References

AMT

Atmospheric Measurement Techniques

AMT

Atmos. Meas. Tech.

1867-8548

Copernicus Publications

Göttingen, Germany

10.5194/amt-7-4081-2014

Multistation intercomparison of column-averaged methane from NDACC and TCCON: impact of dynamical variability

Ostler

¹ Sussmann

¹ Rettinger

¹ Deutscher

N. M.

https://orcid.org/0000-0002-2906-2577

³ ⁴ Dohe

² Hase

² Jones

³ Palm

https://orcid.org/0000-0001-7191-6911

⁴ Sinnhuber

B.-M.

https://orcid.org/0000-0001-9608-7320

Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany

Karlsruhe Institute of Technology, IMK-ASF, Karlsruhe, Germany

University of Wollongong, New South Wales, Wollongong, Australia

Institute of Environmental Physics, University of Bremen, Bremen, Germany

03 12 2014

7 12 4081 4101

2014

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://amt.copernicus.org/articles/7/4081/2014/amt-7-4081-2014.html

The full text article is available as a PDF file from https://amt.copernicus.org/articles/7/4081/2014/amt-7-4081-2014.pdf

Dry-air column-averaged mole fractions of methane (XCH4) retrieved from ground-based solar Fourier transform infrared (FTIR) measurements provide valuable information for satellite validation, evaluation of chemical-transport models, and source-sink-inversions. In this context, Sussmann et al. (2013) have shown that midinfrared (MIR) soundings from the Network for the Detection of Atmospheric Composition Change (NDACC) can be combined with near-infrared (NIR) soundings from the Total Carbon Column Observing Network (TCCON) without the need to apply an overall intercalibration factor. However, in spite of efforts to reduce a priori impact, some residual seasonal biases were identified, and the reasons behind remained unclear. In extension to this previous work, which was based on multiannual quasi-coincident MIR and NIR measurements from the stations Garmisch (47.48° N, 11.06° E, 743 m a.s.l.) and Wollongong (34.41° S, 150.88° E, 30 m a.s.l.), we now investigate upgraded retrievals with longer temporal coverage and include three additional stations (Ny-Ålesund, 78.92° N, 11.93° E, 20 m a.s.l.; Karlsruhe, 49.08° N, 8.43° E, 110 m a.s.l.; Izaña, 28.31° N, 16.45° W, 2.370 m a.s.l.). Our intercomparison results (except for Ny-Ålesund) confirm that there is no overall bias between MIR and NIR XCH4 retrievals, and all MIR and NIR time series reveal a quasi-periodic seasonal bias for all stations, except for Izaña. We find that dynamical variability causes MIR–NIR differences of up to ~ 30 ppb (parts per billion) for Ny-Ålesund, ~ 20 ppb for Wollongong, ~ 18 ppb for Garmisch, and ~ 12 ppb for Karlsruhe. The mechanisms behind this variability are elaborated via two case studies, one dealing with stratospheric subsidence induced by the polar vortex at Ny-Ålesund and the other with a deep stratospheric intrusion event at Garmisch. Smoothing effects caused by the dynamical variability during these events are different for MIR and NIR retrievals depending on the altitude of the perturbation area. MIR retrievals appear to be more realistic in the case of stratospheric subsidence, while NIR retrievals are more accurate in the case of stratosphere–troposphere exchange (STE) in the upper troposphere/lower stratosphere (UTLS) region. About 35% of the FTIR measurement days at Garmisch are impacted by STE, and about 23% of the measurement days at Ny-Ålesund are influenced by polar vortex subsidence. The exclusion of data affected by these dynamical situations resulted in improved agreement of MIR and NIR seasonal cycles for Ny-Ålesund and Garmisch. We found that dynamical variability is a key factor in constraining the accuracy of MIR and NIR seasonal cycles. To mitigate this impact it is necessary to use more realistic a priori profiles that take these dynamical events into account (e.g., via improved models), and/or to improve the FTIR retrievals to achieve a more uniform sensitivity at all altitudes (possibly including profile retrievals for the TCCON data).

References 1

Angelbratt, J., Mellqvist, J., Blumenstock, T., Borsdorff, T., Brohede, S., Duchatelet, P., Forster, F., Hase, F., Mahieu, E., Murtagh, D., Petersen, A. K., Schneider, M., Sussmann, R., and Urban, J.: A new method to detect long term trends of methane (CH4) and nitrous oxide (N2O) total columns measured within the NDACC ground-based high resolution solar FTIR network, Atmos. Chem. Phys., 11, 6167–6183, <a href="http://dx.doi.org/10.5194/acp-11-6167-2011">https://doi.org/10.5194/acp-11-6167-2011</a>, 2011.

Allan, W., Struthers, H., and Lowe, D. C.: Methane carbon isotope effects caused by atomic chlorine in the marine boundary layer: Global model results compared with Southern Hemisphere measurements, J. Geophys. Res., 112, D04306, <a href="http://dx.doi.org/10.1029/2006JD007369">https://doi.org/10.1029/2006JD007369</a>, 2007.

Archer, D.: Methane hydrate stability and anthropogenic climate change, Global Biogeochem. Cy., 4, 521–544, <a href="http://dx.doi.org/10.5194/bg-4-521-2007">https://doi.org/10.5194/bg-4-521-2007</a>, 2007.

