Temporal variations of atmospheric NH3 revealed from space: from intraday cycles to long-term global trends
Résumé
Ammonia NH3 is now widely recognized as a major primary pollutant, deteriorating water, soil and air quality. While the importance of monitoring and regulating atmospheric NH3 emissions has been underlined for decades by experts in the field and endorsed or ratified by a multitude of international organizations, it is only recently that the issue is making its way onto the political agendas. In the past decade, it was discovered that high-resolution infrared satellites observations can measure atmospheric NH3, leading to major progress in our understanding of this atmospheric compound and its sources, and to new possibilities for benchmarking or enforcing regulations.
Currently, several polar-orbiting instruments are in orbit that measure NH3 global distributions twice a day. In this talk, we present the first observations of NH3 from the Geostationary Interferometric Infrared Sounder (GIIRS) onboard the Chinese FY- 4A satellite. GIIRS measures almost all of Asia ten times per day. As its spectral range includes a large portion of the thermal infrared, the instrument allows studying for the first time the diurnal and nocturnal variations of atmospheric NH3. We analyze the daily cycle of NH3 in detail over two small regions in Pakistan and China, and how it varies across different seasons.
In keeping with the temporal theme, we present in the second part of this talk, long term global trends of NH3 derived using the 2008-2018 reanalyzed IASI-NH3 dataset. Trends are presented and analyzed from the regional to the national and global scale.