Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 7 4 2007 10.5194/acpd-7-9561-2007 http://www.atmos-chem-phys-discuss.net/7/9561/2007/ http://www.atmos-chem-phys-discuss.net/7/9561/2007/acpd-7-9561-2007.html http://www.atmos-chem-phys-discuss.net/7/9561/2007/acpd-7-9561-2007.pdf 9561 9633 2007-07-04 Data assimilation of stratospheric constituents: a review W. A. Lahoz swslahoz@rdg.ac.uk Q. Errera R. Swinbank D. Fonteyn Data Assimilation Research Centre, University of Reading, UK BIRA-IASB, Brussels, Belgium Met Office, Exeter, UK now at: Belgian Federal Science Office, Belgium The data assimilation of stratospheric constituents is reviewed. The data assimilation method is introduced, with particular consideration to its application to stratospheric constituent measurements. Differences from meteorological data assimilation are outlined. Historically, two approaches have been used to carry out constituent assimilation. One approach has carried constituent assimilation out as part of a numerical weather prediction system; the other has carried it out in a standalone chemical model, often with a more sophisticated representation of chemical processes. Whereas the aim of the numerical weather prediction approach has been to improve weather forecasts, the aims of the chemical model approach have included providing chemical forecasts and analyses of chemical constituents. A range of constituent assimilation systems developed in these two areas is presented and strengths and weaknesses discussed. The use of stratospheric constituent data assimilation to evaluate models, observations and analyses, and to provide analyses of constituents, monitor ozone, and make ozone forecasts is discussed. Finally, the current state of affairs is assessed, future directions are discussed, and potential key drivers identified. Anderson, J. L.: An ensemble adjustment filter for data assimilation, Mon. Weather Rev., 129, 2884–2903, 2001. Auger, L. and Tangborn, A. V.: A wavelet-based reduced rank Kalman filter for assimilation of stratospheric chemical tracer observations, Mon. Weather Rev., 132, 1220–1237, 2004. Austin, J.: Towards the four-dimensional variational assimilation of stratospheric chemical constituents, J. Geophys. Res., 97, 2569–2588, 1992. Austin, J., Barwell, B. R., Cox, S. J., et al.: The diagnosis and forecast of clear sky ultraviolet levels at the Earth's surface, Met. Apps., 1, 321–336, 1994. Baier, F., Erbertseder, T., Morgenstern, O., et al.: Assimilation of MIPAS observations using a three-dimensional global chemistry-transport model, Quart. J. Roy. Meteorol. Soc., 131, 3529–3542, 2005. Bertaux, J.-L., Kyrölä, E. and Wehr, T.: Stellar occultation technique for atmospheric ozone monitoring: GOMOS on Envisat, Earth. Observ. Q., 67, 17-20, 2000. Bormann, N. and Healy, S.: A fast radiative transfer model for the assimilation of infrared limb radiances from MIPAS: Accounting for horizontal gradients, Quart. J. Roy. Meteorol. Soc., 132, 2357–2376, 2006. Bormann, N., Healy, S. and Hamrud, M.: Assimilation of MIPAS limb radiances in the ECMWF system. Part II: Experiments with a 2-dimensional observation operator, Quart. J. Roy. Meteorol. Soc., 133, 329–346, 2007. Bormann, N., Matricardi, M., and Healy, S. B.: RTMIPAS: A fast radiative transfer model for the assimilation of infrared limb radiances from MIPAS, Quart. J. Roy. Meteorol. Soc., 131, 1631–1653, 2005. Bormann, N. and Thépaut, J.