Validation of the CrIS fast physical NH<sub>3</sub> retrieval with ground-based FTIR

Abstract

Abstract. Presented here is the validation of the CrIS (Cross-track Infrared Sounder) fast physical NH 3 retrieval (CFPR) column and profile measurements using groundbased Fourier transform infrared (FTIR) observations. We use the total columns and profiles from seven FTIR sites in the Network for the Detection of Atmospheric Composition Change (NDACC) to validate the satellite data products. The overall FTIR and CrIS total columns have a positive correlation of r = 0.77 (N = 218) with very little bias (a slope of 1.02). Binning the comparisons by total column amounts, for concentrations larger than 1.0 × 10 16 molecules cm −2 , i.e. ranging from moderate to polluted conditions, the relative difference is on average ∼ 0-5 % with a standard deviation of 25-50 %, which is comparable to the estimated retrieval uncertainties in both CrIS and the FTIR. For the smallest total column range (< 1.0x × 10 16 molecules cm −2 ) where there are a large number of observations at or near the CrIS noise level (detection limit) the absolute differences between CrIS and the FTIR total columns show a slight positive column bias. The CrIS and FTIR profile comparison differences are mostly within the range of the single-level retrieved profile values from estimated retrieval uncertainties, showing average differences in the range of ∼ 20 to 40 %. The CrIS retrievals typically show good vertical sensitivity down into the boundary layer which typically peaks at ∼ 850 hPa (∼ 1.5 km). At this level the median absolute difference is 0.87 (std = ±0.08) ppb, corresponding to a median relative difference of 39 % (std = ±2 %). Most of the absolute andPublished by Copernicus Publications on behalf of the European Geosciences Union. 2646 E. Dammers et al.: Validation of the CrIS fast physical NH 3 retrieval with ground-based FTIR relative profile comparison differences are in the range of the estimated retrieval uncertainties. At the surface, where CrIS typically has lower sensitivity, it tends to overestimate in low-concentration conditions and underestimate in higher atmospheric concentration conditions.

Gas‐aerosol partitioning of ammonia in biomass burning plumes: Implications for the interpretation of spaceborne observations of ammonia and the radiative forcing of ammonium nitrate

“…In addition, changes in the nature of the fire (e.g., degree of flaming) can introduce significant variations in biomass burning emission on diurnal to seasonal time scales, which are not captured by GFED [ Whitburn et al , ]. Recent comparisons with ground‐based Fourier transform infrared [ Dammers et al , , ] show that NH 3 retrieval from IASI has a significant low bias (−50%) which decreases to ≃−25% for columns exceeding 1.5 × 10 16 mol cm −2 . Filtering for high NH 3 columns (>1.5 × 10 16 mol cm −2 ) does not significantly affect the derived .…”

“…The 95% bootstrapped confidence interval of the mean is indicated in bracket. c The derived ER NH 3 ∕CO is a lower bound [Dammers et al, 2017]. d Alvarado et al [2010].…”

“…by GFED [Whitburn et al, 2015]. Recent comparisons with ground-based Fourier transform infrared [Dammers et al, , 2017 show that NH 3 retrieval from IASI has a significant low bias (−50%) which decreases to ≃ −25% for columns exceeding 1.5 × 10 16 mol cm −2 . Filtering for high NH 3 columns (>1.5 × 10 16 mol cm −2 ) does not significantly affect the derived ER NH 3 ∕CO .…”

Dry Deposition of Reactive Nitrogen From Satellite Observations of Ammonia and Nitrogen Dioxide Over North America

“…An example of this over the Arctic during the summer of 2013 is provided in Figure S1 in the supporting information. Initial CrIS validation studies show that CrIS compares well with ground‐based Fourier transform infrared (FTIR) (Dammers et al, ) measurements with a correlation of 0.77, and very little bias (+2%) in the total column values. Initial evaluation of the CrIS surface product using surface point measurements from the Ammonia Monitoring Network (AMoN) during the 2013 warm season shows that even with the inherent sampling differences between the observations they compare well with a correlation of 0.76 and an overall mean difference (AMoN − CrIS) of ~ −15% (refer to the supporting information for more details).…”

Satellite evidence of substantial rain-induced soil emissions of ammonia across the Sahel

“…This increase in microbial activity is accompanied by pulsed emissions of trace gases such as carbon dioxide (CO 2 ; Emmerich, 2003;Huxman et al, 2004;Saetre and Stark, 2004) and NO (e.g., Anderson and Levine, 1986;Davidson, 1992), which can be an important component of annual emissions (Davidson, 1992;Jaeglé et al, 2004). As the availability of NH + 4 is a major control over NH 3 volatilization (Nelson, 1982;Schlesinger and Peterjohn, 1991), a flush of N mineralization and an increase in soil moisture would be expected to trigger an NH 3 emission pulse as well.…”