Detection of extreme events from IASI observations
Résumé
The 3 IASI instruments on-board the Metop satellites have been sounding the atmospheric composition
since 2006. Up to ~30 atmospheric gases can be measured from IASI spectra, allowing the improvement
of weather forecasting, and the monitoring of atmospheric chemistry, and climate variables.
The early detection of extreme events such as fires, pollution episodes, volcanic eruptions, industrial
accidents, is key to take appropriate decisions regarding safety to protect inhabitants and the
environment in the target areas. With IASI providing global observations twice a day in near real time, a
new way for the systematic and continuous detection of exceptional atmospheric events to support
operational decisions is possible.
In this work, we explore and improve a method for the detection and characterization of extreme events,
which relies on the principal component analysis (PCA) method. We assess this PCA-based system by
analysing IASI raw and compressed spectra along with their differences (residuals) for various past and
documented extreme events. The benefits and limitations of this method will be discussed with
comparison with available CO and SO2 IASI products. A new method based on the refined analysis of
residuals for the detection of fires, volcanic eruptions and pollution event is proposed, and could be used
as an automatic detection method for unexpected future events