Copernicus: Sentinel-1 2019
Sentinel-1 mission and its imagery in the period 2019References
• December 5, 2019: The Copernicus Sentinel-1 mission takes us over part of the Brazilian state of Mato Grosso deep in the Amazon interior. 1)
- Ironically, Mato Grosso means ‘great woods’, but, as these colored rectangular shapes portray, much of the tropical forest has been cut down and given over to farming. While this image only shows a small area, Mato Grosso is one of Brazil’s top cattle-producing and crop-producing states, with the main crops including corn, soya and wheat.
- However, although the state has one of the highest historical rates of deforestation in Amazonian Brazil, deforestation is slowing and Mato Grosso is now said to be a global leader in climate-change solutions.
- As an advanced radar mission, Copernicus Sentinel-1 can image the surface of Earth through cloud and rain and regardless of whether it is day or night. This makes it ideal for monitoring areas that tend to be covered by cloud such as rainforests.
• November 26, 2019: Torrential downpours have battered many parts of Italy this month, with extreme flooding wreaking havoc across northern Italy. The province of Alessandria is said to be one of the worst-affected areas according to Italian media, with around 200 people evacuated and 600 said to be left stranded. 2)
- Copernicus Sentinel-1’s radar ability to ‘see’ through clouds and rain, and in darkness, makes it particularly useful for monitoring floods. It can even easily differentiate water bodies, highlighting the difference between the Po River in black, and the extent of the flooding in red.
- Around 500 people were evacuated further north in the Aosta Valley, where many roads were closed in fear of potential avalanches. Part of a viaduct serving the A6 motorway near Savona, in the northern region of Liguria, was washed away by a mudslide – leaving a 30 m gap in the road.
- Images acquired before and after flooding offer immediate information on the extent of inundation and support assessments of property and environmental damage.
- Earlier this month, the Copernicus Emergency Mapping Service was activated to help respond to the floods in northeast Italy, where Venice saw record-breaking water levels and the worst flooding in 50 years.
• November 17, 2019: This week, southeast France was hit by a magnitude 5 earthquake with tremors felt between Lyon and Montélimar. The Copernicus Sentinel-1 radar mission has been used to map the way the ground shifted as a result of the quake. 3)
- Earthquakes are unusual in this part of France, but on 11 November at noon (local time) part of the Auvergne-Rhône-Alpes region was rocked by a quake leading to people having to be evacuated and buildings damaged.
- Scientists are turning to satellite-based radar observations to help understand the nature of the seismic fault and map its location.
- By combining imagery acquired before and after a quake, changes on the ground that occurred between the two acquisition dates lead to rainbow-colored interference patterns in the combined image, known as an ‘interferogram’, which allows scientists to quantify ground movement.
- An acquisition by Copernicus Sentinel-1 was made on 12 November, one day after the event, and was ready to process on ESA’s Geohazards Exploitation Platform (GEP), which is a cloud-based processing environment with on-demand terrain motion mapping services.
- Several users have computed interferograms over the concerned region.
- While several faults are present in the region and marked in geological maps, none were known to be seismically active. The interferogram here shows a series of fringes in the area west of the city of Le Teil and has allowed scientists to identify the fault at the origin of the earthquake. The satellite observation also measured a ground displacement that corresponds to an uplift of up to 8 cm in the southern part of the fault.
- The intensity of the ground motion felt by the inhabitants and measured from space is unusual for this magnitude of event unless the earthquake epicenter is shallow and, indeed, seismic data put the epicenter at between 1 km and 3.5 km below the surface. Observations in the field on 13 November suggest that the rupture propagated up to the surface.
- Floriane Provost, Research Fellow at ESA, said, “The rapid release to the public of up-to-date Copernicus Sentinel-1 based products visualized in a friendly fashion on the GEP geobrowser was followed by a peak of connections. It helped the scientific community better map the location of the fault and to confirm the mechanism of the earthquake.
- “This example shows how the GEP environment contributes to the rapid processing and exchange of information within the geohazards community.”
- Michael Foumelis, researcher at the French Geological Survey BRGM, added, “Field investigations by BRGM experts are on-going, while interferometric synthetic aperture radar results are actually helping them to correlate the distribution of damage with the location of the activated fault and measured ground displacements.”
• November 1, 2019: The Copernicus Sentinel-1 mission takes us over cracks in the Brunt ice shelf, which lies in the Weddell Sea sector of Antarctica. 4)
- First spotted on 31 October 2016, the Halloween crack runs from an area known as McDonald Ice Rumples – which is where the underside of the floating ice sheet is grounded on the shallow seabed. This pinning point slows the flow of ice and crumples the ice surface into waves.
- Chasm 1 on the other hand has been in place for over 25 years. It was previously stable for many years, but in 2012, it was noticed that the dormant crack started extending northwards.
- Now, Chasm 1 and Halloween crack are only separated by a few kilometers. When they meet, an iceberg about the size of Greater London will break off. The two lengthening fractures have been set to intersect for years – it’s only a matter of time for the two to meet.
- The Brunt shelf has been monitored by glaciologists for decades and is constantly changing. Early maps from the 1970s indicate that the ice shelf used to be a mass of small icebergs welded together by sea ice.
