Can C-band synthetic aperture radar be used to estimate soil organic carbon storage in tundra?

Annett Bartsch, Barbara Widhalm, Peter Kuhry, Gustaf Hugelius, Juri Palmtag, Matthias Benjamin Siewert
2016 Biogeosciences  
<p><strong>Abstract.</strong> A new approach for the estimation of soil organic carbon (SOC) pools north of the tree line has been developed based on synthetic aperture radar (SAR; ENVISAT Advanced SAR Global Monitoring mode) data. SOC values are directly determined from backscatter values instead of upscaling using land cover or soil classes. The multi-mode capability of SAR allows application across scales. It can be shown that measurements in C band under frozen conditions represent
more » ... n and surface structure properties which relate to soil properties, specifically SOC. It is estimated that at least 29<span class="thinspace"></span>Pg<span class="thinspace"></span>C is stored in the upper 30<span class="thinspace"></span>cm of soils north of the tree line. This is approximately 25<span class="thinspace"></span>% less than stocks derived from the soil-map-based Northern Circumpolar Soil Carbon Database (NCSCD). The total stored carbon is underestimated since the established empirical relationship is not valid for peatlands or strongly cryoturbated soils. The approach does, however, provide the first spatially consistent account of soil organic carbon across the Arctic. Furthermore, it could be shown that values obtained from 1<span class="thinspace"></span>km resolution SAR correspond to accounts based on a high spatial resolution (2<span class="thinspace"></span>m) land cover map over a study area of about 7<span class="thinspace"></span> × <span class="thinspace"></span>7<span class="thinspace"></span>km in NE Siberia. The approach can be also potentially transferred to medium-resolution C-band SAR data such as ENVISAT ASAR Wide Swath with ∼ <span class="thinspace"></span>120<span class="thinspace"></span>m resolution but it is in general limited to regions without woody vegetation. Global Monitoring-mode-derived SOC increases with unfrozen period length. This indicates the importance of this parameter for modelling of the spatial distribution of soil organic carbon storage.</p>
doi:10.5194/bg-13-5453-2016 fatcat:l7omj6jxm5bgtknervypnfj434