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!

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.

Flip-Sides of Soil Moisture

Soil Moisture changes between 19th and 25th August around Houston, Texas due to rainfall from Hurricane Harvey. Courtesy of NASA Earth Observatory image by Joshua Stevens, using soil moisture data courtesy of JPL and the SMAP science team.

Soil moisture is an interesting measurement as it can be used to monitor two diametrically opposed conditions, namely floods and droughts. This was highlighted last week by maps produced from satellite data for the USA and Italy respectively. These caught our attention because soil moisture gets discussed on a daily basis in the office, due to its involvement in a project we’re working on in Uganda.

Soil moisture can have a variety of meanings depending on the context. For this blog we’re using soil moisture to describe the amount of water held in spaces between the soil in the top few centimetres of the ground. Data is collected by radar satellites which measure microwaves reflected or emitted by the Earth’s surface. The intensity of the signal depends on the amount of water in the soil, enabling a soil moisture content to be calculated.

Floods
You can’t have failed to notice the devastating floods that have occurred recently in South Asia – particularly India, Nepal and Bangladesh – and in the USA. The South Asia floods were caused by monsoon rains, whilst the floods in Texas emanated from Hurricane Harvey.

Soil moisture measurements can be used to show the change in soil saturation. NASA Earth Observatory produced the map at the top of the blogs shows the change in soil moisture between the 19th and 25th August around Houston, Texas. The data is based on measurements acquired by the Soil Moisture Active Passive (SMAP) satellite, which uses a radiometer to measure soil moisture in the top 5 centimetres of the ground with a spatial resolution of around 9 km. On the map itself the size of each of the hexagons shows how much the level of soil moisture changed and the colour represents how saturated the soil is.

These readings have identified that soil moisture levels got as high as 60% in the immediate aftermath of the rainfall, partly due to the ferocity of the rain, which prevented the water from seeping down into the soil and so it instead remained at the surface.

Soil moisture in Italy during early August 2017. The data were compiled by ESA’s Soil Moisture CCI project. Data couresy of ESA. Copyright: C3S/ECMWF/TU Wien/VanderSat/EODC/AWST/Soil Moisture CCI

Droughts
By contrast, Italy has been suffering a summer of drought and hot days. This year parts of the country have not seen rain for months and the temperature has regularly topped one hundred degrees Fahrenheit – Rome, which has seventy percent less rainfall than normal, is planning to reduce water pressure at night for conservation efforts.

This has obviously caused an impact on the ground, and again a soil moisture map has been produced which demonstrates this. This time the data was come from the ESA’s Soil Moisture Climate Change Initiative project using soil moisture data from a variety of satellite instruments. The dataset was developed by the Vienna University of Technology with the Dutch company VanderSat B.V.

The map shows the soil moisture levels in Italy from the early part of last month, with the more red the areas, the lower the soil moisture content.

Summary
Soil moisture is a fascinating measurement that can provide insights into ground conditions whether the rain is falling a little or a lot.

It plays an important role in the development of weather patterns and the production of precipitation, and is crucial to understanding both the water and carbon cycles that impact our weather and climate.

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!

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.

Queen’s Speech Targets Space

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

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

Last week was the State Opening of Parliament in the UK following the General Election, this included the Queen’s Speech which set out the legislation the Government intends introduce in the coming Parliament. As expected, Brexit dominated the headlines and so you may have missed the announcement of the Space Industry Bill.

The space sector has been a growth target for the Government since 2010, when it set an ambitious target of delivering 10% of the global space economy. The last UK Space Agency report covered 2014/15 and indicated the industry was worth £13.7bn – equivalent to 6.5% of the global space economy.

Our space industry is inextricably linked to Europe through the European Space Agency (ESA). Whilst, as we have described before, Brexit won’t affect our role in ESA, other projects such as Copernicus and Galileo are EU led projects and the UK’s future involvement isn’t clear. This Bill is part of the Government’s response, and its aim is to make the UK the most attractive place in Europe for commercial space activities.

We’ve previously written about the current UK licencing and regulatory arrangements for anyone who wants to launch an object into space, as detailed in the Outer Space Act 1986. This Bill will change that framework and has the following key elements:

  • New powers to license a wide range of spaceflight activities, including vertically-launched rockets, spaceplanes, satellite operations, spaceports and other technologies.
  • Comprehensive and proportionate regulatory framework to manage risk.
  • Measures to regulate unauthorised access and interference with spacecraft, spaceports and associated infrastructure.
  • Measures to promote public safety by providing a regulatory framework to cover operational insurance, indemnity and liability.

The Bill itself is based on the draft Spaceflight Bill published in February, together with the Government responses to the twelve recommendations of the Science and Technology Committee Report on the Draft Spaceflight Bill which was issued on the 22nd June.

There are still a number of questions to be answered over the coming months.

  • Limited Liability: Currently, the standard requirement is to have insurance of at least €60 million. However, the draft Bill suggests that insurance requirements will be determined as part of the license application process. Clearly, the different types of spaceflight will have different risks and so having flexibility makes sense; however, until the industry understands this aspects it will be a concerning area of uncertainty.
  • Spaceports: Previously, the Government intended to select a location for a spaceport, but last year this changed to offering licences for spaceports. This means there could be multiple spaceports in the country, but it is questionable whether there is sufficient business to support multiple sites. Given the specialist knowledge and skills needed to launch spacecraft, it is likely that a preferred site will eventually emerge, with or without Government involvement.
  • Speed of Change: Back in 2012 the Government acknowledged that regulations for launching objects into space needed to be revised as they didn’t suit smaller satellites. Since that time satellites have got even smaller, constellation launches are increasing rapidly and costs are decreasing. The legislation and regulations will need to evolve as quickly as the technology, if the UK is to be the most attractive place to do business. Can we do this?