- Calving is a natural process of the life cycle of ice shelves. Although the iceberg is of a considerable size, it will not be the largest of icebergs to calve in Antarctica. In 2017, a chunk of Larsen C broke off spawning one of the largest icebergs on record and changing the outline of the Antarctic Peninsula.
- Ice shelf movement is very unpredictable. Routine monitoring from satellites offer unprecedented views of events happening in remote regions, and show how ice shelves are responding to changes in ice dynamics, air and ocean temperatures.
- As an advanced radar mission, Copernicus Sentinel-1 can image the surface of Earth through cloud and rain and regardless of whether it is day or night. This makes it an ideal mission for monitoring the polar regions, which are in darkness during the winter months and for monitoring tropical forests, which are typically shrouded by cloud.
• October 29, 2019: Hagibis was the biggest typhoon to hit Japan in decades. With extreme events like this, likely to increase in number and in severity as a consequence of climate change, satellites are playing an increasingly important role in understanding and tracking huge storms. 5)
- Different satellites carry different instruments that can provide a wealth of complementary information to understand and to respond to a single event.
- After making landfall on 12 October 2019 on Shizuoka Prefecture’s Izu Peninsula, Hagibis brought record-breaking rainfall, triggered mudslides and caused severe flooding.
- While the storm was still over the ocean, both Copernicus Sentinel-1 and ESA’s SMOS missions were used to track what was going on within and beneath the storm at the sea surface, and Copernicus Sentinel-3 imaged from above.
- The Copernicus Sentinel-1 mission carries an advanced radar instrument to provide an all-weather, day-and-night supply of imagery of Earth’s surface. Its ability to ‘see’ through cloud and rain and in pitch darkness makes it particularly useful to measure the ocean surface wind speed of tropical cyclones.
- As the radar signal penetrates the clouds, the pattern created by the cyclone on the sea surface – known as the ‘roughness’ – can be characterized. This allows the ocean surface wind speed to be calculated. This is possible thanks to the Sentinel-1 image dual polarization combination.
- The high resolution of Sentinel-1 provides an unprecedented detailed insight of the cyclone inner core structure, in particular the eye’s diameter, the radius of maximum winds and the maximum wind speed.
- In the case of Typhoon Hagibis, on 8 October the Sentinel-1 satellite measured the eye’s diameter at the sea surface as 20 km, the radius of maximum wind speed was 25 km and the maximum wind speed was greater than 60 m/s.
- These data are valuable for the Satellite Hurricane Observation Campaign (SHOC), which collect satellite observations to provide a synoptic view of hurricane development and evolution. SHOC involves CLS (Collecte Localisation Satellites), IFREMER (French Research Institute for Exploitation of the Sea) and Météo-France.
- Alexis Mouche from IFREMER states, “The synthetic aperture radar is the only sensor that can characterize extreme winds, greater than 70 m/s, at a high resolution. These measurements complement existing data, helping scientists to better understand the physical mechanisms of these phenomena.
- "This could also lead to a more accurate analysis of tropical cyclones, particularly their ocean surface wind direction and intensity, and can therefore open possibilities in improving hurricane forecasting."
- As well as this, images from before and after a flood offer information on the extent of inundation and can be used to help authorities to assess damage to infrastructure and environment. The Copernicus Sentinel-1 image shows the extent of flooding in red near the cities of Sendai and Ishinomaki on 12 October.
SMOS (Soil Moisture and Ocean Salinity)
- Although originally intended to measure soil moisture and ocean salinity, ESA’s SMOS mission can estimate the wind speed at the sea surface under tropical cyclones.
- The satellite carries a novel microwave sensor to capture images of ‘brightness temperature’. These images correspond to radiation emitted from Earth’s surface, which are usually used to collect information on soil moisture and ocean salinity.
- Strong winds over oceans whip up waves, which in turn affect the microwave radiation from the surface. This means that although strong storms make it difficult to measure salinity, the changes in radiation can be linked to the strength of the wind over the sea.
- While Sentinel-1 provides high resolution information over limited areas, SMOS offers the advantage of a very wide swath providing regular coverage of the entire ocean. These different data complement each other.
- John Knaff, from the NOAA Center for Satellite Applications and Research, says, “Wind field estimates of tropical storms, such as Typhoon Hagibis, are extremely difficult to produce. Over the last few years, satellite observations have become extremely valuable as they are able to estimate surface winds of cyclones.”
- “As track and intensity forecasting errors have become fewer, accurate estimates of the extent and structure of tropical wind field is becoming a higher priority in the tropical cyclone forecasting process. These new capabilities such as wind speed estimates from satellite data are becoming more available to operations, and allow for finer-scale temporal and spatial estimates of tropical cyclone surface wind structures.”
- Nicolas Reul, a scientist at IFREMER says, "The complementing measurements we get from Sentinel-1 and SMOS provide an unprecedented source of information about the surface wind speed structure from the eyewall to the outer core of the high wind region of tropical cyclones. This will help us to better understand the physical mechanisms of these phenomena, and already improves hurricane forecast and warning systems."
• October 17, 2019: A large iceberg, approximately 260 km2, recently calved from the Getz Ice Shelf in West Antarctica. Using images from the Copernicus Sentinel-1 mission from 2 September to 14 October 2019, this animation shows the berg breaking off before spinning around in the Amundsen Sea. 6)
- The Copernicus Sentinel-1 mission carries radar, which can return images regardless of day or night and this allows us year-round viewing, which is especially important through the long, dark, austral winter months.