Belikov, D., Maksyutov, S., Miyasaka, T., Saeki, T., Zhuravlev, R., and Kiryushov, B.: Mass-conserving tracer transport modelling on a reduced latitude-longitude grid with NIES-TM, Geosci. Model Dev., 4, 207–222, <a href="http://dx.doi.org/10.5194/gmd-4-207-2011">https://doi.org/10.5194/gmd-4-207-2011</a>, 2011.

Bergamaschi, P., Frankenberg, C., Meirink, J. F., Krol, M., Villani, M. G., Houweling, S., Dentener, F., Dlugokencky, E. J., Miller, J. B., Gatti, L. V., Engel, A., and Levin, I.: Inverse modeling of global and regional CH4 emissions using SCIAMACHY satellite retrievals, J. Geophys. Res., 114, D22301, <a href="http://dx.doi.org/10.1029/2009JD012287">https://doi.org/10.1029/2009JD012287</a>, 2009.

Bergamaschi, P., Houweling, S., Segers, A., Krol, M., Frankenberg, C., Scheepmaker, R. A., Dlugokencky, E., Wofsy, S. C., Kort, E. A., Sweeney, C., Schuck, T., Brenninkmeijer, C., Chen, H., Beck, V., and Gerbig, C.: Atmospheric CH4 in the first decade of the 21st century: inverse modeling analysis using SCIAMACHY satellite retrievals and NOAA surface measurements, J. Geophys. Res., 118, 7350–7369, <a href="http://dx.doi.org/10.1002/jgrd.50480">https://doi.org/10.1002/jgrd.50480</a>, 2013.

Borsdorff, T. and Sussmann, R.: On seasonality of stratomesospheric CO above midlatitudes: New insight from solar FTIR spectrometry at Zugspitze and Garmisch, Geophys. Res. Lett., 36, L21804, <a href="http://dx.doi.org/10.1029/2009GL040056">https://doi.org/10.1029/2009GL040056</a>, 2009.

Bousquet, P., Ciais, P., Miller, J. B., Dlugokencky, E. J., Hauglustaine, D. A., Prigent, C., Van der Werf, G. R., Peylin, P., Brunke, E. G., Carouge, C., Langenfels, R. L., Lathiere, J., Papa, F., Ramonet, M., Schmidt, M., Steele, L. P., Tyler, S. C., and White, J.: Contribution of anthropogenic and natural sources to atmospheric methane variability, Nature, 443, 439–443, 2006.

Bousquet, P., Ringeval, B., Pison, I., Dlugokencky, E. J., Brunke, E.-G., Carouge, C., Chevallier, F., Fortems-Cheiney, A., Frankenberg, C., Hauglustaine, D. A., Krummel, P. B., Langenfelds, R. L., Ramonet, M., Schmidt, M., Steele, L. P., Szopa, S., Yver, C., Viovy, N., and Ciais, P.: Source attribution of the changes in atmospheric methane for 2006–2008, Atmos. Chem. Phys., 11, 3689–3700, <a href="http://dx.doi.org/10.5194/acp-11-3689-2011">https://doi.org/10.5194/acp-11-3689-2011</a>, 2011.

Butz, A., Guerlet, S., Hasekamp, O., Schepers, D., Galli, A., Aben, I., Frankenberg, C., Hartmann, J. M., Tran, H., Kuze, A., Keppel-Aleks, G., Toon, G., Wunch, D., Wennberg, P., Deutscher, N., Griffith, D., Macatangay, R., Messerschmidt, J., Notholt, J., and Warneke, T.: Toward accurate CO2 and CH4 observations from GOSAT, Geophys. Res. Lett., 38, L14812, <a href="http://dx.doi.org/10.1029/2011GL047888">https://doi.org/10.1029/2011GL047888</a>, 2011.

Chevallier, F., Deutscher, N., Conway, C. J., Ciais, P., Ciattaglia, L., Dohe, S., Fröhlich, M., Gomez-Pelaez, A.J., Griffith, D., Hase, F., Haszpra, L., Krummel, P., Kyrö, E., Labuschagne, C., Langenfelds, R., Machida, T., Maignan, F., Matsueda, H., Morino, I., Notholt, J., Ramonet, M., Sawa, Y., Schmidt, M., Sherlock, V., Steele, P., Strong, K., Sussmann, R., Wennberg, P., Wofsy, S., Worthy, D., Wunch, D., and Zimnoch, M.: Global CO2 surface fluxes inferred from surface air-sample measurements and from surface retrievals of the CO2 total column, Geophys. Res. Lett., 38, L24810, <a href="http://dx.doi.org/10.1029/2011GL049899">https://doi.org/10.1029/2011GL049899</a>, 2011.

