Cooperative Institute for Research in Environmental Sciences

An intercomparison of aerial coverage of the Terra Nova Bay polynya in July-September 2009 as determined using MODIS and AMSR-E satellite imagery

Wegrzyn, K., J. Maslanik, and J. Cassano

2014, Polar Research, in review

Areal coverage of the Terra Nova Bay polynya of Antarctica as measured using different satellite data sets is investigated for the period July 1, 2009 - September 30, 2009. Ice surface temperature data derived from the thermal bands of the MODIS Aqua satellite are used to identify the polynya area as well as ice concentration data derived from AMSR-E passive microwave imagery using two different algorithms (Bootstrap and NASA Team 2 [NT2]). A temperature threshold of 264 K and ice concentration threshold of 70% were applied to the MODIS and passive microwave products respectively to differentiate polynya area from heavier ice cover. Using these thresholds, polynyas were detected in 96% of the total of 92 days using Bootstrap data, 27% using NT2 data, and 77% using MODIS data. The mean polynya area varied between datasets, from a maximum mean of 1972 km2 coverage for the Bootstrap algorithm data to a minimum average area of 825 km2 in the MODIS ISTs. Polynyas persisted for up to 30 days, disappearing for 1 to 2 days, and reappearing for a minimum of 10 days. Overall, the polynya statistics estimated using the Bootstrap concentrations were found to agree better with the IST-derived values, compared to those estimates using NT2 concentrations. Tests of the use of a range of ice concentration thresholds shows the importance of the threshold choice on polynya detection and areal estimation.