-N.: Assimilation of MIPAS limb radiances in the ECMWF system. Part I: Experiments with a 1-dimensional observation operator, Quart. J. Roy. Meteorol. Soc., 133, 309–327, 2007. Bouttier, F. and Courtier, P.: Data assimilation concepts and methods. ECMWF training notes, March 1999, available from http://www.ecmwf.int, 1999. Bovensmann, H., Burrows, J. P., Buchwitz, M., et al.: SCIAMACHY: Mission objectives and measurement modes, J. Atmos. Sci., 56, 127–150, 1999. Burrows, J. P., Weber, M., Buchwitz, M., et al.: The Global Ozone Monitoring Experiment (GOME): Mission Concept and First Scientific Results, J. Atmos. Sci., 56, 151–175, 1999. Burrows, W. R., Vallée, M., Wardle, D. I., et al.: The Canadian operational procedure for forecasting total ozone and UV radiation, Met. Apps., 1, 247–265, 1994. Caplan, P., Derber, J., Gemmill, W., et al.: Changes to the 1995 NCEP operational medium-range forecast model analysis – forecast system, Wea. Forecasting, 12, 581–594, 1997. Cariolle, D. and Déqué, M.: Southern hemisphere medium-scale waves and total ozone disturbances in a spectral general circulation model, J. Geophys. Res., 91, 10 825–10 884, 1986. Cariolle, D. and Morcrette, J.-J.: A linearized approach to the radiative budget of the stratosphere: influence of the ozone distribution, Geophys. Res. Lett., 33, L05806, doi:10.1029/2005GL025597, 2006. Cariolle, D. and Teyssèdre, H.: A revised linear ozone photochemistry parameterization for use in transport and general circulation models: Multi-annual simulations, Atmos. Chem. Phys., 7, 2183–2196, 2007. Carlotti, M., Dinelli, B. M., Raspollini, P., and Ridolfi, M.: Geo-fit approach to the analysis of limb-scanning satellite measurements, Appl. Opt., 41, 1872–1885, 2001. Chapnik, B., Desroziers, G., Rabier, F., and Talagrand, O.: Diagnosis and tuning of observational error statistics in a quasi-operational data assimilation setting, Quart. J. Roy. Meteorol. Soc., 132, 543–565, 2006. Chipperfield, M. P., Khattatov, B. V., and Lary, D. J.: Sequential estimation of stratospheric chemical observations in a three-dimensional model, J. Geophys. Res., 107, 4585, doi:10.1029/2002JD002110, 2002. Cohn, S. E.: Dynamics of short-term univariate forecast error covariances, Mon. Weather Rev., 121, 3123–3149, 1993. Cohn, S. E.: An introduction to estimation theory, J. Meteorol. Soc. Jpn., 75, 257–288, 1997. Cohn, S. E., da Silva, A., Guo, J., et al.: Assessing the effects of data selection with the DAO physical-space statistical analysis system, Mon. Weather Rev., 126, 2913–2926, 1998. Collins, W. J., Rasch, P. J., Eaton, B. E., et al.: Simulating aerosols using a chemical transport model with assimilation of satellite retrievals: Methodology for INDOEX, J. Geophys. Res., 106, 7313–7336, 2001. Connew, P.: Chemical data assimilation using the UKMO Unified Model, Procedings of the SODA workshop on Chemical Data Assimilation, 9–10 December 1998, KNMI, De Bilt, Netherlands, 1999. Coy, L., Allen, D. R., Eckermann, S. D., et al.: Effects of model chemistry and data biases on stratospheric ozone assimilation, Atmos. Chem. Phys., 7, 2917–2935, 2007. Daley, R.: Estimating the wind field from chemical constituent observations: Experiments with a one-dimensional Extended Kalman Filter, Mon. Weather Rev., 123, 181–198, 1995. Davies, T., Cullen, M. J. P., Malcolm, A. J., et al.: A new dynamical core for the Met Office's global and regional modelling of the atmosphere, Quart. J. Roy. Meteorol. Soc., 131, 1759–1782. Dee, D. P.: Bias and data assimilation, Quart. J. Roy. Meteorol. Soc., 131, 3323–3343, 2005. Dee, D. and da Silva, A.: Data assimilation in the presence of forecast bias, Quart. J. Roy. Meteorol. Soc., 124, 269–295, 1998. Dee D. and de Silva, A.: The choice of variable for atmospheric moisture analysis, Mon. Weather Rev., 131, 155–171, 2003. Derber, J., Pan, H.-L., Alpert, J., et al.: Changes to the 1998 NCEP Operational MRF Model Analysis/Forecast system, available from http://www.nws.noaa.gov/om/tpb/449/449body.htm, 1998. Derber, J. C. and Wu, W.