Abstract: Sea ice concentration (SIC) products have been widely used in the detection of polynyas. Eight typical SIC products retrieved from passive microwave remote sensing data (NSIDC-BT-25km, NSIDC-NT2-25km, NSIDC-NT2-12.5km, NSIDC-NTBT-25km, EUMETSAT-BTBR-25km, EUMETSAT-BTBR-10km, UH-ASI- 12.5km and UB-ASI-6.25km) were adopted to detect the Weddell Polynya openings in 2016 and 2017 using five SIC thresholds (15%, 40%, 50%, 60% and 70%) separately. Morphological post-processing operations were then applied to optimize the results. On this basis, the effects of different SIC thresholds, retrieval algorithms, and spatial resolutions of the SIC products on the area/extent of polynya were compared, and the influence of morphological post-processing operations on the results was further explored. The results showed that NSIDC-NTBT-25km demonstrated the highest sensitivity to thresholds, while NASA Team 2 (NT2) algorithm-retrieved SIC products showed the lowest sensitivity and the area/extent of polynya detected from which were generally smaller than those detected by BT (Bootstrap) and ASI (ARTIST Sea Ice) products. High spatial resolution SIC products were more likely to derive polynya with earlier opening times and longer duration, and the area/extent of polynya detected from these were also larger as well. Additionally, spatial resolution exerted the least impact on NT2-retrieved products and had the greatest impact on ASI-retrieved products. Morphological post-processing operations showed some influence on the detected results, yet the effect was less than that of the retrieval algorithms and spatial resolutions.

Key words: microwave remote sensing, sea ice concentration, Weddell Polynya, threshold, morphological processing