We‘re on Stand K31 at Geo Business 2015!

We’ve made it! We’re officially first time exhibitors! After months of discussions, decisions and preparations, at this precise moment you’ll find us on stand K31 at the Geo Business Show 2015 in the Business Design Centre in London.

In a previous week, we discussed our approach to the exhibition and wanting to have something different that stands out without breaking the bank. The blog picture reveals our stand design; we’ve large scale canvas prints of a variety of satellite images coupled with retro items such as a globe and map bunting. We were a little worried about our stand construction, but it all seemed to go went well. Let us know what you think?

South West UK, Pseudo-true colour image. Landsat 8 data courtesy USGS/NASA

South West UK, Pseudo-true colour image. Landsat 8 data courtesy USGS/NASA

In terms of promotional items, we have our brochures, postcards of all the canvas prints, a number of A5 sheets on our key products/services and our pens. In addition, we’re giving away a small canvas Landsat image of South Devon, as shown on the right. Come on drop your business card or complete an entry form off at our stand, and we’ll select the winner tomorrow before the exhibition closes.

Geo Business 2015 runs both today and tomorrow, and so do come along and have a look at our stand. Give us some feedback on our design, enter the competition or just pick up a few postcards or a pen! If you feel like it, talk to us! We’d be glad to discuss remote sensing, Earth observation and all things Pixalytics with you; maybe find out if there is anything we might be able to help you, or your organisation, with. Who knows what ideas, products or solutions our discussions might come up with?

Don’t forget, tomorrow at 12.30pm in Room F, we’re running a free workshop called ‘How to add value to remote sensing by applying cutting edge scientific research to create richer imagery and data’. It would be great to see people there.

Finally, we’ve also previously talked about how we’d determine whether all of this effort is worthwhile. We’ve come up with these three metrics to measure our toe dipping into the exhibition world:

  • New contacts for customers or research partners.
  • In the next four months, gain sufficient new client business from the exhibition to cover our costs – after all this is why we are all exhibiting!
  • Develop a long-term business relationship over the course of the next year.

We’ll let you know how we got on next week. However, if you’re at Geo Business today or tomorrow why not come up and have look, talk to us and take away a few freebies. We’d love to see you.

GEO Business 2015: Adding Value to Remote Sensing

Pixalytics-show preview imageTechnological developments have made it easier, faster and cheaper to launch a satellite, and have enhanced the capabilities of the sensors onboard. This has led to an ever-increasing quantity of available data. Also, there is recognition within the space industry that it’s no longer enough to launch something into orbit, the satellite customers need to also see how they’ll get value from the data it collects.

Our workshop session at GEO Business 2015 will focus on this issue. We’ll be describing the approach we take in ‘How to add value to remote sensing by applying cutting edge scientific research to create richer imagery and data’. Anyone who knows us, or who are regular blog readers, will know that science is firmly at the heart of Pixalytics. We believe Earth observation needs to go beyond the simple provision of remote sensing data or imagery, it should produce new, innovative and unique ways of utilising the terabytes of available data. Our approach includes:

  • Research & Development – Developing innovative techniques by applying new research methodologies, such as our product that measures water heights from space using altimetry data.
  • Repurposing – Using data for more purposes than originally intended, as is happening in the US where they are using ocean colour techniques for inland waters.
  • Merging Data Sets – Using remote sensing data combined with scientific, government or other open source data to produce more than is possible with just one data type.
  • Expanding Markets – Getting people who don’t use remote sensing to think about how they could use it within their businesses and organisations.
  • Blended Solutions – Developing automated processing for data extraction and downloading, which provides visualisation solutions whenever and wherever data is needed.

If you are at GEO Business on Thursday 28th May, our workshop will be taking place just before lunch at 12.30pm in Room F and it would be great to see you there.

Talking of GEO Business, we had a great response to last week’s blog on the things we’d learnt so far preparing for our first exhibition. We had a number of suggestions on how to measure success, which was the one thing we said we didn’t know last week! Interestingly, Elaine Ball Technical Marketing are running a Twitter chat on Thursday at 4pm relating to GEO Business, and one of their questions is looking at this issue of success. It will be good to see more thoughts on the topic.

We also got a lot of advice about exhibiting. The idea of taking a duster along was something we’ve have never thought of, but it seems so obvious when you think about it. The ‘rules’ of running a stand that people sent in made great reading; ensuring we don’t start working on the laptop and phones will be something we’ll have to be vigilant of!

