Near-real time daily IASI/Metop-C ULB-LATMOS ammonia (NH3) L2 product (total column)

The near-real time daily IASI/Metop-C ammonia (NH3) total column dataset (ANNI-NH3-v3) includes the results of a flexible and robust NH3 retrieval algorithm from measurements of the Infrared Atmospheric Sounding Interferometer (IASI). The method is based on the calculation of a hyperspectral range index (HRI) and subsequent conversion to NH3 columns via a neural network. With this method: (1) complete temperature and humidity vertical profiles can be accounted for, (2) third‐party NH3 vertical profile information can be used, and (3) a full measurement uncertainty characterization is provided. Separate neural networks were trained for land and sea observations. The ANNI-v3 IASI product builds on the heritage of version 1 (Witburn et al., 2016), version 2 [(Van Damme et al., 2017)(https://amt.copernicus.org/articles/10/4905/2017/]) and recent improvements in the NN retrieval setup introduced in Franco et al. (2018) for the retrieval of volatiles organic compounds (VOCs). Recommendations for post-filtering the data and for averaging data in time or space are formulated in Van Damme et al. (2017). ANNI-NH3-v3 relies on near real time meteorological parameters provided by Eumetsat (L2 data from IASI PPF). The dataset is available on a global scale from September 2019 till June 2020.