Abstract
Abstract. Despite its clear importance, the monitoring of atmospheric ammonia, including its sources, sinks, and links to the greater nitrogen cycle, remains limited. Satellite data are helping to fill the gap in monitoring from sporadic conventional ground- and aircraft-based observations to better inform policymakers and assess the impact of any ammonia-related policies. Presented is a description and survey that demonstrate the capabilities of the Cross-track Infrared Sounder (CrIS) ammonia product for monitoring, air quality forecast model evaluation, dry deposition estimates, and emission estimates from an agricultural hotspot. For model evaluation, while there is a general agreement in the spatial allocation of known major agricultural ammonia hotspots across North America, the satellite observations show some high-latitude regions during peak forest fire activity often have ammonia concentrations approaching those in agricultural hotspots. The CrIS annual ammonia dry depositions in Canada (excluding the territories) and the US have average and annual variability values of ∼0.8±0.08 and ∼1.23±0.09 Tg N yr−1, respectively. These satellite-derived dry depositions of reactive nitrogen from NH3 with NO2 show an annual ratio of NH3 compared to their sum (NH3+NO2) of ∼82 % and ∼55 % in Canada and the US, respectively. Furthermore, we show the use of CrIS satellite observations to estimate annual and seasonal emissions near Lethbridge, Alberta, Canada, a region dominated by high-emission concentrated animal feeding operations (CAFOs); the satellite annual emission estimate of 37.1±6.3 kt yr−1 is at least double the value reported in current bottom-up emission inventories for this region.
Highlights
Ammonia (NH3) is the most abundant alkaline gas in the atmosphere and has major impacts on air, soil, and water quality
Satellite observations of lower tropospheric ammonia have only been possible in the past decade through concurrent improvements in both the radiometric capabilities of infrared instruments on satellites and the radiative transfer forward modelling and inversion algorithms. This was first demonstrated by Beer et al (2008) with NASA’s Tropospheric Emission Spectrometer (TES) observations, which have since been followed by ammonia observations from the European Space Agency (ESA) Infrared Atmospheric Sounder Interferometer (IASI; Clarisse et al, 2009), the NASA/NOAA Cross-track Infrared Sounder (CrIS; Shephard and Cady-Pereira, 2015),the NASA Atmospheric Infrared Sounder (AIRS; Warner et al, 2016), and the JAXA Greenhouse Gases Observing Satellite (GOSAT; Someya et al, 2020)
Satellite observations of lower tropospheric ammonia are a relatively new development with the initial proof of concept in the past decade (Beer et al, 2008); there is a great potential for advancements in the retrievals and exploration of new applications
Summary
Ammonia (NH3) is the most abundant alkaline gas in the atmosphere and has major impacts on air, soil, and water quality. Satellite observations of lower tropospheric ammonia have only been possible in the past decade through concurrent improvements in both the radiometric capabilities of infrared instruments on satellites and the radiative transfer forward modelling and inversion algorithms This was first demonstrated by Beer et al (2008) with NASA’s Tropospheric Emission Spectrometer (TES) observations, which have since been followed by ammonia observations from the European Space Agency (ESA) Infrared Atmospheric Sounder Interferometer (IASI; Clarisse et al, 2009), the NASA/NOAA Cross-track Infrared Sounder (CrIS; Shephard and Cady-Pereira, 2015),the NASA Atmospheric Infrared Sounder (AIRS; Warner et al, 2016), and the JAXA Greenhouse Gases Observing Satellite (GOSAT; Someya et al, 2020). Presented here is a current survey of the CrIS NH3 fast physical retrieval (CFPR) product characteristics with some example applications
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