Summer SST phenology changes. SST phenology changes over the study area for the 33-year study period, showing a) trends in the summer start date, b) trends in the summer end date, c) the duration of summer, and d) the difference in the absolute magnitudes of the trends in summer start and end date (end yearday minus start yearday: positive (red) regions have stronger summer end date trends). Inserts in a), b), c) map the probability (p values) that slopes are equal to zero. DOI: https://doi.org/10.1525/elementa.240.f7