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How typical were the meteorological conditions in the COPS area during the summer 2007? Heini Wernli Stephan Pfahl Jörg Trentmann University of Mainz. Approach and Outline Data: ECMWF analysis (2007 op. ana. vs. ERA40 1979-2001). Approach and Outline
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How typical were the meteorological conditions in the COPS area during the summer 2007? Heini Wernli Stephan Pfahl Jörg Trentmann University of Mainz
Approach and Outline Data: ECMWF analysis (2007 op. ana. vs. ERA40 1979-2001)
Approach and Outline • Data: ECMWF analysis (2007 op. ana. vs. ERA40 1979-2001) • Consider domain-average for COPS area of: • T, , e, q, ... at 925, 850, 700 hPa • simple variant of KO-index (thermodynamic stability) • wind velocity and direction at 500 hPa • Eady growth rate (baroclinicity at 700 hPa) • cyclone frequency • frequency of upper-level PV cut-offs (small-scale troughs)
Approach and Outline • Data: ECMWF analysis (2007 op. ana. vs. ERA40 1979-2001) • Consider domain-average for COPS area of: • T, , e, q, ... at 925, 850, 700 hPa • simple variant of KO-index (thermodynamic stability) • wind velocity and direction at 500 hPa • Eady growth rate (baroclinicity at 700 hPa) • cyclone frequency • frequency of upper-level PV cut-offs (small-scale troughs) • Show: • maps of seasonal mean & deviation from climatology • probability density functions (2007 vs. climatology) • quantile-quantile plots (2007 vs. climatology)
Approach and Outline • Data: ECMWF analysis (2007 op. ana. vs. ERA40 1979-2001) • Consider domain-average for COPS area of: • T, , e, q, ... at 925, 850, 700 hPa • simple variant of KO-index (thermodynamic stability) • wind velocity and direction at 500 hPa • Eady growth rate (baroclinicity at 700 hPa) • cyclone frequency • frequency of upper-level PV cut-offs (small-scale troughs) • Show: • maps of seasonal mean & deviation from climatology • probability density functions (2007 vs. climatology) • quantile-quantile plots (2007 vs. climatology) • Caveat: • 2007 and climatology have different model resolution!
T at 925 hPa • colder than clim over F • warmer than clim over E Europe • very close to clim in COPS area climatology 1979-2001 deviation from climatology in 2007
e at 925 hPa • slightly above clim in COPS area climatology 1979-2001 deviation from climatology in 2007
Cyclone frequency • above clim over UK / Benelux • below clim in Central Europe climatology 1979-2001 deviation from climatology in 2007
Freq. of upper-level cutoffs • (short wave disturbances) • strongly above clim over UK • above clim in W Europe / COPS climatology 1979-2001 deviation from climatology in 2007
PDFs of domain-average values at 12 UTC Temperature on 925 hPa [°C] specific hum. on 925 hPa [g/kg]
PDFs of domain-average values at 12 UTC KO-Index: e, 500 - e, 850 [K]
PDFs of domain-average values at 12 UTC more SW winds wind direction on 500 hPa
Quantile-quantile plots of domain-averages at 12 UTC T at 925 K
Quantile-quantile plots of domain-averages at 12 UTC Q at 925 K
Quantile-quantile plots of domain-averages at 12 UTC KO Index
Conclusion In summer 2007, the COPS area was characterised by ... ++ cyclones to the NW + passage of short wave troughs + frequency of SW winds at 500 hPa + BL specific humidity (mainly average not extremes) + low tropospheric baroclinicity 0 BL temperature - TD stability (mainly average not extremes)
Eady growth rate • (low tropospheric baroclinicty) • slightly above clim near 45°N • (i.e., over Alps / COPS) climatology 1979-2001 deviation from climatology in 2007
PDFs of domain-average values at 12 UTC Eady growth rate KO-Index: e, 500 - e, 850 [K]