ESMR Sea Ice Concentration dataset 1972-1977

The Electrically Scanning Microwave Radiometer (ESMR) on board the NIMBUS 5 satellite was a one channel 19.35 GHz horizontally polarized microwave radiometer operating from 11. Dec. 1972 to 16. May. 1977 (1617 days) with some interruptions. After a major data gap from 3. Jun. 1975 until 25. Aug. 1975 the instrument was only operated approximately every other day. The data have recently been made available online by NASA in the format which was used for the tape archive (TAP-files). The experimental NIMBUS satellite programme was very successful and there is heritage from it in modern satellite programs and even though ESMR was a predecessor of modern multi-frequency radiometers there are still parts of modern processing methodologies which can be applied to the data to derive the sea ice extent globally. In fact both the dynamical tie-points and the atmospheric noise reduction of the brightness temperatures (Tb’s) can reduce the noise over both ice and open water consistently. These are also the reasons for reprocessing the data. The ESMR sea ice dataset extends the sea ice climate data record with an important period in the 1970s.

搭载于NIMBUS 5号卫星的电扫描微波辐射计（Electrically Scanning Microwave Radiometer，ESMR）为单通道19.35 GHz水平极化微波辐射计，工作时段为1972年12月11日至1977年5月16日，总计1617天，期间存在多次运行中断。1975年6月3日至1975年8月25日出现大规模数据缺失后，该仪器仅约每隔一日运行一次。近期，美国国家航空航天局（NASA）已将该数据集以磁带存档（TAP-files）所用格式在线公开。实验性NIMBUS卫星项目成果斐然，其技术遗产延续至当代卫星项目中；尽管ESMR是现代多频微波辐射计的前身，但仍有诸多现代数据处理方法可应用于该数据集，以反演全球海冰范围。事实上，对亮温（Brightness Temperatures，Tb’s）采用动态锚点法与大气噪声抑制技术，可同时有效降低海冰与开阔水域的观测噪声，这也是本次对该数据集进行重新处理的核心动因。ESMR海冰数据集为海冰气候数据记录补充了20世纪70年代这一关键观测时段。