Fig. 9: Flow diagram representing the different steps (top to bottom) involved in the partition of the Ross Sea area into three phenoregions.

Workflow included: (top) Extraction of the chl-a and time series of sea ice for The Ross Sea, on a pixel-by-pixel basis and transformation of the data to the same 25 km spatial resolution; (middle) Climatological chl-a and the reproducibility of the annual seasonal cycle were computed in the following step. Additionally, the number of days without sea ice was also calculated; (bottom) After a cluster analysis (based on the 3 elements calculated above), three phenoregions were obtained and their different phenological metrics (BStart, BEnd, BDuration, BArea) computed. The metrics were then used in a phenoregion-specific random forest analysis to identify the main abiotic drivers modulating phytoplankton phenology.