Weatherwatch: Arctic ice sheet engages combat submarines

Uneven ice that scatters sonar tests the US and British navies during ICEX military exercisesThe attack submarine HMS Trenchant has joined US submarines in the Arctic for ICEX 2018, military exercises involving practice with dummy torpedo attacks and navigation and surfacing through the ice cover. The ice sheet provides almost perfect concealment for submarines but brings problems too. While the upper surface of the ice is smooth the underside is ridged with keels extending downwards for many me