• Alpert, J. C., , M. Kanamitsu, , P. M. Caplan, , J. G. Sela, , G. H. White, , and E. Kalnay, 1988: Mountain induced gravity wave drag parameterization in the NMC medium-range model. Preprints, Eighth Conf. on Numerical Weather Prediction, Baltimore, MD, Amer. Meteor. Soc., 726–733.

  • Bengtsson, L., , S. Hagemann, , and K. I. Hodges, 2004a: Can climate trends be computed from reanalysis data? J. Geophys. Res., 109 .D11111, doi:10.1029/2004JD004536.

    • Search Google Scholar
    • Export Citation
  • Bengtsson, L., , K. I. Hodges, , and S. Hagemann, 2004b: Sensitivity of the ERA40 reanalysis to the observing system: Determination of the global atmospheric circulation from reduced observations. Tellus, 56A , 456471.

    • Search Google Scholar
    • Export Citation
  • Bouttier, F., , and G. Kelly, 2001: Observing-system experiments in the ECMWF 4D-Var data assimilation system. Quart. J. Roy. Meteor. Soc., 127 , 14691488.

    • Search Google Scholar
    • Export Citation
  • Bromwich, D. H., , and R. L. Fogt, 2004: Strong trends in the skill of the ERA-40 and NCEP–NCAR reanalyses in the high and midlatitudes of the Southern Hemisphere, 1958–2001. J. Climate, 17 , 46034619.

    • Search Google Scholar
    • Export Citation
  • Cadet, D., 1973: Étude du cisaillement du vent horizontal dans la stratosphèrePh.D. thesis, Université de Paris, 104 pp.

  • Cadet, D., , and J. Ovarlez, 1974: La mesure précise de la température dans la troposphère et la basse stratosphère: Équilibre thermodynamique du senseur. Tech. Rep. 62, Laboratoire de Météorologie Dynamique, CNRS, France, 13 pp.

  • Fels, S. B., , and M. D. Schwartzkopf, 1975: The simplified exchange approximation: A new method for radiative transfer calculations. J. Atmos. Sci., 32 , 14751488.

    • Search Google Scholar
    • Export Citation
  • Fourrier, J., , P. Morel, , and P. Sitbon, 1970: Ambient temperature measurements from constant-level balloons. J. Appl. Meteor., 9 , 154157.

    • Search Google Scholar
    • Export Citation
  • Hagan, M. E., , J. M. Forbes, , and F. Vial, 1993: A numerical investigation of the propagation of the quasi 2-day wave into the lower thermosphere. J. Geophys. Res., 98 , 2319323205.

    • Search Google Scholar
    • Export Citation
  • Hagan, M. E., , M. D. Burrage, , J. M. Forbes, , J. Hackney, , W. J. Randel, , and X. Zhang, 1999: GSWM-98: Results for migrating solar tides. J. Geophys. Res., 104 , 68136828.

    • Search Google Scholar
    • Export Citation
  • Hertzog, A., , C. Basdevant, , F. Vial, , and C. R. Mechoso, 2004: The accuracy of stratospheric analyses in the northern hemisphere inferred from long-duration balloon flights. Quart. J. Roy. Meteor. Soc., 130 , 607626.

    • Search Google Scholar
    • Export Citation
  • Hodges, K. I., , B. J. Hoskins, , J. Boyle, , and C. Thorncroft, 2003: A comparison of recent reanalysis datasets using objective feature tracking: Storm tracks and tropical easterly waves. Mon. Wea. Rev., 131 , 20122037.

    • Search Google Scholar
    • Export Citation
  • Jenne, R., 1999: Global observations for reanalysis, 1948-on. Proc. Second WCRP Int. Conf. on Reanalyses, WCRP Series Rep. 109, Waterfield Park, Reading, United Kingdom, World Meteorological Organization, 5–9.