-S.: The use of TOVS cloud-cleared radiances in the NCEP SSI analysis system, Mon. Weather Rev., 126, 2287–2299, 1998. Desroziers, G., Berre, L., Chapnik, B., and Poli, P.: A simple method to diagnose and adapt observation and background errors, Quart. J. Roy. Meteorol. Soc., 131, 3385–3396, 2005. Dessler, A. E.: The Chemistry and Physics of Stratospheric Ozone. Academic Press, 2000. Dethof, A.: Assimilation of ozone retrievals from the MIPAS instrument onboard ENVISAT. ECMWF Tech Memo 428, 2003. Dethof, A.: Monitoring and assimilation of MIPAS, SCIAMACHY and GOMOS retrievals at ECMWF. ESA Contract 17585/03/I-OL: Technical support for global validation of ENVISAT data products, 2004. Dethof, A. and Hólm, E.: Ozone assimilation in the ERA-40 reanalysis project, Quart. J. Roy. Meteorol. Soc., 130, 2851–2872, 2004. Douglass, A. R., Schoeberl, M. R., Rood, R. B., and Pawson, S.: Evaluation of transport in the lower tropical stratosphere in a global chemistry and transport model, J. Geophys. Res., 108, 4529, doi:10.1029/2002JD002696, 2003. ECMWF: ECMWF Newsletter No. 100 – Winter 2006/07, available from http://www.ecmwf.int, 2007. El Amraoui, L., Ricaud, P., Urban, J., et al.: Assimilation of ODIN/SMR O₃ and N₂O measurements in a three-dimensional chemistry transport model, J. Geophys. Res., 109, D22304, doi:10.1029/2004JD004796, 2004. Elbern, H., Strunk, A., Schmidt, H., and Talagrand, O.: Emission rate and chemical state estimation by 4-dimensional variational inversion, Atmos. Chem. Phys. Discuss., 7, 1725–1783, 2007. El Serafy, G. Y. and Kelder, H. M.: Near-real-time approach to assimilation of satellite-retrieved 3D ozone fields in a global model using a simplified Kalman filter, Quart. J. Roy. Meteorol. Soc., 129, 3099–3120, 2003. El Serafy, G. Y., van der A, R. J., Eskes, H. and Kelder, H. M.: Assimilation of 3D ozone field in global chemistry transport models using the full Kalman filter, Adv. Space Res., 30, 2473–2478, 2002. Errera, Q., Bonjean, S., Chabrillat, S., et al.: BASCOE assimilation of ozone and nitrogen dioxide observed by MIPAS and GOMOS: Comparison between the two sets of analyses. ESA Special Publication SP-636, 2007. Errera, Q. and Fonteyn, D.: Four-dimensional variational chemical data assimilation of CRISTA stratospheric measurements, J. Geophys. Res., 106, 12 253–12 265, 2001. Eskes, H. J.: The integration of atmospheric chemistry observations by next generation global/hemispheric and regional and NWP models, in: Chemical Data Assimilation for the Observation of the Earth's Atmosphere, ACCENT/WMO Expert Workshop in support of IGACO, edited by: Barrie, L. A., Burrows, J. P., Monks, P., and Borrell, P., WMO Tech, Report 1360, GAW Report 169, pp 44–49, 2006. Eskes, H. J., Segers, A., and van Velthoven, P. F. J.: Ozone forecasts of the Stratospheric Polar Vortex-Splitting Event in September 2002, J. Atmos. Sci., 62, 812–821, 2005. Eskes, H. J., van Velthoven, P. F. J. and Kelder, H. M.: Global ozone forecasting based on ERS-2 GOME observations, Atmos. Chem. Phys., 2, 271–278, 2002. Eskes, H. J, van Velthoven, P. F. J., Valks, P. J. M., and Kelder, H. M.: Assimilation of GOME total-ozone satellite observations in a three-dimensional tracer-transport model, Quart. J. Roy. Meteorol. Soc., 129, 1663–1681, 2003. Evensen, G.: The Ensemble Kalman filter: theoretical formulation and practical implementation, Ocean Dyn., 53, 343–367, 2003. Eyring, V., Butchart, N., D. W. Waugh, et al.: Assessment of temperature, trace species, and ozone in chemistry-climate model simulations of the recent past, J. Geophys. Res., 111, D22308, doi:10.1029/2006JD007327, 2006. Fierli, F., Hauchecorne, A., Bekki, S., et al.: Data assimilation of stratospheric ozone using a high-resolution transport model, Geophys. Res. Lett., 29, 7381, doi:10.1029/2001GL014272, 2002. Fischer, H., Blom, C., Oelhaf, H., et al.: Envisat MIPAS – An instrument for atmospheric chemistry and climate research, edited by: Readings, C. and Harris, R. A., ESA