freezing index
Link: http://w3id.org/permafrost/v/ipaglossary/t0112
Within: IPA Permafrost Glossary
Definition: The cumulative number of degree-days below 0°C for a given time period.
| Term |
indice de gel
fr
freezing index en |
|---|---|
| Comment |
Four main types of air freezing indices have been used: 1. approximate freezing index - calculated from the mean monthly air temperatures for a specific station without making corrections for positive degree-days (T > 0°C) in spring and fall (Boyd, 1973, 1979); 2. total annual freezing index - calculated by adding all the negative mean daily air temperatures (°C) for a specific station during a calendar year (Harris, 1981); 3. seasonal freezing index - calculated as the arithmetic sum of all the negative and positive mean daily air temperatures (°C) for a specific station during the time period between the highest point in the fall and the lowest point the next spring on the cumulative degree-day time curve (Huschke, 1959); 4. design freezing index - calculated by taking the average of the seasonal freezing indices for the three coldest winters in the most recent 30 years of record. If data for 30 years are not available, then the index is based on the coldest winter in the latest 10-year period of record (U.S. Army/Air Force, 1966). The total annual freezing index has been used to predict permafrost distribution, and the design freezing index is commonly used in engineering to estimate the maximum thickness of lake ice and the maximum depth of frost penetration in the ground. A surface (ground, pavement, etc.) freezing index differs from the air freezing index (see n-factor).
en
|
| dcterms:source |
https://doi.org/10.4224/20386561
xsd:anyURI
|