• October 1, 2019: A huge iceberg has broken off the Amery Ice Shelf in Antarctica. Dubbed D28, the iceberg is around 1600 km2 – about the size of Greater London. Approximately 30 km wide and 60 km long, it is estimated to weigh over 300 billion tons. 7)
- Scientists say that this is the biggest calving of the Amery Ice Shelf in 50 years. Satellites will continue to monitor and track the iceberg, as it poses a threat for ships in the vicinity.
• September 13, 2019: This Copernicus Sentinel-1 image takes us just south of the US border, to the region of Baja California in northwest Mexico. Its capital city, Mexicali, is visible top left of the image (Figure 12). 8)
- The Colorado River, which forms the border between Baja California and Sonora, can be seen cutting through the rich and colorful patchwork of agricultural land at the top right of the image, before it fans out and splits into multiple streams. Flowing for over 2300 km, the Colorado River rises in the central Rocky Mountains in Colorado, flows through the Grand Canyon before crossing the Mexican border and emptying into the Gulf of California, also known as the Sea of Cortez.
- The Colorado River delta once covered a large area of land and, owing to its nutrients carried downstream, supported a large population of plant and bird life. However today, water that flows is trapped by dams and is used for residential use, electricity generation as well as crop irrigation for the nearby Imperial Valley and the Mexicali Valley. The reduction in flow by dams and diversions traps the majority of the river’s sediments before they reach the Gulf of California, impacting water quality.
• September 10, 2019: Reliable maps of sea-ice conditions and forecasts are of vital importance for maritime safety, safe navigation and planning. The continued retreating and thinning of Arctic sea ice calls for a more effective way of producing detailed and timely ice information – which is where artificial intelligence comes in. 9)
- Manual ice-charting from multi-sensor satellite data has been used for years, but it is time-consuming because of the vast area of the Arctic Ocean. In order to provide relevant ice data, there is a need for automated ice observations from satellite data, to integrate into ice forecast models.
- In response to this, the DMI (Danish Meteorological Institute) and DTU (Technical University of Denmark) have initiated the project ASIP (Automated Sea Ice Products) – funded by the Innovation Fund Denmark. The project aims to develop an automatic sea-ice service that can provide more timely and detailed sea-ice information to improve efficiency and safety of marine operations in the Arctic.
- ASIP merges Copernicus Sentinel-1 imagery with other satellite sensor data, such as passive microwave data from the AMSR-2 (Advanced Microwave Scanning Radiometer-2) on JAXA's ALOS-2 satellite mission, to resolve ambiguities that can occur in SAR imagery, such as during windy sea conditions. ASIP uses a convolutional neural network system that is trained with vast datasets of ice charts, to generate ice maps automatically.
- “ASIP will be a great opportunity for users to have an up-to-date map of sea-ice products. We are currently working hard to get this in production and validate it with both the ice experts and the users,” says David Malmgren-Hansen from DTU Compute.
- ASIP will be made freely available through the DMI Ice Service, for maximum value for both public and commercial users.
- David Malmgren-Hansen presented his project at this year’s φ-week event at ESA/ESRIN in Frascati, Italy, which focuses on Earth observation and FutureEO. The week includes a variety of inspiring talks, workshops on how Earth observation can benefit from the latest digital technologies and help shape future missions.
• July 12, 2019: A week after two strong earthquakes struck near the city of Ridgecrest in Southern California, NASA scientists and engineers continue to analyze satellite data for information on fault slips and ruptures. Their observations are helping local authorities assess damage and will also provide useful information to engineers for designing resilient structures that can withstand ruptures like the ones created by the latest quakes. 10)
- The ARIA (Advanced Rapid Imaging and Analysis) team at NASA's Jet Propulsion Laboratory in Pasadena, California, created this map depicting areas that are likely damaged as a result of the recent major earthquakes. The color variation from yellow to red indicates increasingly more significant surface change, or damage. The map covers an area of 155 by 186 miles (250 x 300 km), shown by the large red polygon. Each pixel measures about 30 m across.
- To make the map, the team used SAR (Synthetic Aperture Radar) images from the European Space Agency's Copernicus Sentinel-1 satellites from before and after the sequence of quakes - July 4 and July 10, 2019, respectively. The map may be less reliable over vegetated areas but can provide useful guidance in identifying damaged areas.
- NASA's Disasters Program is in communication with the California Earthquake Clearinghouse, which is coordinating response efforts with the California Air National Guard, the U.S. Geological Service and the Federal Emergency Management Agency. NASA analysts are using data from satellites to produce visualizations of land deformation and potential landslides, among other earthquake impacts, and are making them available to response agencies. NASA's Disasters Program promotes the use of satellite observations in predicting, preparing for, responding to and recovering from disasters around the world. - The ARIA Team's analysis was funded by NASA.
• July 12, 2019: ESA and the Asian Development Bank have joined forces to help the Indonesian government use satellite information to guide the redevelopment following the earthquake and tsunami that devastated the provincial capital of Palu and surroundings last year. 11)
- On 28 September 2018, the Indonesian island of Sulawesi was struck by a 7.5 magnitude earthquake. The epicenter was on the island’s northwest coast – 77 km north of Palu, which lies at the head of a long narrow bay. The quake triggered a tsunami that swept huge surges of water – as high as 10 m – along the bay and swamped the city.
