On the potential of total lightning data for nowcasting of thunderstorms and precipitation. Part II: Assessment of the benefit of total lightning using a MOS (Model Output Statistics) approach.
Zusammenfassung der Projektergebnisse
Since 2003, the Institute for Meteorology and Climatology of the Leibniz University of Hannover (IMUK) operates a regional SAFIR (Surveillance et Alerte Foudre par Interferometrie Radioelectrique) total lightning detection network in Northern Germany. The network consists of three detection stations that form a triangle of about 180 km side length. The primary and secondary network data products commonly encompass the incidence direction, time of event, current intensity/polarity, geographic position and the classification into "cloud to ground " (CG) and "intra-cloud" (1C) lightning events. A close inspection of the observed IMUK SAFIR lightning signals revealed the presence of the considerable noise sources in the detection area. Such interference signals affect detection and positioning of the lightning signals. As possible solutions for the mitigation/elimination of the interference signals several measures were proposed. For instance, the wavelet analysis could help in finding the temporal patterns of the interference signals whereas the identification of the typical lightning ascending times could help in discrimination between lightning and interference signals. A comparison of the peak amplitude and polarity of CG flashes provided by the SAFIR LF antennas (after calibration) and the corresponding BUDS data (BLitzInformationsDienst) revealed that daily, monthly as well as the overall peak amplitude frequency distributions are similar. The existing difference in the total numbers of CG flashes detected by both systems strongly depends on the measured peak amplitude and is greatest at peak amplitudes lower than 40 kA. A literature study on the potential of the total lightning data in weather nowcasting has indicated an importance of this weather information for as well ground as air safety. As the current major applications of the total lightning data, the following fields have been identified and documented: indication of regions of deep convection, nowcasting of hail thunderstorms, distinguishing of the CB-cells out of a larger precipitating area, tracking of the thunderstorm growth and decay, estimation of the CG lightning threat and the air traffic management. During the work of our project team on the delay modelling at major German airports it turned out that in addition to a considerable flight delay caused by thunderstorms and consequently, possible delay mitigation through development of thunderstorm nowcasting tools, the total lightning can directly assist in providing safer and more efficient air traffic management. The focus of the concluding study on the potential applications of the total lightning data was determination of the lightning based polygons as a proxy for high reflectivity regions of thunderstorm cells. Using statistical indicators such as the probability of detection and their differences for subsequent lightning "ages" (tη) false alarm rate and the total hit rate, it has been concluded that 25 min is a reasonable tn for creating the lightning based polygons. Although the probability of detection of thunderstorm cells has a high variability range, the lightning based polygons are certainly an acceptable alternative for the Cb-cell information in the air traffic management in case of missing or disturbed radar images. Within the study, MATLAB Tools for the Cb-Cell approximation, calculation and graphical display of the flash density cores and of the lightning altitude were developed. Namely, the cores of the lightning activity could help define the major updraft areas of Cb-cells around the airports whereas the total lightning altitude information could help air traffic controllers in routing aircraft around airspace with hazardous lightning potential.
Projektbezogene Publikationen (Auswahl)
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(2008). On the potential of total lightning for nowcasting.
Geophysical Research Abstracts, Vol. 7. 2005, 00831.
Markovic D., Tendel J., Hauf T.
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(2007). Comparison of a SAFIR lightning detection network in northern Germany to the operational BUDS network. J. Geophys. Res., 112, D18114
Drüe, C, T. Hauf, U. Finke, S. Keyn, and O. Kreyer
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Comparison of lightning polarity and amplitude. Geophysical Research Abstracts, Vol. 9,03399, 2007
Hehemann, K., Finke, U., Drüe, C., Hauf, T.
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(2008). A statistical study of the weather impact on punctuality at Frankfurt Airport. Meteorological Applications, pp. 293-303
Markovic, D., Hauf, T., Röhner, P. and Spehr, U.
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A statistical study of the weather impact on punctuality at Frankfurt Airport. 13th Conference on Aviation, Range and Aerospace Meteorology, New Orleans, USA, January 2008
Markovic, D., Hauf, T., Röhner, P. and Spehr, U.
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Study on total lightning and flight characteristics during thunderstorm occurrences. Geophysical Research Abstracts, Vol. 10, EGU2008-A-12396, 2008
Markovic, D., Hauf, T.
