How much carbon dioxide do plants absorb?
SSTL’s Optical Payloads Group has commenced a science project that will study fluorescent emissions from vegetation using a remote sensing instrument designed to fly onboard a small satellite.
Carbon dioxide (CO2) is notoriously difficult to measure and so far it has been impossible to calculate the uptake of the Earth’s CO2 sinks with sufficient accuracy for scientific analysis – for example hindering our ability to monitor the efficacy of CO2 mitigation policies. There is an urgent need to improve data on the natural CO2 uptake of vegetation in order to improve our understanding of its influence on the Earth's carbon cycle and its potential to suppress today’s increasing atmospheric CO2 concentration. Even minor changes in ecosystem-scale photosynthesis can have a significant affect on the global carbon balance.
Satellites have made a huge difference to our knowledge of vegetation conditions, but until now most of that information has come from remotely sensing reflected sunlight with multi-spectral Earth observation satellites. There is, however, one additional source of information about vegetation in the optical and near-infrared wavelength range. During photosynthesis part of the energy absorbed by chlorophyll is not used for carbon fixation, but re-emitted at longer wavelengths as fluorescence.
'The European Space Agency (ESA) Fluorescence Explorer (FLEX), which is a candidate for the Earth Explorer 8 missions, aims to provide global maps of vegetation fluorescence that can be converted into an indicator of photosynthetic activity. These data would improve our understanding of how much carbon is stored in plants and their role in the carbon and water cycles.
SSTL will identify one optimised design of an instrument under a 400k€ contract from ESA that will detect the weak radiation emitted in this specific wavelength range from space. The Fluorescence Imaging Spectrometer (FIMAS) instrument will be compact enough to fly on a small satellite as a precursor to the primary instrument onboard FLEX.
