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    2023 updated analysis of the sea-ice concentration in research blocks 4(RB4) and 5(RB5) of Subarea 48.6 with sea-surface temperature and winds and statistical analysis of repeated accessibility

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    Номер документа:
    T. Namba, R. Sarralde, K Teschke, H. Pehlke, T. Brey, S. Hain, T. Okuda, S. Somhlaba and J. Pompert
    Представлено (имя):
    Mr Roberto Sarralde Vizuete (Испания)
    Утверждено (имя):
    Mr Roberto Sarralde Vizuete (Испания)

    An analysis of the Sea Ice Concentration (SIC), Sea Surface Temperature (SST) and winds in Research Blocks (RBs) 48.6_5 and 48.6_4 is presented. The SICs in RB5 from mid-Feb to end Mar 2023 were the lowest in the 2016-2023 period.

    A decreasing trend in SST spikes in both RB4 and RB5 reversed to an increasing trend in 2022 and remaining similar in 2023. This suggests that the cooling phase of a 5-6 year periodical cycle might have changed to a warming phase in 2022. This warming phase corresponds to a decreasing trend in SIC in both RB4 and RB4. In Mar 2023 both contour lines (-1.7°C and -1.0°C) in RB5 were located further South than in 2021 and 2022, which indicates warmer SSTs in Mar 2023 than in 2020-2022 and corresponds to lower SICs in 2023 than in 2020-2022.

    Dominant Northward winds in Feb 2022 and 2023 could have contributed to the lower SICs too by pushing the ice off-shore, and in addition, weaker Westward winds in Feb-Mar in both 2022 and 2023 could have weakened the onshore ice transport dynamic, which resulted in late sea ice recovery in Mar of each year.

    Repeated Accessibility (RA) in RB4 and RB5 was calculated with a SIC threshold (limit of navigability of fishing vessels) at 20 %. The RA analysis presented here (based on SIC maps from 2016 to 2023) shows a significantly lower RA in both RBs compared to an older RA analysis based on SIC maps from 2002 - 2017.