An improved method for calculating the freezing/thawing index using monthly and annual temperature data
Abstract Changes in soil thermal regimes in cold climates have widespread impacts on hydrology, ecology, and the carbon cycle. The annual freezing and thawing index, which is generally calculated using daily temperature, has been widely used to estimate the freezing depth, active layer thickness, an...
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crwiley:10.1002/joc.7085 2024-06-23T07:44:56+00:00 An improved method for calculating the freezing/thawing index using monthly and annual temperature data Liu, Chang Feng, Song Huang, Wei National Natural Science Foundation of China 2021 http://dx.doi.org/10.1002/joc.7085 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7085 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.7085 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7085 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor International Journal of Climatology volume 41, issue 9, page 4548-4561 ISSN 0899-8418 1097-0088 journal-article 2021 crwiley https://doi.org/10.1002/joc.7085 2024-06-04T06:48:42Z Abstract Changes in soil thermal regimes in cold climates have widespread impacts on hydrology, ecology, and the carbon cycle. The annual freezing and thawing index, which is generally calculated using daily temperature, has been widely used to estimate the freezing depth, active layer thickness, and the distribution of permafrost. However, continuous and reliable daily temperature data are scarce in cold climates, while monthly and annual temperature data are more readily available. If daily temperature data are unavailable, these indices can be estimated based on monthly or annual temperature data. In this study, we developed a resampling method for estimating the annual freezing and thawing index and compared the results with those produced by the existing methods. Daily temperature data with a 0.5° resolution over the Northern Hemisphere during 1901–2012 were used to calculate the freezing/thawing index, and then the monthly and annual temperature were calculated and three different approaches were used to estimate the daily temperature and the freezing/thawing index. When the monthly data were used, the resampling method produced the smallest relative error (RE) and mean bias error (MBE), and the largest correlation in estimating the two indices, compared to the two other methods. Although the annual temperature data usually underestimate the freezing/thawing index, the RE is still <5% over most of the high‐latitude regions. The results suggest that if the daily temperature can be reliably estimated using the resampling method, the thermal regimes of permafrost can be reliably estimated using modelled monthly temperature and/or reconstructed past monthly/annual temperature. These estimations can also be used to validate modelled paleo‐permafrost and its variations. Additionally, our results indicate that after the 1970s the annual freezing index (DDF) increased substantially, while the frost index (FI) decreased substantially. Article in Journal/Newspaper Active layer thickness permafrost Wiley Online Library International Journal of Climatology 41 9 4548 4561 |
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English |
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Abstract Changes in soil thermal regimes in cold climates have widespread impacts on hydrology, ecology, and the carbon cycle. The annual freezing and thawing index, which is generally calculated using daily temperature, has been widely used to estimate the freezing depth, active layer thickness, and the distribution of permafrost. However, continuous and reliable daily temperature data are scarce in cold climates, while monthly and annual temperature data are more readily available. If daily temperature data are unavailable, these indices can be estimated based on monthly or annual temperature data. In this study, we developed a resampling method for estimating the annual freezing and thawing index and compared the results with those produced by the existing methods. Daily temperature data with a 0.5° resolution over the Northern Hemisphere during 1901–2012 were used to calculate the freezing/thawing index, and then the monthly and annual temperature were calculated and three different approaches were used to estimate the daily temperature and the freezing/thawing index. When the monthly data were used, the resampling method produced the smallest relative error (RE) and mean bias error (MBE), and the largest correlation in estimating the two indices, compared to the two other methods. Although the annual temperature data usually underestimate the freezing/thawing index, the RE is still <5% over most of the high‐latitude regions. The results suggest that if the daily temperature can be reliably estimated using the resampling method, the thermal regimes of permafrost can be reliably estimated using modelled monthly temperature and/or reconstructed past monthly/annual temperature. These estimations can also be used to validate modelled paleo‐permafrost and its variations. Additionally, our results indicate that after the 1970s the annual freezing index (DDF) increased substantially, while the frost index (FI) decreased substantially. |
author2 |
National Natural Science Foundation of China |
format |
Article in Journal/Newspaper |
author |
Liu, Chang Feng, Song Huang, Wei |
spellingShingle |
Liu, Chang Feng, Song Huang, Wei An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
author_facet |
Liu, Chang Feng, Song Huang, Wei |
author_sort |
Liu, Chang |
title |
An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
title_short |
An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
title_full |
An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
title_fullStr |
An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
title_full_unstemmed |
An improved method for calculating the freezing/thawing index using monthly and annual temperature data |
title_sort |
improved method for calculating the freezing/thawing index using monthly and annual temperature data |
publisher |
Wiley |
publishDate |
2021 |
url |
http://dx.doi.org/10.1002/joc.7085 https://onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7085 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/joc.7085 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/joc.7085 |
genre |
Active layer thickness permafrost |
genre_facet |
Active layer thickness permafrost |
op_source |
International Journal of Climatology volume 41, issue 9, page 4548-4561 ISSN 0899-8418 1097-0088 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/joc.7085 |
container_title |
International Journal of Climatology |
container_volume |
41 |
container_issue |
9 |
container_start_page |
4548 |
op_container_end_page |
4561 |
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1802641726927536128 |