Silver Anniversary for Ocean Altimetry Space Mission

Artist rendering of Jason-3 satellite over the Amazon.
Image Courtesy NASA/JPL-Caltech.

August 10th 1992 marked the launch of the TOPEX/Poseidon satellite, the first major oceanographic focussed mission. Twenty five years, and three successor satellites, later the dataset begun by TOPEX/Poseidon is going strong providing sea surface height measurements.

TOPEX/Poseidon was a joint mission between NASA and France’s CNES space agency, with the aim of mapping ocean surface topography to improve our understanding of ocean currents and global climate forecasting. It measured ninety five percent of the world’s ice free oceans within each ten day revisit cycle. The satellite carried two instruments: a single-frequency Ku-band solid-state altimeter and a dual-frequency C- and Ku-band altimeter sending out pulses at 13.6 GHz and 5.3 GHz respectively. The two bands were selected due to atmospheric sensitivity, as the difference between them provides estimates of the ionospheric delay caused by the charged particles in the upper atmosphere that can delay the returned signal. The altimeter sends radio pulses towards the earth and measures the characteristics of the returned echo.

When TOPEX/Poseidon altimetry data is combined with other information from the satellite, it was able to calculate sea surface heights to an accuracy of 4.2 cm. In addition, the strength and shape of the return signal also allow the determination of wave height and wind speed. Despite TOPEX/Poseidon being planned as a three year mission, it was actually active for thirteen years, until January 2006.

The value in the sea level height measurements resulted in a succeeding mission, Jason-1, launched on December 7th 2001. It was put into a co-ordinated orbit with TOPEX/Poseidon and they both took measurements for three years, which allowed both increased data frequency and the opportunity for cross calibration of the instruments. Jason-1 carried a CNES Poseidon-2 Altimeter using the same C- and Ku-bands, and following the same methodology it had the ability to measure sea-surface height to an improved accuracy of 3.3 cm. It made observations for 12 years, and was also overlapped by its successor Jason-2.

Jason-2 was launched on the 20 June 2008. This satellite carried a CNES Poseidon-3 Altimeter with C- and Ku-bands with the intention of measuring sea height to within 2.5cm. With Jason-2, National Oceanic and Atmospheric Administration (NOAA) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) took over the management of the data. The satellite is still active, however due to suspected radiation damage its orbit was lowered by 27 km, enabling it to produce an improved, high-resolution estimate of Earth’s average sea surface height, which in turn will help improve the quality of maps of the ocean floor.

Following the established pattern, Jason-3 was launched on the 17th January 2016. It’s carrying a Poseidon-3B radar altimeter, again using the same C and Ku bands and on a ten day revisit cycle.

Together these missions have provided a 25 year dataset on sea surface height, which has been used for applications such as:

  • El Niño and La Niña forecasting
  • Extreme weather forecasting for hurricanes, floods and droughts
  • Ocean circulation modelling for seasons and how this affects climate through by moving heat around the globe
  • Tidal forecasting and showing how this energy plays an important role in mixing water within the oceans
  • Measurement of inland water levels – at Pixalytics we have a product that we have used to measure river levels in the Congo and is part of the work we are doing on our International Partnership Programme work in Uganda.

In the future, the dataset will be taken forward by the Jason Continuity of Service (Jason-CS) on the Sentinel-6 ocean mission which is expected to be launched in 2020.

Overall, altimetry data from this series of missions is a fantastic resource for operational oceanography and inland water applications, and we look forward to its next twenty five years!

Landsat Turns 45!

False colour image of Dallas, Texas. The first fully operational Landsat image taken on July 25, 1972, Image courtesy: NASA’s Earth Observatory

Landsat has celebrated forty-five years of Earth observation this week. The first Landsat mission was Earth Resources Technology Satellite 1 (ERTS-1), which was launched into a sun-synchronous near polar orbit on the 23 July 1972. It wasn’t renamed Landsat-1 until 1975. It had an anticipated life of 1 year and carried two instruments: the Multi Spectral Scanner (MSS) and the Return-Beam Vidicon (RBV).

The Landsat missions have data continuity at their heart, which has given a forty-five year archive of Earth observation imagery. However, as technological capabilities have developed the instruments on consecutive missions have improved. To demonstrate and celebrate this, NASA has produced a great video showing the changing coastal wetlands in Atchafalaya Bay, Louisiana, through the eyes of the different Landsat missions.