Publication SP-1229, 2000. Fisher, M.: Background error covariance modelling. In ECMWF Seminar Recent developments in data assimilation for atmosphere and ocean, September 2003, available from http://www.ecmwf.int, 2003. Fisher, M. and Andersson, E.: Developments in 4D-Var and Kalman filtering, ECMWF Tech Memo 347, 2001. Fisher, M. and Lary, D. J.: Lagrangian 4-dimensional variational data assimilation of chemical species, Quart. J. Roy. Meteorol. Soc., 121, 1681–1704, 1995. Fonteyn D., Errera, Q., DeMazière, M., et al.: 4D-Var assimilation of stratospheric aerosol satellite data, Adv. Space Res., 26, 2049–2052, 2001. Fortuin, J. P. F and Kelder, H. L.: An ozone climatology based on ozonesonde and satellite measurements, J. Geophys. Res., 103, 31 709–31 734, 1998. Geer, A. J., Lahoz, W. A., Bekki, S., et al.: The ASSET intercomparison of ozone analyses: method and first results, Atmos. Chem. Phys., 6, 5445–5474, 2006a. Geer, A. J., Lahoz, W. A., Jackson, D. R., et al.: Evaluation of linear ozone photochemistry parametrizations in a stratosphere-troposphere data assimilation system, Atmos. Chem. Phys., 7, 939–959, 2007. Geer, A. J., Peubey, C., Bannister, R., et al.: Assimilation of stratospheric ozone from MIPAS into a global general circulation model: the September 2002 vortex split, Quart. J. Roy. Meteorol. Soc., 132, 231–257, 2006b. Gille, J. C. and Russell, J. M.: The Limb Infrared Monitor of the Stratosphere: Experiment Description, Performance, and Results, J. Geophys. Res., 89, 5125–5140, 1984. Gunson, M. R., Abbas, M. M., Abrams, M. C., et al.: The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment: Deployment on the ATLAS Space Shuttle missions, Geophys. Res. Lett., 23, 2333–2336, 1996. Hadjinicolau, P., Pyle, J. A., Chipperfield, M. P., and Kettleborough, J. A :. Effect of interannual meteorological variability on mid latitude O₃, Geophys. Res. Lett., 24, 2993–2996, 1997. Hollingsworth, A.: Global Earth-system Modelling using Space and in situ data. ECMWF seminar proceedings, September 2005, available from http://www.ecmwf.int, 2005. Hólm, E., Andersson, E., Beljaars, A., et al.: Assimilation and modelling of the hydrological cycle: ECMWF's status and plans. ECMWF Tech Memo 383, 2002. Ide, K., Courtier, P., Ghil, M., and Lorenc, A.: Unified notation for data assimilation: Operational sequential and variational, J. Meteorol. Soc. Jpn., 75, 181–189, 1997. IGACO: The Changing Atmosphere. An Integrated Global Atmospheric Chemistry Observation theme for the IGOS partnership. ESA SP-1282, Report GAW No. 159 (WMO TD No. 1235), September 2004; Implementation up-date, December 2004. Available from: http://www.igospartners.org/docsTHEM.htm, 2004. Jackson, D. R.: Improvements in data assimilation at the Met Office. Forecasting Research Technical Report No. 454, Met Office, 2004. Jackson, D. R.: Assimilation of EOS MLS ozone observations in the Met Office Data Assimilation System, Quart. J. Roy. Meteorol. Soc., accepted, 2007. Jackson, D. R. and Saunders, R.: Ozone data assimilation: Preliminary system. Forecasting Research Technical Report No. 394, Met Office, 2002. Joiner, J., Lee, H.-T., Strow, L. L., et al.: Radiative transfer in the 9.6 $\mu $m HIRS ozone channel using collocated SBUV-determined ozone abundances, J. Geophys. Res., 103, 19 213–19 230, 1998. Juckes, M. N.: Evaluation of MIPAS ozone fields assimilated using a new algorithm constrained by isentropic tracer advection, Atmos. Chem. Phys., 6, 1549–1565, 2006. Kalnay, E.: Atmospheric Modeling, Data Assimilation and Predictability. Cambridge University Press, 2003. Khattatov, B. V.: Multivariate chemical data assimilation. In Data Assimilation for the Earth System, NATO ASI Series, edited by: Swinbank, R., Shutyaev, V. and Lahoz, W. A., Kluwer, 2003. Khattatov, B. V., Gille, J. C., Lyjak, L. V., et al.: Assimilation of photochemically active species and a case analysis of UARS data, J. Geophys. Res., 104, 18 715–18 737, 1999. Khattatov, B. V., Lamarque, J.