- The combination of the earthquake, tsunami, soil liquefaction and landslides claimed well over 2000 lives, destroyed homes, buildings, infrastructure and farmland in several districts.
- With the authorities and relief organizations having spent the last nine months dealing with the aftermath, the shift is now into the recovery phase. This includes the daunting job of rebuilding the areas that were decimated by the disaster – and the Asian Development Bank and ESA have joined forces to help the Indonesian government with the task in hand.
- Through ESA’s program to support sustainable development, the aim here is to provide environmental information products derived from Earth observation data and training in their use to Indonesia through the Asian Development Bank.
- The project, ‘Earth Observation for Sustainable Development – Disaster Risk Reduction’, is led by the Spanish company Indra with the Italian SME Planetek as a partner along with the French Geological Survey BRGM who is the scientific advisor of ESA’s Geohazard Exploitation Platform, an initiative that provides a cloud-processing service to support geological hazard mapping.
- The main purpose of sharing these information products is to help the authorities better understand the hazards associated with seismic activity, flooding and landslides so they can make more informed decisions in elaborating a redevelopment master plan.
- Data from the Copernicus Sentinel-1 radar mission can detect ground movement of millimeters in and across wide areas and, therefore, provides a detailed picture of land deformation.
- Ground-motion maps of before and after the earthquake have been produced through Planetek’s automatic cloud-based ‘Rheticus Displacement’ monitoring service. Accurate to a few millimeters, these maps are based on Copernicus Sentinel-1 radar data and are helping the authorities evaluate the effect that the disaster has had on the land surface stability.
- In addition to these information products, the project also included a week-long course in Jakarta organized by the Asian Development Bank and the Indonesian National Institute of Aeronautics and Space. Attended by more than 60 representatives from numerous Indonesian institutions, experts from Indra, Planetek and BRGM explained technical details, methodologies and usage of these satellite data products.
- Paolo Manunta, who helps ESA with on-site support to the Asian Development Bank, noted, “Users explained that they are particularly interested in the ground deformation maps – they offer great insight into how the land surface has changed and are essential for Indonesia to redevelop effectively.”
- The team has also suggested that the Indonesian government additionally use ESA’s online Geohazard Exploitation Platform, which is designed to support the users looking at seismic risks, volcanoes, subsidence and landslides. It allows the seamless browsing, access and processing of vast amounts of satellite data, plus the software tools to extract useful knowledge.
- The workshop included discussions on how space technology can support hazard and risk mapping in Indonesia and the user feedback obtained will serve as input for discussions between ESA, the Japanese Space Agency and the Asian Development Bank on how to further improve Earth observation for international development.
• June 21, 2019: The Copernicus Sentinel-1 mission takes us over the Lena River Delta, the largest delta in the Arctic. At nearly 4500 km long, the Lena River is one of the longest rivers in the world. The river stems from a small mountain lake in southern Russia, and flows northwards before emptying into the Arctic Ocean, via the Laptev Sea. 12)
- The river is visible in bright yellow, as it splits and divides into many different channels before meandering towards the sea. Sediments carried by the waters flow through a flat plain, creating the Lena River Delta. Hundreds of small lakes and ponds are visible dotted around the tundra.
- The delta’s snow-covered tundra is frozen for most of the year, before thawing and blossoming into a fertile wetland during the brief polar summer – a 32,000 km2 haven for Arctic wildlife. Swans, geese and ducks are some of the migratory birds that breed in the productive wetland, which also supports fish and marine mammals.
- In 1995, the Lena Delta Reserve was expanded, making it the largest protected area in Russia.
• April 12, 2019: The Copernicus Sentinel-1 mission takes us over the busy maritime traffic passing through the English Channel. 13)
- Many vessels crossing at the narrowest part of the English Channel can be seen in the far right of the image. Connecting Dover in England to Calais in northern France, the Strait of Dover is another major route, with over 400 vessels crossing every day. The shortest distance across the Channel is just 33 km, making it possible to see the opposite coastline on a clear day.
- The cities of London and Paris, other towns and buildings and even wind turbines in the English Channel are visible in white owing to the strong reflection of the radar signal.
• March 29, 2019: Separating the Black Sea and the Sea of Marmara, the strait is one of the busiest maritime passages in the world, with around 48,000 ships passing through every year. Daily traffic includes international commercial shipping vessels and oil tankers, as well as local fishing and ferries. Ships in the strait can be seen in the image as multi-colored dots. Three bridges are also visible spanning the strait and connecting the two continents. 14)
- The two identical Copernicus Sentinel-1 satellites carry radar instruments, which can see through clouds and rain, and in the dark, to image Earth’s surface below. The multi-temporal remote sensing technique combines two or more radar images over the same area to detect changes occurring between acquisitions.
- In the far-left of the image of Figure 22, the aqua-green patches of land show the changes in the fields between the three satellite acquisitions.
- Turkey’s most populous city, Istanbul (population of around 15 million residents in its metropolitan area) , can be seen on both sides of the Bosphorus (mostly spelled as Bosporus). The city appears in shades of white owing to the stronger reflection of the radar signal from buildings, which contrasts with the dark black color of the inland lakes and surrounding waters.