In total there have been eight further Landsat missions, but Landsat 6 failed to reach its designated orbit and never collected any data. The missions have been:

  • Landsat 1 launched on 23 July 1972.
  • Landsat 2 launched on 22 January 1975.
  • Landsat 3 was launched on 5 March 1978.
  • Landsat 4 launched on 16 July 1982.
  • Landsat 5 launched on 1 March 1984.
  • Landsat 7 launched on 15 April 1999, and is still active.
  • Landsat 8 launched on 11 February 2013, and is still active.

Landsat 9 is planned to be launched at the end 2020 and Landsat 10 is already being discussed.

Some of the key successes of the Landsat mission include:

  • Over 7 million scenes of the Earth’s surface.
  • Over 22 million scenes had been downloaded through the USGS-EROS website since 2008, when the data was made free-to-access, with the rate continuing to increase (Campbell 2015).
  • Economic value of just one year of Landsat data far exceeds the multi-year total cost of building, launching, and managing Landsat satellites and sensors.
  • Landsat 5 officially set a new Guinness World Records title for the ‘Longest-operating Earth observation satellite’ with its 28 years and 10 months of operation when it was decommissioned in December 2012.
  • ESA provides Landsat data downlinked via their own data receiving stations; the ESA dataset includes data collected over the open ocean, whereas USGS does not, and the data is processed using ESA’s own processor.

The journey hasn’t always been smooth. Although established by NASA, Landsat was transferred to the private sector under the management of NOAA in the early 1980’s, before returning to US Government control in 1992. There have also been technical issues, the failure of Landsat 6 described above; and Landsat 7 suffering a Scan Line Corrector failure on the 31st May 2003 which means that instead of mapping in straight lines, a zigzag ground track is followed. This causes parts of the edge of the image not to be mapped, giving a black stripe effect within these images; although the centre of the images is unaffected the data overall can still be used.

Landsat was certainly a game changer in the remote sensing and Earth observation industries, both in terms of the data continuity approach and the decision to make the data free to access. It has provided an unrivalled archive of the changing planet which has been invaluable to scientists, researchers, book-writers and businesses like Pixalytics.

We salute Landsat and wish it many more years!

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.

Earth Observation Looking Good in 2017!

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

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

2017 is looking like an exciting one for Earth Observation (EO), judging by the number of significant satellites planned for launch this year.

We thought it would be interesting to give an overview of some of the key EO launches we’ve got to look forward to in the next twelve months.

The European Space Agency (ESA) has planned launches of:

  • Sentinel-2B in March, Sentinel-5p in June and Sentinel-3B in August – all of which we discussed last week.
  • ADM-Aeolus satellite is intended to be launched by the end of the year carrying an Atmospheric Laser Doppler Instrument. This is essentially a lidar instrument which will provide global measurements of wind profiles from ground up to the stratosphere with 0.5 to 2 km vertical resolution.

From the US, both NASA and NOAA have important satellite launches:

  • NASA’s Ionospheric Connection Explorer (ICON) Mission is planned for June, and will provide observations of Earth’s ionosphere and thermosphere; exploring the boundary between Earth and space.
  • NASA’s ICESat-2 in November that will measure ice sheet elevation, ice sheet thickness changes and the Earth’s vegetation biomass.
  • In June NOAA will be launching the first of its Joint Polar Satellite System (JPSS) missions, a series of next-generation polar-orbiting weather observatories.
  • Gravity Recovery And Climate Experiment – Follow-On (GRACE_FO) are a pair of twin satellites to extend measurements from the GRACE satellite, maintaining data continuity. These satellites use microwaves to measure the changes in the Earth’s gravity fields to help map changes in the oceans, ice sheets and land masses. It is planned for launch right at the end of 2017, and is a partnership between NASA and the German Research Centre for Geosciences.

Some of the other launches planned include:

  • Kanopus-V-IK is a small Russian remote sensing satellite with an infrared capability to be used for forest fire detection. It has a 5 m by 5 m spatial resolution over a 2000 km swath, and is planned to be launched next month.
  • Vegetation and Environment monitoring on a New MicroSatellite (VENµS), which is partnership between France and Israel has a planned launch of August. As its name suggests it will be monitoring ecosytems, global carbon cycles, land use and land change.
  • KhalifaSat is the third EO satellite of United Arab Emirates Institution for Advanced Science and Technology (EIAST). It is an optical satellite with a spatial resolution of 0.75 m for the visible and near infrared bands.

