17 research outputs found
Next Generation Protocol: Innovating a Resilient Future
Conventional practices do not account for product life beyond end-of-sale – these practices are not sustainable. We have developed an end-of-life protocol that includes a metric that we call the Recovery Rating. The objectives of this Next Generation Protocol, beyond supporting the United Nations’ Sustainable Development Goals, are to encourage the production of goods designed for recovery and to promote the collaboration between consumers, the public, and the private sector to recover goods at their end-of-life. The Recovery Rating that we propose evaluates and quantifies recovery potential of products. The Recovery Rating, which is normed against embodied energy from the Cambridge Engineering Selector by Granta Design, accounts for different tiers of recovery: product, component, and material, and different recovery methods at each tier and material family. We will present the results of our Next Generation Protocol using three case studies: 1) disposal, single use PET bottle, 2) Nalgene® reusable bottle, and 3) vacuum insulated, reusable metal bottle. The findings indicate the Next Generation Protocol produces a viable Recovery Rating for the material tier. We will also present survey data on potential user reactions to symbolic, numerical, and graphical versions of the Recovery Rating. The Recovery Ratings for the product and component tiers require considerations that have yet to be accounted for, such as number of uses and production/processing methods, which we present for future recommendations
The formation and fate of internal waves in the South China Sea
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 521 (2015): 65-69, doi:10.1038/nature14399.Internal gravity waves, the subsurface analogue of the familiar surface gravity
waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their
breaking, they impact a panoply of ocean processes, such as the supply of nutrients
for photosynthesis1, sediment and pollutant transport2 and acoustic transmission3;
they also pose hazards for manmade structures in the ocean4. Generated primarily
by the wind and the tides, internal waves can travel thousands of kilometres from
their sources before breaking5, posing severe challenges for their observation and
their inclusion in numerical climate models, which are sensitive to their effects6-7.
Over a decade of studies8-11 have targeted the South China Sea, where the oceans’
most powerful internal waves are generated in the Luzon Strait and steepen
dramatically as they propagate west. Confusion has persisted regarding their
generation mechanism, variability and energy budget, however, due to the lack of
in-situ data from the Luzon Strait, where extreme flow conditions make
measurements challenging. Here we employ new observations and numerical
models to (i) show that the waves begin as sinusoidal disturbances rather than
from sharp hydraulic phenomena, (ii) reveal the existence of >200-m-high
breaking internal waves in the generation region that give rise to turbulence levels
>10,000 times that in the open ocean, (iii) determine that the Kuroshio western
boundary current significantly refracts the internal wave field emanating from the
Luzon Strait, and (iv) demonstrate a factor-of-two agreement between modelled
and observed energy fluxes that enables the first observationally-supported energy
budget of the region. Together, these findings give a cradle-to-grave picture of
internal waves on a basin scale, which will support further improvements of their
representation in numerical climate predictions.Our work was supported by the U.S. Office of Naval Research and
the Taiwan National Science Council.2015-10-2
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The formation and fate of internal waves in the South China Sea
Internal gravity waves, the subsurface analogue of the familiar
surface gravity waves that break on beaches, are ubiquitous in
the ocean. Because of their strong vertical and horizontal currents,
and the turbulent mixing caused by their breaking, they affect a
panoply of ocean processes, such as the supply of nutrients for
photosynthesis¹, sediment and pollutant transport² and acoustic
transmission³; they also pose hazards for man-made structures in
the ocean⁴. Generated primarily by the wind and the tides, internal
waves can travel thousands of kilometres from their sources before
breaking⁵, making it challenging to observe them and to include
them in numerical climate models, which are sensitive to their
effects[superscript 6,7]. For over a decade, studies[superscript 8–11] have targeted the South
China Sea, where the oceans’ most powerful known internal waves
are generated in the Luzon Strait and steepen dramatically as they
propagate west. Confusion has persisted regarding their mechanism
of generation, variability and energy budget, however,
owing to the lack of in situ data from the Luzon Strait, where
extreme flow conditions make measurements difficult. Here we
use new observations and numerical models to (1) show that the
waves begin as sinusoidal disturbances rather than arising from
sharp hydraulic phenomena, (2) reveal the existence of >200-metre-high breaking internal waves in the region of generation
that give rise to turbulence levels >10,000 times that in the open
ocean, (3) determine that the Kuroshio western boundary current
noticeably refracts the internal wave field emanating from the
Luzon Strait, and (4) demonstrate a factor-of-two agreement
between modelled and observed energy fluxes, which allows us to
produce an observationally supported energy budget of the region.