• March 27, 2019: It is thought that well over a million people have been affected by what is probably the worst storm on record to hit the southern hemisphere. Making landfall on 15 March 2019, Cyclone Idai ripped through Mozambique, Malawi and Zimbabwe, razing buildings to the ground, destroying roads and inundating entire towns, villages and swathes of farmland. The human death toll is still unknown. While humanitarian efforts continue, people are now also facing the mammoth task of picking up the pieces and cleaning up after this devastating storm. 15)
- Images from Copernicus Sentinel-1 contributed to activations triggered in the Copernicus Emergency Management Service and the International Charter Space and Major Disasters. Both services take advantage of observations from several satellites and provide on-demand mapping to help civil protection authorities and the international humanitarian community in the face of major emergencies.
• March 20, 2019: Copernicus Sentinel-1 acquired this radar image of the oil slick, the large, dark patch visible in the center of the image, stretching about 50 km. Marine vessels are identifiable as smaller white points, which could be those assisting in the clean-up process. 16)
- Oil is still emerging from the ship now lying at a depth of around 4500 meters. French authorities trying to reduce the impact of pollution along the coast.
- Satellite radar is particularly useful for monitoring the progression of oil spills because the presence of oil on the sea surface dampens down wave motion. Since radar basically measures surface texture, oil slicks show up well – as black smears on a grey background.
• March 20, 2019: As millions of people in Mozambique, Malawi and Zimbabwe struggle to cope with the aftermath of what could be the southern hemisphere’s worst storm, Copernicus Sentinel-1 is one of the satellite missions being used to map flooded areas to help relief efforts. 17)
- Cyclone Idai swept through this part of southeast Africa over the last few days, leaving devastation in its wake. Thousands of people have died and houses, roads and croplands are under water.
- It is currently thought that well over two million people in the three countries have been affected, but the extent of destruction is still unfolding.
- It is currently thought that well over two million people in the three countries have been affected, but the extent of destruction is still unfolding.
- In order to plan and execute this kind of emergency response it is vital to understand exactly which areas have been affected – especially as accessing people cut off is extremely challenging.
- Satellites orbiting Earth can provide indispensable up-to-date information to observe such events, as shown here on the right from the Copernicus Sentinel-3 mission, and, importantly, to map flooded areas for response teams facing these dire situations.
- The disaster triggered activations in both the Copernicus Emergency Mapping Service and the International Charter Space and Major Disasters.
- Both services take advantage of observations from several satellites and provide on-demand mapping to help civil protection authorities and the international humanitarian community in the face of major emergencies.
- The image of Figure 25 is from Copernicus Sentinel-1 and shows the extent of flooding, depicted in red, around the port town of Beira in Mozambique on 19 March. The image of Figure 27 uses the mission to map the flood for relief response through the Copernicus Emergency Mapping Service.
- Sentinel-1’s radar ability to ‘see’ through clouds and rain, and in darkness, makes it particularly useful for monitoring floods.
- Images acquired before and after flooding offer immediate information on the extent of inundation and support assessments of property and environmental damage.
• March 14, 2019: The Bering Strait is a sea passage that separates Russia and Alaska. It is usually covered with sea ice at this time of year – but as this image captured by the Copernicus Sentinel-1 mission on 7 March 2019 shows, it is virtually ice-free. 18)
- The extent of sea ice in the Bering Sea has dropped lower than it has been since written records began in 1850, and is most likely because of warm air and water temperatures. On average, the fluctuating sea ice in this region increases until early April, depending on wind and wave movement.
- To travel between Arctic and Pacific, marine traffic passes through the Bering Strait. Owing to the reduction of ice in the region, traffic has increased significantly.
- The Copernicus Sentinel-1 satellites provide images to generate maps of sea-ice conditions for safe passage in the busy Arctic waters, as well as distinguish between thinner, more navigable first-year ice and thicker, more hazardous ice. Each satellite carries an advanced radar instrument to image Earth’s surface through cloud and rain, regardless of whether it is day or night.
• March 14, 2019: The Copernicus Sentinel-1 radar mission shows how cracks cutting across Antarctica’s Brunt ice shelf are on course to truncate the shelf and release an iceberg about the size of Greater London – it’s just a matter of time. 19)
- The Brunt ice shelf is an area of floating ice bordering the Coats Land coast in the Weddell Sea sector of Antarctica.
- The Brunt ice shelf is at its maximum extent during the satellite era and compared to images collected by Argon declassified intelligence satellite photographs in 1963 and maps made by Frank Worsley during the Endurance expedition into the Weddell Sea in 1915.
- History shows that the last event was in 1971 when a portion of ice calved north of the Ice Rumples and in what appears to have been a previous iteration of today’s Halloween Crack which is separating along lines of weakness.
- Mark Drinkwater, Head of ESA’s Earth and Mission Science Division, says, “Importantly, tracking the entire ice shelf movement reveals a lot going on north of the Halloween Crack, where the shelf flows in a more northerly direction. Meanwhile, this divergence is splitting the northern and southern parts of the shelf along the Halloween Crack. Interestingly, the animation also reveals a widening split right across the Ice Rumples, which may also put the structural integrity of this northern outer segment into question. We have been observing the Brunt ice shelf for decades and it is constantly changing. Early maps made in the 1970s indicate that the ice shelf was more like a mass of small icebergs welded together by sea ice.”