-F., Lyjak, L. V., et al.: Assimilation of satellite observations of long-lived chemical species in global chemistry transport models, J. Geophys. Res., 105, 29 135–29 144, 2000. Khattatov, B., Lyjak, L., and Gille, J.: On applications of photochemical models to the design of measurement strategies, Geophys. Res. Lett., 28, 2377–2380, 2001. Kistler, R., Kalnay, E., Collins, W., et al.: The NCEP-NCAR 50-year reanalysis: Monthly means CD-ROM and documentation, Bull. Am. Meteorol. Soc., 82, 247–267, 2001. Küll, V., Riese, M., Tie, X., et al.: NO_y partitioning and aerosol influences in the stratosphere. J. Geophs. Res., 107, 8183, doi:10.1029/2001JD00001246, 2002. Lahoz, W. A.: Chemical data assimilation: Choices and challenges. In Chemical Data Assimilation for the Observation of the Earth's Atmosphere, ACCENT/WMO Expert Workshop in support of IGACO, edited by: Barrie, L. A., Burrows, J. P., Monks, P., Borrell, P., WMO Tech, Report 1360, GAW Report 169, 106–110, 2006. Lahoz, W. A., Brugge, R., Jackson, D. R., et al.: An Observing System Simulation Experiment to evaluate the scientific merit of wind and ozone measurements from the future SWIFT instrument, Quart. J. Roy. Meteorol. Soc., 131, 503–523, 2005. Lahoz, W. A., Geer, A. J., Bekki, S., et al.: The Assimilation of Envisat data (ASSET) project, Atmos. Chem. Phys., 7, 1773–1796, 2007. Lary, D. J.: Data assimilation: a powerful tool for atmospheric chemistry, Phil. Trans. R. Soc. Lond., A357, 3445–3457, 1999. Lary, D. J., Khattatov, B., and Mussa, H. Y.: Chemical data assimilation: A case study of solar occultation data from the ATLAS 1 mission of the Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS), J. Geophys. Res., 108, 4556, doi:10.101029/2003JD003500, 2003. Lemus-Deschamps, L., Grainger, S., Rikus, L., et al.: Australian UV and ozone forecasting system, available from http://www.bom.gov.au/bmrc/mdev/expt/uvindex/uvi.shtml, 2005. Levelt, P. F., Khattatov, B. V., Gille, J. C., et al.: Assimilation of MLS ozone measurements in the global three-dimensional chemistry transport model ROSE, Geophys. Res. Lett., 25, 4493–4496, 1998. Levelt, P. F., van den Oord, G. H. J., Dobber, M. R., et al.: The Ozone Monitoring Instrument, IEEE Trans. Geosci. Remote Sensing, 44, 1093–1101, 2006. Logan, J. A.: An Analysis of Ozonesonde Data for the Troposphere: Recommendations for Testing 3-D Models, and Development of a Gridded Climatology for Tropospheric Ozone, J. Geophys. Res., 104, 16 115–16 149, 1999. Long, C. S.: UV Index forecasting practices around the world. SPARC Newsletter no. 21, June 2003, 2003. Lorenc, A. C., Roulstone, I., and White, A.: On the choice of control fields in var. Forecasting Research Technical Report No. 419, The Met Office, 2004. Lyster, P. M., Cohn, S. E., Ménard, R., et al.: Parallel implementation of a Kalman filter for constituent data assimilation, Mon. Weather Rev., 125, 1674–1686, 1997. McCormack J. P., Eckermann S. D., Coy, L., et al.: NOGAPS-ALPHA model simulations of stratospheric ozone during the SOLVE2 campaign, Atmos. Chem. Phys., 4, 2401–2423, 2004. McLaughlin, D., O'Neill, A., Derber, J., and Kamachi, M.: Opportunities for enhanced collaboration within the data assimilation community, Quart. J. Roy. Meteorol. Soc., 131, 3683–3693, 2005. McLinden, C. A., Olsen, S. C., Hannegan, B., et al.: Stratospheric ozone in 3-D models: A simple chemistry and the cross-tropopause flux, J. Geophys. Res., 105, 14 653–14 665, 2000. McNally, A. P., Watts, P., Smith, J., et al.: The assimilation of AIRS radiance data at ECMWF, Quart. J. Roy. Meteorol. Soc., 132, 935–958, 2006. McPeters, R. D., Bhartia, P. K., Krueger, A., et al.: Earth Probe Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide. NASA Reference Publication 1998-206895, 1998. Marchand, M., Bekki, S., Denis, L., and Pommereau, J-P.: Test of the nightime polar stratospheric NO₂ decay using wintertime SAOZ measurements and chemical data assimilation, Geophys. Res. Lett., 30, 1920, doi:10.1029/2003GL017582, 2003. Marchand, M., Bekki, S., Hauchecorne, A., and Bertaux, J.