Finally, one of the most intriguing launches involves three satellites that form the next part of India’s CartoSat mission. These satellites will carry both high resolution multi- spectral imagers and a panchromatic camera, and the mission’s focus is cartography. It’s not these three satellites that make this launch intriguing, it is the one hundred other satellites that will accompany them!

The Indian Space Research Organisation’s Polar Satellite Launch Vehicle, PSLV-C37, will aim to launch a record 103 satellites in one go. Given that the current record for satellites launched in one go is 37, and that over the last few years we’ve only had around two hundred and twenty satellites launched in an entire year; this will be a hugely significant achievement.

So there you go. Not a fully comprehensive list, as I know there will be others, but hopefully it gives you a flavour of what to expect.

It certainly shows that the EO is not slowing down, and the amount of data available is continuing to grow. This of course gives everyone working in the industry more challenges in terms of storage and processing power – but they are good problems to have. Exciting year ahead!

Will Earth Observation’s power base shift in 2017?

Blue Marble image of the Earth taken by the crew of Apollo 17 on Dec. 7 1972. Image Credit: NASA

Blue Marble image of the Earth taken by the crew of Apollo 17 on Dec. 7 1972.
Image Credit: NASA

We’re only a few days into 2017, but this year may see the start of a seismic shift in the Earth Observation (EO) power base.

We’ve previously described how the sustainable EO industry really began this week thirty nine years ago. On 6th January 1978 NASA deactivated Landsat-1; it had already launched Landsat-2, carrying the same sensors, three years earlier and with guaranteed data continuity our industry effectively began.

Since then the USA, though the data collected by NASA and NOAA satellites, has led the EO global community. This position was cemented in 2008 when it made all Landsat data held by the United States Geological Survey (USGS) freely available, via the internet, to anyone in the world. This gave scientists three decades worth of data to start investigating how the planet had changed, and companies sprang up offering services based entirely on Landsat data. This model of making data freely available has been so transformational, that the European Union decided to follow it with its Copernicus Programme.

Landsat-1 and 2 were followed by 4, 5, 7 & 8 – sadly Landsat 6 never made its orbit – and Landsat 9 is planned for launch in 2020. The USA’s role EO leadership has never been in question, until now.

US President-elect Donald Trump and his team have already made a number of statements indicating that they intended to cut back on NASA’s Earth Science activities. There are a variety of rumours suggesting reasons for this change of approach. However, irrespective of the reason, slashing the current $2 billion Earth Science budget will have huge consequences. Whilst all of this is just conjecture at the moment, the reality will be seen after 20th January.

Against this America backdrop sits the Copernicus Programme, with the European Space Agency due to launch another three satellites this year:

  • Sentinel 2B is planned for March. This is the second of the twin constellation optical satellites offering a spatial resolution of 10 m for the visible bands. The constellation will revisit the same spot over the equator every five days, with a shorter temporal resolution for higher latitudes.
  • June is the scheduled month for the launch of the Sentinel 5 Precursor EO satellite to measure air quality, ozone, pollution and aerosols in the Earth’s atmosphere. This will be used to reduce the data gaps between Envisat, which ended in 2012, and the launch of Sentinel-5.
  • Sentinel 3B is due to launched in the middle of the year, and like 2B is the second in a twin satellite constellation. This pair is mainly focussed on the oceans and measure sea surface topography, sea and land surface temperature, and ocean and land colour. It will provide global coverage every two days with Sea and Land Surface Temperature Radiometer (SLSTR) and the Ocean and Land Colour Instrument (OLCI).

These launches will take give the Copernicus programme seven satellites collecting a wide variety of optical and radar data across the entire planet, which is then made freely available to anyone. It’s obvious to see what will fill any vacuum created by a reduction in Earth Science in the USA.

Depending on how much of the next US President’s rhetoric is turned into action, we may start to see the shift of the EO power base to Europe. Certainly going to be an interesting year ahead!

GOES-R Goes Up!

Artist impression of the GOES-R satellite. Image courtesy of NASA.

