ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-3937-2011 On the structural changes in the Brewer-Dobson circulation after 2000 Bönisch H. 1 Engel A. 1 Birner Th. 2 Hoor P. 3 Tarasick D. W. 4 Ray E. A. 5 6 Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA Institute for Atmospheric Physics, University of Mainz, Germany Environment Canada, Downsview, Ontario, Canada Chemical Sciences Division, Earth Systems Research Laboratory, NOAA, Boulder, CO, USA Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA 28 04 2011 11 8 3937 3948 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/3937/2011/acp-11-3937-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/3937/2011/acp-11-3937-2011.pdf

In this paper we present evidence that the observed increase in tropical upwelling after the year 2000 may be attributed to a change in the Brewer-Dobson circulation pattern. For this purpose, we use the concept of transit times derived from residual circulation trajectories and different in-situ measurements of ozone and nitrous dioxide. Observations from the Canadian midlatitude ozone profile record, probability density functions of in-situ N<sub>2</sub>O observations and a shift of the N<sub>2</sub>O-O<sub>3</sub> correlation slopes, taken together, indicate that the increased upwelling in the tropics after the year 2000 appears to have triggered an intensification of tracer transport from the tropics into the extratropics in the lower stratosphere below about 500 K. This finding is corroborated by the fact that transit times along the shallow branch of the residual circulation into the LMS have decreased for the same time period (1993–2003). On a longer time scale (1979–2009), the transit time of the shallow residual circulation branch show a steady decrease of about −1 month/decade over the last 30 yr, while the transit times of the deep branch remain unchanged. This highlights that changes in the upwelling across the tropical tropopause are not sufficient as an indicator for changes in the entire Brewer-Dobson circulation.

 References % vor jede Referenz Andrews, D. G., Holton, J. R., and Leovy, C. B.: Middle atmosphere dynamics, International geophysics series, v 40, Academic Press, Orlando, xi, 489 pp., 1987. Appenzeller, C., Holton, J. R., and Rosenlof, K. H.: Seasonal variation of mass transport across the tropopause, J. Geophys. Res., 101, 15071–15078, 1996. Austin, J. and Li, F.: On the relationship between the strength of the Brewer-Dobson circulation and the age of stratospheric air, Geophys. Res. Lett., 33, L17807, http://dx.doi.org/10.1029/2006gl026867doi:10.1029/2006gl026867, 2006. Beuermann, R., Konopka, P., Brunner, D., Bujok, O., Gunther, G., McKenna, D. S., Lelieveld, J., Muller, R., and Schiller, C.: High-resolution measurements and simulation of stratospheric and tropospheric intrusions in the vicinity of the polar jet stream, Geophys. Res. Lett., 29, 1577, http://dx.doi.org/10.1029/2001gl014162doi:10.1029/2001gl014162, 2002. Birner, T. and Bönisch, H.: Residual circulation trajectories and transit times into the extratropical lowermost stratosphere, Atmos. Chem. Phys., 11, 817–827, http://dx.doi.org/10.5194/acp-11-817-2011doi:10.5194/acp-11-817-2011, 2011. Bönisch, H., Engel, A., Curtius, J., Birner, Th., and Hoor, P.: Quantifying transport into the lowermost stratosphere using simultaneous in-situ measurements of SF6 and CO<sub>2</sub>, Atmos. Chem. Phys., 9, 5905–5919, http://dx.doi.org/10.5194/acp-9-5905-2009doi:10.5194/acp-9-5905-2009, 2009. Bregman, A., Arnold, F., Burger, V., Fischer, H., Lelieveld, J., Scheeren, B. A., Schneider, J., Siegmund, P. C., Strom, J., Waibel, A., and Wauben, W. M. F.: In situ trace gas and particle measurements in the summer lower stratosphere during STREAM II: Implications for