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The oceanic particle flux controls, in part, ocean biogeochemical cycles and long-term carbon sequestration. The Oceanic Flux Program (OFP), the longest running time series of its kind, has continuously measured the deep particle flux in the oligotrophic Sargasso Sea southeast of Bermuda since 1978. This paper describes the deep flux climatology at the OFP site over the 1978–2022 time period. Mass flux at 500 m, 1500 m and 3200 m depths has averaged 27.2, 34.8 and 36.8 mg m−2 d-1, respectively. Carbonates comprise ∼ 60 % of the flux, with lesser amounts of organic matter, opal and lithogenics. Flux magnitude and composition vary seasonally with large interannual variability, particularly in the winter/spring flux maximum. Flux frequency distributions are strongly skewed, especially at 500 m depth where flux magnitude and compositional variability are highest. Flux seasonality, skewness and compositional heterogeneity decrease markedly with depth. A significant component of the deep flux is sourced from large particle production in the deep water column (e.g. suspended material repackaging) rather than directly from the overlying export flux. Lithogenic flux increases five-fold between 500 m and 3200 m depths, underscoring the importance of deep lateral advection and lithogenic particle removal via particle cycling processes. Multidecadal averages in deep carbon fluxes are compared with concurrent monthly data on overlying net primary production (PP) and surface export flux (EF, measured by drifting traps at 150 m depth) at the nearby Bermuda Atlantic Time Series (BATS) site. Carbon fluxes are temporally coherent throughout the water column (within the sample resolution) and lag primary production by ∼ one month. Approximately 0.6 %, 0.5 % and 0.4 % of PP reaches the 500, 1500 and 3200 m depth horizons, respectively, with the highest depth penetration occurring during the Jan-Mar period of peak primary production. Annually, 7.6 % and 6.2 % of the EF reaches the1500 and 3200 m depth horizons, respectively, with the highest transfer efficiency (9.1 % and 7.4 %, respectively at 1500 and 3200 m depths) during the post-bloom (Apr-Jun) period. The OFP flux climatology summarized here provides an important baseline for assessing future consequences of a changing climate on ocean functioning in the oligotrophic North Atlantic gyre. 

Abstract Tropical cyclones (hurricanes) generate intense surface ocean cooling and vertical mixing resulting in nutrient upwelling into the photic zone and episodic phytoplankton blooms. However, their influence on the deep ocean remains unknown. Here we present evidence that hurricanes also impact the ocean's biological pump by enhancing export of labile organic material to the deep ocean. In October 2016, Category 3 Hurricane Nicole passed over the Bermuda Time Series site in the oligotrophic NW Atlantic Ocean. Following Nicole's passage, particulate fluxes of lipids diagnostic of fresh phytodetritus, zooplankton, and microbial biomass increased by 30–300% at 1,500 m depth and 30–800% at 3,200 m depth. Mesopelagic suspended particles following Nicole were also enriched in phytodetrital material and in zooplankton and bacteria lipids, indicating particle disaggregation and a deepwater ecosystem response. Predicted climate‐induced increases in hurricane frequency and/or intensity may significantly alter ocean biogeochemical cycles by increasing the strength of the biological pump.