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PV/Humidity precursors

PV/Humidity precursors. Gwendal Rivière, Karine Maynard, Philippe Arbogast GAME; CNRM/GMAP/RECYF CNRS; Météo-France. Rationale: upper-level features are associated to stratospheric intrusions into the upper troposphere that can be identified using satellite data (WV, ozone…). There are :.

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PV/Humidity precursors

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  1. PV/Humidity precursors Gwendal Rivière, Karine Maynard, Philippe Arbogast GAME; CNRM/GMAP/RECYF CNRS; Météo-France

  2. Rationale: upper-level features are associated to stratospheric intrusions into the upper troposphere that can be identified using satellite data (WV, ozone…). There are : • Dry patterns • High PV patterns

  3. Tools : sensitivity studies • To humidity (corrections) • To PV(inversion) • Within ARPEGE (global, 23km resolution over western Europe)+Aladin (Lam, 10km)+AROME (LAM over France, 2.5km resolution, NH)

  4. PV/q correction (z) after 1D-var Iso-PV DPV/q Iso-q Methodology PV/specific humidity modifications z y x

  5. Case studies • Sensitivity to PV and humidity in the case of a Mediterranean MCS • Sensitivity of Klaus windstorm to humidity • Sensitivity of Klaus windstorm to PV. Application of initial condition improvement.

  6. NOS (PV modification) NOHUS (Hu modification) NOHUC (Hu modification)

  7. CTRL NOS NOHUS NOHUC

  8. Case studies • Sensitivity to PV and humidity in the case of a Mediterranean MCS • Sensitivity of Klaus windstorm to humidity • Sensitivity of Klaus windstorm to PV. Application of initial condition improvement.

  9. Case studies • Sensitivity to PV and humidity in the case of a Mediterranean MCS • Sensitivity of Klaus windstorm to humidity • Sensitivity of Klaus windstorm to PV. Application of initial condition improvement.

  10. PV+column ozone (METEOSAT)

  11. ARPEGE +27h ARPEGE +24h (with modified PV) MSLP

  12. ARPEGE +27h ARPEGE +24h (with modified PV)ARPEGE +21h wind gusts > 35 m/s

  13. Conclusions (1) • In the case of the Mediterranean MCS (05 Sept 2005) the precipitating activity seems to be sensitive to mid to upper-level moisture and to PV. • Upper-level PV, as it triggers a low-level southerly flow over the gulf of Lion, indirectly contributes to convective activity. • Moisture gradients are likely area for convective initiation and also seem to help the stationarity (crucial to understand since it is associated with strong accumulated precipitations

  14. Conclusions (2) • Klaus windstorm activity is weakly sensitive to initial condition humidity • On the one hand, it is not possible to recognize the diabatic Rossby wave behaviour in that case • On the other hand, diabatic processes are reduced for about 6h. Afterwards remnants of diabatic processes may be found in the vicinity of the tropopause downstream wrt the cyclone • Klaus windstorm behaves like a type-B cyclone development since it is sensitive to upper-PV. • IC failures may be corrected by experts (forecasters) and the subsequent forecast may be eventually improved .

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