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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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Atmos. Meas. Tech., 10, 2645-2667, 2017
https://doi.org/10.5194/amt-10-2645-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
25 Jul 2017
Validation of the CrIS fast physical NH3 retrieval with ground-based FTIR
Enrico Dammers1, Mark W. Shephard2, Mathias Palm3, Karen Cady-Pereira4, Shannon Capps5,a, Erik Lutsch6, Kim Strong6, James W. Hannigan7, Ivan Ortega7, Geoffrey C. Toon8, Wolfgang Stremme9, Michel Grutter9, Nicholas Jones10, Dan Smale11, Jacob Siemons2, Kevin Hrpcek12, Denis Tremblay13, Martijn Schaap14, Justus Notholt3, and Jan Willem Erisman1,15 1Cluster Earth and Climate, Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
2Environment and Climate Change Canada, Toronto, Ontario, Canada
3Institut für Umweltphysik, University of Bremen, Bremen, Germany
4Atmospheric and Environmental Research (AER), Lexington, Massachusetts, USA
5Department of Mechanical Engineering, University of Colorado, Boulder, Colorado, USA
6Department of Physics, University of Toronto, Toronto, Ontario, Canada
7NCAR, Boulder, Colorado, USA
8Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
9Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Mexico City, Mexico
10University of Wollongong, Wollongong, Australia
11National Institute of Water and Atmosphere, Lauder, New Zealand
12University of Wisconsin-Madison Space Science and Engineering Center (SSEC), Madison, Wisconsin, USA
13Science Data Processing, Inc., Laurel, MD, USA
14TNO Built Environment and Geosciences, Department of Air Quality and Climate, Utrecht, the Netherlands
15Louis Bolk Institute, Driebergen, the Netherlands
anow at: Civil, Architectural, and Environmental Engineering Department, Drexel University, Philadelphia, Pennsylvania, USA
Abstract. Presented here is the validation of the CrIS (Cross-track Infrared Sounder) fast physical NH3 retrieval (CFPR) column and profile measurements using ground-based 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  ×  1016 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 (< 1.0  × 1016 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 and 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.

Citation: Dammers, E., Shephard, M. W., Palm, M., Cady-Pereira, K., Capps, S., Lutsch, E., Strong, K., Hannigan, J. W., Ortega, I., Toon, G. C., Stremme, W., Grutter, M., Jones, N., Smale, D., Siemons, J., Hrpcek, K., Tremblay, D., Schaap, M., Notholt, J., and Erisman, J. W.: Validation of the CrIS fast physical NH3 retrieval with ground-based FTIR, Atmos. Meas. Tech., 10, 2645-2667, https://doi.org/10.5194/amt-10-2645-2017, 2017.
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Presented here is the validation of the CrIS fast physical retrieval (CFPR) NH3 column and profile measurements using ground-based Fourier transform infrared (FTIR) observations. 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). Furthermore, we find that CrIS and FTIR profile comparison differences are mostly within the range of the estimated retrieval uncertainties, with differences in the range of ~ 20 to 40 %.
Presented here is the validation of the CrIS fast physical retrieval (CFPR) NH3 column and...
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