The global ammonia (NH3) emissions more than doubled since the pre-industrial level. This pollutant, which affects the air quality, mainly comes from the fertiliser and cattle intensification but the sources are difficult to identify.
The absorption signal of ammonia is extremely low: once emitted, ammonia only remains a short time in the atmosphere. The emissions registers are thus quite imprecise and the global and systematic monitoring of this compound is difficult. Nevertheless, the series of environmental effects are amazing: high concentrations of ammonia affect wildlife, plants and local air quality.
IASI is an instrument developed by CNES on board the EUMETSAT's METOP operational platforms to improve the meteorological forecasts thanks to accurate measurements of the water vapour and atmospheric temperature.
Even if it was not initially thought for this use, IASI identified in 2008 some thirty major ammonia sources in the Earth's atmosphere and put in evidence the global underestimates of the ammonia sources number in several regions of the world.
The investigators of LATMOS-IPSL (CNRS/UPMC/UVSQ) in a partnership with Belgium investigators of the Free University of Brussels, designed a method to isolate this volatile compound's signature from the instrument's background noise and so increase the measurements' accuracy. By filtering the data on ammonia and accumulating them during a year of continuous observations (more than one million measurements per day flying by every point of the whole planet, twice), they obtained concentration maps and compared them to the recent atmospheric patterns.
Thanks to the analysis of the spectrographs provided by the IASI instrument, many minority components of the atmosphere could be identified:
- carbon monoxide
- carbon dioxide