The UK Space Industry is in for a roller coaster over the coming years. Brexit will undoubtedly be challenging, and will throw up many threats; whereas the Space Industry Bill will offer opportunities. To be successful companies will need to tread a careful path.

Locusts & Monkeys

Soil moisture data from the SMOS satellite and the MODIS instrument acquired between July and October 2016 were used by isardSAT and CIRAD to create this map showing areas with favourable locust swarming conditions (in red) during the November 2016 outbreak. Data courtesy of ESA. Copyright : CIRAD, SMELLS consortium.

Spatial resolution is a key characteristic in remote sensing, as we’ve previously discussed. Often the view is that you need an object to be significantly larger than the resolution to be able to see it on an image. However, this is not always the case as often satellites can identify indicators of objects that are much smaller.

We’ve previously written about satellites identifying phytoplankton in algal blooms, and recently two interesting reports have described how satellites are being used to determine the presence of locusts and monkeys!

Locusts

Desert locusts are a type of grasshopper, and whilst individually they are harmless as a swarm they can cause huge damage to populations in their paths. Between 2003 and 2005 a swarm in West Africa affected eight million people, with reported losses of 100% for cereals, 90% for legumes and 85% for pasture.

Swarms occur when certain conditions are present; namely a drought, followed by rain and vegetation growth. ESA and the UN Food and Agriculture Organization (FAO) have being working together to determine if data from the Soil Moisture and Ocean Salinity (SMOS) satellite can be used to forecast these conditions. SMOS carries a Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) instrument – a 2D interferometric L-band radiometer with 69 antenna receivers distributed on a Y-shaped deployable antenna array. It observes the ‘brightness temperature’ of the Earth, which indicates the radiation emitted from planet’s surface. It has a temporal resolution of three days and a spatial resolution of around 50 km.

By combining the SMOS soil moisture observations with data from NASA’s MODIS instrument, the team were able to downscale SMOS to 1km spatial resolution and then use this data to create maps. This approach then predicted favourable locust swarming conditions approximately 70 days ahead of the November 2016 outbreak in Mauritania, giving the potential for an early warning system.

This is interesting for us as we’re currently using soil moisture data in a project to provide an early warning system for droughts and floods.

Monkeys

Earlier this month the paper, ‘Connecting Earth Observation to High-Throughput Biodiversity Data’, was published in the journal Nature Ecology and Evolution. It describes the work of scientists from the Universities of Leicester and East Anglia who have used satellite data to help identify monkey populations that have declined through hunting.

The team have used a variety of technologies and techniques to pull together indicators of monkey distribution, including:

  • Earth observation data to map roads and human settlements.
  • Automated recordings of animal sounds to determine what species are in the area.
  • Mosquitos have been caught and analysed to determine what they have been feeding on.

Combining these various datasets provides a huge amount of information, and can be used to identify areas where monkey populations are vulnerable.

These projects demonstrate an interesting capability of satellites, which is not always recognised and understood. By using satellites to monitor certain aspects of the planet, the data can be used to infer things happening on a much smaller scale than individual pixels.

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.

Small Sea Salinity & Satellite Navigation Irrigation

Artists impression of the Soil Moisture and Ocean Salinity (SMOS) satellite. Image courtesy of ESA – P. Carril.

A couple of interesting articles came out in the last week relating to ESA’s Soil Moisture and Ocean Salinity (SMOS) mission. It caught our attention, as we’re currently knee deep in SMOS data at the moment, due to the soil moisture work we’re undertaking.

SMOS was launched in November 2009 and uses the interferometry technique to make worldwide observations of soil moisture over land and salinity over the ocean. Although its data has also been used to measure floating ice and calculate crop-yield forecasts.

The satellite carries the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS) instrument, which is a 2D interferometric L-band radiometer with 69 antenna receivers distributed on a Y-shaped deployable antenna array. It has a temporal resolution of three days, with a spatial resolution of around 50 km.

A recent ESA article once again showed the versatility of SMOS, reporting that it was being used to measure the salinity in smaller seas, such as the Mediterranean. This was never an anticipated outcome due to radio interference and the land-sea boundary contamination – where the land and ocean data can’t be distinguished sufficiently to provide high quality measurements.

However, the interference has been reduced by shutting down illegal transmitters interrupting the SMOS signal and the land-sea contamination has been reduced by work at the Barcelona Expert Centre to change the data processing methodology.

All of this has meant that it’s possible to use SMOS to look at how water flows in and out of these smaller seas, and impact on the open oceans. This will help complement the understanding being gained from SMOS on ocean climate change, ocean acidification and the El Niño effect.

A fascinating second article described a new methodology for measuring soil moisture using reflected satellite navigation signals. The idea was originally from ESA engineer Manuel Martin-Neira, who worked on SMOS – which we accept is a bit more of a tenuous link, but we think it works for the blog! Manuel proposed using satellite navigation microwave signals to measure terrestrial features such as the topography of oceans.

This idea was further developed by former ESA employee Javier Marti, and his company Divirod, and they have created a product to try and reduce the overuse of irrigation. According to Javier, the system compares reflected and direct satnav signals to reveal the moisture content of soil and crops and could save around 30% of water and energy costs, and improve crop yields by 10-12%. It is a different methodology to SMOS, but the outcome is the same. The work is currently been tested with farmers around the Ogallala aquifer in America.

For anyone working in soil moisture, this is an interesting idea and shows what a fast moving field remote sensing is with new approaches and products being developed all the time.