  • Kållberg, P., , A. Simmons, , S. Uppala, , and M. Fuentes, 2004: The ERA-40 archive. ERA-40 Project Rep. Series 17, ECMWF, Shinfield Park, Reading, United Kingdom, 31 pp.

  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kanamitsu, M., 1989: Description of the NMC global data assimilation and forecast system. Wea. Forecasting, 4 , 334342.

  • Kistler, R., and Coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82 , 247267.

    • Search Google Scholar
    • Export Citation
  • Lacis, A. A., , and J. E. Hansen, 1974: A parameterization for the absorption of solar radiation in the Earth’s atmosphere. J. Atmos. Sci., 31 , 118133.

    • Search Google Scholar
    • Export Citation
  • Lott, F., , and M. J. Miller, 1997: A new subgrid-scale orographic drag parametrization: Its formulation and testing. Quart. J. Roy. Meteor. Soc., 123 , 101127.

    • Search Google Scholar
    • Export Citation
  • Marshall, G. J., 2002: Trends in Antarctic geopotential height and temperatures: A comparison between radiosonde and NCEP–NCAR reanalysis data. J. Climate, 15 , 659674.

    • Search Google Scholar
    • Export Citation
  • Mlawer, E. J., , S. J. Taubman, , P. D. Brown, , M. J. Iacono, , and A. S. Clough, 1997: Radiative transfer for inhomogeneous atmospheres: RRTM a validated correlated-k model for the longwave. J. Geophys. Res., 102 , 1666316682.

    • Search Google Scholar
    • Export Citation
  • Mo, K. C., , X. L. Wang, , R. Kistler, , M. Kanamitsu, , and E. Kalnay, 1995: Impact of satellite data on the CDAS-reanalysis system. Mon. Wea. Rev., 123 , 124139.

    • Search Google Scholar
    • Export Citation
  • Morel, P., , and W. Bandeen, 1973: The EOLE experiment: Early results and current objectives. Bull. Amer. Meteor. Soc., 54 , 298306.

  • Morel, P., , and M. Desbois, 1974: Mean 200-mb circulation in the southern hemisphere deduced from EOLE balloon flights. J. Atmos. Sci., 31 , 394407.

    • Search Google Scholar
    • Export Citation
  • Pan, H-L., , and W-S. Wu, 1995: Implementing a mass flux convection parameterization package for the NMC medium-range forecast model. NMC Office Note 409, 40 pp.

  • Simmons, A. J., , and J. K. Gibson, 2000: The ERA-40 project plan. ERA-40 Project Rep. Series 1, ECMWF, Shinfield Park, Reading, United Kingdom, 63 pp.

  • Simmons, A. J., , P. D. Jones, , V. da Costa Bechtold, , A. C. M. Beljaars, , P. W. Kållberg, , S. Saarinen, , S. M. Uppala, , and N. Wedi, 2004: Comparison of trends and low-frequency variability in CRU, ERA-40, and NCEP–NCAR analyses of surface air temperature. J. Geophys. Res., 109 .D24115, doi:10.1029/2004JD005306.

    • Search Google Scholar
    • Export Citation
  • Sitbon, P., 1975: Platform location and data collection by satellite systems. IEEE Trans. Geosci. Electr., 13 , 217.

  • Sterl, A., 2004: On the (in)homogeneity of reanalysis products. J. Climate, 17 , 38663873.

  • Tiedtke, M., 1989: A comprehensive mass flux scheme for cumulus parameterization in large-scale models. Mon. Wea. Rev., 117 , 17791800.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1982: Seasonality in southern hemisphere eddy statistics at 500 mb. J. Atmos. Sci., 39 , 25072520.

  • Trenberth, K. E., 1991: Storm tracks in the southern hemisphere. J. Atmos. Sci., 48 , 21592178.