Cicerone, R. J. and Oremland, R. S.: Biogeochemical aspects of atmospheric methane, Global Biogeochem. Cy., 2, 299–327, <a href="http://dx.doi.org/10.1029/GB002i004p00299">https://doi.org/10.1029/GB002i004p00299</a>, 1988.

de Laat, A. T. J., Gloudemans, A. M. S., Schrijver, H., Aben, I., Nagahama, Y., Suzuki, K., Mahieu, E., Jones, N. B., Paton-Walsh, C., Deutscher, N. M., Griffith, D. W. T., De Mazière, M., Mittermeier, R. L., Fast, H., Notholt, J., Palm, M., Hawat, T., Blumenstock, T., Hase, F., Schneider, M., Rinsland, C., Dzhola, A. V., Grechko, E. I., Poberovskii, A. M., Makarova, M. V., Mellqvist, J., Strandberg, A., Sussmann, R., Borsdorff, T., and Rettinger, M.: Validation of five years (2003–2007) of SCIAMACHY CO total column measurements using ground-based spectrometer observations, Atmos. Meas. Tech., 3, 1457–1471, <a href="http://dx.doi.org/10.5194/amt-3-1457-2010">https://doi.org/10.5194/amt-3-1457-2010</a>, 2010.

De Mazière, M., Vigouroux, C., Bernath, P. F., Baron, P., Blumenstock, T., Boone, C., Brogniez, C., Catoire, V., Coffey, M., Duchatelet, P., Griffith, D., Hannigan, J., Kasai, Y., Kramer, I., Jones, N., Mahieu, E., Manney, G. L., Piccolo, C., Randall, C., Robert, C., Senten, C., Strong, K., Taylor, J., Tétard, C., Walker, K. A., and Wood, S.: Validation of ACE-FTS v2.2 methane profiles from the upper troposphere to the lower mesosphere, Atmos. Chem. Phys., 8, 2421–2435, <a href="http://dx.doi.org/10.5194/acp-8-2421-2008">https://doi.org/10.5194/acp-8-2421-2008</a>, 2008.

Dlugokencky, E. J., Nisbet E. G., Fisher R., and Lowry, D.: Global atmospheric methane: budget, changes and dangers, Phil. Trans. R. Soc. A, 369, 2058–2072, <a href="http://dx.doi.org/10.1098/rsta.2010.0341">https://doi.org/10.1098/rsta.2010.0341</a>, 2011.

Dohe, S., Sherlock, V., Hase, F., Gisi, M., Robinson, J., Sepúlveda, E., Schneider, M., and Blumenstock, T.: A method to correct sampling ghosts in historic near-infrared Fourier transform spectrometer (FTS) measurements, Atmos. Meas. Tech., 6, 1981–1992, <a href="http://dx.doi.org/10.5194/amt-6-1981-2013">https://doi.org/10.5194/amt-6-1981-2013</a>, 2013.

Frankenberg, C., Warneke, T., Butz, A., Aben, I., Hase, F., Spietz, P., and Brown, L. R.: Pressure broadening in the 2ν3 band of methane and its implication on atmospheric retrievals, Atmos. Chem. Phys., 8, 5061–5075, <a href="http://dx.doi.org/10.5194/acp-8-5061-2008">https://doi.org/10.5194/acp-8-5061-2008</a>, 2008.

Fraser, A., Palmer, P. I., Feng, L., Boesch, H., Cogan, A., Parker, R., Dlugokencky, E. J., Fraser, P. J., Krummel, P. B., Langenfelds, R. L., O'Doherty, S., Prinn, R. G., Steele, L. P., van der Schoot, M., and Weiss, R. F.: Estimating regional methane surface fluxes: the relative importance of surface and GOSAT mole fraction measurements, Atmos. Chem. Phys., 13, 5697–5713, <a href="http://dx.doi.org/10.5194/acp-13-5697-2013">https://doi.org/10.5194/acp-13-5697-2013</a>, 2013.

Garcia, R. R., Marsh, D. R., Kinnison, D. E., Boville, B. A., and Sassi, F.: Simulation of secular trends in the middle atmosphere, 1950–2003, J. Geophys. Res., 112, D09301, <a href="http://dx.doi.org/10.1029/2006JD007485">https://doi.org/10.1029/2006JD007485</a>, 2007.

Geibel, M. C., Messerschmidt, J., Gerbig, C., Blumenstock, T., Chen, H., Hase, F., Kolle, O., Lavrič, J. V., Notholt, J., Palm, M., Rettinger, M., Schmidt, M., Sussmann, R., Warneke, T., and Feist, D. G.: Calibration of column-averaged CH4 over European TCCON FTS sites with airborne in-situ measurements, Atmos. Chem. Phys., 12, 8763–8775, <a href="http://dx.doi.org/10.5194/acp-12-8763-2012">https://doi.org/10.5194/acp-12-8763-2012</a>, 2012.

Hase, F., Hannigan, J. W., Coffey, M. T., Goldman, A., Höpfner, M., Jones, N. B., Rinsland, C. P., and Wood, S. W.: Intercomparison of retrieval codes used for the analysis of high-resolution, ground-based FTIR measurements, J. Quant. Spectrosc. Radiat. Transfer, 87, 25–52, 2004.

Houweling, S., van der Werf, G. R., Goldewijk, K. K., Roeckmann, T., and Aben, I.: Early anthropogenic CH4 emissions and the variation of CH4 and 13CH4 over the last millennium, Global Biogeochem. Cy., 22, GB1002, <a href="http://dx.doi.org/10.1029/2007GB002961">https://doi.org/10.1029/2007GB002961</a>, 2008.

