Freeze-thaw index is an important sensitive indicator of climate change, and is also widely used in the study of frozen soil changes. The research on the spatial distribution characteristics and time variation trend of freezing and thawing index in the global scope can provide a basis for the global frozen soil environment assessment, engineering construction and coping with climate change. This data set is based on the daily temperature observation data of more than 14000 stations covering the global land from 1973 to 2021 to calculate the air freezing index (FI) and air melting index (TI). The freezing/thawing index is the cumulative value of the daily average temperature below/above 0 ℃ during the freezing/thawing period. Considering that the index calculation should cover the whole freezing/thawing period and ensure the continuity of the calculation period, the northern hemisphere takes July 1 of that year to June 30 of the next year as a freezing period, and takes January 1 to December 30 of that year as a melting period, while the southern hemisphere has the opposite freezing/thawing period. The stations with missing survey years were not filled, which, on the one hand, avoided the uncertainty error caused by interpolation on the results, and on the other hand, retained the authenticity and accuracy of the data as much as possible. The study of global freeze-thaw index can effectively and comprehensively understand the near surface heat state, and can provide important support for exploring the changes of freeze-thaw state.

File naming and required software

File name: Air freezing index (FI) and air melting index (TI) are stored in FI.rar and TI.rar compressed package formats respectively. GSOD in each file_ FI_ 010010-99999. xls or GSOD_ TI_ 010010-99999. xls is stored in this format, representing GSOD (Global Surface Summary of the Day), FI (Air Freezing Index), TI (Air Melting Index), 010010-99999 (Station No.) respectively.
Data reading method: all table files in the dataset can be opened with excel program, and the main contents are station (1-2 columns), longitude and latitude (3-4 columns), altitude (5 columns), annual minute (6 columns), freezing/melting index (7 columns).

Data Citations Data citation guideline What's data citation?

Cite as:

Peng, X., Chen, C., Mu, C. (2022). Global air freeze-thaw index based on observations（1973-2021）. A Big Earth Data Platform for Three Poles, DOI: 10.11888/Cryos.tpdc.272845. CSTR: 18406.11.Cryos.tpdc.272845. (Download the reference： RIS | Bibtex )

Related Literatures:

1. Peng, X., Zhang, T., Liu, Y., & Luo, J. (2019). Past and projected freezing/thawing indices in the northern hemisphere. Journal of Applied Meteorology and Climatology, 58(3), 495-510.( View Details | Bibtex)

Using this data, the data citation is required to be referenced and the related literatures are suggested to be cited.

Support Program

Research on the mechanism, influence and climate effect of rapid change in the Arctic (No:2019YFA0607003)

the National Natural Science Foundation of China (Grants 42171120)

the National Natural Science Foundation of China ( 42161160328)

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