Legend to Figure 31: This Copernicus Sentinel-2 image from 7 February 2019 shows two lengthening fractures: a large chasm running northwards and a split, dubbed Halloween Crack, that has been extending eastwards since October 2016. They are now only separated by a few kilometers. The Halloween Crack runs from an area known as McDonald Ice Rumples, which is where the underside of the otherwise floating ice sheet is grounded on the shallow seabed. This pinning point slows the flow of ice and crumples the ice surface into waves. Routine monitoring by satellites with different observing capabilities offer unprecedented views of events happening in remote regions like Antarctica, and how ice shelves manage to retain their structural integrity in response to changes in ice dynamics, air and ocean temperatures.
- As the ice flows down the steep coastal area and across the grounding line into the floating ice shelf, it fractures into a series of regular blocks. The structural integrity of the shelf relies on the fractures being filled over decades by marine ice and snow. Since Copernicus Sentinel-1 radar penetrates through the surface snow, this pattern of fractures is revealed to give Brunt its skeletal-like appearance.
- When the chasm and cracks around McDonald ice rumples finally intersect, it is likely that the northern end of the calved iceberg remains pinned by its grounding point, leaving the southern end of the berg to swing out into the ocean.
- Although it may be the biggest berg observed to break off Brunt, compared to the recent Larsen ice shelf iceberg A68, for example, it won’t be a particularly large one. However, the concern is that this calving could allow the ice left behind to flow more freely towards the ocean.
- “We are now poised for this eventual calving, which could have consequences for the ice shelf as a whole. After the 1971 calving, ice shelf velocities are reported to have doubled from 1 to 2 m/day. So we will be carefully monitoring the ice shelf with the combination of both Copernicus Sentinel-1 and Copernicus Sentinel-2, which carries an optical instrument, to see how the dynamics influence the integrity of the remaining ice sheet,” continues Dr Drinkwater.
- With the ice shelf currently deemed unsafe, the British Antarctic Survey (BAS) has closed up their Halley VI research station, which was repositioned south of Halloween Crack and east of the chasm in 2017.
- The station used to be operational all year round, but this is the third winter running that it has had to close because of potential danger.
- There has been a permanent research station on Brunt since the late 1950s, but in 2016–17 the base was dragged 23 km to its current, more secure location. If it had not been moved, it would now be on the seaward side of the chasm.
- Routine monitoring by satellites with different observing capabilities offer unprecedented views of events happening in remote regions like Antarctica, and how ice shelves manage to retain their structural integrity in response to changes in ice dynamics, air and ocean temperatures.
- The Copernicus Sentinel-1 mission carries radar, which can return images regardless of day or night and this allows us year-round viewing, which is especially important through the long, dark, austral winter months. A recent image from the Copernicus Sentinel-2 mission provides complementary information.
• February 22, 2019: When Mount Agung, a volcano on the island of Bali in Indonesia erupted in November 2017, the search was on to find out why it had stirred. Thanks to information on ground deformation from the Copernicus Sentinel-1 mission, scientists now have more insight into the volcano’s hidden secrets that caused it to reawaken. 20)
- After lying dormant for more than 50 years, Mount Agung on the Indonesian holiday island of Bali rumbled back to life in November 2017, with smoke and ash causing airport closures and stranding thousands of visitors.
- Fortunately, it was preceded by a wave of small earthquakes, signalling the imminent eruption and giving the authorities time to evacuate around 100,000 people to safety.
- The prior event in 1963, however, claimed almost 2000 lives and was one of the deadliest volcanic eruptions of the 20th century. Knowing Agung’s potential for devastation, scientists have gone to great lengths to understand this volcano’s reawakening.
- And, Agung has remained active, slowly erupting on and off since 2017.
- Bali is home to two active stratovolcanoes, Agung and Batur, but relatively little is known of their underlying magma plumbing systems. A clue came from the fact that Agung’s 1963 eruption was followed by a small eruption at its neighboring volcano, Batur, 16 km away.
- A paper published recently in Nature Communications describes how a team of scientists, led by the University of Bristol in the UK, used radar data from the Copernicus Sentinel-1 mission to monitor the ground deformation around Agung. 21)
- Their findings may have important implications for forecasting future eruptions in the area, and indeed further afield.
- They used the remote sensing technique of InSAR (Interferometric Synthetic Aperture Radar), where two or more radar images over the same area are combined to detect slight surface changes.
- Tiny changes on the ground cause differences in the radar signal and lead to rainbow-colored interference patterns in the combined image, known as a SAR interferogram. These interferograms can show how land is uplifting or subsiding.
- Juliet Biggs from Bristol University’s School of Earth Sciences, said, “Using radar data from the Copernicus Sentinel-1 radar mission and the technique of InSAR, we are able to map any ground motion, which may indicate that fresh magma is moving beneath the volcano.”
- In the study, which was carried out in collaboration with the Center for Volcanology and Geological Hazard Mitigation in Indonesia, the team detected uplift of about 8–10 cm on Agung’s northern flank during the period of intense earthquake activity prior to the eruption.
- Fabien Albino, also from Bristol's School of Earth Sciences and who led the research, added, “Surprisingly, we noticed that both the earthquake activity and the ground deformation signal were five kilometers away from the summit, which means that magma must be moving sideways as well as vertically upwards. - Our study provides the first geophysical evidence that Agung and Batur volcanoes may have a connected plumbing system. This has important implications for eruption forecasting and could explain the occurrence of simultaneous eruptions such as in 1963.”
