IEEE publication on comparison of microwave sea ice retrieval algorithms

Sea-ice concentration: standard deviation of all the algorithms from the ensemble mean, %. (a), (b) 1979–2012 March and September, respectively, 5 algorithms. (c), (d) 1992–2012 March and September, respectively, 11 algorithms.Sea-ice concentration: standard deviation of all the algorithms from the ensemble mean, %. (a), (b) 1979–2012 March and September, respectively, 5 algorithms. (c), (d) 1992–2012 March and September, respectively, 11 algorithms.

Nansen Center scientists Dr. Natalia Ivanova and Ola M. Johannessen have implemented and inter-compared eleven algorithms for the passive-microwave measurement of sea-ice. Daily, monthly and annual Arctic sea-ice concentration, area and extent were calculated by the algorithms using daily microwave brightness temperatures from SMMR, SSM/I, and SSMIS for the period 1979–2012.  

The differences between the 11 sea-ice concentration estimates—structural uncertainties—were quantified and analyzed spatially and seasonally. The algorithms differ in annual sea-ice area by 0.0–1.3 million km2 and in extent by 0.0–0.6 million km2. Linear trends for 34- and 21-year periods were calculated and compared for sea-ice concentration, area and extent. Low-frequency algorithms obtained annual Arctic sea-ice area decrease of 0.534–0.573 million km2 per decade (0.439–0.491 million km2 per decade for the extent) over the period 1979 to 2012, and a decrease of 0.866–0.975 million km2 per decade (0.767–0.812 million km2 per decade for the extent) for the 1992–2012 period. High-frequency algorithms obtained a decrease of 0.766–0.978 million km2 per decade in the area and 0.758–0.814 million km2 per decade in the extent over the period 1992–2012. Results for all the algorithms have close agreement on the strength of the negative trend in Arctic sea-ice area and extent, but are individually biased from the mean. The algorithms’ ensemble mean and standard deviation in sea-ice concentration, describing part of the uncertainty, are presented to provide users with more insight into the uncertainties and potential biases of sea-ice concentration data.  

The paper Retrieval of Arctic Sea Ice Parameters by Satellite Passive Microwave Sensors: A Comparison of Eleven Sea Ice Concentration Algorithms by Natalia Ivanova, Ola M. Johannessen, Leif Toudal Pedersen, and Rasmus T. Tonboe published in the IEEE Transactions on Geoscience and Remote Sensing, VOL. 52, NO. 11, November 2014.

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