O<sub>3</sub> production, J. Atmos. Chem., 26, 275–310, 1997. Bregman, A., Lelieveld, J., van den Broek, M. M. P., Siegmund, P. C., Fischer, H., and Bujok, O.: N<sub>2</sub>O and O<sub>3</sub> relationship in the lowermost stratosphere: A diagnostic for mixing processes as represented by a three-dimensional chemistry-transport model, J. Geophys. Res., 105, 17279–17290, 2000. Brewer, A. W.: Evidence for a World Circulation Provided by the Measurements of Helium and Water Vapour Distribution in the Stratosphere, Q. J. Roy. Meteorol. Soc., 75, 351–363, 1949. Brunner, D., Staehelin, J., Kuensch, H.-R., and Bodeker, G. E.: A Kalman filter reconstruction of the vertical ozone distribution in an equivalent latitude – potential temperature framework from TOMS/GOME/SBUV total ozone observations, J. Geophys. Res., 111, 1–20, http://dx.doi.org/10.1029/2005jd006279doi:10.1029/2005jd006279, 2006a. Brunner, D., Staehelin, J., Maeder, J. A., Wohltmann, I., and Bodeker, G. E.: Variability and trends in total and vertically resolved stratospheric ozone based on the CATO ozone data set, Atmos. Chem. Phys., 6, 4985–5008, http://dx.doi.org/10.5194/acp-6-4985-2006doi:10.5194/acp-6-4985-2006, 2006b. Bujok, O., Tan, V., Klein, E., Nopper, R., Bauer, R., Engel, A., Gerhards, M. T., Afchine, A., McKenna, D. S., Schmidt, U., Wienhold, F. G., and Fischer, H.: GHOST – A novel airborne gas chromatograph for in situ measurements of long-lived tracers in the lower stratosphere: Method and applications, J. Atmos. Chem., 39, 37–64, 2001. Butchart, N., Scaife, A., Bourqui, M., de Grandpré, J., Hare, S., Kettleborough, J., Langematz, U., Manzini, E., Sassi, F., Shibata, K., Shindell, D., and Sigmond, M.: Simulations of anthropogenic change in the strength of the Brewer–Dobson circulation, Clim. Dynam., 27, 727–741, http://dx.doi.org/10.1007/s00382-006-0162-4doi:10.1007/s00382-006-0162-4, 2006. Collins, J. E., Sachse, G. W., Anderson, B. E., Weinheimer, A. J., Walega, J. G., and Ridley, B. A.: AASE-II in-Situ Tracer Correlations of Methane, Nitrous-Oxide, and Ozone as Observed Aboard the DC-8, Geophys. Res. Lett., 20, 2543–2546, 1993. Dobson, G. M. B.: Origin and Distribution of the Polyatomic Molecules in the Atmosphere, Proceedings of the Royal Society of London Series a-Mathematical and Physical Sciences, 236, 187–193, 1956. Engel, A., Bönisch, H., Brunner, D., Fischer, H., Franke, H., Günther, G., Gurk, C., Hegglin, M., Hoor, P., Königstedt, R., Krebsbach, M., Maser, R., Parchatka, U., Peter, T., Schell, D., Schiller, C., Schmidt, U., Spelten, N., Szabo, T., Weers, U., Wernli, H., Wetter, T., and Wirth, V.: Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview, Atmos. Chem. Phys., 6, 283–301, http://dx.doi.org/10.5194/acp-6-283-2006doi:10.5194/acp-6-283-2006, 2006. Engel, A., Mobius, T., Bönisch, H., Schmidt, U., Heinz, R., Levin, I., Atlas, E., Aoki, S., Nakazawa, T., Sugawara, S., Moore, F., Hurst, D., Elkins, J., Schauffler, S., Andrews, A., and Boering, K.: Age of stratospheric air unchanged within uncertainties over the past 30 years, Nature Geoscience, 2, 28–31, http://dx.doi.org/10.1038/Ngeo388doi:10.1038/Ngeo388, 2009. Fischer, H., Wienhold, F. G., Hoor, P., Bujok, O., Schiller, C., Siegmund, P., Ambaum, M., Scheeren, H. A., and Lelieveld, J.: Tracer correlations in the northern high latitude lowermost stratosphere: Influence of cross-tropopause mass exchange, Geophys. Res. Lett., 27, 97–100, 2000. Forster, P. M. D. and Shine, K. P.: Radiative forcing and temperature trends from stratospheric ozone changes, J. Geophys. Res., 102, 10841–10855, 1997. Garcia, R. R. and Randel, W. J.: Acceleration of the Brewer-Dobson circulation due to increases in greenhouse gases, J. Atmos. Sci., 65, 2731–2739, http://dx.doi.org/10.1175/2008jas2712.1doi:10.1175/2008jas2712.1, 