Background
Glacier mass balance responds to changes in climate and may be used as a proxy indicator. How-ever, several obstacles oppose mass balance change detection using field observations and optical remote sensing techniques at high latitudes. To overcome these problems we investigated the capa-bility of s...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.509.4167 http://www.eproceedings.org/static/vol02_1/02_1_engeset1.pdf |
| Summary: | Glacier mass balance responds to changes in climate and may be used as a proxy indicator. How-ever, several obstacles oppose mass balance change detection using field observations and optical remote sensing techniques at high latitudes. To overcome these problems we investigated the capa-bility of satellite SAR to detect changes in mass balance and glacier facies. Eight years of winter ERS SAR data from Kongsvegen, Svalbard, were analysed. The results indicate that variations in mass balance cannot be retrieved from winter SAR backscatter imagery on an annual basis. The dis-tinct zones observed in winter SAR imagery are firstly the firn accumulation zone, and secondly a low backscatter zone. The first zone is the part of the glacier where accumulation is in the form of firn metamorphism, while the second zone incorporates the superimposed ice accumulation area and ablation area. The firn edge altitude (FEA) was automatically retrieved for 31 of the 40 glaciers. The FEA did not change from year to year and gave a time-averaged value. The mapping method for firn edge detection was robust and can be used to produce a baseline data set with which to de-tect and measure future changes. The lower backscatter zone could be divided into two sub-zones. Separation was not equally easy from year to year, and no simple and robust retrieval method was found. The boundary between these two sub-zones did not migrate up and down the glacier from year to year, as would be expected if it corresponded to the lower limit of the late-autumn superim-posed ice zone and the equilibrium line. This boundary could be detected on 20 of the 40 glaciers, and corresponded to the estimated mean equilibrium line altitude. |
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