Houweling, S., Aben, I., Breon, F.-M., Chevallier, F., Deutscher, N., Engelen, R., Gerbig, C., Griffith, D., Hungershoefer, K., Macatangay, R., Marshall, J., Notholt, J., Peters, W., and Serrar, S.: The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements, Atmos. Chem. Phys., 10, 9981–9992, <a href="http://dx.doi.org/10.5194/acp-10-9981-2010">https://doi.org/10.5194/acp-10-9981-2010</a>, 2010.

Houweling, S., Krol, M., Bergamaschi, P., Frankenberg, C., Dlugokencky, E. J., Morino, I., Notholt, J., Sherlock, V., Wunch, D., Beck, V., Gerbig, C., Chen, H., Kort, E. A., Röckmann, T., and Aben, I.: A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements, Atmos. Chem. Phys., 14, 3991–4012, <a href="http://dx.doi.org/10.5194/acp-14-3991-2014">https://doi.org/10.5194/acp-14-3991-2014</a>, 2014.

Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J. G., Dlugokencky, E. J., Bergamaschi, P., Bergmann, D., Blake, D. R., Bruhwiler, L., Cameron-Smith, P., Castaldi, S., Chevallier, F., Feng, L., Fraser, A., Heimann, M., Hodson, E. L., Houweling, S., Josse, B., Fraser, P. J., Krummel, P. B., Lamarque, J. F., Langenfelds, R. L., Le Quere, C., Naik, V., O'Doherty, S., Palmer, P. I., Pison, I., Plummer, D., Poulter, B., Prinn, R. G., Rigby, M., Ringeval, B., Santini, M., Schmidt, M., Shindell, D. T., Simpson, I., Spahni, R., Steele, L. P., Strode, S. A., Sudo, K., Szopa, S., van der Werf, G. R., Voulgarakis, A., van Weele, M., Weiss, R. F., Williams, J. E., and Zeng, G.: Three decades of global methane sources and sinks, Nat. Geosci., 6, 813–823, <a href="http://dx.doi.org/10.1038/ngeo1955">https://doi.org/10.1038/ngeo1955</a>, 2013.

Kohlhepp, R., Ruhnke, R., Chipperfield, M. P., De Mazière, M., Notholt, J., Barthlott, S., Batchelor, R. L., Blatherwick, R. D., Blumenstock, Th., Coffey, M. T., Demoulin, P., Fast, H., Feng, W., Goldman, A., Griffith, D. W. T., Hamann, K., Hannigan, J. W., Hase, F., Jones, N. B., Kagawa, A., Kaiser, I., Kasai, Y., Kirner, O., Kouker, W., Lindenmaier, R., Mahieu, E., Mittermeier, R. L., Monge-Sanz, B., Morino, I., Murata, I., Nakajima, H., Palm, M., Paton-Walsh, C., Raffalski, U., Reddmann, Th., Rettinger, M., Rinsland, C. P., Rozanov, E., Schneider, M., Senten, C., Servais, C., Sinnhuber, B.-M., Smale, D., Strong, K., Sussmann, R., Taylor, J. R., Vanhaelewyn, G., Warneke, T., Whaley, C., Wiehle, M., and Wood, S. W.: Observed and simulated time evolution of HCl, ClONO2, and HF total column abundances, Atmos. Chem. Phys., 12, 3527–3556, <a href="http://dx.doi.org/10.5194/acp-12-3527-2012">https://doi.org/10.5194/acp-12-3527-2012</a>, 2012.

Lin, M., Fiore, A. M., Cooper, O. R., Horowitz, L. W., Langford, A. O., Levy II, H., Johnson, B. J., Naik, V., Oltmans, S. J., and Senff, C. J.: Springtime high surface ozone events over the western United States: Quantifying the role of stratospheric intrusions, J. Geophys. Res., 117, D00V22, <a href="http://dx.doi.org/10.1029/2012JD018151">https://doi.org/10.1029/2012JD018151</a>, 2012.

Lindenmaier, R., Strong, K., Batchelor, R. L., Chipperfield, M. P., Daffer, W. H., Drummond, J. R., Duck, T. J., Fast, H., Feng, W., Fogal, P. F., Kolonjari, F., Manney, G. L., Manson, A., Meek, C., Mittermeier, R. L., Nott, G. J., Perro, C., and Walker, K. A.: Unusually low ozone, HCl, and HNO3 column measurements at Eureka, Canada during winter/spring 2011, Atmos. Chem. Phys., 12, 3821–3835, <a href="http://dx.doi.org/10.5194/acp-12-3821-2012">https://doi.org/10.5194/acp-12-3821-2012</a>, 2012.

Messerschmidt, J., Geibel, M. C., Blumenstock, T., Chen, H., Deutscher, N. M., Engel, A., Feist, D. G., Gerbig, C., Gisi, M., Hase, F., Katrynski, K., Kolle, O., Lavrič, J. V., Notholt, J., Palm, M., Ramonet, M., Rettinger, M., Schmidt, M., Sussmann, R., Toon, G. C., Truong, F., Warneke, T., Wennberg, P. O., Wunch, D., and Xueref-Remy, I.: Calibration of TCCON column-averaged CO2: the first aircraft campaign over European TCCON sites, Atmos. Chem. Phys., 11, 10765–10777, <a href="http://dx.doi.org/10.5194/acp-11-10765-2011">https://doi.org/10.5194/acp-11-10765-2011</a>, 2011.

