Plants grow and thrive through photosynthesis, a process that converts sunlight into energy. During photosynthesis, plants emit what is called fluorescence – light invisible to the naked eye but detectable by satellites orbiting hundreds of miles above Earth. NASA scientists have now established a method to turn this satellite data into global maps of the subtle phenomenon in more detail than ever before.
Machinery inside the chloroplasts of plant cells converts sunlight to energy, emitting fluorescence in the process. Scientists can detect the fluorescence fingerprint in satellite data.
Image Credit: NASA Goddard's Conceptual Image Lab/T. Chase
Healthy plants use the energy from sunlight to perform photosynthesis, and re-emit some of that light as a faint but measureable glow. In short, abundant fluorescence indicates active photosynthesis and a well functioning plant, while low or no fluorescence can mean that the plant is stressed or shutting down. Maps of the phenomenon give scientists a direct look at plant health.
The new maps – produced by Joanna Joiner of NASA's Goddard Space Flight Center in Greenbelt, Md., and colleagues – boast a 16-fold increase in spatial resolution and a three-fold increase in temporal resolution over the first proof-of-concept maps released in 2011 from a different satellite instrument. Improved global measurements could have implications for farmers interested in early indications of crop stress and ecologists looking to better understand global vegetation and carbon cycle processes.
"For the first time, we are able to globally map changes in fluorescence over the course of a single month," Joiner said. "This lets us use fluorescence to observe, for example, variation in the length of the growing season."
Vegetation dynamics, including the northward migration of plant growth during the northern hemisphere springtime, is already observed indirectly by satellite data used measure the "greenness" of light reflected from Earth's surface. Fluorescence measurements complement the greenness measurements by providing direct and immediate information about plant productivity. For example, the researchers saw plants start to shut down in the fall before their leaves turned colors. They also clearly detected early plant growth during the warm spring of 2012.
The maps were possible due to the development of a new way to identify the very faint fluorescence signal collected by the Global Ozone Monitoring Instrument 2 (GOME-2) instrument on Metop-A, a European meteorological satellite. Acquiring the measurement is complicated by the fluorescence signal mixing with that of sunlight reflected from Earth's surface and clouds, and the absorption of sunlight by gases in the atmosphere.
To identify fluorescence, Joiner and colleagues took advantage of that fact that each of these signals has its own unique spectral signature akin to a fingerprint – whether from fluorescence, Earth's surface or the atmosphere. Match the fingerprint associated with fluorescence and scientists can tease out that data from the rest of the light.
Detangling the signal from atmospheric influences was a complexity not present in the pioneering research in 2011, when Joiner and colleagues produced the first global maps that proved the concept of measuring global land plant fluorescence from space. That study relied on data from a spectrometer aboard a Japanese satellite called the Greenhouse Gases Observing Satellite (GOSAT). Researchers analyzed an unusually dark section of the infrared portion of the solar spectrum where there is little background light, making it possible to distinguish the faint fluorescence signal.
Despite its complexities, the new method allows for more frequent measurements capable of producing higher resolution maps. Previous observations with GOSAT relied on averaging the data over areas of 200 square kilometers every month. Now, with GOME-2, scientists average the data over areas of just 50 square kilometers about every 10 days. The study was published online for review in April in Atmospheric Measurement Techniques.
"The more precise and more frequent sampling is valuable, allowing us to zoom in on the regions with the highest fluorescence signals," Joiner said. "Our data indicate that agricultural areas in the U.S. Midwest are some of the most productive lands on Earth. We can also now correlate our satellite fluorescence measurements with tower-based observations of carbon dioxide taken up by plants."
The research also paves the path for fluorescence studies based on measurements from future atmospheric or fluorescent-specific observations. Such observations could come from NASA's Orbiting Carbon Observatory-2, a mission designed to measure carbon dioxide that will launch no sooner than July 2014, and the European Space Agency's Fluorescence Explorer mission, which could be selected in 2015 for launch toward the end of the decade.Kathryn Hansen
Kathryn Hansen | EurekAlert!
Sharpening the X-ray view of the nanocosm
23.03.2018 | Changchun Institute of Optics, Fine Mechanics and Physics
Drug or duplicate?
23.03.2018 | Fraunhofer-Institut für Angewandte Festkörperphysik IAF
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
23.03.2018 | Event News
19.03.2018 | Event News
16.03.2018 | Event News
23.03.2018 | Materials Sciences
23.03.2018 | Agricultural and Forestry Science
23.03.2018 | Physics and Astronomy