Goossens, Rudi

Lhermitte, Stefaan

Veraverbeke, Sander

Verstraeten, Willem

English

Ghent University Academic Bibliography

Geophysical Research AbstractsVol. 12, EGU2010-254, 2010EGU General Assembly 2010© Author(s) 2009Assessing the temporal sensitivity of the differenced Normalized BurnRatio (dNBR) to estimate burn severity using MODIS time seriesSander Veraverbeke (1), Stefaan Lhermitte (2), Willem Verstraeten (3), and Rudi Goossens (1)(1) Ghent University, Department of geography, Gent, Belgium (sander.veraverbeke@ugent.be), (2) Universidad de La Serene,CEAZA, La Serena, Chile, (3) KU Leuven, Geomatics Engineering, Leuven, BelgiumThe temporal sensitivity of the differenced Normalized Burn Ratio (dNBR) to assess burn severity was evaluatedfor the case of the 2007 Peloponnese (Greece) wildfires. Prior to the analysis, a pixel-based control plot selectionprocedure was initiated for each burned pixel based on time series similarity of the pre-fire year 2006. Post-firenear infrared (NIR) dramatically dropped immediately post-fire, while the highest MIR reflectance values werereached three weeks after the fire. Both NIR and MIR reflectance showed an increased variability during thewet Mediterranean winter. Due to the process of early vegetation recovery, the burned pixels’ NIR reflectanceapproached the control pixels’ values during the productive spring-time. Because of the three weeks post-firedelay in MIR reflectance increase, the NBR drop and dNBR peak were obtained synchronously. Both the standarddeviation of the NBR and dNBR were high during winter, as a consequence of the simultaneous increase in NIRand MIR reflectance variability. In spite of the high variation in dNBR during winter, this moment is suboptimalto estimate burn severity due to low rates of image availability and low optimality values. Index performance wasclearly lower during winter and spring because vegetation regeneration clearly diminishes the distance in the bi-spectral feature space to which the dNBR is sensitive at the favor of displacements to which the index is insensitive.In contrast, NIR reflectance, MIR reflectance, NBR, dNBR and dNBR optimality changes achieved a maximumthree weeks post. Consequently this was the optimal time to estimate burn severity in our case study retaining amaximal degree of information with a high reliability. Conclusions should be verified for other fires and in otherecoregions.

Assessing the temporal sensitivity of the differenced Normalized Burn Ratio (dNBR) to estimate burn severity using MODIS time series

https://biblio.ugent.be/publication/975958/file/975959

Assessing the temporal sensitivity of the differenced Normalized Burn Ratio (dNBR) to estimate burn severity using MODIS time series

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Ghent University Academic Bibliography