Glacier inventory

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A glacier inventory (also a glacier cadastre ) is an inventory of the glaciers of a larger area with their topographical and other significant properties. Essential data are the geographic coordinates , the area, the length, the height range and the exposure . A component of more recent glacier inventories is, in particular, a digital recording of the entire glacier profile that can be used for geographic information systems (GIS). The first glacier inventories were drawn up for parts of the Alps at the end of the 19th century .

The creation of a global glacier inventory was initiated during the International Hydrological Decade in 1968; the first status report of the resulting World Glacier Inventory (WGI) was published in 1989. A supplement to the WGI results from the Global Land Ice Measurements from Space (GLIMS) project, which began in the mid-1990s . The focus here is on the semi-automated acquisition of data on the basis of satellites , in particular the radiometric data from ASTER .

history

The first efforts to collect data on the glaciers in an area were made in the Alps . Already in the middle of the 19th century there were quite accurate maps of individual glaciers, but the maps of the time covering larger regions were too imprecise to be able to derive data from them in the sense of a glacier inventory. The first compilation that can be used in this regard was published in 1988 by Eduard Richter for the Eastern Alps .

The main impetus for compiling a global glacier inventory came from hydrology . In the 1960s, it was found that estimates of the glaciated area outside the continental ice sheets of Greenland and Antarctica differed considerably. In 1969 a working group headed by Fritz Müller was set up to develop guidelines for a global glacier inventory. A Temporary Technical Secretariat (TTS) was set up in 1973 with the support of UNESCO , the United Nations Environment Program (UNEP) and the International Commission in order to achieve as international participation as possible for the Word Glacier Inventory (WGI) to be drawn up on this basis on Snow and Ice (ICSI) at ETH Zurich . The TTS conducted training courses worldwide and was also responsible for compiling and storing the data. In 1989 the World Glacier Monitoring Service (WGMS), the successor organization of the TTS, published a first status report. In 1998 the WGMS and the National Snow and Ice Data Center (NSIDC) decided to work together to complete the data of the WGI and make it available online.

The idea of using earth observation satellites to collect glacier data was proposed in 1986. With the dissolution of the Thematic Mapper , which has been used to collect remote sensing data since 1982 , it seemed possible for the first time to automatically capture glacier maps. In combination with geographic information systems (GIS) and digital elevation models (DHM), the data of interest for a glacier inventory can be automatically obtained. This procedure should enable the completion of the global glacier inventory to be accelerated. For this purpose, the Global Land Ice Measurements from Space (GLIMS) project was launched in 1995 , but due to the different technological orientation, this led to a database parallel to the WGI .

trouble

The biggest problem when compiling glacier inventories is the correct interpretation of the image material - regardless of whether it was obtained using satellites or airplanes. There are both methodological questions - for example which parts are to be assigned to which glacier - as well as practical problems such as clouds, fresh snow, debris cover and low-contrast images. When comparing the data from two glacier inventories, care must also be taken to ensure that the assessment of the location of the ice sheets for ice caps or other larger contiguous ice surfaces matches, i.e. the division into individual glaciers corresponds.

Another important question is how to deal with perennial snow, i.e. snow fields that last for several years. According to the guidelines of the WGI, perennial snow must also be recorded. This also makes sense from a hydrological perspective. However, if one wants to draw conclusions about climate changes from the data in the glacier inventory , it seems unfavorable to take into account perennial snow, as its presence often depends heavily on the topography , for example in the form of avalanche deposits, which often remain unchanged over decades. It is also difficult to distinguish between seasonal snow and snow that lasts for several years. For this reason, it may be cheaper to only record areas within which bare ice is also visible.

Web links

Individual evidence

  1. ^ Editing of the Swiss Lexicon, Glacier Commission of the Swiss Academy of Natural Sciences (ed.): Glaciers, snow and ice. Verlag Schweizer Lexikon Mengis + Ziehr, Horw / Luzern 1993, ISBN 3-9520144-2-7
  2. ↑ a b c d e f g h Frank Paul: Inventory of Glaciers. In: Vijay P. Singh, Pratap Singh, Umesh K. Haritashya (Eds.): Encyclopedia of Snow, Ice and Glaciers. Springer, Dordrecht 2011, pp. 650 ff., ISBN 978-90-481-2641-5
  3. ↑ Eduard Richter: The glaciers of the Eastern Alps. In: Handbooks for German Regional and Folklore Studies 3, Engelhorn Verlag, Stuttgart. 1888
  4. ↑ a b Atsumu Ohmura: Completing the World Glacier Inventory. In: Annals of Glaciology. Volume 50, pp. 144–148, 2009 ( online ; PDF; 276 kB)
  5. ^ National Snow and Ice Data Center: World Glacier Inventory Documentation. Retrieved May 15, 2013