2008. Haynes, P. H., McIntyre, M. E., Shepherd, T. G., Marks, C. J., and Shine, K. P.: On the "Downward Control" of Extratropical Diabatic Circulations by Eddy-Induced Mean Zonal Forces, J. Atmos. Sci., 48, 651–678, 1991. Hegglin, M. I. and Shepherd, T. G.: O<sub>3</sub>-N<sub>2</sub>O correlations from the Atmospheric Chemistry Experiment: Revisiting a diagnostic of transport and chemistry in the stratosphere, J. Geophys. Res., 112, D19301, http://dx.doi.org/10.1029/2006jd008281doi:10.1029/2006jd008281, 2007. Hegglin, M. I., Brunner, D., Peter, T., Hoor, P., Fischer, H., Staehelin, J., Krebsbach, M., Schiller, C., Parchatka, U., and Weers, U.: Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere, Atmos. Chem. Phys., 6, 1331–1350, http://dx.doi.org/10.5194/acp-6-1331-2006doi:10.5194/acp-6-1331-2006, 2006. Hoor, P., Fischer, H., Lange, L., Lelieveld, J., and Brunner, D.: Seasonal variations of a mixing layer in the lowermost stratosphere as identified by the CO-O3 correlation from in situ measurements, J. Geophys. Res., 107, 4044, http://dx.doi.org/10.1029/2000jd000289doi:10.1029/2000jd000289, 2002. Hoor, P., Gurk, C., Brunner, D., Hegglin, M. I., Wernli, H., and Fischer, H.: Seasonality and extent of extratropical TST derived from in-situ CO measurements during SPURT, Atmos. Chem. Phys., 4, 1427–1442, http://dx.doi.org/10.5194/acp-4-1427-2004doi:10.5194/acp-4-1427-2004, 2004. Hoor, P., Fischer, H., and Lelieveld, J.: Tropical and extratropical tropospheric air in the lowermost stratosphere over Europe: A CO-based budget, Geophys. Res. Lett., 32, L07802, http://dx.doi.org/10.1029/2004gl022018doi:10.1029/2004gl022018, 2005. Lelieveld, J., Bregman, B., Arnold, F., Burger, V., Crutzen, P. J., Fischer, H., Waibel, A., Siegmund, P., and van Velthoven, P. F. J.: Chemical perturbation of the lowermost stratosphere through exchange with the troposphere, Geophys. Res. Lett., 24, 603–606, 1997. Li, F., Austin, J., and Wilson, J.: The Strength of the Brewer-Dobson Circulation in a Changing Climate: Coupled Chemistry-Climate Model Simulations, J. Climate, 21, 40–57, http://dx.doi.org/10.1175/2007JCLI1663.1doi:10.1175/2007JCLI1663.1, 2008. McFarlane, N. A.: The Effect of Orographically Excited Gravity-Wave Drag on the General-Circulation of the Lower Stratosphere and Troposphere, J. Atmos. Sci., 44, 1775–1800, 1987. McIntyre, M. E. and Palmer, T. N.: The "surf zone" in the stratosphere, J. Atmos. Terr. Phys., 46, 825–849, 1984. McLandress, C. and Shepherd, T. G.: Simulated Anthropogenic Changes in the Brewer-Dobson Circulation, Including Its Extension to High Latitudes, J. Climate, 22, 1516–1540, http://dx.doi.org/10.1175/2008JCLI2679.1doi:10.1175/2008JCLI2679.1, 2009. Neu, J. L. and Plumb, R. A.: Age of air in a "leaky pipe" model of stratospheric transport, J. Geophys. Res., 104, 19243–19255, 1999. Onogi, K., Tsutsui, J., Koide, H., Sakamoto, M., Kobayashi, S., Hatsushika, H., Matsumoto, T., Yamazaki, N., Kamahori, H., Takahashi, K., Kadokura, S., Wada, K., Kato, K., Oyama, R., Ose, T., Mannoji, N., and Taira, R.: The JRA-25 Reanalysis, J. Meteorol. Soc. Japan, 85, 369–432, 2007. Pan, L. L., Randel, W. J., Gary, B. L., Mahoney, M. J., and Hintsa, E. J.: Definitions and sharpness of the extratropical tropopause: A trace gas perspective, J. Geophys. Res., 109, D23103, http://dx.doi.org/10.1029/2004jd004982doi:10.1029/2004jd004982, 2004. Plumb, R. A.: A "tropical pipe" model of stratospheric transport, J. Geophys. Res., 101, 3957–3972, 1996. Plumb, R. A.: Stratospheric Transport, J. Meteorol. Soc. Japan, 80, 793–809, 2002. Plumb, R. A.: Tracer interrelationships in the stratosphere, Rev. Geophys., 45, RG4005, http://dx.doi.org/10.1029/2005rg000179doi:10.1029/2005rg000179, 2007. Plumb, R. A. and Ko, M. K. W.: Interrelationships between Mixing Ratios of Long