Large-scale modelling of environments favourable for dry lightning occurrence

Lightning that occurs with relatively little accompanying rainfall, known as dry lightning, is one of the main ignition sources for wildfires throughout the world. A method for indicating large-scale environments favourable to the occurrence of dry lightning is examined here. The method is designed to be of coarse spatial and temporal scales, for potential application to global climate models. It is developed based on atmospheric conditions obtained from reanalyses, in conjunction with lightning observations from a ground-based network of sensors during the period from 2002 to 2013. The method is applied to global climate model simulations to examine the influence of increasing atmospheric greenhouse gas concentrations on the projected frequency of occurrence of dry lightning activity in Australia. The results indicate considerable seasonal and spatial variability of the projected changes in environments favorable to dry lightning occurrence. Given the importance of dry lightning to the area burnt by fires, long-term changes in dry lightning activity could potentially have a range of significant impacts, including in relation to fire regimes, ecology, fire emissions and emergency management.