Our stand kit is coming together, although we’re still holding our breath over a couple of promised deliveries. How the construction of the stand will come together is shrouded in a little mystery for us, but it will certainly make next Tuesday entertaining.

If any blog readers are around the Business Design Centre next Wednesday and Thursday, please come up and say hello, we’d love to meet you; and you will have the chance to win the free prize raffle we’ll be running on the stand. Hope to see you next week!

5 Things We’ve Learnt Preparing For Our First Exhibition & the 1 Thing We Haven’t!

GlobePixalytics is becoming a conference exhibitor! After years of attending conferences, we decided, for the first time, to become an exhibitor. We are undertaking two exhibitions this year, and our first is GEO Business 2015 taking place later this month on the 27th and 28th at the Business Design Centre, in London. As complete novices in the exhibition world, we’ve had an interesting learning curve. Here are five lessons we’ve learnt during our preparation, and the one thing we still don’t know.

  1. Everything Costs! We bought an exhibition space, which has three walls and our name above it. We knew we’d have fill the shell to create the stand, but hadn’t realised exactly what this meant. It’s obvious now, but we hadn’t thought about the need to have electricity connected on the stand, various options for furniture, hiring equipment, getting things to our stand and how you actually attach items to the stand. We discovered that there is a solution to these, and numerous other things, but they all have a cost. Buying the stand space is only the start, and this has made us rethink everything from stand design to our travel arrangements.
  2. Stand Design. We knew we couldn’t compete with the big firms with their cappuccino machines, freshly baked cakes and leather chairs. We had to go for something different, and so we’ve attempted to create interesting, intriguing, slightly vintage and cost effective stand (see lesson 1!). If you are at GEO Business come along and tell us what you think. As a sneak preview, the blog picture is part of our stand.
  3. Promotional Items. You need to have promotional items, freebies and things to hand out; but the question is what? We wanted items that were interesting, promoted us and ideally would make it back to the desks of potential customers. We discounted novelty items, expensive items (see lesson 1!) and unwrapped sweets (you never known where people’s hands have been!). We’ve settled for pens (useful, and might make it back to desks) and postcards (interesting and promoting us); wrapped sweets are still being debated, you’ll have to come onto the stand to find out the decision.
  4. Talk To People, Not The Internet. A lot of the exhibition preparation can be done on the internet and by email, but we had lots of questions. We found it was far easy to talk to people, rather than simply fill out forms. We gained a lot of information by talking to the conference organising team (thank you Danielle) the company hiring the audio-visual equipment were helpful and our promotional material suppliers (Adam from Redrok was great!).
  5. Expect Phone Calls. We got a lot of phone calls once our participation was on the exhibition website, all of which were trying to sell us something! The most surprising were the numerous, and we do mean numerous, calls we’ve had offering us discounted hotel rooms.

So these are the five things we’ve learnt in our preparation, and I’m sure there will be more to learn during the stand construction and the exhibition itself. So what about the one thing we haven’t learnt? The thing we have no idea about is whether all of this effort will be worth it.

So a question for all experienced exhibitioners, how do you decide if an exhibition stand has been worthwhile? Is it the number of business cards collected, number of people spoken to, amount of publicity generated or is it about the amount of new work generated? Drop us a comment, or a tweet to @pixalytics, telling us how you measure exhibition success.

If you are coming to GEO Business 2015, please drop by the stand and say hello.

How to Measure Heights From Space?

Combining two Sentinel-1A radar scans from 17 and 29 April 2015, this interferogram shows changes on the ground that occurred during the 25 April earthquake that struck Nepal. Contains Copernicus data (2015)/ESA/Norut/PPO.labs/COMET–ESA SEOM INSARAP study

Combining two Sentinel-1A radar scans from 17 and 29 April 2015, this interferogram shows changes on the ground that occurred during the 25 April earthquake that struck Nepal. Contains Copernicus data (2015)/ESA/Norut/PPO.labs/COMET–ESA SEOM INSARAP study

Accurately measuring the height of buildings, mountains or water bodies is possible from space. Active satellite sensors send out pulses of energy towards the Earth, and measure the strength and origin of the energy received back enabling them to determine of the heights of objects struck by the pulse energy on Earth.

This measurement of the time it takes an energy pulse to return to the sensor, can be used for both optical and microwave data. Optical techniques such as Lidar send out a laser pulse; however within this blog we’re going to focus on techniques using microwave energy, which operate within the Ku, C, S and Ka frequency bands.

