Time Series Particle Flux Measurements in the Sargasso Sea

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

Investigators

Abstract

Understanding ocean variability over interannual and decadal time-scales is of widespread interest and increasing relevance given the concerns over anthropogenic perturbations of global climate and ocean chemistry due to increases in greenhouse gases. The contributions of long-term observations to our understanding of how the ocean works are numerous and far-reaching. Yet, such studies are exceedingly rare- especially those with a biogeochemical and deep ocean focus. Since 1978, the Oceanic Flux Program (OFP), originally founded and managed by at the Woods Hole Oceanographic Institution and now managed by the Bermuda Institute of Ocean Science (BIOS), has continuously measured particle fluxes in the deep Sargasso Sea. The 34+ year 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 "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 physical variability, meteorological forcing and ecosystem responses. This award will provide three more years of funding for this unique and fundamental oceanographic time-series. As the record lengthens, we are better able to put into perspective the observed flux patterns in terms of the interplay between climate and ocean functioning. The colocation of complementary research programs at the Bermuda Time-Series Site: the OFP, the Bermuda Atlantic Time-Series (BATS), the Bermuda Testbed Mooring (BTM, 1994-2007), as well as new advances in ship-based, moored and autonomous observational capabilities at the site 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 information about ocean biogeochemistry, preserved as chemical signals in recovered flux materials, continues to be revealed as ever more sophisticated analytical research tools are applied. 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 ship time, 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 research. (4) Educational experiences provided by the OFP broaden the research experiences and science directions of many young students and early investigators at critical junctures in their careers. Of particular value are opportunities to become directly involved with observational oceanography, time-series research and integrated ship- and mooring-based research activities occurring at the Bermuda Time Series site