Median Sea Ice Extent for the Arctic

Areas of the ocean that have frozen are considered “sea ice,” and can vary from slushy, barely solid areas to sheets of ice that are meters thick. Since the late 1970s, satellites have been used to monitor both the extent and concentration of sea ice around the world. Each day, the National Snow and Ice Data Center generates sea ice extent analyses from a variety of microwave satellite data sources. This layer may be used in conjunction with the Arctic Sea Ice Extent layer, which provides context for the sea ice extent for any given month. Data Source National Snow and Ice Data Center Sea Ice Index Revisions Apr 8, 2026: Updated field details to include descriptions and value types. Also cleaned up field aliases and trimmed unused fields.海洋冻结区域被称为海冰（sea ice），其形态跨度广泛，从半融松软的近固态区域，直至数米厚的平整冰盖均有涵盖。 自20世纪70年代末起，人类便通过卫星对全球范围内的海冰范围与浓度开展监测工作。 每日，美国国家冰雪数据中心（National Snow and Ice Data Center）都会基于多种微波卫星数据源生成海冰范围分析产品。 该图层可与北极海冰范围图层（Arctic Sea Ice Extent layer）搭配使用，后者可为任意指定月份的海冰范围提供背景参考信息。 数据源：美国国家冰雪数据中心海冰索引（National Snow and Ice Data Center Sea Ice Index）。 更新记录：2026年4月8日——完善字段详情，补充字段描述与数值类型说明；梳理字段别名并移除未使用的冗余字段。