Altimetry is a traditional technique for measuring heights. This type of technique is termed Low Resolution Mode, as it sends out a pulse of energy that return as a wide footprint on the Earth’s surface. Therefore, care needs to be taken with variable surfaces as the energy reflected back to the sensor gives measurements from different surfaces. The signal also needs to be corrected for speed of travel through the atmosphere and small changes in the orbit of the satellite, before it can be used to calculate a height to centimetre accuracy. Satellites that use this type of methodology include Jason-2, which operates at the Ku frequency, and Saral/AltiKa operating in the Ka band. Pixalytics has been working on a technique to measure river and flood water heights using this type of satellite data. This would have a wide range of applications in both remote area monitoring, early warning systems, disaster relief, and as shown in the paper ‘Challenges for GIS remain around the uncertainty and availability of data’ by Tina Thomson, offers potential for the insurance and risk industries.

A second methodology for measuring heights using microwave data is Interferometric Synthetic Aperture Radar (InSAR), which uses phase measurements from two or more successive satellite SAR images to determine the Earth’s shape and topography. It can calculate millimetre scale changes in heights and can be used to monitor natural hazards and subsidence. InSAR is useful with relatively static surfaces, such as buildings, as the successive satellite images can be accurately compared. However, where you have dynamic surfaces, such as water, the technique is much more difficult to use as the surface will have naturally changed between images. Both ESA’s Sentinel-1 and the CryoSat-2 carry instruments where this technique can be applied.

The image at the top of the blog is an interferogram using data collected by Sentinel-1 in the aftermath of the recent earthquake in Nepal. The colours on the image reflect the movement of ground between the before, and after, image; and initial investigations from scientists indicates that Mount Everest has shrunk by 2.8 cm (1 inch) following the quake; although this needs further research to confirm the height change.

From the largest mountain to the smallest changes, satellite data can help measure heights across the world.

Ocean Colour Cubes

August 2009 Monthly Chlorophyll-a Composite; data courtesy of the ESA Ocean Colour Climate Change Initiative project

August 2009 Monthly Chlorophyll-a Composite; data courtesy of the ESA Ocean Colour Climate Change Initiative project

It’s an exciting time to be in ocean colour! A couple of weeks ago we highlighted the new US partnership using ocean colour as an early warning system for harmful freshwater algae blooms, and last week a new ocean colour CubeSat development was announced.

Ocean colour is something very close to our heart; it was the basis of Sam’s PhD and a field of research she is highly active in today. When Sam began studying her PhD, Coastal Zone Color Scanner (CZCS) was the main source of satellite ocean colour data, until it was superseded by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) that became the focus of her role at Plymouth Marine Laboratory.

Currently, there are a number ocean colour instruments in orbit:

  • NASA’s twin MODIS instruments on the Terra and Aqua satellites
  • NOAA’s Visible Infrared Imager Radiometer Suite (VIIRS)
  • China’s Medium Resolution Spectral Imager (MERSI), Chinese Ocean Colour and Temperature Scanner (COCTS) and Coastal Zone Imager (CZI) onboard several satellites
  • South Korea’s Geostationary Ocean Color Imager (GOCI)
  • India’s Ocean Colour Monitor on-board Oceansat-2

Despite having these instruments in orbit, there is very limited global ocean colour data available for research applications. This is because the Chinese data is not easily accessible outside China, Oceansat-2 data isn’t of sufficient quality for climate research and GOCI is a geostationary satellite so the data is only for a limited geographical area focussed on South Korea. With MODIS, the Terra satellite has limited ocean colour applications due to issues with its mirror and hence calibration; and recently the calibration on Aqua has also become unstable due to its age. Therefore, the ocean colour community is just left with VIIRS; and the data from this instrument has only been recently proved.

With limited good quality ocean colour data, there is significant concern over the potential loss of continuity in this valuable dataset. The next planned instrument to provide a global dataset will be OLCI onboard ESA’s Sentinel 3A, due to be launched in November 2015; with everyone having their fingers crossed that MODIS will hang on until then.

Launching a satellite takes time and money, and satellites carrying ocean colour sensors have generally been big, for example, Sentinel 3A weighs 1250 kg and MODIS 228.7 kg. This is why the project was announced last week to build two Ocean Colour CubeSats is so exciting; they are planned to weigh only 4 kg which reduces both the expense and the launch lead time.

