Vegetation State and Fire occurrence
LSA SAF Derived Fraction of Vegetation Cover provides information for live fuel conditions in case of biomass burning as seen from Meteosat
- June 21, 2024
Fractional Vegetation Cover (FVC) defines an important structural property of a plant canopy, accounting for the amount of vegetation distributed in a horizontal perspective. FVC is related to the vegetation contribution for emissivity and land surface temperature, both depending on climate and vegetation types. In this connection, FVC is relevant for a wide range of Land Biosphere Applications such as agriculture and forestry, environmental management and land use, hydrology, natural hazards monitoring and management, vegetation-soil dynamics monitoring, drought conditions and fire scar extent.
Figure 1: Dynamics of LSA-SAF FVC over Bulgaria during early summer (July 2023) with superimposed thermal anomaly detected by SEVIRI MPEF FIR product.
This vegetation state characteristic is updated daily and its operational application can be a valuable source of information for spatial-temporal dynamics of land surface state. FVC seasonal dynamics on a regional scale is essential to identify drought conditions reflected by vegetated land surface greenness and for environmental monitoring of related extremes like wild fires. This is especially important for regions with Mediterranean climate influences like south-eastern part of Europe, in particular the territory of Bulgaria, where drought episodes occur regularly.
Maps of daily updated LSA SAF FVC with superimposed thermal anomalies (fires) detected from satellites can provide a better insight into wild fire landscape environment and for monitoring probability of its widespread. Active fire monitoring by SEVIRI MPEF FIR product each 15 minutes or each 5 minutes from the Rapid Scan Service is illustrated on Figure 2.
The number of fast developing and extending fires in early summer (July 2023) increases with decline of green vegetation fraction, as seen by LSASAF FVC Meteosat based product. Illustration for territory of Bulgaria (Figure 2) in July 2023 shows:
- 128 fire pixels are detected by SEVIRI observations at locations with FVC values 0.2 - 0.5;
- Only 18 fire pixels are located in areas with higher FVC, between 0.5 - 0.8;
- Less than 15 % of the fires detected by MPEF FIR fire product occur in areas with FVC > 0.5.
Monitoring dynamics of fraction of vegetation cover from space can depict the relation between drought and fire occurrence. Maps for selected days of the active fire season over Bulgaria (August-October 2023) illustrate that fires occur at areas with low FVC (0.2-0.4), mainly at low-level parts.
The transition of summer to the autumn season in 2023 is characterized by increase fire activity due to severe drought environment. For Bulgaria this is the hottest October for the last 90 years, based on data from meteorological measurements, with monthly mean temperatures positive anomalies between +2 and +5.5 °С. Monthly precipitation sums over the country were between 0 and 53% from the climatic norms. Due to extremely hot and dry environment, FVC declines up to 30% for most of the low-level parts and 220 FIR detections, higher than in September are registered.
Fires can occur in mountain forests at declined FVC values, illustrated on Figure 3.
August 2023: 631 fire pixels detected in 16 days
September 2023: 155 fire pixels detected in 13 days
October 2023: 220 fire pixels detected in 16 days
Figure 2: Dynamics of Fraction of Vegetation Cover over Bulgaria during summer-autumn fire season (August-October 2023) with superimposed thermal anomaly detected by SEVIRI MPEF FIR product.
Day-time detections
Night-time detections
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Figure 3: Fires detected from 27to 29 of October 2019 in Bulgaria: left panels show large fires over at conifer forest in the national park Rila mountain, with FVC ~ 45.5%; right panel shows large fires in tdry grass and bush areas of the Balkan mountains, with FVC ~48%.
Conclusion
Temporal and spatial dynamics of biophysical parameter FVC provides information for the changes of the amount of green vegetation distribution and thus may serve as a reference for the location and the extend of live vegetation dryness.
Since live vegetation (fuel) dryness favors wild fires occurrence and spread, operational use of LSASAF FVC product on a regional scale as a background of satellite detections of thermal anomalies can provide an instant view of biomass burning in the landscape environment.