Institut für Physik der Atmosphäre 1
Evaluation of a numerical thunderstorm study with POLDIRAD
and lightning observations
Oberpaffenhofen, 8 February 2002
Thorsten Fehr
Institut für Physik der Atmosphäre
Deutsches Zentrum für Luft- und Raumfahrt, e.V. (DLR)
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 2
Motivation
Investigation of Nitrogen oxides (NOx) produced by lightning
Idealized case study with “realistic” dynamics Evaluation of simulation results with
observations EULINOX Project
Excellent data coverage for the 21 July 1998 storm Radar, lightning, aircraft, radiosondes ...
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 3
Lightning and Polarimetric RadarONERA ITF System 3D-Detection of
Lightning (114 MHz)
Interferometer
DLR Polarimetric Doppler Radar:
POLDIRAD
C-Band ( = 5.45 cm) Doppler Winds Polarimetric
Capabilities Hydrometeor
Classification
BLIDS: Siemens AG 2D-
Positioning (VLF/LF)
Time-of-Arrival
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 4
Numerical Model
Mesoscale Model MM5 non-hydrostatic Bulk microphysics flat orography
Resolution x=1km 50 vertical levels
Initialization : “Single Sounding” “Hot Bubble”
Lightning Parameterization Modified approach
by Price and Rind, 1998
Total Flash Frequency:
ffl = 1.29x10-6 wmax
4.55
Ratio of intracloud (IC) to cloud-to-ground(CG) flashes: = fIC/fCG = P4(Zfr)
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 5
Radar and ModelMM5 (1.5°)
POLDIRAD (1°)
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 6
Radar and Model: Supercell
Radar Model
Velocity 11±2 ms-1 9.5±1 ms-1
Direction 74±5° 59±2°
Angle(SZ,MZ) 52±6° 46±3°
Overshooting 14±0.5 km 14.5±0.5 km
Anvil Top 12±0.5 km 11.5±0.5 km
Echo Overhang/Weak Echo Region
Strong midlevel cyclonic rotation
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 7
Lightning and Model
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 8
Lightning and Model: Supercell Good Correlation
during strong convection
Poor correspondence during decay/strati-form stage
Parameterization cannot applied for the complete lifecycle
New Concepts (?)
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 9
ITF Lightning Data and POLDIRAD (I)
Reflectivity and 1 min of ITF activity
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 10
ITF Lightning Data and POLDIRAD (II)
Classification: Höller et al., 1994
21 July 98 Storm
Most flashes in graupel/hail regions
Gra
up
el
Hail
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 11
Conclusions for Model Supercell Comparison with Radar data shows significant
similarities
The lightning parameterization produces comparable flash frequencies for the convective regime
Simulated Supercell represents the observed storm in general dynamical and microphysical properties
Model storm can be use for further studies (lightning NOx, development of new parameterizations, ...)
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 12
Outlook Improved lightning parameterization:
Flightning = Flightning(vi, qi, vi,qi) Radar Polarimetry
Assimilation of meteorological parameters derived from lightning observations, e.g.:
z = z(fCG) RR = RR(flightning)
Adverse weather warning
Thorsten Fehr, Institut für Physik der Atmosphäre, DLR 13