noun
second-year ice
Technical term in glaciology and oceanography for sea ice that has survived one summer's melt and is in its second winter of growth.
北極海では、二年氷が広範囲に分布している。
In the Arctic Ocean, second-year ice is widely distributed.
多年氷 is multi-year ice that has survived at least two summers, making it even thicker and harder than 二年氷.
Compound of 二年 (two years) and 氷 (ice), literally 'two-year ice'. The reading ごおり is a rendaku form of こおり (氷).