Sea Ice Index: ice cover and trends in ice cover in the Arctic and Antarctic oceans, Version 3, 1978-present

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 GeoTIFF and 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.
Fetterer, F., K. Knowles, W. N. Meier, M. Savoie, and A. K. Windnagel. 2017, updated daily. Sea Ice Index, Version 3. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: https://doi.org/10.7265/N5K072F8. 13 Nov 2020.

海冰指数（Sea Ice Index）可用于快速概览北极与南极全域的海冰变化情况。该数据集提供了自1978年11月至今的一致且实时更新的海冰范围与海冰密集度图像（PNG格式），以及对应的数据值（存储为GeoTIFF与ASCII文本文件格式）。海冰指数图像还展示了以1981—2010年为30年参考期计算得到的海冰覆盖趋势与距平值。

本数据集的图像与数据采用统一标准生成，使得该指数的时间序列可适用于海冰覆盖长期趋势分析。数据集包含月度与逐日两类产品，不过针对长期趋势分析更推荐使用月度产品：一方面逐日产品的误差可在月度产品中被平均抵消，另一方面海冰的逐日变化往往由短期天气过程主导。

数据引用：Fetterer F.、Knowles K.、Meier W.N.、Savoie M.、Windnagel A.K.，该数据集自2017年起每日更新。海冰指数（第3版），美国科罗拉多州博尔德市，国家雪冰数据中心（National Snow and Ice Data Center, NSIDC）。DOI：https://doi.org/10.7265/N5K072F8，2020年11月13日更新。