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Key Points and FAQ
tab_left Key Points tab_right
  • Glaciers are an important component of Polar landscape.
  • Remote sensing data and tools are very useful in monitoring glaciers over time.
  • Medium resolution satellite images, such as those from Landsat Enhanced Thematic Mapper have sufficient spatial resolution (15 – 30m) to map the terminus location of most glaciers.
  • Mendenhall glacier has been retreating in recent years.

tab_left Frequently Asked Questions tab_right
  • Q: Where can I read more about climate change?
    A: A good resource for further reading on this topic is Scientific Facts on Climate Change.

  • Q: Where can I get free USGS topo maps?
    A: There are various ways to obtain topographic maps from the USGS in various formats. The easiest format for GIS analyses is scanned version available as Digital Raster Graphic (DRG). DRGs can be downloaded mostly from regional data clearinghouses such as the Alaska State Geospatial Data Clearinghouse.

  • Q: Where can I get free Landsat imagery?
    A: Free Landsat imagery is available from AmericaView, a nationwide program that focuses on satellite remote sensing data and technologies in support of applied research, K-16 education, workforce development, and technology transfer. The data is mostly distributed by the state affiliates. For Alaska you can download Landsat from AlaskaView.

  • Q: Why was the aerial photo that was acquired at 20 cm spatial resolution resampled to 2 m spatial resolution for this case study? Does this resampling not affect image quality?
    A: The analysis in this case study uses data sets at different scales. Aerial photography acquired at very high resolution certainly provides the maximum information. However, a topographic map at 1:24000 scale is not able to geomorphologically describe the glacier at the same level of detail than the aerial photographs. Hence, it was resampled to a more comparable resolution. The resampling method has an affect on the image quality. A bilinear interpolation is perfectly adequate to downsample the aerial photo mosaic without losing information.

  • Q: The processing described in this case study helps to compute the area glacial snow/ice that has changed. From this area can we compute the volume of change?
    A: The data used in this case study only cover the two-dimensional aspects of glacier change analysis. In order to calculate the volume changes three-dimensional information in form of field measurements or multi-temporal digital elevation models need to be used. For further reading on related techniques refer to "The physical basis of glacier volume-area scaling" (Bahr et al., 1997).

logos Geophysical Institute University of Alaska Fairbanks Alaska Space Grant Program