Real-time Tracking and Nowcasting of Thunderstorms (rTNT)
Lightning strokes largely occur in a sharply delineated area. This allows them to be easily grouped into storm cells, which are then depicted as a geographical polygon. In turn, the definition of a storm cell enables the features of the storm to be determined. The most important parameters in this respect include the size of the storm cell, number of intra-cloud and cloud-to-ground strokes, density and frequency of lightning strokes, as well as the average altitude of the intracloud strokes.
nowcast’s rTNT algorithm calculates storm cells in real-time. With every new lightning stroke, the cell is updated with respect to all its parameters, which are made available in real-time. Moreover, rTNT ascertains the intensity of the thunderstorm and identifies the risk of hailstorms.
If a new storm cell is tracked for a few minutes, further parameters arise such as the speed of the path taken by the storm as well as direction and development of the thunderstorm. This information forms the basis for nowcasting. The length of the nowcasting depends on the intensity and tendency of the thunderstorm.
In addition, rTNT identifies the cell nuclei which give rise to particular meteorological hazards. These areas are marked as sub-cells. With regards to the calculation of these areas, the development of the number and altitude of the intra-cloud strokes play an especially decisive role when it comes to the identification of socalled lightning jumps. In areas with particularly strong convectional currents, i.e. especially powerful upwinds, increased lightning activity is registered which, with growing storm intensity, spreads to ever-increasing altitudes. Using the information pertaining to the altitude and number of intra-cloud strokes, the intensity of the convectional currents and thus the severity of the thunderstorm may be indirectly derived.
nowcast’s Cell Tracking and Nowcasting are based exclusively on lightning data. No additional parameters are included in the calculation.