The project, called SOCON (Sustained Ocean Observation from Nanosatellites), will see Clyde Space, from Glasgow in the UK, will build an initial two prototype SeaHawk CubeSats with HawkEye Ocean Colour Sensors, with a ground resolution of between 75 m and 150 m per pixel to be launched in early 2017. The project consortium includes the University of North Carolina, NASA’s Goddard Space Flight Centre, Hawk Institute for Space Sciences and Cloudland Instruments. The eventual aim is to have constellations of CubeSats providing a global view of both ocean and inland waters.

There are a number of other planned ocean colour satellite launches in the next ten years including following on missions such as Oceansat-3, two missions from China, GOCI 2, and a second VIIRS mission.

With new missions, new data applications and miniaturised technology, we could be entering a purple patch for ocean colour data – although purple in ocean colour usually represents a Chlorophyll-a concentration of around 0.01 mg/m3 on the standard SeaWiFS colour palette as shown on the image at the top of the page.

We’re truly excited and looking forward to research, products and services this golden age may offer.

Are you Celebrating Earth Day!

Animation of the biosphere created using SeaWiFS data; courtesy of NASA/OBPG

Animation of the biosphere created using SeaWiFS data; courtesy of NASA/OBPG

Did you know today, the 22nd April, is the globally celebrated International Mother Earth Day? Also known simply as Earth Day, over one billion people participate in this event every year, and 2015 is the 45th Anniversary.

The first Earth Day took place in 1970 in America, when approximately 20 million citizens got involved in rallies to show support for environmental reform. This level of backing was one of the key factors that led to the creation of the US Environmental Protection Agency on the 2nd December later that year, together with the passing of a variety of environmental legislation. Earth Day continued to grow in popularity with particularly big celebrations in 1990 and 2000; then in 2009 the United Nations passed a resolution designated the 22nd April as International Mother Earth Day. The resolution acknowledged that the Earth and its ecosystems are our home, and in order to achieve a balance among the economic, social, and environmental needs of present and future generations, it was necessary to promote harmony with nature and the Earth.

Six years later almost two hundred countries celebrate the event, which is co-ordinated by the Earth Day Network, and this year’s theme is ‘It’s Our Turn To Lead.’ and has three key messages:

  • Sustainable Development: Ensuring the future economic development of the world is built on a sustainable, low carbon footing.
  • Making Everyone’s Voices Heard: Getting world leaders to pay attention to the voices across the world who want change.
  • Getting A Global Environmental Treaty: Making the 2015 United Nations Climate Change Conference, to held at the start of December in Paris, the one that secures a binding, global climate treaty.

There are events both online and all over the world, you can check what is happening close to you on this website.

In the modern calendar, there are lot of ‘Days’ for lots of things and you may wonder whether they worth supporting; well consider what the first Earth Day achieved in 1970. So what do you think? Is it worth it standing up and having your voice heard for Earth Day in 2015?

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.

Lidar: From space to your garage and pocket

Lidar data overlaid on an aerial photo for Pinellas Point, Tampa Bay, USA. Data courtesy of the NASA Experimental Airborne Advanced Research Lidar (EAARL), http://gulfsci.usgs.gov/tampabay/data/1_lidar/index.html

Lidar data overlaid on an aerial photo for Pinellas Point, Tampa Bay, USA. Data courtesy of the NASA Experimental Airborne Advanced Research Lidar (EAARL), http://gulfsci.usgs.gov/tampabay/data/1_lidar/index.html

Lidar isn’t a word most people use regularly, but recent developments in the field might see a future where is becomes part of everyday life.

Lidar, an acronym for LIght Detection And Ranging, was first developing in the 1960’s and is primarily a technique for measuring distance; however, other applications include atmospheric Lidar which measures clouds, particles and gases such as ozone. The system comprises of a laser, a scanner and GPS position receiving, and it works by emitting a laser pulse towards a target, and measuring the time it takes for the pulse to return.

There are two main types of Lidar used within remote sensing for measuring distance, topographic and bathymetric; topographic Lidar uses a near infrared laser to map land, while bathymetric Lidar uses water-penetrating green light to measure the seafloor. The image at the top of the blog is a bathymetric Lidar overlaying an aerial photograph Pinellas Point, Tampa Bay in the USA, showing depths below sea level in metres. Airborne terrestrial Lidar applications have also been expanded to include measuring forest structures and tree canopies mapping; whilst there’s ground based terrestrial laser scanners for mapping structures such as buildings.

