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An intercomparison of total column-averaged nitrous oxide between ground-based FTIR TCCON and NDACC measurements at seven sites and comparisons with the GEOS-Chem model

Journal Article


Abstract


  • Nitrous oxide (N 2 O) is an important greenhouse gas and it can also generate nitric oxide, which depletes ozone in the stratosphere. It is a common target species of ground-based Fourier transform infrared (FTIR) nearinfrared (TCCON) and mid-infrared (NDACC) measurements. Both TCCON and NDACC networks provide a longterm global distribution of atmospheric N 2 O mole fraction. In this study, the dry-air column-averaged mole fractions of N 2 O (XN 2 O) from the TCCON and NDACC measurements are compared against each other at seven sites around the world (Ny-Ålesund, Sodankylä, Bremen, Izaña, Réunion, Wollongong, Lauder) in the time period of 2007–2017. The mean differences in XN 2 O between TCCON and NDACC (NDACC–TCCON) at these sites are between -3:32 and 1.37 ppb (-1:1 %–0.5 %) with standard deviations between 1.69 and 5.01 ppb (0.5 %–1.6 %), which are within the uncertainties of the two datasets. The NDACC N 2 O retrieval has good sensitivity throughout the troposphere and stratosphere, while the TCCON retrieval underestimates a deviation from the a priori in the troposphere and overestimates it in the stratosphere. As a result, the TCCON XN 2 O measurement is strongly affected by its a priori profile. Trends and seasonal cycles of XN 2 O are derived from the TCCON and NDACC measurements and the nearby surface flask sample measurements and compared with the results from GEOS-Chem model a priori and a posteriori simulations. The trends and seasonal cycles from FTIR measurement at Ny-Ålesund and Sodankylä are strongly affected by the polar winter and the polar vortex. The a posteriori N 2 O fluxes in the model are optimized based on surface N 2 O measurements with a 4D-Var inversion method. The XN 2 O trends from the GEOS-Chem a posteriori simulation (0:97-0:02 (1) ppb yr-1) are close to those from the NDACC (0:93- 0:04 ppb yr-1) and the surface flask sample measurements (0:93-0:02 ppb yr-1). The XN 2 O trend from the TCCON measurements is slightly lower (0:81-0:04 ppb yr-1) due to the underestimation of the trend in TCCON a priori simulation. The XN 2 O trends from the GEOS-Chem a priori simulation are about 1.25 ppb yr-1, and our study confirms that the N 2 O fluxes from the a priori inventories are overestimated. The seasonal cycles of XN 2 O from the FTIR measurements and the model simulations are close to each other in the Northern Hemisphere with a maximum in August–October and a minimum in February–April. However, in the Southern Hemisphere, the modeled XN 2 O values show a minimum in February–April while the FTIR XN 2 O retrievals show different patterns. By comparing the partial column-averaged N 2 O from the model and NDACC for three vertical ranges (surface–8, 8–17, 17–50 km), we find that the discrepancy in the XN 2 O seasonal cycle between the model simulations and the FTIR measurements in the Southern Hemisphere is mainly due to their stratospheric differences.

Authors


  •   Zhou, Minqiang (external author)
  •   Langerock, Bavo (external author)
  •   Wells, Kelley (external author)
  •   Millet, Dylan B. (external author)
  •   Vigouroux, C (external author)
  •   Sha, Mahesh Kumar. (external author)
  •   Hermans, Christian (external author)
  •   Metzger, J -M. (external author)
  •   Kivi, Rigel (external author)
  •   Heikkinen, Pauli (external author)
  •   Smale, D (external author)
  •   Pollard, David F. (external author)
  •   Jones, Nicholas B.
  •   Deutscher, Nicholas M.
  •   Blumenstock, Thomas (external author)
  •   Schneider, Matthias (external author)
  •   Palm, Mathias (external author)
  •   Notholt, Justus (external author)
  •   Hannigan, James W. (external author)
  •   de Maziere, Martine (external author)

Publication Date


  • 2019

Citation


  • Zhou, M., Langerock, B., Wells, K. C., Millet, D. B., Vigouroux, C., Sha, M. Kumar., Hermans, C., Metzger, J., Kivi, R., Heikkinen, P., Smale, D., Pollard, D. F., Jones, N., Deutscher, N. M., Blumenstock, T., Schneider, M., Palm, M., Notholt, J., Hannigan, J. W. & De Maziere, M. (2019). An intercomparison of total column-averaged nitrous oxide between ground-based FTIR TCCON and NDACC measurements at seven sites and comparisons with the GEOS-Chem model. Atmospheric Measurement Techniques, 12 (2), 1393-1408.

