sentinel-2 pseudo-true colour composite from 2016 with a Kompsat-3 Normalized Difference Vegetation Index (NDVI) product from 2015 inset. The greener the NDVI product the more green the vegetation is, although the two datasets were collected in different years so the planting within the field varies.

We’ve really enjoyed working with Stockbridge Technology Centre Ltd (STC), Manterra Ltd, and Cranfield University, who were the partners in the project. Up until last week all the work was done via telephone and email, and so it was great to finally meet them in-person, hear about the successful project and discuss ideas for the future.

If no-one is there when an iceberg is born, does anyone see it?

Larsen C ice Shelf including A68 iceberg. Image acquired by MODIS Aqua satellite on 12th July 2017. Image courtesy of NASA.

The titular paraphrasing of the famous falling tree in the forest riddle was well and truly answered this week, and shows just how far satellite remote sensing has come in recent years.

Last week sometime between Monday 10th July and Wednesday 12th July 2017, a huge iceberg was created by splitting off the Larsen C Ice Shelf in Antarctica. It is one of the biggest icebergs every recorded according to scientists from Project MIDAS, a UK-based Antarctic research project, who estimate its area of be 5,800 sq km and to have a weight of more a trillion tonnes. It has reduced the Larsen C ice Shelf by more than twelve percent.

The iceberg has been named A68, which is a pretty boring name for such a huge iceberg. However, icebergs are named by the US National Ice Centre and the letter comes from where the iceberg was originally sited – in this case the A represents area zero degrees to ninety degrees west covering the Bellingshausen and Weddell Seas. The number is simply the order that they are discovered, which I assume means there have been 67 previous icebergs!

After satisfying my curiosity on the iceberg names, the other element that caught our interest was the host of Earth observation satellites that captured images of either the creation, or the newly birthed, iceberg. The ones we’ve spotted so far, although there may be others, are:

  • ESA’s Sentinel-1 has been monitoring the area for the last year as an iceberg splitting from Larsen C was expected. Sentinel-1’s SAR imagery has been crucial to this monitoring as the winter clouds and polar darkness would have made optical imagery difficult to regularly collect.
  • Whilst Sentinel-1 was monitoring the area, it was actually NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Aqua satellite which confirmed the ‘birth’ on the 12th July with a false colour image at 1 km spatial resolution using band 31 which measures infrared signals. This image is at the top of the blog and the dark blue shows where the surface is warmest and lighter blue indicates a cooler surface. The new iceberg can be seen in the centre of the image.
  • Longwave infrared imagery was also captured by the NOAA/NASA Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite on July 13th.
  • Similarly, NASA also reported that Landsat 8 captured a false-colour image from its Thermal Infrared Sensor on the 12th July showing the relative warmth or coolness of the Larsen C ice shelf – with the area around the new iceberg being the warmest giving an indication of the energy involved in its creation.
  • Finally, Sentinel-3A has also got in on the thermal infrared measurement using the bands of its Sea and Land Surface Temperature Radiometer (SLSTR).
  • ESA’s Cryosat has been used to calculate the size of iceberg by using its Synthetic Aperture Interferometric Radar Altimeter (SIRAL) which measured height of the iceberg out of the water. Using this data, it has been estimated that the iceberg contains around 1.155 cubic km of ice.
  • The only optical imagery we’ve seen so far is from the DEMIOS1 satellite which is owned by Deimos Imaging, an UrtheCast company. This is from the 14th July and revealed that the giant iceberg was already breaking up into smaller pieces.

It’s clear this is a huge iceberg, so huge in fact that most news agencies don’t think that readers can comprehend its vastness, and to help they give a comparison. Some of the ones I came across to explain its vastness were:

  • Size of the US State of Delaware
  • Twice the size of Luxembourg
  • Four times the size of greater London
  • Quarter of the size of Wales – UK people will know that Wales is almost an unofficial unit of size measurement in this country!
  • Has the volume of Lake Michigan
  • Has the twice the volume of Lake Erie
  • Has the volume of the 463 million Olympic-sized swimming pools; and
  • My favourite compares its size to the A68 road in the UK, which runs from Darlington to Edinburgh.

This event shows how satellites are monitoring the planet, and the different ways we can see the world changing.

Great Barrier Reef Coral Bleaching

Great Barrier Reef off the east coast of Australia where currents swirl in the water around corals. Image acquired by Landsat-8 on 23 August 2013. Image Courtesy of USGS/ESA.

Coral bleaching on the Great Barrier Reef in Australia was worse than expected last year, and a further decline is expected in 2017 according to the Great Barrier Reef Marine Park Authority. In a document issued this week they noted that, along with reefs across the world, the Great Barrier Reef has had widespread coral decline and habitat loss over the last two years.

We’ve written about coral bleaching before, as it’s a real barometer of climate change. To put the importance of the Great Barrier Reef into context:

  • It’s 2300 km long and covers an area of around 70 million football pitches;
  • Consists of 3000 coral reefs, which are made up from 650 different types of hard and soft coral; and
  • Is home to over 1500 types of fish and more than 100 varieties of sharks and rays.

Coral bleaching occurs when water stress causes coral to expel the photosynthetic algae, which give coral their colours, exposing the skeleton and turning them white. The stress is mostly due to higher seawater temperatures; although cold water stresses, run-off, pollution and high solar irradiance can also cause bleaching. Whilst bleaching does not kill coral immediately, it does put them at a greater risk of mortality from storms, poor water quality, disease and the crown-of-thorns starfish.

Last year the Great Barrier Reef suffered its worst bleaching on record, aerial and in-water surveys identified that 29% of shallow water coral reefs died in 2016; up from the original estimation of 22%. The most severe mortality was in an area to the north of Port Douglas where 70% of the shallow water corals died. This is hugely sad news to Sam and I, as we explored this area of the Great Barrier Reef ourselves about fifteen years ago.

Whilst hugely concerning, there is also a little hope! There was a strong recovery of coral in the south of the Great Barrier Reef, as bleaching and other impacts were less.

Images from the Copernicus Sentinel-2A satellite captured on 8 June 2016 and 23 February 2017 show coral turning bright white for Adelaide Reef, Central Great Barrier Reef. Data courtesy of Copernicus/ESA, and contains modified Copernicus Sentinel data (2016–17), processed by J. Hedley; conceptual model by C. Roelfsema

The coral bleaching event this year has also been captured by Sentinel-2. Scientists from ESA’s Sen2Coral project have used change detection techniques to determine bleaching. Images between January and April showed areas of coral turning bright white and then darkening, although it was unclear whether the darkening was due to coral recovery or dead coral being overgrown with algae. In-water surveys were undertaken, which confirmed the majority of the darkened areas were algal overgrowth.

This work has proved that coral bleaching can be seen from space, although it needs to be supported by in-situ work. ESA intends to develop a coral reef tool, which will be part of the open-source Sentinel Application Platform (SNAP) toolkit. This will enable anyone to monitor the health of coral reefs worldwide and hopefully, help protect these natural wonders.