Ammonia (NH3) Volatilization in Agricultural Fields from IASI and GEOS-Chem
Résumé
Emissions from agricultural activities contribute to air pollution, and are themselves affected by meteorology and climate change. Soil fertilization and manure management practices are the main sources of the trace-gas ammonia (NH3) in the atmospheric budget. Atmospheric ammonia can subsequently lead to the formation of fine particulate matter (PM2.5), causing deleterious effects on air quality. Previous studies have established the capability of the Infrared Atmospheric Sounding Interferometer (IASI) instruments aboard the Metop satellites to measure ammonia from space. This series of instruments provide a continuous view of the global atmosphere since the end of 2007, allowing us to study ammonia and many other pollutants relevant to air quality and climate. In this work we explore the interactions between atmospheric ammonia, land surface processes, and meteorological conditions.
First, we look at the spatiotemporal variability of ammonia, focusing on different regions around the globe. We show that ammonia variability in these regions is mainly driven by agricultural practices and meteorology, and further find that periods of fertilizer application can be identified through analysis of the ammonia-temperature relationship.
We also derive the emission potential of ammonia ⌈soil in areas with intensive agricultural practices during the growing season. ⌈soil has previously been investigated in field experiments and in controlled laboratory environments, but rarely on a regional/global scale using satellite measurements. We show that its value depends mainly on (i) skin temperature, (ii) ammonia concentration in the atmosphere, (iii) the rate of exchange between the soil and the atmosphere, and (iv) the lifetime of ammonia. Chemistry transport model simulations (GEOS-Chem), reanalysis data products, and IASI observations are used to derive and show, for the first time, ⌈soil distributions over Europe during the growing season. Finally, using two different socioeconomic climate model scenario simulations, along with the derived ⌈soil, we estimate the impacts of climate change (warming) alone on ammonia concentrations under different socioeconomic pathways scenarios.