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the study of Atlantic cyclogenesis in several directions. Model resolution will be carried from T L 95 to T L 799 (grid resolutions of roughly 210 to 25 km) using the global European Centre for Medium-Range Weather Forecasts (ECMWF) forecast model system. Forty-year ECMWF Re-Analysis (ERA-40) data (roughly equivalent to T L 159 resolution) will be compared with model simulations, looking at the life cycle of cyclone development associated with strong pressure-drag events. Vertical structure of the
the study of Atlantic cyclogenesis in several directions. Model resolution will be carried from T L 95 to T L 799 (grid resolutions of roughly 210 to 25 km) using the global European Centre for Medium-Range Weather Forecasts (ECMWF) forecast model system. Forty-year ECMWF Re-Analysis (ERA-40) data (roughly equivalent to T L 159 resolution) will be compared with model simulations, looking at the life cycle of cyclone development associated with strong pressure-drag events. Vertical structure of the
warming event in September). Our analysis makes no a priori assumptions regarding the structural evolution of the organized response as the data are not projected upon predetermined modes of variability (such as the SAM). In fact, the distinctions between SFW-associated variability and SAM structures represent a key result of the paper. 2. Data and methods The basic input data for our study are the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) daily average
warming event in September). Our analysis makes no a priori assumptions regarding the structural evolution of the organized response as the data are not projected upon predetermined modes of variability (such as the SAM). In fact, the distinctions between SFW-associated variability and SAM structures represent a key result of the paper. 2. Data and methods The basic input data for our study are the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) daily average
and anticyclonic baroclinic wave life cycles that stem from idealized simulations of the evolution of baroclinic waves (e.g., Davies et al. 1991 ; Thorncroft et al. 1993 ). a. Baroclinic life cycles and background flow setting The life cycles of baroclinic waves are a long-standing theme in meteorological research [see Simmons (1998) for a review]. The life cycle concept is of direct interest to the forecasting community ( Bjerknes and Solberg 1922 ) and also plays a central role in the
and anticyclonic baroclinic wave life cycles that stem from idealized simulations of the evolution of baroclinic waves (e.g., Davies et al. 1991 ; Thorncroft et al. 1993 ). a. Baroclinic life cycles and background flow setting The life cycles of baroclinic waves are a long-standing theme in meteorological research [see Simmons (1998) for a review]. The life cycle concept is of direct interest to the forecasting community ( Bjerknes and Solberg 1922 ) and also plays a central role in the
, 2001 : Stratospheric harbingers of anomalous weather regimes. Science , 294 , 581 – 584 . Baldwin , M. P. , D. B. Stephenson , D. W. J. Thompson , T. J. Dunkerton , A. J. Charlton , and A. O’Neill , 2003 : Stratospheric memory and skill of extended-range weather forecasts. Science , 301 , 636 – 640 . Black , R. X. , 2002 : Stratospheric forcing of surface climate in the Arctic oscillation. J. Climate , 15 , 268 – 277 . Black , R. X. , B. A. McDaniel , and W. A
, 2001 : Stratospheric harbingers of anomalous weather regimes. Science , 294 , 581 – 584 . Baldwin , M. P. , D. B. Stephenson , D. W. J. Thompson , T. J. Dunkerton , A. J. Charlton , and A. O’Neill , 2003 : Stratospheric memory and skill of extended-range weather forecasts. Science , 301 , 636 – 640 . Black , R. X. , 2002 : Stratospheric forcing of surface climate in the Arctic oscillation. J. Climate , 15 , 268 – 277 . Black , R. X. , B. A. McDaniel , and W. A
of U is typical of midtropospheric winds. The full-year means of zonal-mean U over southern latitudes are shown in Fig. 1 . The model winds closely match the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA) result also shown, including both a jet peak around 50°S and an extended northern flank. The data used are from the whole years 1958–2001 from the ERA-40 project described by Kållberg et al. (2004) , including levels through 30 hPa. Within the troposphere
of U is typical of midtropospheric winds. The full-year means of zonal-mean U over southern latitudes are shown in Fig. 1 . The model winds closely match the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA) result also shown, including both a jet peak around 50°S and an extended northern flank. The data used are from the whole years 1958–2001 from the ERA-40 project described by Kållberg et al. (2004) , including levels through 30 hPa. Within the troposphere
scale of baroclinic waves. J. Atmos. Sci. , 31 , 1515 – 1525 . Simmons , A. J. , M. Hortal , G. Kelly , A. McNally , A. Untch , and S. Uppala , 2005 : ECMWF analyses and forecasts of stratospheric winter polar vortex break-up: September 2002 in the Southern Hemisphere and related events. J. Atmos. Sci. , 62 , 668 – 689 . Sommeria , J. , S. D. Meyers , and H. L. Swinney , 1989 : Laboratory model of a planetary eastward jet. Nature , 337 , 58 – 61 . Sommeria , J
scale of baroclinic waves. J. Atmos. Sci. , 31 , 1515 – 1525 . Simmons , A. J. , M. Hortal , G. Kelly , A. McNally , A. Untch , and S. Uppala , 2005 : ECMWF analyses and forecasts of stratospheric winter polar vortex break-up: September 2002 in the Southern Hemisphere and related events. J. Atmos. Sci. , 62 , 668 – 689 . Sommeria , J. , S. D. Meyers , and H. L. Swinney , 1989 : Laboratory model of a planetary eastward jet. Nature , 337 , 58 – 61 . Sommeria , J