- Part of European Union’s fleet of Copernicus missions, Sentinel-1 is a two-satellite constellation that can provide interferometric information every six days – important for monitoring rapid change. Each satellite carries an advanced radar instrument that can image Earth’s surface through cloud and rain and regardless of whether it is day or night.
- ESA’s Copernicus Sentinel-1 mission manager, Pierre Potin, noted, “We see the mission is being used for a multitude of practical applications, from mapping floods to charting changes in ice. Understanding processes that are going on below the ground’s surface – as demonstrated by this new research – is clearly important, especially when these natural processes can put people’s lives and property at risk.”
- While the European Union is at the helm of Copernicus, ESA develops, builds and launches the dedicated Sentinel satellites. It also operates some of the missions and ensures the availability of data from third party missions contributing to the Copernicus program.
• February 1, 2019: This week's edition of the Earth from Space program features a Copernicus Sentinel-1 image over one of the areas in Iraq that suffered flooding recently. 22)
- The town of Kut is in the lower-center of the image. It lies within a sharp ‘U-bend’ of the Tigris River, which can be seen meandering across the full width of the image. The image has been processed to show floods in red, and it is clear to see that much of the area was affected including agricultural fields around the town. Dark patches in the image, including the large patch in the center , however, indicate that there was no or little change between the satellite acquisitions.
- After the searing dry heat of summer, November typically signals the start of Iraq’s ‘rainy season’ –but November 2018 brought heavier rainstorms than usual. Many parts of the country were flooded as a result. Thousands of people had to be evacuated, and infrastructure, agricultural fields and other livelihoods were destroyed, and tragically the floods also claimed lives. Declared an emergency, the International Charter Space and Major Disasters was activated. The Charter takes advantage of observations from a multitude of satellites to aid emergency relief. Images from Copernicus Sentinel-1 contributed to this particular effort.
- The two identical Copernicus Sentinel-1 satellites carry radar instruments, which can see through clouds and rain, and in the dark, to image Earth’s surface below. This capability is particularly useful for monitoring and mapping floods, as the image shows. Satellite images play an increasingly important role in responding to disaster situations, especially when lives are at risk. Also, after an event, when damage assessments are needed and plans are being made to rebuild, images from satellites are a valuable resource.
• January 10, 2019: Images acquired every six days by the European Union’s Copernicus Sentinel-1 satellites are being used to map ground movement across two billion measurement sites in Norway, revealing shifts as small as one millimeter a year. 23)
- Thanks to this information, the Geological Survey of Norway, the Norwegian Water Resources and Energy Directorate, and the Norwegian Space Center have recently launched the Norwegian Ground Motion Service – InSAR Norway.
- This new service will provide the basis for strategic governmental use of interferometry in Norway. Interferometry is a technique involving multiple repeat satellite radar images over the same scene that are combined to identify slight alterations between acquisitions, thus 'spotting the difference’.
- The service will map ground deformation caused by, for example, subsidence. It will also assess the risk of landslides and monitor changes in infrastructure in urban areas. Furthermore, the service will lead to downstream commercial and public use – for instance in sectors such as big data analysis, insurance, real estate, structural engineering and transport infrastructure.
- The service will also benefit road and rail authorities, municipalities and city planners, as well as citizens.
- InSAR Norway aims to find all unstable rock slopes in Norway that could collapse catastrophically, and understand the geologic conditions of each unstable slope and rank them based upon their hazard and risk, and establishing a 24/7 early-warning system where necessary.
- John Dehls, from the Geological Survey of Norway, stated, “Setting-up such an operational ground motion service has had significant technical challenges. However, we are already seeing the first benefits. New critical areas prone to large landslides were discovered within days of the first dataset being produced. These will be followed up with fieldwork next summer. - We consider that the information provided by the InSAR Norway service will be of interest not only for public and commercial entities, but also for citizens. We have decided to provide the related data at full resolution, freely and openly to everyone. Furthermore, InSAR Norway data will be maintained and updated at regular intervals, thus creating predictability for long-term operational users”.
Legend to Figure 37: On 29 November 2018, NGU, NVE and the NSC (Norwegian Space Center) launched the operational Norwegian Ground Motion Service with InSAR subsidence data at full resolution, free and open to everyone on the InSAR Norway portal. More than 25,000 users accessed the service in the first week of operation.
- The Norwegian research institute, Norut, and the Dutch company PPO.Labs, have been the research and development partners for InSAR Norway, through the KSAT-GMS partnership with the Norwegian Kongsberg Satellite Services (KSAT). The official unveiling was the result of several years of intensive research and development activities, from the design phase of innovative algorithms to implementation and operationalization of the service.
- The main goal of this free service is to produce operational Interferometric Synthetic Aperture Radar (InSAR) ground deformation measurements over Norway and improve accessibility of InSAR results for public and commercial users.
- InSAR Norway will provide the basis for strategic governmental use of interferometry in Norway, by mapping ground deformation such as subsidence, assessing rock-slide risks and by monitoring infrastructure in cities. Furthermore, the service will be a tool for creating downstream commercial and public use, for instance in geotechnical, climate, big data analysis, insurance, real estate, structural engineering and transport infrastructure applications. The service will also benefit users such as road authorities, railroad authorities, municipalities and city planners, as well as citizens.
