Size-dependent validation of MODIS MCD64A1 burned area over six vegetation types in boreal Eurasia: Large underestimation in croplands

Chunmao Zhu,Yugo Kanaya,Masahiko Saito,Hideki Kobayashi

doi:10.1038/s41598-017-03739-0

Chunmao Zhu, Yugo Kanaya + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-03739-0

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Abstract

Pollutants emitted from wildfires in boreal Eurasia can be transported to the Arctic, and their subsequent deposition could accelerate global warming. The Moderate Resolution Imaging Spectroradiometer (MODIS) MCD64A1 burned area product is the basis of fire emission products. However, uncertainties due to the “moderate resolution” (500 m) characteristic of the MODIS sensor could be introduced. Here, we present a size-dependent validation of MCD64A1 with reference to higher resolution (better than 30 m) satellite products (Landsat 7 ETM+, RapidEye, WorldView-2, and GeoEye-1) for six ecotypes over 12 regions of boreal Eurasia. We considered the 2012 boreal Eurasia burning season when severe wildfires occurred and when Arctic sea ice extent was historically low. Among the six ecotypes, we found MCD64A1 burned areas comprised only 13% of the reference products in croplands because of inadequate detection of small fires (<100 ha). Our results indicate that over all ecotypes, the actual burned area in boreal Eurasia (15,256 km2) could have been ~16% greater than suggested by MCD64A1 (13,187 km2) when applying the correction factors proposed in this study. This implies the effects of wildfire emissions in boreal Eurasia on Arctic warming could be greater than currently estimated.

Highlights

IntroductionAtmospheric transport of fire-emitted pollutants (e.g., black carbon particles) to the Arctic and their subsequent deposition is believed to accelerate Arctic warming[18, 19]
Atmospheric transport of fire-emitted pollutants to the Arctic and their subsequent deposition is believed to accelerate Arctic warming[18, 19]
Comparison of the burned areas derived from Moderate Resolution Imaging Spectroradiometer (MODIS) with those generated from higher resolution satellite products could provide fundamental information regarding the accuracy and future applicability of the burned area products

Summary

Introduction

Atmospheric transport of fire-emitted pollutants (e.g., black carbon particles) to the Arctic and their subsequent deposition is believed to accelerate Arctic warming[18, 19]. A recent simulation study indicated that 68% of black carbon deposited over the Arctic could originate from biomass burning, of which boreal Eurasian vegetation fires could contribute 85%21. The contribution of boreal fires to climate change in the Arctic is highly variable depending on the emission inventories used. The GFED adopts burned area products detected by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, incorporating information of fuel loading, combustion completeness, and emission factors. The latest version of GFED, GFED version 4 uses the MODIS MCD64A1 burned area product[24]. Was generated based on a hybrid algorithm that incorporates active fires and changes in multitemporal spectral indices[24]. Using stratified random sampling and reference data, Padilla et al found that the MODIS MCD45 product could detect only 48% of the global burned area[27]. Based on QuickBird and WorldView-2 (resolution:

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