The First Global Map of Atmospheric Ammonia (NH3) as Observed by the HIRAS/FY-3D Satellite

Atmospheric ammonia (NH3) is a chemically active trace gas that plays an important role in the atmospheric environment and climate change. Satellite remote sensing is a powerful technique to monitor NH3concentration based on the absorption lines of NH3in the thermal infrared region. In this study, we establish a retrieval algorithm to derive the NH3column from the Hyperspectral Infrared Atmospheric Sounder (HIRAS) onboard the Chinese FengYun (FY)-3D satellite and present the first atmospheric NH3column global map observed by the HIRAS instrument. The HIRAS observations can well capture NH3hotspots around the world, e.g., India, West Africa, and East China, where large NH3emissions exist. The HIRAS NH3columns are also compared to the space-based Infrared Atmospheric Sounding Interferometer (IASI) measurements, and we find that the two instruments observe a consistent NH3global distribution, with correlation coefficient (R) values of 0.28–0.73. Finally, some remaining issues about the HIRAS NH3retrieval are discussed.