Gaussen Index

You can help expand this article with text translated from the corresponding article in Spanish. (September 2021) Click [show] for important translation instructions.
  • View a machine-translated version of the Spanish article.
  • Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia.
  • Consider adding a topic to this template: there are already 5,022 articles in the main category, and specifying|topic= will aid in categorization.
  • Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article.
  • You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing Spanish Wikipedia article at [[:es:Índice xerotérmico de Gaussen]]; see its history for attribution.
  • You may also add the template {{Translated|es|Índice xerotérmico de Gaussen}} to the talk page.
  • For more guidance, see Wikipedia:Translation.

The Gaussen Index (or Bagnouls-Gaussen Index) or xerothermic index is a method of calculating and comparing aridity.

According to Henri Gaussen (French botanist and biogeographer), a given period is said to be arid, when: P < 2 × T {\displaystyle P<{2\times T}} .[1][2]

(P: total precipitation in millimeters over the given period, T: average temperature in °C over the given period)

The resulting index number indicates the number of biologically dry days in a year for a given location (it therefore ranges between 0 and 365). The data includes not only precipitation stricto sensu but also fog, dew and humidity of the air.

In general, it is accepted that an environment is non-arid when the index is less than 100, semi-arid between 100 and 290, arid between 290 and 350, and hyperarid between 350 and 365.

This index is very useful for the use of an ombrothermic diagram [fr], the latter always constructed on the scale model: 1 °C = 2 mm precipitation.

Other indices such as the Louis Emberger rainfall quotient (which is not unique) have been defined. However, the Gaussen index which is simple and precise is still preferable.[3] Indeed Henri Gaussen defines precisely the 4 nuances of Mediterranean climate just against this index,[4] while Emberger defines the level of humidity in a region of Mediterranean climate but does not support precisely this Mediterranean climate.[3]

The calculation does not reflect reality because it is based on averages. For example, according to the calculation, we find a total of 0 biologically dry days in Lyon, for 60 biologically dry days in Marseille.[5]

References

  1. ^ Gaussen and Bagnouls 1952, pp. 10–11.
  2. ^ Gaussen and Bagnouls 1957, p. 194.
  3. ^ a b Tassin, Claude (31 May 2012). Paysages végétaux du domaine méditerranéen : bassin méditerranéen, Californie, Chili central, Afrique du Sud, Australie méridionale [Mediterranean Vegetation Landscapes : Mediterranean basin, California, Central Chile, South Africa, South Australia] (in French). Marseille: IRD Éditions. ISBN 978-2-7099-1731-5.
  4. ^ Gaussen and Bagnouls 1957, p. 200.
  5. ^ Gaussen and Bagnouls 1952, p. 12.

Bibliography

  • Gaussen, Henri; F., Bagnouls (12 January 1952). "L'indice xérothermique" [The xerothermic index]. Bulletin de l'Association de géographes français (in French). 29 (222–223): 10–16. doi:10.3406/bagf.1952.7361.
  • Gaussen, Henri; Bagnouls, F. (1953). Saison sèche et indice xérothermique [Dry seasons and the Xerothermic index] (in French). University of Toulouse, Faculty of Sciences. OCLC 893798321.
  • Gaussen, Henri; Bagnouls, F. (1957). "Les climats biologiques et leur classification" [Biological climates and their classification]. Annales de Géographie (in French). 6 (355): 193–220. doi:10.3406/geo.1957.18273.