engleski

Lightning activity as an indicator of severe convective storms with the overshooting tops

Deep convective storms with the overshooting tops (OTs) often produce hazardous weather conditions such as heavy rainfall, damaging winds, large hail, cloud to ground (CG) lightning and even tornadoes. Heavy rainfall induced by the convective activity often influences human lives and activities and can cause a large property damage as a result of flash floods. Several recent investigations noted the relationship between the frequency of positive CG flashes and the severity of the storms. The present study combines infrared and water vapor channels from Meteosat 9 satellite with lightning data from the Lightning Location System, which is part of the International Lightning Detection Network in Europe (LINET). Deep convective clouds with OTs are detected using a COMB method based on the infrared window (IRW, 10.8 μm) channel and the absorption channels of water vapor (WV, 6.2 μm) and ozone (O3, 9.7 μm) in form of brightness temperature differences (BTDs). COMB method combines the criteria for the IRW brightness temperature and the criteria for two BTDs, WV-IRW and O3-IRW. All pixels with O3-IRW BTD larger than 13 K in the region where IRW brightness temperature is lower than 215 K and WV-IRW BTD larger than 4 K are characterized as OTs. The LINET system detects total lightning discharge, but it also separately detects CG, or intra cloud and cloud to cloud strokes (IC). The mentioned system covers a wide area approximately from 30°N 10°W to 65°N 35°E. In a radial distance of 100 km, the minimum detectable signal is in the range of 1-2 kA, and IC and CG discharges locations are detected with an accuracy of (+-) 100 m. In this study type, height and amplitude of lightning strokes in convective clouds with OTs are analyzed. The relationship between penetrative convective clouds and atmospheric discharges is presented, and the ability of using general lightning characteristics in severe weather nowcasting and warnings is tested.

lightning; convection; overshooting top

nije evidentirano