Observation of perennial Arctic sea ice melt and freeze‐up using passive microwave data

The onset of spring melt and autumn freeze‐up of Arctic sea ice are shown, through comparison with coincident ERS‐1 synthetic aperture radar (SAR) and surface air temperature data, to produce significant and detectable changes in the passive microwave signature. Melt onset is marked by a sharp rise in brightness temperatures resulting from the increased emissivity of moisture in the snow cover. Freeze‐up is accompanied by a sharp drop in...