Monteil, G., Houweling, S., Butz, A., Guerlet, S., Schepers, D., Hasekamp, O., Frankenberg, C., Scheepmaker, R., Aben, I., and Röckmann, T.: Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations, J. Geophys. Res. Atmos., 118, 11807–11823, <a href="http://dx.doi.org/10.1002/2013JD019760">https://doi.org/10.1002/2013JD019760</a>, 2013.

Morino, I., Uchino, O., Inoue, M., Yoshida, Y., Yokota, T., Wennberg, P. O., Toon, G. C., Wunch, D., Roehl, C. M., Notholt, J., Warneke, T., Messerschmidt, J., Griffith, D. W. T., Deutscher, N. M., Sherlock, V., Connor, B., Robinson, J., Sussmann, R., and Rettinger, M.: Preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from GOSAT short-wavelength infrared spectra, Atmos. Meas. Tech., 4, 1061–1076, <a href="http://dx.doi.org/10.5194/amt-4-1061-2011">https://doi.org/10.5194/amt-4-1061-2011</a>, 2011.

Nash, E. R., Newman, P. A., Rosenfield, J. E., and Schoeberl, M. R.: An objective determination of the polar vortex using Ertel's potential vorticity, J. Geophys. Res., 101, 9471–9478, 1996.

Patra, P. K., Takigawa, M., Ishijima, K., Choi, B.-C., Cunnold, D., Dlugokencky, E. J., Fraser, P., Gomez-Pelaez, A. J., Goo, T.-Y., Kim, J.-S., Krummel, P., Langenfelds, R., Meinhardt, F., Mukai, H., O'Doherty, S., Prinn, R. G., Simmonds, P., Steele, P., Tohjima, Y., Tsuboi, K., Uhse, K., Weiss, R., Worthy, D., and Nakazawa, T. : Growth rate, seasonal, synoptic, diurnal variations and budget of methane in lower atmosphere, J. Meteorol. Soc. Jpn., 87, 635–663, 2009.

Patra, P. K., Houweling, S., Krol, M., Bousquet, P., Belikov, D., Bergmann, D., Bian, H., Cameron-Smith, P., Chipperfield, M. P., Corbin, K., Fortems-Cheiney, A., Fraser, A., Gloor, E., Hess, P., Ito, A., Kawa, S. R., Law, R. M., Loh, Z., Maksyutov, S., Meng, L., Palmer, P. I., Prinn, R. G., Rigby, M., Saito, R., and Wilson, C.: TransCom model simulations of CH4 and related species: linking transport, surface flux and chemical loss with CH4 variability in the troposphere and lower stratosphere, Atmos. Chem. Phys., 11, 12813–12837, <a href="http://dx.doi.org/10.5194/acp-11-12813-2011">https://doi.org/10.5194/acp-11-12813-2011</a>, 2011.

Pougatchev, N. S., Connor, B. J., and Rinsland, C. P.: Infrared measurements of the ozone vertical distribution above Kitt Peak, J. Geophys. Res., 100, 16689–16697, 1995.

Rothman, L. S., Barbe, A., Benner, D. C., Brown, L. R., Camy-Peyret, C., Carleer, M. R., Chance, K., Clerbaux, C., Dana, V., Devi, V. M., Fayt, A., Flaud, J. M., Gamache, R. R., Goldman, A., Jacquemart, D., Jucks, K. W., Lafferty, W. J., Mandin, J. Y., Massie, S. T., Nemtchinov, V., Newnham, D. A., Perrin, A., Rinsland, C. P., Schroeder, J., Smith, K. M., Smith, M. A. H., Tang, K., Toth, R. A., Vander Auwera, J., Varanasi, P., and Yoshino, K.: The HITRAN molecular spectroscopic database: edition of 2000 including updates through 2001, J. Quant. Spectrosc. Radiat. Transfer, 82, 5–44, 2003.

Rothman, L. S., Jacquemart, D., Barbe, A., Benner, D. C., Birk, M., Brown, L. R., Carleer, M. R., Chackerian, C., Chance, K., Coudert, L. H., Dana, V., Devi, V. M., Flaud, J. M., Gamache, R. R., Goldman, A., Hartmann, J. M., Jucks, K. W., Maki, A. G., Mandin, J. Y., Massie, S. T., Orphal, J., Perrin, A., Rinsland, C. P., Smith, M. A. H., Tennyson, J., Tolchenov, R. N., Toth, R. A., Vander Auwera, J., Varanasi, P., and Wagner, G.: The HITRAN 2004 molecular spectroscopic database, J. Quant. Spectrosc. Rad. Trans., 96, 139–204, <a href="http://dx.doi.org/10.1016/j.jqsrt.2004.10.008">https://doi.org/10.1016/j.jqsrt.2004.10.008</a>, 2005.

