Worldwide spatial and temporal ammonia (NH3) variability revealed by IASI
Abstract
As a short-lived species, ammonia (NH3) is highly variable in time and space, and
while ground based measurements are possible, they are sparse and their coverage
is largely heterogeneous. Consequently, spatial and temporal patterns of NH3
emissions and their strength are poorly known and account for the largest
uncertainties in the nitrogen cycle.
IASI is measuring since 8 years NH3 columns at a high spatiotemporal resolution.
The aim of this work is to assess distributions and to investigate, from a global to a
local scale, the variability of NH3 using this remarkable time series. We first look at
yearly distributions (2008-2015) to identify the main source processes and areas.
Seasonal patterns and inter-annual variability are then investigated at subcontinental
scale by looking at global composite seasonal means and monthly time series over
various regions around the world, considering separately but simultaneously
measurements from IASI morning and evening overpasses. The relations between
the NH3 atmospheric abundance and emission processes is emphasized at smaller
regional scale by extracting at high spatial resolution the global climatology of the
month of maxima columns. Finally, IASI observations are exploited to identify and
track industrial NH3 emissions.