Artist impression of the GOES-R satellite. Image courtesy of NASA.

On Saturday, 19th November, at 10.42pm GMT the Geostationary Operational Environmental Satellite-R Series (GOES-R) is due to be launched from Cape Canaveral in Florida, USA.

The GOES-R is a geostationary weather satellite operated by the National Oceanic & Atmospheric Administration (NOAA) Department of the US Government. It will the latest in the NOAA’s GOES series of satellites, and will take the moniker GOES-16 once it is in orbit, joining the operational GOES satellite constellation comprising of GOES-13, GOES-14 & GOES-15.

It will be put into a geostationary orbit at around 35 800 km above the Earth which will allow it to match the Earth’s rotation, meaning that it will effectively stay over a specific point on the Earth. It will be located approximately at 137 degrees West longitude, and through the constellation will provide coverage for North, Central and South America together with the majority of the Atlantic and Pacific Oceans.

Artists impression GOES-R satellite and its instruments. Image courtesy of NASA.

Artists impression GOES-R satellite and its instruments. Image courtesy of NASA.

The instrument suite aboard the satellite has three types: Earth facing instruments, sun facing instruments and space environment instruments.

Earth Facing Instruments: these are the ones we’re most excited about!

  • Advanced Baseline Imager (ABI) is the main instrument and is a passive imaging radiometer with 16 different spectral bands: two visible bands – Blue and Red with a spatial resolution of 0.5km, four near-infrared with spatial resolutions of 1 km; and ten infrared bands with a spatial resolution of 2 km. As its in a geostationary orbit its temporal resolution is extremely high with the full mode being where the Western Hemisphere is imaged every 5 – 15 minutes, whereas in its Mesocale mode (providing a 1000 km x 1000 km swath) the temporal resolution is only 30 seconds.
  • Geostationary Lightning Mapper (GLM) is, as the name suggests, an instrument that will measure total lightning, and both in-cloud and cloud-to-ground lightning across the Americas. It is an optical imager with a single spectral band of 777.4 nm which can detect the momentary changes in the optical scene caused by lightning. The instrument has a spatial resolution of approximately 10 km.

Sun Facing Instruments

  • Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) instrument has two sensors to monitor solar irradiance in the upper atmosphere; these are the Extreme Ultraviolet Sensor (EUVS) and the X-Ray Sensor (XRS).
  • Solar Ultraviolet Imager is a telescope monitoring the sun in the extreme ultraviolet wavelength range.

Space Environment Monitoring Instruments

  • Space Environment In-Situ Suite (SEISS) consists of four sensors:
    • Energetic Heavy Ion Sensor (EHIS) to measure the proton, electron, and alpha particle fluxes at geostationary orbit.
    • Magnetospheric Particle Sensor (MPS) is a magnetometer measuring the magnitude and direction of the Earth’s ambient magnetic field; and has two sensors the MPS-LO and MPS-HI.
    • Solar and Galactic Proton Sensor (SGPS) will, as the name indicates, measure the solar and galactic protons found in the Earth’s magnetosphere.
  • Magnetometer will measure of the space environment magnetic field that controls charged particle dynamics in the outer region of the magnetosphere.

The ABI instrument is the most interesting to us in terms of Earth observation, and it will produce a remarkable 25 individual products including Aerosol Detection, Cloud and Moisture Imagery, Cloud Optical Depth, Cloud Particle Size Distribution, Cloud Top Measurements, Derived Motion Winds & Stability Indices, Downward Shortwave Radiation at the Surface, Fire/Hot Spotting, Hurricane Intensity Estimation, Land Surface Temperature, Moisture & Vertical Temperature Profiles, Rainfall Rate, Reflected Shortwave Radiation at the Top Of Atmosphere, Sea Surface Temperature, Snow Cover, Total Precipitable Water and Volcanic Ash. If you want to look at the details of specific products then there are Algorithm Theoretical Basis Documents (ABTDs) available, which are like a detailed scientific paper, and can be found here.

The GOES-R is the first in a series of four satellites to provide NOAA with improved detection and observation of environmental events. It is not a cheap series of satellite, with the cost of developing, launching and operating this series estimated to be around $11 billion. However, this will provide observations up to 2036.

We’re excited by this launch, and are looking forward to being able to utilise some of this new generation weather information.

