Arctic ice transformations: multiyear ice changes in comparison with summer minima

Passive satellite microwave data provide an extended time series for long-term monitoring of polar processes. Though the Arctic ice cover is composed of several types of ice, two major types of ice, which have explicitly different microwave emissivities, dominate in the region. These are first-year and multi-year ice, the latter having survived at least one summer. Since multi-year ice is the thickest type of ice, its amount is an essential parameter for mass balance studies of the ice pack, and an important indicator of climate change. The potential for studying variations in multi-year ice from satellite passive microwave data has scarcely been realized, despite distinctive first-year and multi-year ice signatures, at least in winter when melt effects are absent. Passive microwave observations may inadequately represent multi-year ice parameters, even in winter. The authors' objective is to make a comparable analysis using a different algorithm applied to the twenty years of passive microwave satellite observations begun by SMMR data which has been provided from 1979-87 and followed by the Special Sensor Microwave Imager (SSM/I) data from 1987-present. From this analysis, they assess the ability of brightness temperature data to serve as meaningful baseline time series for multi-year ice climate studies.