-L.: Validation of the self-consistency of GOMOS NO₃, NO₂ and O₃ data using chemical data assimilation, Geophys. Res. Lett., 31, L10107, doi:10.1029/2004GL019631, 2004. Massart, S., Cariolle, D., and Peuch, V.-H.: Towards an improvement of the atmospheric ozone distribution and variability by the assimilation of satellite data, C.R. Geosciences, 15, 1305–1310, 2004. Mathison, C., Jackson, D. R., and Keil, M.: Methods of improving the representation of ozone in the Met Office model. NWP Tech. Report No. 502, Met Office, 2007. Ménard, R. and Chang, L.-P.: Stratospheric assimilation of chemical tracer observations using a Kalman filter, part II: Chi-squared validated results and analysis of variance and correlation dynamics, Mon. Weather Rev., 128, 2672–2686, 2000. Ménard, R., Cohn, S. E., Chang, L. P., and Lyster, P. M.: Stratospheric assimilation of chemical tracer observations using a Kalman filter, part I: Formulation, Mon. Weather Rev., 128, 2654–2671, 2000. Migliorini, S., Piccolo, C., and Rodgers, C. D.: Intercomparison of direct and indirect measurements: MIPAS versus sonde ozone profiles, J. Geophys. Res., 109, D19316, doi:10.1029/2004JD004988, 2004. Miller, A. J., Nagatani, R. M., Flynn, L. E., et al.: A cohesive total ozone data set from the SBUV(/2) satellite system. J. Geophys. Res., 107, 4701, doi:10.1029/2001JD000853, 2002. Molod, A., Helfand, H. M., and Takacs, L. L.: The climatology of parameterized physical processes in the GEOS-1 GCM and their impact on the GEOS-1 data assimilation system, J. Clim., 9, 764–785, 1996. Monge-Sanz, B. M., Chipperfield, M. P., Simmons, A. J., and Uppala, S. M.: Mean age of air and transport in a CTM: Comparison of different ECMWF analyses, Geophys. Res. Lett., 34, L04801, doi:10.1029/2006GL028515, 2007. Morcrette, J.-J.: Ozone radiation interactions in the ECMWF forecast system. ECMWF Tech Memo 375, 2003. Müller, M. D., Bhartia, P. K., and \vStajner, I.: Assimilation of SBUV version 8 radiances into the GEOS DAS. Proceedings of the Quadrennial Ozone Symposium, GOS, Kos, Greece, June 2004. Available from ftp://gmaoftp.gsfc.nasa.gov/pub/papers/ivanka/ozone_papers/QOS04.Mueller.pdf, 2004. Murtagh, D., Fisk, U., Merino, F., et al.: An overview of the Odin atmospheric mission, Can. J. Phys., 80, 309–319, 2002. Nakajima, H., Sugita, T., Yokota, T., et al.: Characteristics and performance of the Improved Limb Atmospheric Spectrometer-II (ILAS-II) on board the ADEOS-II satellite, J. Geophys. Res., 111, D11501, doi:10.1029/2005JD006334, 2006. Offermann, D., Grossman, K.-U., Barthol, P., et al.: The cryogenic infrared spectrometer and telescopes for the atmosphere (CRISTA) experiment and middle atmosphere variability, J. Geophys. Res., 104, 16 311–16 327, 1999. Oikonomou, E. and O'Neill, A.: An evaluation of water vapour and ozone in the ERA-40 reanalysis compared with UARS data, J. Geophys. Res., 111, D14109, doi:10.1029/2004JD005341, 2006. Orsolini, Y. J. and Nikulin, G.: A low-ozone episode during the European heat wave of August 2003, Quart. J. Roy. Meteorol. Soc., 132, 667–680, 2006. Ott, E., Hunt, B. R., Szunyogh, I., et al.: A local ensemble Kalman filter for atmospheric data assimilation, Tellus, 56A, 415–428, 2004. Parrish, D. and Derber, J. C.: The National Meteorological Center's spectral statistical interpolation analysis system,. Mon. Weather Rev., 120, 1747–1763, 1992. Peuch, A., Thépaut, J.