Woods Hole Oceanographic Institution

About: Woods Hole Oceanographic Institution is a nonprofit organization based out in Falmouth, Massachusetts, United States. It is known for research contribution in the topics: Population & Mantle (geology). The organization has 5685 authors who have published 18396 publications receiving 1202050 citations. The organization is also known as: WHOI.

Consistently dated Atlantic sediment cores over the last 40 thousand years

Abstract: Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core chronology, and computed the associated dating uncertainties, using a new deposition modeling technique. This is the first set of consistently dated marine sediment cores enabling paleoclimate scientists to evaluate leads/lags between circulation and climate changes over vast regions of the Atlantic Ocean. Moreover, this data set is of direct use in paleoclimate modeling studies.

Fractionation of pyroxene-phyric MORB at low pressure: An experimental study

Abstract: One-atmosphere melting experiments are used to assess the role of clinopyroxene in producing the compositional variations observed in mid-ocean-ridge basalts (MORBs) from the North Atlantic. Analog models of natural glasses and associated phenocrysts show that several possible parental magmas may undergo low pressure fractional crystallization involving olivine and spinel, followed by plagioclase, and then by augite. The phenocryst phase assemblages in natural deep-sea basalts are closely correlated with the major element compositions of their associated quenched glasses, and the projections of these glasses on the Oliv-Cpx-Qtz pseudoternary correspond to the 1-atmosphere phase boundaries and reaction points defined by laboratory experiments. Comparison of natural phenocryst's with experimental phases indicates that the augites preserved in moderately fractionated MORB from the FAMOUS area may have formed at or near the ocean floor and need not be relics of high pressure processes.

Global ocean storage of anthropogenic carbon

Abstract: The global ocean is a significant sink for anthropogenic carbon (C-ant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of C-ant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of C-ant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data-based estimates of the distribution and inventory of C-ant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data assimilation techniques which combine ocean interior estimates of C-ant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of C-ant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate C-ant. Our review also highlights the importance of repeat measurements of hydro-graphic and biogeochemical parameters to estimate the storage of C-ant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based C-ant estimates provide important constraints on forward ocean models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of C-ant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 +/- 31 PgC (+/- 20% uncertainty). This estimate includes a broad range of values, suggesting that a combination of approaches is necessary in order to achieve a robust quantification of the ocean sink of anthropogenic CO2.

Sedimentation of biogenic matter in the deep ocean

Abstract: The major constituents of biogenic particles that settle through the water column of the ocean are carbonate tests, opaline shells, and particulate organic matter (cellular and amorphous). This paper describes the quality and quantity of such fluxes to the deep ocean and compares them with biogenic remains in the bottom sediment. Studies of samples collected during PARFLUX sediment trap experiments in the Atlantic and Pacific have shown that 60 to 90% of the total particulate flux is of biogenic origin; the contribution of biogenic materials decreases with increasing depth. Carbonate hard parts accounted for 30 to 60% and were the largest constituents in pelagic sediments at temperate and tropical areas. Combustible components ranged from 10 to 30% with zooplankton remains and fecal pellets accounting for the bulk of the organic flux. Amorphous fine particles were also significant in the organic flux. The atomic ratios of organic constituents in settling particles deviated systematically from the ‘Redfield ratio’ of 106:16:1 (C:N:P) for marine plankton. In the mesopelagic depths the ratio was 200:21:1, and in the bathypelagic depths the ratio was 300:33:1, with a wide range of variation in phosphorus. The residence time of biogenic particles in the deep-ocean water columns is relatively short and the particles can be expected to arrive at the abyssal floor without major dissolution and remineralization (excepting small opal particles). Fine organic particles such as cell remains and pigmented granules are a major source of organic carbon and nitrogen at deep traps. Microscopic study suggests that the fine organic particles were once included in larger but loosely-formed particles that settled rapidly. Such particles dispersed from settling fecal pellets or similar particles are reintroduced into the water column resulting in ‘secondary’ suspended particles. Such particles may eventually be remineralized while in suspension. The decomposition rate of organic carbon in the deep water was estimated to be about 2.2 mg C m−2 day−1, a rate consistent with rates of oxygen consumption estimated by other investigators. The bottom sediment is enriched in refractory lithogenic particles because of the remineralization of biogenic matter. A hypothetical benthic transition layer serves as a reservoir of benthic activity and can exist under certain conditions at the abyssal floor.

Reconstruction of Caribbean climate change over the past 10,500 years

Abstract: A high-resolution reconstruction of Caribbean climate is presented based on O-18/O-16 ratios in ostracod shells from Lake Miragoane, Haiti. The variations which are found can be largely explained by orbitally induced variations in seasonal insolation which modified the intensity of the annual cycle.