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Moist Physics Response to the Modifications of the Initial Profile

14 ALADIN Workshop, Innsbruck, 1-4 June,2004 ________________________________________________________________________________________________________________________________________________________________________________. Moist Physics Response to the Modifications of the Initial Profile.

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Moist Physics Response to the Modifications of the Initial Profile

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  1. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Moist Physics Response to the Modifications of the Initial Profile Doina Banciu, NIMH Romania Eric Bazile, CNRM/GMAP, Meteo-France

  2. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Motivation of the work Radar data assimilation reflectivity condensed water clouds and precipitation above a given level + cloudtop (from satellite) The aim: to get some knowledge about the physics response to the foreseen profile changes whithin radar data assimilation ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  3. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Method • Use of 1D model • analysis of model results after 1 step integration - variation of precipitation amount - • Statistical approach • different profiles samples, extracted from the 3D ALADIN model • Modification setup • Modification of specific humidity, temperature and humidity convergence • For layers of different depth • * at the top of the cloud • * for the low troposphere Tacking into account the characteristics of condensation schemes in ARPEGE/ALADIN model - no prognostic equation for condensed water - elimination of over-saturation in 1 step ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  4. Nancy 186 profiles stratiform & convective Troyes 64 profiles mainly stratiform Nantes 190 profiles mainly convective

  5. Mean Profile Average over the 1D profiles after 1 step integration Troyes Nancy (stratiform) (stratiform & convective) Nantes (convective)

  6. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Modification Qv – series 1 each Qv profile was modified by adding a constant value between -0.5 and +0.5 g/kg - for different layer depths of 1000, 2000, 3000,4000,5000 m - for different position of the modified layer between 500 and 7500 m Constraint: - minimum value of Qv = 1.E-15 for each profile 1 step integration - starting from the corespondent modified profile - output compared with the reference run ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  7. Modif.1 Qv - stratiform sample- Variation of the surface precipitation [mm/hour] : mod - ref p o s i t i o n o f m o d i f i e d l a y e r [km] Delta Qv [g/kg] Delta Qv [g/kg]

  8. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Modification Qv– series 2 each Qv profile was modified by setting the specific humidity to: Qsat*Coef (1.02) - for different layer depths of 1000, 2000, 3000,4000,5000, 6000 m - the modified layer is applied at the cloud top Definition of the cloud: - if there is stratiform precipitation: cloud bottom: the maximum precipitation level cloud top: the level where the precipitation = 0 (upward) - if there is not stratiform precipitation: cloud bottom = cloud top = level of maximum relative humidity for each profile 1 step integration - starting from the corespondent modified profile - output compared with the reference run ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  9. Modif.2 Qv - stratiform sample- Variation of the maximum precipitation: mod - ref Qv=1.02*Qsat Convection scheme switched on Convection scheme switched off

  10. - stratiform&convective sample- Modif.2 Qv Variation of the maximum precipitation mod ref

  11. - convective sample- Modif.2 Qv Variation of the maximum precipitation: mod -ref mod ref

  12. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Modification of the temperature each profile was modified by adding to the temperature a constant value: 1.5 K - for different layer depths of 50 100, 200, ….1000 m - the modified layer is applied at the surface => CAPE increase Definition of the convective cloud: - if there is convective precipitation: cloud bottom: the maximum precipitation level cloud top: the level where the precipitation = 0 (upward) For each profile 1 step integration - starting from the corespondent modified profile - output compared with the reference run ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  13. Temperature modification - convective sample- Variation of the maximum precipitation

  14. Temperature modification - convective sample- Dependency of precipitation variation on the modified layer depth Base < 500m Base: 500-750 m Base: 750 -1000m Base > 1000m

  15. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Modification of the humidity convergence each profile the humidity convergence was set up to 1.5 of the initial value - for different layer depths of 200, …2000 m - the modified layer is applied at the surface Definition of the convective cloud: - if there is convective precipitation: cloud bottom: the maximum precipitation level cloud top: the level where the prcipitation = 0 (upward) For each profile 1 step integration - starting from the corespondent modified profile - output compared with the reference run ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  16. - convective sample- Humidity convergence modification Variation of the maximum precipitation on the  Qv conv. integral

  17. - convective sample- Humidity convergence modification Variation of the maximum precipitation

  18. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Conclusion The moist physics is sensitive to the initial profile modifications of: - specific humidity - temperature - humidity convergence ………..nothing new …. The problemis the possibility of controling the response to the modification The control degree depends mainly on the profile type convective  stratiform ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

  19. 14 ALADIN Workshop, Innsbruck, 1-4 June,2004________________________________________________________________________________________________________________________________________________________________________________ Conclusion Resolved (stratiform) precipitation can be (relatively) easily modified in a controlled manner, by modifying the specific humidity around the saturation value • The relation between: • amount of vapour added/substracted & variation of precipitation amount depend on: • the profile type (mainly stratiform or convective or mixed) • the departure from the saturation • the cloud depth It is more complicated to modify the model unresolved (convective) precipitation (by modifying temperature and humidity convergence) in a controlled manner More information are necessary !! about - the humidity convergence profile - the level where convection is triggered ________________________________________________________________________________________________________________________________________________________________________________ Moist Physics response to the Modification of the Initial Profile

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