-N., and Pailleux, J.: Dynamical impact of total-ozone observations in a four-dimensional variational assimilation, Quart. J. Roy. Meteorol. Soc., 126, 1641–1659, 2000. Pham, D. T.: Stochastic methods for sequential data assimilation in strongly nonlinear systems, Mon. Weather Rev., 129, 1194–1207, 2001. Plumb, R. A. and Ko, M. K. W.: Interrelationships between mixing ratios of long-lived stratospheric constituents, J. Geophys. Res., 97, 10 145–10 156, 1992. Polavarapu, S., Ren, S., Rochon, Y., et al.: Data assimilation with the Canadian Middle Atmosphere Model, Atmos.-Ocean, 43, 77–100, 2005a. Polavarapu, S., Shepherd, T. G., Rochon, Y., and Ren, S.: Some challenges of middle atmosphere data assimilation, Quart. J. Roy. Meteorol. Soc., 131, 3513–3527, 2005b. Raspollini, P., Belotti, C., Burgess, A., et al.: MIPAS level 2 operational analyses, Atmos. Chem. Phys., 6, 5605–5630, 2006. Rawlins, F., Ballard, S. P., Bovis, K. J., et al.: The Met Office global four-dimensional variational data assimilation scheme, Quart. J. Roy. Meteorol. Soc., 133, 347–362, 2007. Riishøjgaard, L.-P.: On four-dimensional variational assimilation of ozone data in weather-prediction models, Quart. J. Roy. Meteorol. Soc., 122, 1545–1572, 1996. Riishøjgaard, L.-P.: A direct way of specifying flow-dependent background error correlations for meteorological analysis systems, Tellus, 50, 42–57, 1998. Riishøjgaard, L.-P., \vStajner, I., and Lou, G.-P.: The GEOS ozone data assimilation system, Adv. Space Res., 25, 1063–1072, 2000. Roche, A. E., Kumer, J. B., Mergenthaler, J. L., et al.: The Cryogenic Limb Array Etalon Spectrometer (CLAES) on UARS: Experiment Description and Performance, J. Geophys. Res., 98, 10 763–10 775, 1993. Rodgers, C. D.: Inverse Methods for Atmospheric Sounding: Theory and Practice. World Scientific Publishing Co., Singapore, 2000. Rood, R. B.: Ozone assimilation. In Data Assimilation for the Earth System, NATO ASI Series, edited by: Swinbank, R., Shutyaev, V. and Lahoz, W. A., Kluwer, 2003. Rood, R. B.: Assimilation of stratospheric meteorological and constituent observations: A Review. SPARC Newsletter no. 25, July 2005, 2005. Rösevall, J. D., Murtagh, D. P., Urban, J., and Jones, A. K.: A study of polar ozone depletion based on sequential assimilation of satellite data from the ENVISAT/MIPAS and Odin/SMR instruments, Atmos. Chem. Phys., 7, 899–911, 2007. Russell III, J. M., Gordley, L. L., Park, J. H., et al.: The Halogen Occultation Experiment, J. Geophys. Res., 98, 10 777–19 797, 1993. Sassi, F., Boville, B. A., Kinnison, D., and Garcia, R. R.: The effects of interactive ozone chemistry on simulations of the middle atmosphere, Geophys. Res. Lett., 32, L07811, doi:10.1029/2004GL022131, 2005. Saunders, R., Matricardi, M., and Brunel, P.: An improved fast radiative transfer model for assimilation of satellite radiance observations, Quart. J. Roy. Meteorol. Soc., 125, 1407–1426, 1999. Schoeberl, M. R., Douglass, A. R., Zhu, Z., and Pawson, S.: A comparison of the lower stratospheric age spectra derived from a general circulation model and two data assimilation systems, J. Geophys. Res., 108, 4113, doi:10.1029/2002JD002652, 2003. Segers, A. J., Eskes, H. J., van der A, R. J., et al.: Assimilation of GOME ozone profiles and a global chemistry-transport model, Quart. J. Roy. Meteorol. Soc., 131, 477–502, 2005. Simmons, A. J., Hortal, M., Kelly, G., et al.: ECMWF analyses and forecasts of stratospheric winter polar vortex breakup: September 2002 in the Southern Hemishere and related events, J. Atmos. Sci., 62, 668–689, 2005. SPARC: Assessment of upper tropospheric and lower stratospheric water vapour. WCRP-113, WMO/TD No. 1043, SPARC Report No. 2, Eds. D. Kley, J.M. Russell and C. Phillips, 2000. \vStajner, I., Riishøjgaard, L.