Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Nature Geoscience 1027-1033 MONDE 2022 fdi:010089890 ENG Nature Geoscience 1752-0894 ISI:000883294100001 10.1038/s41561-022-01057-3 https://www.documentation.ird.fr/hor/fdi:010089890 https://www.documentation.ird.fr/intranet/publi/2024-03/010089890.pdf 15 Horizon (IRD) Phytoplankton biomass exhibits substantial year-to-year changes, and understanding these changes is crucial to fisheries management and projecting future climate. These annual changes result partly from low-frequency climate modes that also lead to variations in sea surface temperature (SST). Here we evaluate the contribution of small scales to annual fluctuations based on a global analysis of satellite observations of sea surface chlorophyll (SChl), an indicator of phytoplankton biomass, and of SST from 1999 to 2018. We disentangle the spatio-temporal scales of variability in the time series and find that besides the prominent seasonal cycle, SChl is dominated by high-frequency fluctuations (<three months) at small spatial scales (<50 km)-which accumulates over annual scales in contrast to SST. The results suggest that observations and models with high spatio-temporal resolutions are necessary to understand annual changes in SChl. The rapid response of SChl to small-scale physical processes, combined with intrinsic ecosystem interactions and air-sea interaction feedbacks, may explain the differences between annual variations in SST and SChl. Annual variations of phytoplankton biomass can be explained by processes acting on small spatio-temporal scales, according to a global analysis of satellite observations of sea surface chlorophyll and temperature from 1999 to 2018. 034 ; 036 UR182