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| | | | | | | New ESA sounder sees through ice to unveil Greenland bedrock
14 July 2009
| This image represents a 60 km-long profile taken from the first flight. It is based on shallow-sounding data with 85 MHz bandwidth for the transmitted pulse. The surface echo appears in the top part of the image as a red line. Due to the high sensitivity of the instrument, the signal received as a double bounce is also detected and is visible as a pale blue line, parallel to the surface. However, this feature does not correspond to a true echo and is considered, according to the radar lexicon, as a 'ghost'. Finally, the subsurface echo also appears in pale blue and shows increasing bedrock depth from left to right. In the left-hand part of the image, the two-way time delay of the subsurface echo relative to the surface one is about 10 microseconds, corresponding to an ice depth of about 1 km.
Credits: ESA | |  |  | |
| | | | | Air Greenland's Twin Otter aircraft that carried the Polaris instrument. Inset shows yellow Polaris antenna mounted under the aircraft fuselage.
Credits: DTU | | | | |
| | | | | Location of the four flight segments over Greenland during the Polaris campaign.
Credits: Google Maps/ESA | | | | |
| | | | | | A detailed representation of the bedrock is shown in this image. It was obtained by processing deep-sounding data, with 30 MHz bandwidth for the transmitted pulse. This image shows a 13 km profile, and refers to the same flight as the shallow-sounding image - see white rectangle on the other sounding image in this article. | | | | |
| | | | | The internal reflection horizons are the result of constructive and destructive interference among the individual reflection by the depth/age layers (isochrones) integrated over the radar range resolution cell. The reflection horizons, hence, do not provide indirect information on the isochrone characteristics.
Credits: ESA | | | | |
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