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Long-Term Changes of Phytoplankton in the Southern Ocean

7 Appendix A

Figure S1: Annual rates of change in photosynthetically available radiation (PAR) and cloud fraction (CF). (A) PAR trend from Globcolour data over the 1998 to 2021 time frame. Contours represent the mean positions of frontal regions from north to south: red - Northern Boundary (NB), orange - Subantarctic Front (SAF), yellow - Polar Front (PF), green - Southern Antarctic Circumpolar Current Front (SACCF), and blue - Southern Boundary (SB). (B) Cloud fraction trend derived from Coperncius CLARA-A3 (S1B) over 1998 to 2020.

Table S1. Number of observations (n) used to calculate monthly mean chlorophyll-a concentrations for each frontal region and the Southern Ocean.

Month 40°S–NB NB–SAF SAF–PF PF–SACCF SACCF–SB SB–AntCoastline Southern Ocean
Jan 26 26 26 26 26 26 26
Feb 26 26 26 26 26 26 26
Mar 26 26 26 26 26 26 26
Apr 26 26 26 26 26 16 26
May 26 26 26 26 9 0 18
Jun 26 26 26 1 0 0 0
Jul 26 26 26 19 0 0 2
Aug 26 26 26 26 26 0 26
Sep 26 26 26 26 26 0 26
Oct 26 26 26 26 26 0 26
Nov 26 26 26 26 26 8 26
Dec 26 26 26 26 26 26 26
A graph of a graph Description automatically generated with medium confidence
A graph of a graph Description automatically generated with medium confidence

Figure S2: 1998–2023 time series of annual total number of available data points in the Copernicus-GlobColour data set.

A group of images of a map Description automatically generated
A group of images of a map Description automatically generated

Figure S3. Significance maps for the trends of of sea-surface temperature (SST), mixed-layer depth (MLD), wind speed (WS) and photosynthetically available radiation (PAR) displayed in Figure 2.7.

A graph of different sizes of bars AI-generated content may be incorrect.
A graph of different sizes of bars AI-generated content may be incorrect.

Figure S4: Average Chl-a concentrations per frontal regions and sectors of the SO from the ESA OC-CCI data (1998-2023). 26-year average Chl-a values (mg m-3) \[mean, SE\] within (A) each frontal region and the entire SO, where NB= northern boundary, SAF= Sub Antarctic Front, PF=Polar Front, SACCF= Southern ACC Front, SB= Southern boundary, and (B) the Indian, Pacific and Atlantic Sectors of the SO.

A graph of different colored lines AI-generated content may be incorrect.
A graph of different colored lines AI-generated content may be incorrect.

Figure S5: Annual average surface Chl-a (mg m-3) from 1998 to 2023 in the SO and the six frontal regions (A). For clarity, the six frontal regions, as indicated (B to G) are shown separately with their standard error, based on the ESA OC-CCI merged ocean colour product. The dashed lines are the linear trends, and the "DC" values indicated in each panel are the decadal Chl-a changes, in mg Chl-a m-3). The asterisks (*) denote significance level at 95% confidence.

A graph of different colored lines AI-generated content may be incorrect.
A graph of different colored lines AI-generated content may be incorrect.

Figure S6: 1998–2023 time series of annual average surface Chl-a for the Ardyna’s provinces.

A graph with different colored lines and dots AI-generated content may be incorrect.
A graph with different colored lines and dots AI-generated content may be incorrect.

Figure S7: 1998–2023 time series of annual average surface Chl-a for fixed latitudinal bands.

A collage of images of the earth Description automatically generated
A collage of images of the earth Description automatically generated

Figure S8: Seasonal composite of sea ice coverage in the Southern Ocean. The yellow line indicates the Southern Boundary (SB) front, the red line in the Southern Australian Circumpolar Current (ACC) Front (SACCF) and the green line the Polar front (PF).

Figure S9: Time-series comparison of satellite-observed and U-Net-reconstructed chlorophyll a (Chl-a) across Southern Ocean frontal zones from 2003 to 2017. Satellite Chl-a is shown in blue, while reconstructed Chl-a is shown in red.