Time Series Particle Flux Measurements in the Sargasso Sea

Bermuda Institute Of Ocean Sciences (Bios), Inc., St. George'S

Investigators

Abstract

Since 1978, the Oceanic Flux Program (OFP) has continuously measured particle fluxes in the deep Sargasso Sea. The three decade OFP time-series is, by far, the longest of its kind and unique in its focus on the deep ocean. OFP has produced a unique, albeit edited, record of temporal variability in the so-called biological pump, a term loosely applied here to material transfer from the surface to the deep ocean. The OFP provided the first direct evidence for seasonality in the deep ocean and the tight coupling between deep fluxes and upper ocean processes. It has provided clear evidence of the intensity of biological reprocessing of flux and scavenging of suspended material in mesopelagic waters. The record has documented interannual and longer variations in deep fluxes and shorter term fluctuations driven by the interactions between mesoscale variability and meteorological forcing. The time-series is becoming long enough to begin study of variability in terms of multiyear basin-scale climatic forcing, such as the North Atlantic Oscillation. This award will provide renewal funding for this unique and fundamental oceanographic time-series. As the record gets longer, we are better able to put into perspective the observed fluctuations in terms of the interplay between climate and ocean functioning. The colocation of coordinated and complementary research programs at the Bermuda Time-Series Site- the OFP mooring, the Bermuda Atlantic Time-Series (BATS) shipbased biogeochemical observations, and anticipated future moored and autonomous technologies such as gliders present unparalleled opportunities to study the coupled interactions among ocean physics, biology and chemistry and material fluxes, and how these in turn are linked to atmospheric and climatic forcing. New analytical techniques, unimaginable when the OFP first began, are being applied to the sample archive, revealing new information about ocean processes that is embodied in the composition of recovered flux materials. There will be several significant broader impacts: (1) Systematic, long-term biogeochemical observations, such as those provided by the OFP, are essential to gain an understanding of natural oceanic variability and to provide a reference point in which to interpret the repercussions of possible future climate change scenarios. (2) Previous NSF review panels have recognized the OFP as an invaluable "community resource". The OFP will continue to share its resources- sample material, data, ancillary shiptime, and use of the mooring platform- with researchers and students to make possible a diverse range of investigations at a very low cost to the community. (3) The OFP sample archive is a rare treasure. The sample material to be collected will continue to be invaluable for current and future biogeochemical and climate studies. (4) Educational experiences provided by the OFP will broaden the research experiences and science horizons of many young investigators at a critical juncture. Of particular value are opportunities to become directly involved with observational oceanography, time-series research and integrated ship-based research activities occuring at the Bermuda Time Series site.