Journal article Open Access

Evaluation of aMetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments

Högström, Elin; Heim, Birgit; Bartsch, Annett; Bergstedt, Helena; Pointner, Georg


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{
  "DOI": "10.1029/2018JF004658", 
  "container_title": "Journal of Geophysical Research: Earth Surface", 
  "language": "eng", 
  "title": "Evaluation of aMetOp ASCAT-Derived Surface Soil Moisture Product in Tundra Environments", 
  "issued": {
    "date-parts": [
      [
        2018, 
        11, 
        12
      ]
    ]
  }, 
  "abstract": "<p>Satellite-derived surface soil moisture data are available for the Arctic, but detailed validation<br>\nis still lacking. Previous studies have shown low correlations between in situ and modeled data. It is<br>\nhypothesized that soil temperature variations after soil thaw impact MetOp ASCAT satellite-derived surface<br>\nsoil moisture (SSM) measurements in wet tundra environments, as C band backscatter is sensitive to<br>\nchanges in dielectric properties. We compare in situ measurements of water content within the active layer<br>\nat four sites across the Arctic in Alaska (Barrow, Sagwon, Toolik) and Siberia (Tiksi), taken in the spring after<br>\nthawing and in autumn prior to freezing. In addition to the long-term measurement fields, where sensors<br>\nare installed deeper in the ground, we designed a monitoring setup for measuring moisture very close<br>\nto the surface in the Lena River Delta, Siberia. The volumetric water content (VWC) and soil temperature<br>\nsensors were placed in the moss organic layer in order to account for the limited penetration depth of<br>\nthe radar signal. ASCAT SSM variations are generally very small, in line with the low variability of in situ<br>\nVWC. Short-term changes after complete thawing of the upper organic layer, however, seem to be mostly<br>\ninfluenced by soil temperature. Correlations between SSM and in situ VWC are generally very low, or even<br>\nnegative. Mean standard deviation matching results in a comparably high root-mean-square error (on<br>\naverage 11%) for predictions of VWC. Further investigations and measurement networks are needed to<br>\nclarify factors causing temporal variation of C band backscatter in tundra regions.</p>", 
  "author": [
    {
      "family": "H\u00f6gstr\u00f6m, Elin"
    }, 
    {
      "family": "Heim, Birgit"
    }, 
    {
      "family": "Bartsch, Annett"
    }, 
    {
      "family": "Bergstedt, Helena"
    }, 
    {
      "family": "Pointner, Georg"
    }
  ], 
  "type": "article-journal", 
  "id": "2636627"
}
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