Rothman, L. S., Gordon, I. E., Barbe, A., Benner, D. C., Bernath, P. F., Birk, M., Boudon, V., Brown, L. R., Campargue, A., Champion, J., Chance, K., Coudert, L. H., Dana, V., Devi, V. M., Fally, S., Flaud, J.M., Gamache, R. R., Goldman, A., Jacquemart, D., Kleiner, I., Lacome, N., Lafferty, W. J., Mandin, J., Massie, S. T., Mikhailenko, S. N., Miller, C. E., Moazzen-Ahmadi, N., Naumenko, O. V., Nikitin, A. V., Orphal, J., Perevalov, V. I., Perrin, A., Predoi-Cross, A., Rinsland, C. P., Rotger, M., Šimečková, M., Smith, M. A. H., Sung, K., Tashkun, S. A., Tennyson, J., Toth, R. A., Vandaele, A. C., and Vander Auwera, J.: The HITRAN 2008 molecular spectroscopic database, J. Quant. Spectrosc. Radiat. Transfer, 110, 533–572, 2009.

Saad, K. M., Wunch, D., Toon, G. C., Bernath, P., Boone, C., Connor, B., Deutscher, N. M., Griffith, D. W. T., Kivi, R., Notholt, J., Roehl, C., Schneider, M., Sherlock, V., and Wennberg, P. O.: Derivation of tropospheric methane from TCCON CH4 and HF total column observations, Atmos. Meas. Tech., 7, 2907–2918, <a href="http://dx.doi.org/10.5194/amt-7-2907-2014">https://doi.org/10.5194/amt-7-2907-2014</a>, 2014.

Saito, R., Patra, P. K., Deutscher, N., Wunch, D., Ishijima, K., Sherlock, V., Blumenstock, T., Dohe, S., Griffith, D., Hase, F., Heikkinen, P., Kyrö, E., Macatangay, R., Mendonca, J., Messerschmidt, J., Morino, I., Notholt, J., Rettinger, M., Strong, K., Sussmann, R., and Warneke, T.: Technical Note: Latitude-time variations of atmospheric column-average dry air mole fractions of CO2, CH4 and N2O, Atmos. Chem. Phys., 12, 7767–7777, <a href="http://dx.doi.org/10.5194/acp-12-7767-2012">https://doi.org/10.5194/acp-12-7767-2012</a>, 2012.

Sapart, S. J., Monteil, G., Prokopiou, M., van de Wal, R. S. W., Kaplan, J. O., Sperlich, P., Krumhardt, K. M., van der Veen, C., Houweling, S., Krol, M. C., Blunier, T., Sowers, T., Martinerie, P., Witrant, E., Dahl-Jensen, D., and Röckmann, T.: Natural and anthropogenic variations in methane sources during the past two millennia, Nature, 490, 85–88, <a href="http://dx.doi.org/10.1038/nature11461">https://doi.org/10.1038/nature11461</a>, 2012.

Schneising, O., Bergamaschi, P., Bovensmann, H., Buchwitz, M., Burrows, J. P., Deutscher, N. M., Griffith, D. W. T., Heymann, J., Macatangay, R., Messerschmidt, J., Notholt, J., Rettinger, M., Reuter, M., Sussmann, R., Velazco, V. A., Warneke, T., Wennberg, P. O., and Wunch, D.: Atmospheric greenhouse gases retrieved from SCIAMACHY: comparison to ground-based FTS measurements and model results, Atmos. Chem. Phys., 12, 1527–1540, <a href="http://dx.doi.org/10.5194/acp-12-1527-2012">https://doi.org/10.5194/acp-12-1527-2012</a>, 2012.

Sepúlveda, E., Schneider, M., Hase, F., Garc\'ia, O. E., Gomez-Pelaez, A., Dohe, S., Blumenstock, T., and Guerra, J. C.: Long-term validation of tropospheric column-averaged CH4 mole fractions obtained by mid-infrared ground-based FTIR spectrometry, Atmos. Meas. Tech., 5, 1425–1441, <a href="http://dx.doi.org/10.5194/amt-5-1425-2012">https://doi.org/10.5194/amt-5-1425-2012</a>, 2012.

Sepúlveda, E., Schneider, M., Hase, F., Barthlott, S., Dubravica, D., Garc\'ia, O. E., Gomez-Pelaez, A., González, Y., Guerra, J. C., Gisi, M., Kohlhepp, R., Dohe, S., Blumenstock, T., Strong, K., Weaver, D., Palm, M., Sadeghi, A., Deutscher, N. M., Warneke, T., Notholt, J., Jones, N., Griffith, D. W. T., Smale, D., Brailsford, G. W., Robinson, J., Meinhardt, F., Steinbacher, M., Aalto, T., and Worthy, D.: Tropospheric CH4 signals as observed by NDACC FTIR at globally distributed sites and comparison to GAW surface in situ measurements, Atmos. Meas. Tech., 7, 2337–2360, <a href="http://dx.doi.org/10.5194/amt-7-2337-2014">https://doi.org/10.5194/amt-7-2337-2014</a>, 2014.

Sinnhuber, B.-M., Stiller, G., Ruhnke, R., von Clarmann, T., Kellmann, S., and Aschmann, J.:, Arctic winter 2010/2011 at the brink of an ozone hole, Geophys. Res. Lett., 38, L24814, <a href="http://dx.doi.org/10.1029/2011GL049784">https://doi.org/10.1029/2011GL049784</a>, 2011.

Sprenger, M. and Wernli, H.: A northern hemispheric climatology of crosstropopause exchange for the ERA15 time period (1979–1993), J. Geophys. Res., 108, 8521, <a href="http://dx.doi.org/10.1029/2002JD002636">https://doi.org/10.1029/2002JD002636</a>, 2003.

