The European Space Agency - Climate Change Initiative (ESA-CCI) sea-ice Essential Climate Variable (ECV) project, phase 2, (ESA-SICCI2) ran from 2015 through 2018 (see http://esa-cci.nersc.no/). The main aim of phase 2 of the ESA-SICCI project was to further enhance development, production and evaluation of satellite-based sea ice ECV data sets, namely of sea-ice concentration and sea-ice thickness.
One element of the evaluation of the ECVs produced was the comparison of the sea-ice ECV data sets with manual, visual ship-based observations of the sea-ice cover.
For this purpose, within ESA SICCI phase 2, a standardized data set of such observations was created for both polar regions covering the period June 2002 through December 2015. These observations comprise visual, i.e. by human eye, regularly and manually conducted observations of the total sea-ice concentration and various other sea-ice parameters of the three thickest sea-ice types within a radius of one kilometer around the ship while the ship cruises through polar waters.