Beyond Norway: towards a European ground motion service (Ref. 24)
- "We are very proud of the state-of-the-art tools and methods our team from NGU, NSC, NVE, Norut, PPO.Labs and KSAT-GMS have been able to develop for the InSAR Norway operational ground motion service. Personally, I think this is a breakthrough for applied operational nation-wide large-scale use of InSAR."
- A European–wide Copernicus ground motion service based on Sentinel-1 data is under planning by the European Commission in partnership with the European Environment Agency and the states participating in the Copernicus Earth Observation program.
- "This is a very important and valuable development also for Europe, which we look forward to supporting, as well as collaborating with the European Commission and nations in Europe to make it happen successfully", concluded Dag Anders Moldestad and John Dehls.
1) ”Mato Grosso, Brazil,” ESA Applications, 5 December 2019, URL: http://www.esa.int/ESA_Multimedia/Images/2019/12/Mato_Grosso_Brazil
2) ”Floods in northern Italy,” ESA Applications, 26 November 2019, URL: http://www.esa.int/ESA_Multimedia/Images/2019/11/Floods_in_northern_Italy
3) ”French earthquake fault mapped,” ESA / Applications / Observing the Earth / Copernicus / Sentinel-1, 17 November 2019, URL: http://www.esa.int/Applications
4) ”Halloween crack,” ESA, 01 November 2019, URL: http://www.esa.int/ESA_Multimedia/Images/2019/11/Halloween_crack
5) ”Tracking Typhoon Hagibis from space,” ESA / Applications / Observing the Earth, 29 October 2019, URL: http://www.esa.int/Applications/Observing_the_Earth/Tracking_Typhoon_Hagibis_from_space
6) ”B47 breaks off Getz Ice Shelf,” ESA, 17 October 2019, URL: http://www.esa.int/spaceinimages/Images/2019/10/B47_breaks_off_Getz_Ice_Shelf
7) ”Amery Iceberg,” ESA, 1 October 2019, URL: http://www.esa.int/spaceinimages/Images/2019/10/Amery_Iceberg
8) ”Earth from Space: Baja California,” ESA, 13 September 2019, URL: https://www.esa.int/spaceinimages/Images/2019/09/Baja_California_Mexico
9) ”Using artificial intelligence to automate sea-ice charting,” ESA, Observing the Earth, 10 September 2019, URL: http://www.esa.int/Our_Activities/Observing_the_Earth
10) Esprit Smith, ”NASA's ARIA Team Maps California Quake Damage,” NASA/JPL News, 12 July 2019, URL: https://www.jpl.nasa.gov/news/news.php?release=2019-143
11) ”Using satellite information to help rebuild after a disaster,” ESA, 12 July 2019, URL: http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/Using_satellite_information_to_help_rebuild_after_a_disaster
12) ”Lena River Delta,” ESA, Earth observation image of the week, 21 June 2919, URL: http://www.esa.int/spaceinimages/Images/2019/06/Lena_River_Delta
13) ”English Channel,” ESA Earth observation image of the week, 12 April 2019, URL: http://m.esa.int/spaceinimages/Images/2019/04/English_Channel
14) ”The Bosphorus Strait, Turkey,” ESA, Earth observation image of the week, 29 March 2019, URL: http://m.esa.int/spaceinimages/Images/2019/03/The_Bosphorus_Strait_Turkey
15) ”Receding waters,” ESA, 27 March 2019, URL: https://www.esa.int/spaceinimages/Images/2019/03/Receding_waters
16) ”Grande America oil spill imaged,” ESA, 20 March 2019, URL: http://m.esa.int/spaceinimages/Images/2019/03/Grande_America_oil_spill_imaged
17) ”Copernicus Sentinel-1 maps floods in wake of Idai,” ESA, 20 March 2019, URL: http://m.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/Copernicus_Sentinel-1_maps_floods_in_wake_of_Idai
18) ”Bering in dire straits,” ESA, 14 March 2019, URL: http://m.esa.int/spaceinimages/Images/2019/03/Bering_in_dire_straits
19) ”Sentinels monitor converging ice cracks,” ESA, 14 March 2019, URL: http://m.esa.int/Our_Activities/Observing_the_Earth
20) ”Copernicus Sentinel-1 reveals shared plumbing led to Agung awakening,” ESA, 22 February 2019, URL: http://m.esa.int/Our_Activities/Observing_the_Earth
21) Fabien Albino, Juliet Biggs & Devy Kamil Syahbana, ”Dyke intrusion between neighboring arc volcanoes responsible for 2017 pre-eruptive seismic swarm at Agung,” Nature Communication, Volume 10, Article number: 748, Published: 14 February 2019, https://doi.org/10.1038/s41467-019-08564-9, URL: https://www.nature.com/articles/s41467-019-08564-9.pdf
22) ”Iraq flood,” ESA, Earth observation image of the week, 1 February 2019, URL: http://m.esa.int/spaceinimages/Images/2019/02/Iraq_flood
23) ”Copernicus Sentinel-1 maps Norway in motion,” ESA, 10 January 2019, URL: http://m.esa.int/Our_Activities/Observing_the_Earth
24) ”Copernicus Sentinel-1 data fuel Norwegian ground motion service,” ESA, 10 January 2019, URL: https://sentinels.copernicus.eu/web/sentinel/news
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).References Back to top