Monitoring ocean acidification from space

Enhanced pseudo-true colour composite of the United Kingdom showing coccolithophore blooms in light blue. Image acquired by MODIS-Aqua on 24th May 2016. Data courtesy of NASA.

Enhanced pseudo-true colour composite of the United Kingdom showing coccolithophore blooms in light blue. Image acquired by MODIS-Aqua on 24th May 2016. Data courtesy of NASA.

What is ocean acidification?
Since the industrial revolution the oceans have absorbed approximately 50% of the CO2 produced by human activities (The Royal Society, 2005). Scientists previously saw this oceanic absorption as advantageous, however ocean observations in recent decades have shown it has caused a profound change in the ocean chemistry – resulting in ocean acidification (OA); as CO2 dissolves into the oceans it forms carbonic acid, lowering the pH and moving the oceans into a more acidic state. According to the National Oceanic Atmospheric Administration (NOAA) ocean pH has already decreased by about 30% and some studies suggest that if no changes are made, by 2100, ocean pH will decrease by 150%.

Impacts of OA
It’s anticipated OA will impact many marine species. For example, it’s expected it will have a harmful effect on some calcifying species such as corals, oysters, crustaceans, and calcareous plankton e.g. coccolithophores.

OA can significantly reduce the ability of reef-building corals to produce their skeletons and can cause the dissolution of oyster’s and crustacean’s protective shells, making them more susceptible to predation and death. This in turn would affect the entire food web, the wider environment and would have many socio-economic impacts.

Calcifying phytoplankton, such as coccolithophores, are thought to be especially vulnerable to OA. They are the most abundant type of calcifying phytoplankton in the ocean, and are important for the global biogeochemical cycling of carbon and are the base of many marine food webs. It’s projected that OA may disrupt the formation and/or dissolution of coccolithophores, calcium carbonate (CaCO3) shells, impacting future populations. Thus, changes in their abundance due to OA could have far-reaching effects.

Unlike other phytoplankton, coccolithophores are highly effective light scatterers relative to their surroundings due to their production of highly reflective calcium carbonate plates. This allows them to be easily seen on satellite imagery. The figure at the top of this page shows multiple coccolithophore blooms, in light blue, off the coast of the United Kingdom on 24th March 2016.

Current OA monitoring methods
Presently, the monitoring of OA and its effects are predominantly carried out by in situ observations from ships and moorings using buoys and wave gliders for example. Although vital, in situ data is notoriously spatially sparse as it is difficult to take measurements in certain areas of the world, especially in hostile regions (e.g. Polar Oceans). On their own they do not provide a comprehensive and cost-effective way to monitor OA globally. Consequently, this has driven the development of satellite-based sensors.

How can OA be monitored from space?
Although it is difficult to directly monitor changes in ocean pH using remote sensing, satellites can measure sea surface temperature and salinity (SST & SSS) and surface chlorophyll-a, from which ocean pH can be estimated using empirical relationships derived from in situ data. Although surface measurements may not be representative of deeper biological processes, surface observations are important for OA because the change in pH occurs at the surface first.

In 2015 researchers at the University of Exeter, UK became the first scientists to use remote sensing to develop a worldwide map of the ocean’s acidity using satellite imagery from the European Space Agency’s Soil Moisture and Ocean Salinity (SMOS) satellite that was launched in 2009 and NASA’s Aquarius satellite that was launched in 2011; both are still currently in operation. Thermal mounted sensors on the satellites measure the SST while the microwave sensors measure SSS; there are also microwave SST sensors, but they have a coarse spatial resolution.

Future Opportunities – The Copernicus Program
The European Union’s Copernicus Programme is in the process of launching a series of satellites, known as Sentinel satellites, which will improve understanding of large scale global dynamics and climate change. Of all the Sentinel satellite types, Sentinels 2 and 3 are most appropriate for assessment of the marine carbonate system. The Sentinel-3 satellite was launched in February this year andwill be mainly focussing on ocean measurements, including SST, ocean colour and chlorophyll-a.

Overall, OA is a relatively new field of research, with most of the studies being conducted over the last decade. It’s certain that remote sensing will have an exciting and important role to play in the future monitoring of this issue and its effects on the marine environment.

Blog written by Charlie Leaman, BSc, University of Bath during work placement at Pixalytics.