Together, these findings give a cradle-to-grave picture of internal
waves on a basin scale, which will support further improvements of
their representation in numerical climate predictions
The Formation and Fate of Internal Waves In the South China Sea
Internal gravity waves, the subsurface analogue of the familiar surface gravity waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their breaking, they affect a panoply of ocean processes, such as the supply of nutrients for photosynthesis1, sediment and pollutant transport2 and acoustic transmission3; they also pose hazards for man-made structures in the ocean4. Generated primarily by the wind and the tides, internal waves can travel thousands of kilometres from their sources before breaking5, making it challenging to observe them and to include them in numerical climate models, which are sensitive to their effects6,7. For over a decade, studies8-11 have targeted the South China Sea, where the oceans\u27 most powerful known internal waves are generated in the Luzon Strait and steepen dramatically as they propagate west. Confusion has persisted regarding their mechanism of generation, variability and energy budget, however, owing to the lack of in situ data from the Luzon Strait, where extreme flow conditions make measurements difficult. Here we use new observations and numerical models to (1) show that the waves begin as sinusoidal disturbances rather than arising from sharp hydraulic phenomena, (2) reveal the existence of gt;200-metre-high breaking internal waves in the region of generation that give rise to turbulence levels \u3e10,000 times that in the open ocean, (3) determine that the Kuroshio western boundary current noticeably refracts the internal wave field emanating from the Luzon Strait, and (4) demonstrate a factor-of-two agreement between modelled and observed energy fluxes, which allows us to produce an observationally supported energy budget of the region. Together, these findings give a cradle-to-grave picture of internal waves on a basin scale, which will support further improvements of their representation in numerical climate predictions
Continental crust generated in oceanic arcs
Thin oceanic crust is formed by decompression melting of the upper mantle at mid-ocean ridges, but the origin of the
thick and buoyant continental crust is enigmatic. Juvenile continental crust may form from magmas erupted above intraoceanic
subduction zones, where oceanic lithosphere subducts beneath other oceanic lithosphere. However, it is unclear
why the subduction of dominantly basaltic oceanic crust would result in the formation of andesitic continental crust at the
surface. Here we use geochemical and geophysical data to reconstruct the evolution of the Central American land bridge,
which formed above an intra-oceanic subduction system over the past 70Myr. We find that the geochemical signature
of erupted lavas evolved from basaltic to andesitic about 10Myr ago - coincident with the onset of subduction of more
oceanic crust that originally formed above the Galápagos mantle plume. We also find that seismic P-waves travel through
the crust at velocities intermediate between those typically observed for oceanic and continental crust. We develop a
continentality index to quantitatively correlate geochemical composition with the average P-wave velocity of arc crust
globally. We conclude that although the formation and evolution of continents may involve many processes, melting
enriched oceanic crust within a subduction zone - a process probably more common in the Archaean - can produce juvenile continental crust
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State of the California Current Ecosystem in 2021: Winter is coming?
In late 2020, models predicted that a strong La Niña would take place for the first time since 2013, and we assessed whether physical and biological indicators in 2021 were similar to past La Niñas in the California Current Ecosystem (CCE). The Pacific Decadal Oscillation and Oceanic Niño Index indeed remained negative throughout 2021; the North Pacific Gyre Oscillation Index, however, remained strongly negative. The seventh largest marine heatwave on record was unexpectedly present from April to the end of 2021; however, similar to past La Niñas, this mass of warm water mostly remained seaward of the continental shelf. As expected from past La Niñas, upwelling and chlorophyll were mostly high and sea surface temperature was low throughout the CCE; however, values were close to average south of Point Conception. Similar to past La Niñas, abundances of lipid-rich, northern copepods off Oregon increased. In northern California, unlike past La Niñas, the body size of North Pacific krill (Euphausia pacifica) was close to average. Predictably, overall krill abundance was above average in far northern California but, unexpectedly, below average south of Cape Mendocino. Off Oregon, similar to past La Niñas, larval abundances of three of six coastal species rose, while five of six southern/offshore taxa decreased in 2021. Off California, as expected based on 2020, Northern Anchovy (Engraulis mordax) were very abundant, while Pacific Sardine (Sardinops sagax) were low. Similar to past La Niñas, market squid (Doryteuthis opalescens) and young of the year (YOY) Pacific Hake (Merluccius pacificus), YOY sanddabs (Citharichthys spp.), and YOY rockfishes (Sebastes spp.) increased. Southern mesopelagic (e.g., Panama lightfish Vinciguerria lucetia, Mexican lampfish Triphoturus mexicanus) larvae decreased as expected but were still well above average, while northern mesopelagic (e.g., northern lampfish Stenobrachius leucopsarus) larvae increased but were still below average. In line with predictions, most monitored bird species had above-average reproduction in Oregon and California. California sea lion (Zalophus californianus) pup count, growth, and weight were high given the abundant Anchovy forage. The CCE entered an enduring La Niña in 2021, and assessing the responses of various ecosystem components helped articulate aspects of the system that are well understood and those that need further study