Lived Stratospheric Constituents, J. Geophys. Res., 97, 10145–10156, 1992. Proffitt, M. H., Aikin, K., Tuck, A. F., Margitan, J. J., Webster, C. R., Toon, G. C., and Elkins, J. W.: Seasonally averaged ozone and nitrous oxide in the Northern Hemisphere lower stratosphere, J. Geophys. Res., 108, 4110, http://dx.doi.org/10.1029/2002jd002657doi:10.1029/2002jd002657, 2003. Randel, W. J., Wu, F., Vomel, H., Nedoluha, G. E., and Forster, P.: Decreases in stratospheric water vapor after 2001: Links to changes in the tropical tropopause and the Brewer-Dobson circulation, J. Geophys. Res., 111, D12312, http://dx.doi.org/10.1029/2005jd006744doi:10.1029/2005jd006744, 2006. Ray, E. A., Moore, F. L., Rosenlof, K. H., Davis, S. M., Boenisch, H., Morgenstern, O., Smale, D., Rozanov, E., Hegglin, M., Pitari, G., Mancini, E., Braesicke, P., Butchart, N., Hardiman, S., Li, F., Shibata, K., and Plummer, D. A.: Evidence for changes in stratospheric transport and mixing over the past three decades based on multiple data sets and tropical leaky pipe analysis, J. Geophys. Res., 115, D21304, http://dx.doi.org/10.1029/2010jd014206doi:10.1029/2010jd014206, 2010. Rosenlof, K. H.: Seasonal Cycle of the Residual Mean Meridional Circulation in the Stratosphere, J. Geophys. Res., 100, 5173–5191, 1995. Rosenlof, K. H. and Reid, G. C.: Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection, J. Geophys. Res., 113, D06107, http://dx.doi.org/10.1029/2007jd009109doi:10.1029/2007jd009109, 2008. Rosenlof, K. H., Tuck, A. F., Kelly, K. K., Russell, J. M., and McCormick, M. P.: Hemispheric asymmetries in water vapor and inferences about transport in the lower stratosphere, J. Geophys. Res., 102, 13213–13234, 1997. Russell, J. M., Gordley, L. L., Park, J. H., Drayson, S. R., Hesketh, W. D., Cicerone, R. J., Tuck, A. F., Frederick, J. E., Harries, J. E., and Crutzen, P. J.: The Halogen Occultation Experiment, J. Geophys. Res., 98, 10777–10797, 1993. Shepherd, T. G.: Transport in the middle atmosphere, J. Meteorol. Soc. Japan, 85B, 165–191, 2007. Singh, H. B., Chen, Y., Gregory, G. L., Sachse, G. W., Talbot, R., Blake, D. R., Kondo, Y., Bradshaw, J. D., Heikes, B., and Thornton, D.: Trace chemical measurements from the northern midlatitude lowermost stratosphere in early spring: Distributions, correlations, and fate, Geophys. Res. Lett., 24, 127–130, 1997. Solomon, S., Rosenlof, K. H., Portmann, R. W., Daniel, J. S., Davis, S. M., Sanford, T. J., and Plattner, G. K.: Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming, Science, 327, 1219–1223, http://dx.doi.org/10.1126/science.1182488doi:10.1126/science.1182488, 2010. Sparling, L. C.: Statistical perspectives on stratospheric transport, Rev. Geophys., 38, 417–436, http://dx.doi.org/10.1029/1999rg000070doi:10.1029/1999rg000070, 2000. Tarasick, D. W., Fioletov, V. E., Wardle, D. I., Kerr, J. B., and Davies, J.: Changes in the vertical distribution of ozone over Canada from ozonesondes: 1980–2001, J. Geophys. Res., 110, 1–19, http://dx.doi.org/10.1029/2004jd004643doi:10.1029/2004jd004643, 2005. Volk, C. M., Elkins, J. W., Fahey, D. W., Salawitch, R. J., Dutton, G. S., Gilligan, J. M., Proffitt, M. H., Loewenstein, M., Podolske, J. R., Minschwaner, K., Margitan, J. J., and Chan, K. R.: Quantifying transport between the tropical and mid-latitude lower stratosphere, Science, 272, 1763–1768, 1996. Wernli, H. and Davies, H. C.: A Lagrangian-based analysis of extratropical cyclones .1. The method and some applications, Q. J. Roy. Meteorol. Soc., 123, 467–489, 1997. Ziereis, H., Schlager, H., Fischer, H., Feigl, C., Hoor, P., Marquardt, R., and Wagner, V.: Aircraft measurements of tracer correlations in the Arctic subvorter region during the Polar Stratospheric Aerosol Experiment (POLSTAR), J. Geophys. Res., 105, 24305–24313, 2000.