Stocker, T., Qin, D., Plattner, G. K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M. (Eds.): Summary for Policymakers, Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2013.

Stohl, A. and Trickl, T.: A textbook example of long-range transport: Simultaneous observation of ozone maxima of stratospheric and North American origin in the free troposphere over Europe, J. Geophys. Res., 104, 30445–30462, 1999.

Stohl, A., Spichtinger-Rakowsky, N., Bonasoni, P., Feldmann, H., Memmesheimer, M., Scheel, H. E., Trickl, T., Hübener, S. H., Ringer, W., and Mandl, M.: The influence of stratospheric intrusions on alpine ozone concentrations, Atmos. Environ., 34, 1323–1354, 2000.

Stohl, A., Bonasoni, P., Cristofanelli, P., Collins, W., Feichter, J., Frank, A., Forster, C., Gerasopoulos, E., Gäggeler, H., James, P., Kentarchos, T., Kromp-Kolb, H., Krüger, B., Land, C., Meloen, J., Papayannis, A., Priller, A., Seibert, P., Sprenger, M., Roelofs, G. J., Scheel, H. E., Schnabel, C., Siegmund, P., Tobler, L., Trickl, T., Wernli, H., Wirth, V., Zanis, P., and Zerefos, C.: Stratosphere-troposphere exchange: a review, and what we have learned from STACCATO, J. Geophys. Res., 108, 8516, <a href="http://dx.doi.org/10.1029/2002JD002490">https://doi.org/10.1029/2002JD002490</a>, 2003.

Sussmann, R., Stremme, W., Buchwitz, M., and de Beek, R.: Validation of ENVISAT/SCIAMACHY columnar methane by solar FTIR spectrometry at the Ground-Truthing Station Zugspitze, Atmos. Chem. Phys., 5, 2419–2429, <a href="http://dx.doi.org/10.5194/acp-5-2419-2005">https://doi.org/10.5194/acp-5-2419-2005</a>, 2005.

Sussmann, R., Borsdorff, T., Rettinger, M., Camy-Peyret, C., Demoulin, P., Duchatelet, P., Mahieu, E., and Servais, C.: Technical Note: Harmonized retrieval of column-integrated atmospheric water vapor from the FTIR network – first examples for long-term records and station trends, Atmos. Chem. Phys., 9, 8987–8999, <a href="http://dx.doi.org/10.5194/acp-9-8987-2009">https://doi.org/10.5194/acp-9-8987-2009</a>, 2009.

Sussmann, R., Forster, F., Rettinger, M., and Jones, N.: Strategy for high-accuracy-and-precision retrieval of atmospheric methane from the mid-infrared FTIR network, Atmos. Meas. Tech., 4, 1943–1964, <a href="http://dx.doi.org/10.5194/amt-4-1943-2011">https://doi.org/10.5194/amt-4-1943-2011</a>, 2011.

Sussmann, R., Forster, F., Rettinger, M., and Bousquet, P.: Renewed methane increase for five years (2007–2011) observed by solar FTIR spectrometry, Atmos. Chem. Phys., 12, 4885–4891, <a href="http://dx.doi.org/10.5194/acp-12-4885-2012">https://doi.org/10.5194/acp-12-4885-2012</a>, 2012.

Sussmann, R., Ostler, A., Forster, F., Rettinger, M., Deutscher, N. M., Griffith, D. W. T., Hannigan, J. W., Jones, N., and Patra, P. K.: First intercalibration of column-averaged methane from the Total Carbon Column Observing Network and the Network for the Detection of Atmospheric Composition Change, Atmos. Meas. Tech., 6, 397–418, <a href="http://dx.doi.org/10.5194/amt-6-397-2013">https://doi.org/10.5194/amt-6-397-2013</a>, 2013.

Toon, G. C., Farmer, C. B., Schaper, P.W., Lowes, L. L., Norton, R. H., Schoeberl, M. R., Lait, L. R., and Newman, P. A.: Evidence for subsidence in the 1989 Polar winter stratosphere from airborne infrared composition measurements, J. Geophys. Res., 97, 7963–7970, 1992.

Trickl, T., Cooper, O. C., Eisele, H., James, P., Mücke, R., and Stohl, A.: Intercontinental transport and its influence on the ozone concentrations over central Europe: Three case studies, J. Geophys. Res., 108, 8530, <a href="http://dx.doi.org/10.1029/2002JD002735">https://doi.org/10.1029/2002JD002735</a>, 2003.

Trickl, T., Feldmann, H., Kanter, H.-J., Scheel, H.-E., Sprenger, M., Stohl, A., and Wernli, H.: Forecasted deep stratospheric intrusions over Central Europe: case studies and climatologies, Atmos. Chem. Phys., 10, 499–524, <a href="http://dx.doi.org/10.5194/acp-10-499-2010">https://doi.org/10.5194/acp-10-499-2010</a>, 2010.

Trickl, T., Vogelmann, H., Giehl, H., Scheel, H.-E., Sprenger, M., and Stohl, A.: How stratospheric are deep stratospheric intrusions?, Atmos. Chem. Phys., 14, 9941–9961, <a href="http://dx.doi.org/10.5194/acp-14-9941-2014">https://doi.org/10.5194/acp-14-9941-2014</a>, 2014.