As a user getting freely accessible airborne Lidar data isn’t easy, but there are some places that offer datasets including:

Spaceborne terrestrial Lidar has been limited, as it has to overcome a number of challenges:

  • It’s an active remote sensing technique, which means it requires a lot more power to run, than passive systems and for satellites this means more cost.
  • It’s an optical system that like all optical systems is affected by cloud cover and poor visibility, although interestingly it works more effectively at night, as the processing doesn’t need to account for the sun’s reflection.
  • Lidar performance decreases with inverse square of the distance between the target and the system.
  • Lidar collects individual points, rather than an image, and images are created by combining lots of individual points. Whilst multiple overflies are possible quickly in a plane, with a satellite orbiting the Earth you’re effectively collecting lines of points over a number of days, which takes time.

The only satellite that studied the Earth’s surface using Lidar is NASA’s Ice, Cloud and Land Elevation Satellite – Geoscience Laser Altimeter system (IceSAT-GLAS); launched in 2003, it was decommissioned in 2010. It measured ice sheet elevations and changes, together with cloud and aerosol height profiles, land elevation and vegetation cover, and sea ice thickness; and you find its data products here. IceSAT-GLAS 2 is scheduled for launch in 2017. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), part of the satellite A-Train, is a joint NASA and CNES mission launched in 2006. Originally designed as an atmospheric focused Lidar, it has since developed marine applications that led to the SABOR campaign we discussed in previous blog.

Beyond remote sensing, Lidar may become part of every household in the future, if recent proof-of-concepts come to fruition. The Google self-drive car uses a Lidar as part of its navigation system to generate a 3D maps of the surrounding environment. In addition, research recently published in Optics Express, by Dr. Ali Hajimiri of California Institute of Technology has described the potential of a tiny Lidar device capable of turning mobile phones into 3D scanning devices. Using a nanophotonic coherent imager, the proof-of-concept device has put together a 3-D image of the front of a U.S. penny from half a meter away, with 15-μm depth resolution and 50-μm lateral resolution.

Lidar has many remote sensing and surveying applications, however, in the future we all could have lasers in our garage and pockets.

Collaborative Earth Observation

This image combines two Sentinel-1A radar scans from 3 and 15 January 2015 to show ice velocities on outlet glaciers of Greenland’s west coast. Courtesy of Copernicus data (2015)/ESA/Enveo

This image combines two Sentinel-1A radar scans from 3 and 15 January 2015 to show ice velocities on outlet glaciers of Greenland’s west coast. Courtesy of Copernicus data (2015)/ESA/Enveo

Establishing Earth observation systems are large and expensive projects with the combination of satellite development and launch alongside the ground based infrastructure, but the direct Earth observation community itself is fairly small. Working collaboratively and in partnerships can therefore help leverage initiatives, funding, research and publicity to demonstrate the value, and benefits, of our industry to the wider world.

Last week saw the announcement of three international collaborations for the UK, two at a national level and one at a local Pixalytics level! Firstly, the UK Space Agency announced 7 new collaborative projects between UK companies and international partners, funded through the International Partnerships Space Programme to develop satellite technology and applications in emerging economies.

The projects included e-learning solutions for schools in Tanzania, developing satellite air navigation, low cost telecommunications CubeSats, enhancing digital connectivity in Kenya and developing instruments for the next generation of meteorological and disaster management satellites. They were also two Earth Observation specific projects:

  • Enabling Kazakhstan’s Earth observation capability by developing and testing ground receiving stations ahead of the planned 2016 launch of the KazSTSAT small satellite mission, which will produce over 70 gigabytes of data daily.
  • Oceania Pacific Recovery and Protection in Disaster (RAPID) system which will aim to improve the use of satellite data in the aftermath of natural disasters, by getting critical decision influencing information to people in the field as quickly as possible.

The second collaboration was the UK signing the Ground Segment Cooperation agreement with ESA for the EU’s Copernicus programme. This sees the establishment of a data hub in Harwell to provide UK users with easier access to the free and publicly available data from the Copernicus Sentinel missions, and a wide range of complementary missions. The Sentinel missions will form the backbone of this data, with 14 planned satellite launches by 2025; eventually providing around 8 terabytes of data daily. Launched in 2014, Sentinel-1A is the first mission and carries a C-band Synthetic Aperture Radar (SAR) instrument providing all-weather, day-and-night imagery of the Earth’s surface; it is producing some stunning images including the one at the top of this blog. Next up will be Sentinel-2A this summer which will offer optical data across 13 spectral bands, with 4 bands at 10 m spatial resolution, 6 bands at 20 m and 3 bands at 60 m.

The final collaborative partnership is closer to home; as Pixalytics is delighted to announce that we have an international PhD student, through the European Union’s Erasmus Programme, coming to work with us over the summer.