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An Assessment of ECMWF and NCEP–NCAR Reanalyses in the Southern Hemisphere at the End of the Presatellite Era: Results from the EOLE Experiment (1971–72)

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  • 1 Laboratoire de Météorologie Dynamique, Université Pierre et Marie Curie, IPSL, CNRS, Palaiseau, France
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Abstract

This article estimates the biases and standard deviations of the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) and the 50-yr National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) Reanalysis (NN50) in the upper troposphere and lower stratosphere in 1971–72. These estimates are obtained by comparing the reanalyzed temperatures and winds with EOLE observations, a dataset collected during 480 superpressure-ballon flights in the Southern Hemisphere (SH). Dedicated algorithms have been developped to control the quality of this dataset and a stringent selection has been performed on the observations. None of the atmospheric centers has assimilated the EOLE dataset, which is therefore fully independent from the reanalyses. It is furthermore argued that the statistics obtained in this study at the end of the presatellite era may be representative of the reanalysis accuracy since 1957. The results of these comparisons indicate that NN50 tends to be a few degrees colder than the observations in the SH subpolar latitudes, while ERA-40 is less hit by this cold-pole issue. Both reanalyses, on the other hand, are found to be warmer than the observations by about 1 K in the subtropics. In contrast, the wind comparisons only exhibit nonsignificant or small reanalysis biases, even though the reanalyzed subtropical jet is slightly displaced equatorward with respect to the observations. The ability of reanalyses to capture the atmospheric synoptic-scale variability in the upper troposphere is assessed by computing the standard deviations of the reanalysis minus observation differences. The ERA-40 and NN50 standard deviations show a maximum (i.e., a poorer reanalysis accuracy) in the SH storm track. However, ERA-40 standard deviations are found to be much larger than NN50 standard deviations. The standard deviations also exhibit a marked decrease above the continents, stressing the heterogeneity of the atmospheric observation network during the presatellite era. Finally, in contrast with previous studies, the reanalysis accuracy does not appear to be better during summer than during winter.

Corresponding author address: A. Hertzog, Laboratoire de Météorologie Dynamique, École Polytechnique, F-91128 Palaiseau CEDEX, France. Email: hertzog@lmd.polytechnique.fr

Abstract

This article estimates the biases and standard deviations of the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) and the 50-yr National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) Reanalysis (NN50) in the upper troposphere and lower stratosphere in 1971–72. These estimates are obtained by comparing the reanalyzed temperatures and winds with EOLE observations, a dataset collected during 480 superpressure-ballon flights in the Southern Hemisphere (SH). Dedicated algorithms have been developped to control the quality of this dataset and a stringent selection has been performed on the observations. None of the atmospheric centers has assimilated the EOLE dataset, which is therefore fully independent from the reanalyses. It is furthermore argued that the statistics obtained in this study at the end of the presatellite era may be representative of the reanalysis accuracy since 1957. The results of these comparisons indicate that NN50 tends to be a few degrees colder than the observations in the SH subpolar latitudes, while ERA-40 is less hit by this cold-pole issue. Both reanalyses, on the other hand, are found to be warmer than the observations by about 1 K in the subtropics. In contrast, the wind comparisons only exhibit nonsignificant or small reanalysis biases, even though the reanalyzed subtropical jet is slightly displaced equatorward with respect to the observations. The ability of reanalyses to capture the atmospheric synoptic-scale variability in the upper troposphere is assessed by computing the standard deviations of the reanalysis minus observation differences. The ERA-40 and NN50 standard deviations show a maximum (i.e., a poorer reanalysis accuracy) in the SH storm track. However, ERA-40 standard deviations are found to be much larger than NN50 standard deviations. The standard deviations also exhibit a marked decrease above the continents, stressing the heterogeneity of the atmospheric observation network during the presatellite era. Finally, in contrast with previous studies, the reanalysis accuracy does not appear to be better during summer than during winter.

Corresponding author address: A. Hertzog, Laboratoire de Météorologie Dynamique, École Polytechnique, F-91128 Palaiseau CEDEX, France. Email: hertzog@lmd.polytechnique.fr

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