Microwave Signals Reveal Sea Ice Changes

Satellites can tell the difference between brand new sea ice and ancient ice just by its microwave

glow. Here’s how it works: the surface of the Earth naturally emits microwave

radiation. Open water has a low glow, but when it freezes into new ice,

it glows much brighter. Old, multi-year ice that has survived a summer melt has a signature

somewhere in between. Using sensors like AMSR2, scientists read these different

signals to create daily maps of sea ice concentration. They even use complex algorithms to filter

out interference from clouds and snow cover. This technology continues a nearly

40-year record, giving us the primary tool to witness the dramatic changes happening in the