Remote sensing and Earth observation are becoming increasingly collaborative, and is only likely to continue in the future. Everyone should encourage and support these developments, as working together will achieve much more than working alone.

Goodbye HICO, Hello PACE – Ocean Colour’s Satellite Symmetry

HICO™ Data, image of Hong Kong from the Oregon State University HICO Sample Image Gallery, provided by the Naval Research Laboratory

HICO™ Data, image of Hong Kong from the Oregon State University HICO Sample Image Gallery, provided by the Naval Research Laboratory

Ocean colour is the acorn from which Pixalytics eventually grew, and so we were delighted to see last week’s NASA announcement that one of their next generation ocean colour satellites is now more secure with a scheduled launched for 2022.

Unsurprisingly the term ocean colour refers to the study of the colour of the ocean, although in reality it’s a name that includes a suite of different products, with the central one for the open oceans being the concentration of phytoplankton. Ocean colour is determined by the how much of the sun’s energy the ocean scatters and absorbs, which in turn is dependent on the water itself alongside substances within the water that include phytoplankton and suspended sediments together with dissolves substances and chemicals. Phytoplankton can be used a barometer of the health of the oceans; in that phytoplankton are found where nutrient levels are high and oceans with low nutrients have little phytoplankton. Sam’s PhD involved the measurement of suspended sediment coming out of the Humber estuary back in 1995, and it’s remained an active field of her research for the last 20 years.

Satellite ocean colour remote sensing began with the launch of NASA’s Coastal Zone Colour Scanner (CZCS) on the 24th October 1978. It had six spectral bands, four of which were devoted to ocean colour, and a spatial resolution of around 800m. Despite only having an anticipated lifespan of one year, it operated until the 22nd June 1986 and has been used as a key dataset ever since. Sadly, CZCS’s demise marked the start of a decade gap in NASA’s ocean colour data archive.

Although there were some intermediate ocean colour missions, it was the launch of the Sea-viewing Wide Field-of-view (SeaWiFS) satellite that brought the next significant archive of ocean colour data. SeaWiFS had 8 spectral bands optimized for ocean colour and operated at a 1 km spatial resolution. One of Sam’s first jobs was developing a SeaWiFS data processor, and the satellite collected data until the end of its mission in December 2010.

Currently, global ocean colour data primarily comes from either NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the twin Aqua and Terra satellites, or the Visible Infrared Imaging Radiometer Suite (VIIRS) which is on a joint NOAA / NASA satellite called Suomi NPP. MODIS has 36 spectral bands and spatial resolution ranging from 250 to 1000 m; whilst VIIRS has twenty two spectral bands and a resolution of 375 to 750 m.

Until recently, there was also the ONR / NRL / NASA Hyperspectral Imager for the Coastal Ocean (HICO) mission on-board the International Space Station. It collected selected coastal region data with a spectral resolution range of 380 to 960nm and 90m spatial resolution. It was designed to collect only one scene per orbit and has acquired over 10,000 such scenes since its launch. However, unfortunately it suffered during a solar storm in September 2014. Its retirement was officially announced a few days ago with the confirmation that it wasn’t possible to repair the damage.

In the same week we wave goodbye to HICO, NASA announced the 2022 launch of the Pre-Aerosol and ocean Ecosystem (PACE) mission in a form of ocean colour symmetry. PACE is part of the next generation of ocean colour satellites, and it’s intended to have an ocean ecosystem spectrometer/radiometer called built by NASA’s Goddard Space Flight Centre and will measure spectral wavebands from ultraviolet to near infrared. It will also have an aerosol/cloud polarimeter to help improve our understanding of the flow, and role, of aerosols in the environment.

PACE will be preceded by several other missions with an ocean colour focus including the European Sentinel-3 mission within the next year; it will have an Ocean and Land Colour Instrument with 21 spectral bands and 300 m spatial resolution, and will be building on Envisat’s Medium Resolution Imaging Spectrometer (MERIS) instrument. Sentinel-3 will also carry a Sea and Land Surface Temperature Radiometer and a polarimeter for mapping aerosols and clouds. It should help to significantly improve the quality of the ocean colour data by supporting the improvement of atmospheric correction.

Knowledge the global phytoplankton biomass is critical to understanding the health of the oceans, which in turn impacts on the planet’s carbon cycle and in turn affects the evolution of our planet’s climate. A continuous ocean colour time series data is critical to this, and so we are already looking forward to the data from Sentinel-3 and PACE.