a, [Chla] anomaly map from December 2019 to February 2020 in comparison to their climatologies. A large portion of the ocean basin (solid black box) was selected to calculate [Chla] time-series. STF, Subtropical Front; SAF, Subantarctic Front. b, Time-series of average [Chla] in the selected box region. Monthly climatological values shown in solid black line. Red and blue areas denote monthly data higher or lower than climatological values, respectively. c, Monthly average [Chla] in individual years in the selected box region. Grey lines, historical years; solid black line, monthly climatologies; dashed black line, 2002 Australian wildfire season; red line, 2019–2020 Australian wildfire season.