Scopus Eid


  • 2-s2.0-85062538489

Number Of Pages


  • 15

Start Page


  • 1393

End Page


  • 1408

Volume


  • 12

Issue


  • 2

Place Of Publication


  • Germany

Abstract


  • Nitrous oxide (N 2 O) is an important greenhouse gas and it can also generate nitric oxide, which depletes ozone in the stratosphere. It is a common target species of ground-based Fourier transform infrared (FTIR) nearinfrared (TCCON) and mid-infrared (NDACC) measurements. Both TCCON and NDACC networks provide a longterm global distribution of atmospheric N 2 O mole fraction. In this study, the dry-air column-averaged mole fractions of N 2 O (XN 2 O) from the TCCON and NDACC measurements are compared against each other at seven sites around the world (Ny-Ålesund, Sodankylä, Bremen, Izaña, Réunion, Wollongong, Lauder) in the time period of 2007–2017. The mean differences in XN 2 O between TCCON and NDACC (NDACC–TCCON) at these sites are between -3:32 and 1.37 ppb (-1:1 %–0.5 %) with standard deviations between 1.69 and 5.01 ppb (0.5 %–1.6 %), which are within the uncertainties of the two datasets. The NDACC N 2 O retrieval has good sensitivity throughout the troposphere and stratosphere, while the TCCON retrieval underestimates a deviation from the a priori in the troposphere and overestimates it in the stratosphere. As a result, the TCCON XN 2 O measurement is strongly affected by its a priori profile. Trends and seasonal cycles of XN 2 O are derived from the TCCON and NDACC measurements and the nearby surface flask sample measurements and compared with the results from GEOS-Chem model a priori and a posteriori simulations. The trends and seasonal cycles from FTIR measurement at Ny-Ålesund and Sodankylä are strongly affected by the polar winter and the polar vortex. The a posteriori N 2 O fluxes in the model are optimized based on surface N 2 O measurements with a 4D-Var inversion method. The XN 2 O trends from the GEOS-Chem a posteriori simulation (0:97-0:02 (1) ppb yr-1) are close to those from the NDACC (0:93- 0:04 ppb yr-1) and the surface flask sample measurements (0:93-0:02 ppb yr-1). The XN 2 O trend from the TCCON measurements is slightly lower (0:81-0:04 ppb yr-1) due to the underestimation of the trend in TCCON a priori simulation. The XN 2 O trends from the GEOS-Chem a priori simulation are about 1.25 ppb yr-1, and our study confirms that the N 2 O fluxes from the a priori inventories are overestimated. The seasonal cycles of XN 2 O from the FTIR measurements and the model simulations are close to each other in the Northern Hemisphere with a maximum in August–October and a minimum in February–April. However, in the Southern Hemisphere, the modeled XN 2 O values show a minimum in February–April while the FTIR XN 2 O retrievals show different patterns. By comparing the partial column-averaged N 2 O from the model and NDACC for three vertical ranges (surface–8, 8–17, 17–50 km), we find that the discrepancy in the XN 2 O seasonal cycle between the model simulations and the FTIR measurements in the Southern Hemisphere is mainly due to their stratospheric differences.

Authors


  •   Zhou, Minqiang (external author)
  •   Langerock, Bavo (external author)
  •   Wells, Kelley (external author)
  •   Millet, Dylan B. (external author)
  •   Vigouroux, C (external author)
  •   Sha, Mahesh Kumar. (external author)
  •   Hermans, Christian (external author)
  •   Metzger, J -M. (external author)
  •   Kivi, Rigel (external author)
  •   Heikkinen, Pauli (external author)
  •   Smale, D (external author)
  •   Pollard, David F. (external author)
  •   Jones, Nicholas B.
  •   Deutscher, Nicholas M.
  •   Blumenstock, Thomas (external author)
  •   Schneider, Matthias (external author)
  •   Palm, Mathias (external author)
  •   Notholt, Justus (external author)
  •   Hannigan, James W. (external author)
  •   de Maziere, Martine (external author)

Publication Date


  • 2019

Citation


  • Zhou, M., Langerock, B., Wells, K. C., Millet, D. B., Vigouroux, C., Sha, M. Kumar., Hermans, C., Metzger, J., Kivi, R., Heikkinen, P., Smale, D., Pollard, D. F., Jones, N., Deutscher, N. M., Blumenstock, T., Schneider, M., Palm, M., Notholt, J., Hannigan, J. W. & De Maziere, M. (2019). An intercomparison of total column-averaged nitrous oxide between ground-based FTIR TCCON and NDACC measurements at seven sites and comparisons with the GEOS-Chem model. Atmospheric Measurement Techniques, 12 (2), 1393-1408.

Scopus Eid


  • 2-s2.0-85062538489

Number Of Pages


  • 15

Start Page


  • 1393

End Page


  • 1408

Volume


  • 12

Issue


  • 2

Place Of Publication


  • Germany