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