Lightning-caused forest fires in Switzerland
Lightning is the primary natural cause of wildfire ignition throughout the world. Lightning-caused fires usually do not receive too much attention compared to human-started fires. However, lightning fires can be an essential part of the fire regime in some zones of the world (e.g. in boreal forests) and during some months of the year (i.e. in summer) in other areas such as the Alps. There is still so much to learn about this kind of fires.
During my postdoc at WSL, my colleagues and I explored lightning fire data in Switzerland. The main conclusions of this research are the following:
1) Lightning-caused fires are a common natural phenomenon in the Swiss Alps in summer, although there is a great spatial and inter-annual variability (Moris et al. 2019).
2) It is possible to identify a set of lightning that probably caused forest fires by combining wildfire and lightning data. However, the method chosen to match lightning and fire data is critical when searching for the igniting stroke of a lightning-caused fire (Moris et al. 2020a).
3) In the Swiss Alps, the annual number of lightning-caused fires are their annual burned area correlate with drought-related summer weather variables, such as vapor pressure deficit (VPD) and fire weather index (FWI; Moris et al. 2020b).
These are the main research outputs:
Moris JV, Conedera M, Nisi L, Pezzatti GB. 2020b. Lightning fires and summer drought: is there a relationship? Schweizerische Zeitschrift für Forstwesen 171: 281-287. (In German) https://doi.org/10.3188/szf.2020.0281
Moris JV, Conedera M, Nisi L, Bernardi M, Cesti G, Pezzatti GB. 2020a. Lightning-caused fires in the Alps: identifying the igniting strokes. Agricultural and Forest Meteorology 290: 107990. https://doi.org/10.1016/j.agrformet.2020.107990
Moris JV, Conedera M, Pezzatti B. 2019. Lightning-caused forest fires in Switzerland. WSL Research Day, 25 June, Birmensdorf (Switzerland). pdf