Input data set: Lightning (ISIMIP4b)

Lightning flash rates are provided on the ISIMIP 0.5° × 0.5° grid.

- UKESM1-3-LL: Flash rates are obtained directly from the climate model at daily resolution. An additional monthly version has been produced by temporal aggregation of the daily data.

- EC-Earth3-ESM-1-1: As the model does not output lightning flash rates, monthly estimates were derived from the model's convective available potential energy (CAPE) fields using an anomaly-based approach calibrated against observed lightning stroke density from the WGLC dataset (World Wide Lightning Location Network Global Lightning Climatology). The procedure is as follows:
1. Calculate CAPE anomalies by subtracting the 1992–2021 climatological mean from the monthly CAPE time series.
2. Convert the anomalies to z-scores by dividing them by the 1992–2021 climatological standard deviation.
3. Limit the z-scores to the range of −5 to +5 standard deviations to avoid unrealistically large values in regions with very low CAPE variability.
4. Multiply the resulting z-scores by the climatological standard deviation of observed WGLC lightning stroke density and add the WGLC climatological mean. This produces a monthly lightning time series whose variability is driven by the EC-Earth CAPE anomalies while retaining the spatial climatology of observed lightning.
5. Remap the resulting fields to the ISIMIP 0.5° grid using first-order conservative remapping.

CAPE has been produced with the code from this repository: https://github.com/ARVE-Research/CAPEcalc while the method above was kindly applied to the EC-Earth data by Jed Kaplan from the University of Calgary.

UKESM1-3-LL: Native daily lightning flash-rate output from the UKESM1-3-LL climate model. Monthly data are derived by temporal aggregation.

EC-Earth3-ESM-1-1: Monthly lightning estimates derived by Jed O. Kaplan using EC-Earth CAPE fields and the WGLC observed lightning climatology.

The WGLC dataset is described in:

Kaplan, J. O. and Lau, K. H.-K. (2021). The WGLC global gridded lightning climatology and time series. Earth System Science Data, 13, 3219–3237. https://doi.org/10.5194/essd-13-3219-2021

WGLC dataset: https://doi.org/10.5281/zenodo.4774528