Assessment and validation of Meteosat SEVIRI fire radiative power (FRP) retrievals over Kruger National Park

• A fire’s location within a pixel impacts fire radiative power retrieval by 12–––14% • Intercomparison of fire radiative power on a fire ‘cluster’ basis is recommended. • SEVIRI FRP in good agreement with helicopter mounted thermal camera data. Satellite burned area, active fire and fire radiative power (FRP), are key to quantifying fire activity and are one of 54 essential climate variables (ECV) and it is important to validate these data to ensure their consistency. This study investigates some of the factors that influence FRP retrieval and uses Meteosat Spinning Enhanced Visible and InfraRed Imager (SEVIRI) data to do so. Analysis of the influence of a fire’s location within a SEVIRI pixel on FRP was carried out using fire simulations which indicate that FRP varies by up to 14 % at nadir for a single sensor and by up to 55 % when intercomparing simulated FRP from different SEVIRI sensors. Intercomparison between actual MET-11 and MET-08 FRP data on a per-pixel basis reveals a high degree of scatter (81.9 MW), strong correlation (R = 0.72), low bias (∼1 MW) and an average percentage difference of 15.7 %. Variability is reduced when aggregated to fire ‘clusters’ which improves the correlation (R = 0.96) and reduces the average percentage difference (4.2 %). Validation of MET-08 and MET-11 FRP retrievals using FRP from helicopter mounted longwave infrared (LWIR) and midwave infrared (MWIR) thermal cameras is carried out over five prescribed burns. The results reveal good agreement between the SEVIRI and thermal camera FRP although the SEVIRI FRP is typically overestimated compared to that from the LWIR camera. This study illustrates some of the challenges validating satellite FRP which should be accounted for when defining uncertainty thresholds for product requirements and in developing FRP validation protocols.