The total annual freezing and thawing indices are defined as thecumulative number of degree-days when air temperatures are below andabove zero degrees Celsius. The total annual freezing index has beenwidely used to predict permafrost distribution; estimate themaximum thickness of sea, lake, and river ice, and the maximum depth ofground-frost penetration; and classify snow types. The annual totalthawing index has been used to predict permafrost distribution and toestimate the maximum depth of thaw in frozen ground. Both totalfreezing and thawing indices are important parameters for engineeringdesign in cold regions.Data coverage is global. The data set contains the total annual freezing and thawing indices with a spatial resolution of 0.5 degreeslatitude by 0.5 degrees longitude. Two data files are available, forthe freeze and thaw indices respectively, in flat binary format. Eachfile is approximately 1 MB in size. The total annual freezing andthawing indexes were calculated based upon the monthly mean airtemperature by Legates and Willmott (1990).