Sensitivity of Lightning Flash Frequency to Climate Changes in the Earth System Model of Low Spatial Resolution

The Climber-2.3 Earth system model of intermediate complexity (EMIC) is extended by a lightning flash frequency (LFF) calculation scheme adapted to the low temporal and spatial resolution of the model. In the control numerical experiment, the model generally reproduces the spatial and seasonal distribution of LFF realistically (compared to the Lightning Imaging Sensor/Optical Transient Detector (LIS/OTD) satellite data), except for the region over the Pacific Ocean, where LFF is overestimated. The globally averaged annual mean LFF in Climber-2.3 varies between 46 and 48 s(-1) (also within the uncertainty interval of the LIS/OTD data). Climate warming under a doubling of atmospheric CO2 leads to an increase in the LFF over most regions in all seasons, especially over the subpolar Northern Hemisphere landmass in summer (with relative sensitivity up to 95% degrees C-1). In turn, climate cooling under decreasing atmospheric CO2 concentration leads to the highest LFF sensitivity over the subtropics of the Southern Hemisphere (with the corresponding coefficient up to 30% degrees C-1), while in June-August it is exhibited over the subpolar landmass of the Northern Hemisphere in summer. At the global level, the sensitivity of the LFF to a single change in surface temperature is equal to 7.8% degrees C-1 when the climate is warming and 4.2% degrees C-1 when it is cooling. The sensitivity of LFF to climate change is generally consistent with that obtained by other models.