-P., and Rood, R. B.: The GEOS ozone data assimilation system: Specification of error statistics,. Quart. J. Roy. Meteorol. Soc., 127, 1069–1094, 2001. \vStajner, I. and Wargan, K.: Antarctic stratospheric ozone from the assimilation of occultation data, Geophys. Res. Lett., 31, L18108, doi:10.1029/2004GL020846, 2004. \vStajner, I., Wargan, K., Chang, L.-P., et al.: Assimilation of ozone profiles from the Improved Limb Atmospheric Spectrometer-II: Study of Antarctic ozone, J. Geophys. Res., 111, D11514, doi:10.1029/2005JD006448, 2006. \vStajner, I., Winslow, N., Rood, R. B., and Pawson, S.: Monitoring of observation errors in the assimilation of satellite ozone data, J. Geophys. Res., 109, D06309, doi:10.1029/2003JD006309, 2004. Streibel, M., Rex, M., von der Gathen, P., et al.: Chemical ozone loss in the Arctic winter 2002/2003 determined with Match, Atmos. Chem. Phys., 6, 2783–2792, 2006. Struthers, H., Brugge, R., Lahoz, W. A., et al.: Assimilation of ozone profiles and total column measurements into a global general circulation model, J. Geophys. Res., 107, 4438, doi:10.1029/2001JD000957, 2002. Swinbank, R., Ménard, R., and Riishøjgaard, L.-P.: Anisotropic error correlation modelling in a simple 2-D assimilation system. In Proceedings of the 3$^rd$ International Symposium on assimilation of observations in meteorology and oceanography (Québec City, Canada 7–11 June 1999), World Weather Research Programme Report no. 2, WMO/TD no. 986, 353–356, 2000. Talagrand, O.: Bayesian estimation. Optimal interpolation. Statistical linear estimation, in: Data Assimilation for the Earth System, NATO ASI Series, edited by: Swinbank, R., Shutyaev, V., and Lahoz, W. A., Kluwer, 2003a. Talagrand, O.: Variatonal assimilation. Adjoint equations, in: Data Assimilation for the Earth System, NATO ASI Series, edited by: Swinbank, R., Shutyaev, V., and Lahoz, W. A., Kluwer, 2003b. Talagrand, O.: A posteriori validation of assimilation algorithms, in: Data Assimilation for the Earth System, NATO ASI Series, edited by: Swinbank, R., Shutyaev, V., and Lahoz, W. A., Kluwer, 2003c. Tan, W. W., Geller, M. A., Pawson, S., and da Silva, A.: A case study of excessive subtropical transport in the stratosphere of a data assimilation system, J. Geophys. Res., 109, D11102, doi:10.1029/2003JD004057, 2004. Trenberth, K. (Ed.): Climate System Modeling, Cambridge University Press, Cambridge, 1992. Uppala, S. M., Kållberg, Simmons, A. J., et al.: The ERA-40 re-analysis, Quart. J. Roy. Meteorol. Soc., 131, 2961–3012, 2005. Vigouroux, C., De Mazière, M., Errera, Q., et al.: Comparison between ground-based FTIR and MIPAS N₂O and HNO₃ profiles before and after assimilation in BASCOE. Atmos. Chem. Phys., 7, 377-396, 2007. Wang, K.-Y., Lary, D. J., Shallcross, D. E., et al.: A review on the use of the adjoint method in four-dimensional atmospheric-chemistry data assimilation, Quart. J. Roy. Meteorol. Soc., 127, 2181–2204, 2001. Wargan, K., \vStajner, I., Pawson, S., et al.: Assimilation of ozone data from the Michelson Interferometer for Passive Atmospheric Sounding, Quart. J. Roy. Meteorol. Soc., 131, 2713–2734, 2005. Waters, J.W.: Atmospheric measurements by the MLS experiments: Results from UARS and plans for the future. Adv. Space Res., 21, 1363-1372, 1998. Waters, J. W., Froidevaux, L., Harwood, R. S., et al.: The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura satellite, IEEE Trans. Geosci. Remote Sensing, 44, 1075–1092, 2006. Weaver, A. T. and Courtier, P.: Correlation modelling on the sphere using a generalized diffusion equation, Quart. J. Roy. Meteorol. Soc., 127, 1815–1846, 2001. WMO: Scientific Assessment of Ozone Depletion, 2006. World Meteorological Organization, Global Ozone Research and Monitoring Project, Report No. 50, available from http://www.wmo.ch/web/arep/reports/ozone_2006/ozone_asst_report.html, 2006.