Four reasons why 2016 will be big for Earth observation

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

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

2016 has caught its first few rays of sunlight, but is already shaping up to be an exciting year for Earth observation (EO). Here are four reasons why:

Reason One
China launched the world’s most sophisticated geostationary satellite, Gaofen 4, on the 28th December – okay I know that was technically 2015, but it will begin operating in 2016! Gaofen 4 is part of the China High-Resolution Earth Observation System (CHEOS) that aims have a suite of seven high definition satellites, with varied specifications, providing real-time all day global coverage in all weathers by 2020. Unusually for EO, the Gaofen 4 high-resolution satellite is in a fixed-point 36,000 km geosynchronous orbit focusing on China and the surrounding area.

It has two optical instruments: a visible light imager with 50 m resolution, and an infrared imager with 400 m resolution. The main applications are disaster prevention, disaster relief, agricultural planning and climate change monitoring.

Reason Two
NASA awarded the contract to build Landsat-9’s Operational Land Imager-2 (OLI) instrument to Ball Aerospace & Technologies Corporation on 31st December – yes, I know that was 2015 too!

OLI will have eight spectral wavebands with a resolution of 30 m, and one panchromatic waveband with a resolution of 15 m. This will help extend the Landsat archive that has over 40 years of continuous satellite images. Interestingly despite having a similar number of optical bands as ESA’s comparable Sentinel 2 satellites; the spatial resolution is poorer as Sentinel 2 has 10 m resolution for its visible wavebands.

Reason Three
There are a number of significant EO satellite launches planned for the coming twelve months. Highlights include for:

  • Jason 3 ocean altimetry mission on January 17th
  • ESA’s Sentinel 3A on 4th February
  • Astro-H X-ray observatory on February 12th
  • ESA’s Sentinel-1B on 14th April
  • Ten SkySat Earth observation satellites for Google/Skybox Imaging over the summer
  • Worldview 4 in September
  • Geostationary Operational Environmental Satellite R-Series Program (GOES-R), a NASA/NOAA next-generation geostationary weather satellite, in October
  • Planet Labs are expected to deploy a significant number of small satellites from the International Space Station during the year, starting with Flock 2e’s twelve satellites, to enable them to provide terrestrial images for the entire Earth.

Reason Four
EO is a growing industry that had sales of $1.6 billion in 2014, up 60% from five years earlier. With the investment and development currently happening within the industry, it is anticipated that this growth will continue. Pixalytics is one example!

The focus in this, and future years, will be getting a broader user base for satellite imagery including providing more operational services using near real time imagery. This should offer potential new applications, services and markets to support the ongoing growth.

You can be part of it! Satellite imagery is no longer just for governments, space agencies or research bodies. Satellites still provide the large scale climate change, ocean and land monitoring; but there can also provide small scale support on everything from crop/field management, building and smart city planning, traffic/parking monitoring and even counting animals from space.

If you want to see how Earth observation might benefit your company, get in touch. We’d be happy to talk through what might be possible – you’ll never know unless you ask!

Ocean Colour Partnership Blooms

Landsat 8 Natural Colour image of Algal Blooms in Lake Erie acquired on 01 August 2014. Image Courtesy of NASA/USGS.

Landsat 8 Natural Colour image of Algal Blooms in Lake Erie acquired on 01 August 2014. Image Courtesy of NASA/USGS.

Last week NASA, NOAA, USGS and the US Environmental Protection Agency announced a $3.6 million partnership to use satellite data as an early warning system for harmful freshwater algae blooms.

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. Shellfish filter large quantities of water and can concentrate the algae in their tissues, allowing it to enter the marine food chain and potentially causing a risk to human consumption. Blooms can also contaminate drinking water. For example, last August over 40,000 people were banned from drinking water in Toledo, Ohio, after an algal bloom in Lake Erie.

The partnership will use the satellite remote sensing technique of ocean colour as the basis for the early warning system.  Ocean colour isn’t a new technique, it has been recorded as early as the 1600s when Henry Hudson noted in his ship’s log that a sea pestered with ice had a black-blue colour.

