Month on the World’s Oceans

San Francisco USA, Pseudo-true colour image. Landsat 8 data courtesy USGS/NASA/ESA

San Francisco USA, Pseudo-true colour image. Landsat 8 data courtesy USGS/NASA/ESA

June’s been a really busy month for me on the world’s oceans. I’ve not actually been out on the water, but flying over it having attended both the World Ocean Summit and the International Ocean Colour Science (IOCS) meeting. Both of these events focussed on the oceans, although they had very different participants and perspectives. In addition, the 8th June was also World Oceans Day and had the theme ‘Healthy Oceans, Healthy Planet’.

The World Ocean Summit, organised by The Economist, took place at the start of June in Cascais, Portugal. It focused on the development of the blue economy, with most of the participants from governments or non-profit non-governmental organizations. There were a number of talks highlighting the potential innovation opportunities the world’s ocean might offer, and the policy and worldwide governance framework needed. Throughout the summit, there was a repeatedly voiced concern over the state of the world’s oceans, and the serious peril and decline it’s in. Whilst many large organisations are now looking to exploit the oceans, many local communities have been doing this for years and they are seeing changes and challenges. The oceans are an integral part of Earth’s ecosystem, and without them we could not survive on this planet. The resources are potentially huge, but tapping into these requires a co-ordinated bottom up approach. Otherwise we risk damaging the ocean and our own existence.

My second major event was IOCS last week in San Francisco, and as the name suggests the meeting focused on mapping and understanding the ocean through the use of ocean colour remote sensing i.e., detecting and quantifying what causes changes in the colour. The participants were mostly scientists, students and space agencies, who were discussing current work and future plans. There was obvious excitement over the launch of Sentinel-2 (which incidentally occurred successfully very early yesterday morning) and Sentinel-3, which will carry the OLCI ocean colour sensor, due to be launched towards the end of this year. Cloud cover remains a limiting factor in many locations, as clouds get in the way when optically sensing of the ocean and so the more data collected the better insight we’ll gain into the complexities of the biological processes.

There were lots of new areas of focus discussed at the meeting. I was particularly interested in exporting of carbon to the deep ocean and the calculation of uncertainties i.e., how well have we estimated the values that have been derived.

I was also fascinated by the development in our understanding of rapidly changing ecosystems, such as the Arabian Sea and high latitude polar oceans, which are strongly affected by the effects of climate changing; for example, the reduction of the snow cover over the Himalayan-Tibetan Plateau region changes the strength of the Asian monsoon season, which in turn impacts the phytoplankton that bloom in the Arabian Sea. This has caused a particular species of plankton to bloom (Noctiluca, also known as sea sparkle because it can glow when disturbed at night), which are eaten by jellyfish but can negatively affect fisheries as they’re too big for zooplankton to eat.

I’d love to say after a busy month it’s good be home, but I’ve not quite got there yet! I went straight from San Francisco to Switzerland, where this week I’m attending the 2015 Dragon Symposium that’s focused on an Earth observation scientific exchange programme between the European Space Agency and China.

The Science Behind Springwatch

Last Wednesday Pixalytics made it’s TV debut on the BBC2 Springwatch programme, where they showed a video we’d made on phytoplankton blooms.  The video was based on NASA MODIS-Aqua daily images. MODIS, or the Moderate-Resolution Imaging Spectroradiometer, is an optical sensor that’s used for mapping the both land and the oceans. It can be thought of as a digital camera that operates at a number of different wavelengths of light.

Spring 2014 phytoplankton image

Spring 2014 phytoplankton image, MODIS data from NASA with movie animation by Pixalytics Ltd.

As an ocean colour sensor it detects the change in colour of the ocean caused by what’s both dissolved and suspended in the water, e.g. the microscopic plants of the sea that are called phytoplankton. The chlorophyll pigments in plants (both on land and in the oceans) absorb light at blue and red wavelengths making waters high in phytoplankton appear green in colour. This colour change is picked up by chlorophyll algorithms (mathematical equations) and equated to changes in concentration that are displayed using a rainbow colour palette, which goes from purple to blue, green, yellow and red as the concentrations go from low to high values. Black on the imagery is where there’s no data, which for optical imagery is primarily due to cloud cover.

MODIS is on both the Aqua (travels south to north over the equator in the afternoon) and Terra (north to south across the equator in the morning) satellites, which orbit the Earth several times a day collecting strips of imagery 2330 km wide at a spatial resolution of around 1 km. The strips from a day are combined to create a daily composite image, and by looking at images over time we can see the changes in the phytoplankton concentrations as we as we move out of the winter through months into spring. The ‘spring bloom’ is an increase in phytoplankton concentrations as the days become lighter and the phytoplankton make use of the nutrients mixed into the surface waters over the winter.