Sea Ice Index, Version 2

The Sea Ice Index provides a quick look at Arctic- and Antarctic-wide changes in sea ice. It is a source for consistent, up-to-date sea ice extent and concentration images, in PNG format, and data values, in ASCII text files, from November 1978 to the present. Sea Ice Index images also depict trends and anomalies in ice cover calculated using a 30-year reference period of 1981 through 2010. The images and data are produced in a consistent way that makes the Index time-series appropriate for use when looking at long-term trends in sea ice cover. Both monthly and daily products are available. However, monthly products are better to use for long-term trend analysis because errors in the daily product tend to be averaged out in the monthly product and because day-to-day variations are often the result of short-term weather.海冰指数（Sea Ice Index）可快速展示北极与南极全域的海冰变化态势。本数据集提供自1978年11月至今的格式统一、实时更新的海冰覆盖范围与密集度图像（PNG格式），以及对应的数据值（存储于ASCII文本文件中）。海冰指数图像还展示了以1981至2010年这一30年参考周期计算得到的海冰覆盖趋势与异常值。 所有图像与数据均采用统一标准生成，使得该指数的时间序列数据适用于海冰覆盖长期趋势分析。当前可获取月度与单日两类产品，但针对长期趋势分析更推荐使用月度产品：其一，单日产品的误差可在月度汇总过程中被平均抵消；其二，逐日海冰变化通常由短期天气事件导致。