Phytoplankton within algae blooms are microscopic, some only 1,000th of a millimetre in size, and so it’s not possible to see individual organisms from space. Phytoplankton contain a photosynthetic pigment visible with the human eye, and in sufficient quantities this material can be measured from space. As the phytoplankton concentration increases the reflectance in the blue waveband decreases, whilst the reflectance in the green waveband increases slightly. Therefore, a ratio of blue to green reflectance can be used to derive quantitative estimates of the concentration of phytoplankton.

The US agency partnership is the first step in a five-year project to create a reliable and standard method for identifying blooms in US freshwater lakes and reservoirs for the specific phytoplankton species, cyanobacteria. To detect blooms it will be necessary to study local environments to understand the factors that influence the initiation and evolution of a bloom.

It won’t be easy to create this methodology as inland waters, unlike open oceans, have a variety of other organic and inorganic materials suspended in the water through land surface run-off, which will also have a reflectance signal. Hence, it will be necessary to ensure that other types of suspended particulate matter are excluded from the prediction methodology.

It’s an exciting development in our specialist area of ocean colour. We wish them luck and we’ll be looking forward to their research findings in the coming years.

Can Earth Observation answer your question?

The opportunities and challenges of utilising Earth observation (EO) data played out in microcosm in our house over the weekend. On Sunday afternoon, I was watching highlights of the Formula One Singapore Grand Prix which takes place on the harbour streets of Marina Bay and is the only night race of the season. To ensure the drivers can see, there are over 1,500 light projectors installed around the circuit giving an illumination of around 3,000 lux.

Whilst watching I wondered aloud whether we’d be able to see the track from space with the additional floodlights. My idle wondering caught Sam’s interest far more than the actual race and she decided to see if she could answer the question. The entire circuit is just over five kilometres long, but it’s a loop and so an approximate two kilometre footprint; any imagery would need a spatial resolution less than this. The final difficulty is that the data needed to be this weekend, as the circuit is only floodlit for the racing.

Within a few laps Sam had identified free near real time night data available from United States National Oceanic & Atmospheric Administration (NOAA) which covered the required area and timeframe. This was from the Visible Infrared Imaging Radiometer Suite (VIIRS) using it’s Day/Night band with a 750m spatial resolution – this resolution meant we would not be able to see the outline of the track as it would be represented by only three or four pixels, but it would be interesting to see if we could identify the track feature. By the end of the race Sam had selected and downloaded the data, and so we could answer my question. However, it turned out to be not quite that easy.

VIIRS Singapore night time imagery, data courtesy of NOAA

VIIRS Singapore night time imagery, data courtesy of NOAA

NOAA data uses a slightly different format to the image processing packages we had, and we couldn’t initially see what we’d downloaded. Sam had to write some computer code to modify the packages to read the NOAA data. For anyone thinking this is an odd way to spend a Sunday evening, to Sam this was a puzzle to solve and she was enjoying herself! After some rapid coding we were able to view the image, but unfortunately the Saturday data wasn’t useful. On Monday we tried again, the Sunday race took place on a clear night and we’ve got a good image of the area, which you can see above. On the larger image you can clearly the Indonesian Islands with Jakarta shining brightly, up through the Java Sea where the lights of some ships are visible and then at the top of the image is Singapore; the zoomed in version of Singapore is the inset image.

Despite the floodlights used for the race, Singapore and some of the surrounding Malaysian cities are so bright at night that the additional lights simply contribute to the overall illumination, rather than making the track stand out. Hence the answer to my question is that the 2014 floodlit Singapore F1 street circuit can’t be distinguished from the surrounding area at this spatial resolution. Of course if we purchased high resolution imagery we may be able to see more detail, but we thought that was going a bit far for my idle wondering!

EO can answer questions like these quickly; and whilst we know not many businesses are dependent on whether the Singapore Grand Prix can be seen from space, but change this to what is the light pollution in your area, what is happening in terms of deforestation in the middle of the jungle, what phytoplankton are doing in the middle of the ocean or whatever question you might have, then EO might be able to provide the answer in a short space of time.

However, there are two main difficulties in getting the answer. Firstly, you’ve got to know where to find the data and secondly, what do with it when you get it. Currently this can be challenging without specialist knowledge, making it inaccessible for the general population. In the coming weeks, we’re going to write some blogs looking at the freely EO data available, and the easiest way of viewing it. Hopefully, this may to help you answer your own questions. In the meantime if you have questions you want answered, get in touch, we’d be happy to help.