Classification methods for monitoring Arctic sea ice using OKEAN passive/active two-channel microwave data

This paper presents methods classifying Arctic sea ice using both passive a nd active (2-channel) microwave imagery acquired by the Russian OKEAN 01 po lar-orbiting satellite series. Methods and results are compared to sea ice classifications derived from nearly coincident Special Sensor Microwave Ima ger (SSM/I) and Advanced Very High Resolution Radiometer (AVHRR) image data of the Barents, Kara, and Laptev Seas. The Russian OKEAN 01 satellite data were collected over weekly intervals during October 1995 through December 1997 Methods are presented for calibrating, georeferencing ng a,zn classify ing the raw active radar and passive microwave OKEAN 01 data, and for corre cting the OKEAN 01 microwave radiometer calibration wedge based on concurre nt 37 GHz horizontal polarization SSM/I brightness temperature data. Sea ic e type and ice concentration algorithms utilized OKEAN's two-channel radar and passive microwave data in a linens mixture model based on the measured values of brightness temperature and radar together with a priori knowledge about the scattering parameters and natural emissivities of basic sea ice types. OKEAN 01 data and algorithms tended to classify lower concentrations Of young or first-year sea ice when concentrations were less than 60%, and to produce higher concentrations of multi-year sea ice when concentrations were greater than 40%, when compared to estimate produced from SSM/I data. Overall, total sea ice concentration maps derived independently from OKEAN 01, SSM/I, and AVHRR satellite imagery were all highly correlated, with un iform biases, and mean differences In total ice concentration of less than four. percent (sd<15%). Published by Elsevier Science Inc.