THE BLACK FOREST STORM OF 15 JULY 2007: NUMERICAL SIMULATION AND SENSITIVITY STUDIES Evelyne Richard 1, Jean-Pierre Chaboureau 1 Cyrille Flamant 2 and Cédric Champollion 3 1. Laboratoire d’Aérologie, CNRS/UPS Toulouse, France 2. LATMOS/IPSL, CRNS/UPMC, Paris, France 3. Géosciences, Montpellier, France
COPS IOP8b – 15 July 2007 (Courtesy of DLR) > 60 dBz 12 km
Radar reflectivity : Time evolution of the 10 dBZ contour Montancy radar Simulation (ECMWF) 12:15 –13:00 13:15 – 14:00 14:15 – 15:00 15:15 – 16:00
Radar reflectivity : Time evolution of the 10 dBZ contour Montancy radar Simulation (ARPEGE) 12:15 –13:00 13:15 – 14:00 14:15 – 15:00 15:15 – 16:00
Motivations and outlines The real time Meso-NH forecast of this event was surprisingly good … but ■ Is this good forecast obtained for the good reasons? ■ What makes the ARPEGE based forecast different? CAPE / CIN Surface conditions Sensitivity tests
CAPE MESO-NH / ECMWFMESO-NH ARPEGE 11:00 UTC 14:00 UTC
CIN MESO-NH / ECMWFMESO-NH / ARPEGE 11:00 UTC 14:00 UTC
Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM Water vapor mixing ratio (g/kg) OBS. ECMWF ARPEGE
Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM OBS. ECMWF ARPEGE Potential temperature (K)
Surface moisture analysis : 00UTC ECMWF ARPEGE
Sensitivity tests ■ ECMWF surface moisture reduced by 20% ■ ECMWF surface moisture reduced by 50% Thermodynamical conditions Convection
Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM OBS. ECMWF ARPEGE Potential temperature (K)
Water vapor mixing 13 UTC Control Observation 20% reduction
Water vapor mixing 13 UTC Observation 20% reduction 50% reduction
Cloud top height (color) + Instant precipitation 15 UTC Control 20% reduction 50% reduction Convection is strongly controlled by initial moisture conditions
Summary / Conclusion ■ Convection is well captured by the ECMWF- based Meso-NH forecast although the PBL is too cold and too moist. ■ The PBL structure is more correct in the ARPEGE-based MESO-NH forecast but convection is over predicted. ■ There is a large discrepancy between ECMWF and ARPEGE surface moisture analysis ■ The sensitivity tests shows that the convection triggering is strongly controlled by the surface moisture conditions ■ Do we have enough data to validate the surface moisture conditions?
MESO-NH Forecasts 3 domains (32, 8, and 2 km) with 2-way interaction. 30h forecast starting at 00 UTC from ECMWF analysis Mixed phase microphysics (including hail particles) No convection parameterization in the 2km-mesh model 16/07 06UTC MNH-ECM 12UTC 12UTC15/07 00UTCMNH-ARP MNH-ECM MNH-ECM Run starting from the ECMWF analysis and forced with ECMWF forecasts MNH-ARP MNH-ARP: Run starting from the ARPEGE analysis and forced with ARPEGE forecasts 16UTC Convection over the Black-Forest
Karlruhe Meiztreizheim Achern Hornisgrinde Heselbach Burnhaupt TIME 6 KM 0 KM COR
Morning Afternoon 1000 m 2000 m Rv mod – 2g/kg Squares : Rv obs ( 2 lidars + Do28)
Water vapor mixing ratio : 13:00 – 13:30 UTC Lidar observations Lidar observations
Water vapor mixing ratio : 13:00 – 13:30 UTC Meso-NH Forecast Lidar observations
Upward motion
Convergence > s -1 +
11 UTC 12 UTC 13 UTC14 UTC
Convergence > s-1 + the surface
Moisture supply Soundings (3 hourly) Airborne lidar (Leandre II + DLR Dial) In situ aircraft data (Dornier 28) Soundings (3 hourly) Airborne lidar (Leandre II + DLR Dial) In situ aircraft data (Dornier 28)
Convergence line in the lee of the Feldberg : Feldberg Radar 13:08 UTC Doppler velocity 900hPa > 7g/kg Meso-NH Forecast 13:00 UTC
Water vapor mixing ratio : 13:00 – 13:30 UTC Meso-NH Forecast Lidar observations
Observation / Simulation METEOSAT TB = 280 K METEOSAT TB = 280 K
Observation / Simulation MONTANCY R = 1dBZ MONTANCY R = 1dBZ METEOSAT TB = 280 K METEOSAT TB = 280 K