In a world of increasing uncertainty, social science is helping to tackle food insecurity by mapping vegetation cover from space.
Summary
The UN Food and Agriculture Organisation (FAO) estimates that up to 40% of crops are lost to plant pests and diseases every year. This, coupled with an increasing global population and a changing climate extending some insect pest ranges, means the ability to monitor and inform timely responses to disease outbreaks is becoming ever more important.
Researchers at the University of Southampton, led by Professor Jadu Dash, developed a number of algorithms which estimate the chlorophyll content of land-based vegetation in near real-time. This research significantly enhanced the European Space Agency’s and European Commission’s ability to monitor global vegetation from space, generating huge benefits for providing timely and targeted responses to poor harvests and plant disease outbreaks.
Monitoring crop yields from space: informing the European Space Agency’s approach to environmental monitoring
“The innovative product (OTCI) that was developed by Dash’s team now contributes to an overall observation system that allows us to better understand how our planet is evolving and how it is responding to climate change and at the same time allows us to better understand climate change itself.”
European Space Agency
The challenge
The UN Food and Agriculture Organisation (FAO) estimates that up to 40% of crops are lost to plant pests and diseases every year. With climate change extending the period over which some insect pests are active each year or extending their distribution range and with the FAO forecasting that the world will need 50% more food by 2050 to feed an increasing global population, the ability to monitor and inform timely responses to disease outbreaks is more important than ever.
The chlorophyll content and concentration of vegetation is a good indication of its productivity and condition. Therefore, being able to estimate and monitor this in near real-time provides agricultural service providers with essential information on yields, plant health and also carbon sequestration and fluxes. All of this is useful in not only being able to respond to poor harvests but also helps with understanding how vegetation is responding to a changing climate.
The research
In 2004, researchers at the University of Southampton developed an algorithm which used imagery from the European Space Agency’s (ESA) Medium Resolution Imaging Spectrometer (MERIS) satellite sensor to estimate the chlorophyll content of vegetation. When contact was unexpectedly lost with the satellite carrying the MERIS sensor in 2012, the Southampton team, led by Professor Jadu Dash, used the original algorithm along with information about different user requirements to research and develop a second vegetation chlorophyll content product (OTCI).
OTCI uses data from ESA’s Sentinel-3A optical sensor, an ocean and land observation satellite which was launched in 2016 and forms part of the European Union’s Copernicus programme, which aims to develop innovative ways of using satellite datasets to monitor the environment. This was the first time the ESA had produced an operational product dedicated to monitoring global vegetation.
Subsequent research by the team has involved the development of new procedures to validate satellite-derived vegetation chlorophyll content products, including developing new techniques to analyse time series data and to assess the accuracy of satellite-derived land products. The latter includes providing ground data to ensure that the quality of satellite products as part of the Copernicus programme are accurate and fit for purpose (this is called ground-based observations for validation or GBOV).
“The key changes this [work] will enable is providing accurate information to a lot of people. That includes people on the ground – farmers who may [want to] have access to information about how good their crops are doing, to the policymaker level who wants to look into the overall view of a specific country or specific region to identify areas which are producing well or identifying underperforming crop lines. That will enable them to develop policies so that the productivity of those lands can come to the same level.”
Professor Jadu Dash
The impact
Since the ESA launched the Copernicus Sentinel 3 satellite in 2016, the ESA has used the OTCI as a near real-time data product on the chlorophyll content of vegetation across the globe. This has been used by Copernicus users to monitor and manage terrestrial ecosystems, including forest and crop health – in 2017 alone, over 1,000 terabytes of Sentinel 3 OTCI data was downloaded.
The team’s research into ground-based observations for validation led to them providing validation procedures for three other Copernicus vegetation products which are used by more than 6,000 organisations and users worldwide for a range of activities including monitoring biodiversity and drought surveillance. One example of such use is the European Commission’s Joint Research Centre using two of these products to provide information to a Europe-wide crop early warning programme which supports food security assessments.
Aside from uses of the Copernicus programme, in 2018 the World Bank recommended the use of one of the team’s developed algorithms for maize crop yield estimates in Uganda.
“It [this work] put the ESA and Copernicus programme in a unique and leading position for monitoring the state of vegetation all over the world.”
Philippe Goryl Head of Sentinel Data Quality Managers, European Space Agency