Aller au contenu principal

    2024 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.

    Demander un document de réunion
    Numéro du document:
    WG-SAM-2024/07
    Auteur(s):
    Namba, T., R. Sarralde, K Teschke, H. Pehlke, T. Okuda, S. Somhlaba and J. Pompert
    Soumis par:
    Roberto Sarralde Vizuete (Espagne)
    Approuvé par:
    Roberto Sarralde Vizuete (Espagne)
    Résumé

    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 and RB4 from Jan to Mar 2024 were the lowest in the 2017-2024 period.

    A decreasing trend in SST spike sizes in both RB5 and RB4 reversed to an increasing trend in 2022, continuing in both 2023 and 2024. This suggests that the cooling phase of a 5-6 year periodical cycle might have changed to a warming phase in 2022. The warming phase corresponds to a decreasing trend in SIC in both RB5 and RB4. In Jan and Mar 2024 both contour lines (-1.7°C and -1.0°C) in RB5 were located further South or West (or disappeared) than in 2021, 2022 and 2023, which indicates warmer SST distribution in Mar 2024 than in 2021-2023 and corresponds to lower SIC distribution in 2024 than in 2021-2023.

    Dominant Northward and weaker Eastward winds in Jan-Mar 2024 (also Jan-Mar in 2023) could have contributed to the lower SICs too by pushing the ice off-shore, and in addition, weaker Eastward winds in Feb-March in 2024 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 2012 to 2024) shows a significantly lower RA in RB5 compared to RB4. While in RB4 there seems to be a trend for fishing activities to be concentrated in the most accessible areas, this is not the case in RB5.