We analyzed the sea-ice concentration for the southern ice-shelf areas of 48.6 during the latest four seasons using two satellite data, LANCE-MODIS data and AMSR2 of “Shizuku” processed byUniversity Bremen.
Figure 1 shows the overall of the topography and ice condition with Shinsei maru No. 3 trace in 2015/16 season (the detailed trace will be presented at the PowerPoint slide in the WG-SAM-16 meeting).
Figure 2 shows the sea-ice dynamics during the last four seasons (2013-2016) for the two research blocks, 48.6_4 and 48.6_5. The sea-ice concentration during January-March for block 48.6_4 was lowest in 2016, and Japan and South Africa vessels has conducted fishing operation as they scheduled and completed almost all the catch limit allocated.
Figure 3 focused the sea-ice dynamics in and around block 48.6_5 during the latest four seasons. As for 2015/16 season, the fast sea-ice had still occupied the block except for the southern part near the continent in February 1st (Figure 3). Shinsei maru No. 3 had conducted the operations in block 48.6_4 almost all the time in January following the operations in block 48.6_3, then moved to block 48.6_5 in February 4th. However, there had been no appropriate route for her to enter the block, thus she left for the northern part of Subarea 48.6 in February 8th. However, the sea-ice disappeared in the eastern part of the block in February 21st after she left. The sea-ice was becoming thick around whole block in March 11th, but disappeared in the eastern part of the block again in March 21st.
Figure 4 shows the time series of sea-ice concentration during January-March for the latest four seasons in the two research blocks. The sea-ice concentration for block 48.6_4 was much lower throughout the period in 2016 (red line in the upper figure) than the preceding three seasons. The sea-ice concentration for block 48.6_5 stayed at averaged level of the latest seasons during January-February but showed the lowest level in March in 2016 (red line in the lower figure).
As Figures 3 and 4, the sea-ice condition in 2015/16 season was the most favorable to enter 48.6_5 during the latest four seasons. It was however unfortunate that Shinsei maru No. 3 could not enter the research block 48.6_5 because she missed the opportunity to go into the block even though there were apparently free of ice for some part in some timing after late February.
We try to analyze the sea-ice dynamics in relation to environmental factors such as wind and ocean currents to predict the sea-ice condition for the following seasons, which will enable the vessels to conduct the effective research toward the robust stock assessment. We will develop the research plan and make the presentation on that in the coming WG-FSA meeting.