Wang, Z., Deutscher, N. M., Warneke, T., Notholt, J., Dils, B., Griffith, D. W. T., Schmidt, M., Ramonet, M., and Gerbig, C.: Retrieval of tropospheric column-averaged CH4 mole fraction by solar absorption FTIR-spectrometry using N2O as a proxy, Atmos. Meas. Tech., 7, 3295–3305, <a href="http://dx.doi.org/10.5194/amt-7-3295-2014">https://doi.org/10.5194/amt-7-3295-2014</a>, 2014.

Washenfelder, R. A., Wennberg, P. O., and Toon, G. C.: Tropospheric methane retrieved from ground-based near-IR solar absorption spectra, Geophys. Res. Lett., 30, 2226, <a href="http://dx.doi.org/10.1029/2003GL017969">https://doi.org/10.1029/2003GL017969</a>, 2003.

Wernli, H. and Davies, H. C.: A Lagrangian-based analysis of extratropical cyclones, I, The method and some applications, Q. J. R. Meteorol. Soc., 123, 467–489, 1997.

Wofsy, S. C. and the HIPPO Science Team and Cooperating Modellers and Satellite Teams: TS6 HIAPER Pole-to-Pole Observations (HIPPO): fine-grained, global-scale measurements of climatically important atmospheric gases and aerosols, Philos. T. Roy. Soc. A, 369, 2073–2086, <a href="http://dx.doi.org/10.1098/rsta.2010.0313">https://doi.org/10.1098/rsta.2010.0313</a>, 2011.

Wunch, D., Toon, G. C., Wennberg, P. O., Wofsy, S. C., Stephens, B. B., Fischer, M. L., Uchino, O., Abshire, J. B., Bernath, P., Biraud, S. C., Blavier, J.-F. L., Boone, C., Bowman, K. P., Browell, E. V., Campos, T., Connor, B. J., Daube, B. C., Deutscher, N. M., Diao, M., Elkins, J. W., Gerbig, C., Gottlieb, E., Griffith, D. W. T., Hurst, D. F., Jiménez, R., Keppel-Aleks, G., Kort, E. A., Macatangay, R., Machida, T., Matsueda, H., Moore, F., Morino, I., Park, S., Robinson, J., Roehl, C. M., Sawa, Y., Sherlock, V., Sweeney, C., Tanaka, T., and Zondlo, M. A.: Calibration of the Total Carbon Column Observing Network using aircraft profile data, Atmos. Meas. Tech., 3, 1351–1362, <a href="http://dx.doi.org/10.5194/amt-3-1351-2010">https://doi.org/10.5194/amt-3-1351-2010</a>, 2010.

Wunch, D., Toon, G. C., Blavier, J.-F. L., Washenfelder, R. A., Notholt, J., Connor, B. J., Griffith, D. W. T., Sherlock, V., and Wennberg, P. O.: The Total Carbon Column Observing Network, Phil. Trans. R. Soc. A, 369, 2087–2112, <a href="http://dx.doi.org/10.1098/rsta.2010.0240">https://doi.org/10.1098/rsta.2010.0240</a>, 2011a.

Wunch, D., Wennberg, P. O., Toon, G. C., Connor, B. J., Fisher, B., Osterman, G. B., Frankenberg, C., Mandrake, L., O'Dell, C., Ahonen, P., Biraud, S. C., Castano, R., Cressie, N., Crisp, D., Deutscher, N. M., Eldering, A., Fisher, M. L., Griffith, D. W. T., Gunson, M., Heikkinen, P., Keppel-Aleks, G., Kyrö, E., Lindenmaier, R., Macatangay, R., Mendonca, J., Messerschmidt, J., Miller, C. E., Morino, I., Notholt, J., Oyafuso, F. A., Rettinger, M., Robinson, J., Roehl, C. M., Salawitch, R. J., Sherlock, V., Strong, K., Sussmann, R., Tanaka, T., Thompson, D. R., Uchino, O., Warneke, T., and Wofsy, S. C.: A method for evaluating bias in global measurements of CO2 total columns from space, Atmos. Chem. Phys., 11, 12317–12337, <a href="http://dx.doi.org/10.5194/acp-11-12317-2011">https://doi.org/10.5194/acp-11-12317-2011</a>, 2011b.

Xiong, X., Barnet, C., Maddy, E., Wofsy, S. C., Chen, L., Karion, A., and Sweeney, C.: Detection of methane depletion associated with stratospheric intrusion by atmospheric infrared sounder (AIRS), Geophys. Res. Lett., 40, 2455–2459, <a href="http://dx.doi.org/10.1002/grl.50476">https://doi.org/10.1002/grl.50476</a>, 2013.

Yoshida, Y., Ota, Y., Eguchi, N., Kikuchi, N., Nobuta, K., Tran, H., Morino, I., and Yokota, T.: Retrieval algorithm for CO2 and CH4 column abundances from short-wavelength infrared spectral observations by the Greenhouse gases observing satellite, Atmos. Meas. Tech., 4, 717–734, <a href="http://dx.doi.org/10.5194/amt-4-717-2011">https://doi.org/10.5194/amt-4-717-2011</a>, 2011.