Global Annual Freezing and Thawing Indices, Version 1

The total annual freezing and thawing indices are defined as the cumulative number of degree-days when air temperatures are below and above zero degrees Celsius. The total annual freezing index has been widely used to predict permafrost distribution, estimate the maximum thickness of sea, lake, and river ice, and the maximum depth of ground-frost penetration, and classify snow types. The annual total thawing index has been used to predict permafrost distribution and to estimate the maximum depth of thaw in frozen ground. Both total freezing and thawing indices are important parameters for engineering design 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 degrees latitude by 0.5 degrees longitude. Two data files are available, for the freeze and thaw indices respectively, in flat binary format. Each file is approximately 1 MB in size. The total annual freezing and thawing indexes were calculated based upon the monthly mean air temperature by Legates and Willmott (1990).年冻结总指数与年融化总指数分别定义为：空气温度低于0摄氏度时的度日（degree-days）累积数，以及空气温度高于0摄氏度时的度日累积数。年冻结总指数已被广泛用于预测多年冻土（permafrost）分布、估算海冰、湖冰与河冰的最大厚度，以及地面冻深的最大值，并可用于积雪类型分类。年融化总指数则被用于预测多年冻土分布，并估算冻土的最大融化深度。冻结与融化总指数均为寒区工程设计的重要参数。 该数据集的覆盖范围为全球，包含年冻结总指数与年融化总指数，空间分辨率为0.5°纬度×0.5°经度。数据集提供两个数据文件，分别对应冻结指数与融化指数，采用扁平二进制（flat binary）格式存储，单个文件大小约为1 MB。年冻结与融化总指数由Legates和Willmott（1990）基于月平均气温计算得到。