By inverting EarthScope long-period magnetotelluric (MT) data from the southeastern United States (SEUS), we obtain electrical conductivity images that provides key insights into the geodynamics of this region. Significantly, we resolve a highly electrically resistive block that extends to mantle depths beneath the modern Piedmont and Coastal Plain physiographic provinces....
To investigate the effects of logging, three small watersheds in the Alsea River basin on the west slope of the Oregon Coast Range were selected for study. This was an interdisciplinary investigation to evaluate the influence of specific logging methods on stream regimen and on aquatic resources. The study plan...
We examined long-term changes in daily streamflow associated with forestry practices with two datasets (this one and the original Alsea Streamflow dataset (1972) over a 60-year period (1959–2017) in the Alsea Watershed Study, Oregon Coast Range, Pacific Northwest, USA. In this contemporary period, 2006 to 2017 (12 water years), data...
We present a new hypothesis to explain the millennial-scale temperature variability recorded in ice cores known as Dansgaard-Oeschger (DO) cycles. We propose that an ice shelf acted in concert with sea ice to set the slow and fast timescales of the DO cycle, respectively. The abrupt warming at the onset...
In this technical note, a steady-state analytical solution of concentrations of a parent solute reacting to a daughter solute, both of which are undergoing transport and multirate mass transfer, is presented. Although the governing equations are complicated, the resulting solution can be expressed in simple terms. A function of the...
Tides in the Delaware Bay (USA) have been modeled from 7000 years before present (7 ka) to the present day and for selected future sea-level rise scenarios (100 years, 300 years). Historic bathymetries were constructed through use of glacial isostatic adjustment models and a very high spatial resolution (< 100...
The residual of the surface energy budget is represented as the linearized sum of energy losses due to storage, advection and flux underestimation. Individual contributions to the residual can be quantified through constrained multiple linear regression which identifies the site specific processes that are responsible for the lack of energy...
The carbon system of the western Arctic Ocean is undergoing a rapid transition as sea ice extent and thickness decline. These processes are dynamically forcing the region, with unknown consequences for CO2 fluxes and carbonate mineral saturation states, particularly in the coastal regions where sensitive ecosystems are already under threat...
Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream...
Reconciling rates of organic carbon export from the euphotic zone with the consumption of organic material in the dark ocean remains one of the major quantitative uncertainties of the ocean carbon cycle. Euphotic zone net community production (NCP) provides one broad constraint on export flux and potential carbon drawdown. However,...
Biomass burning is a significant contributor to atmospheric carbon emissions but may also provide an avenue in which fire-affected ecosystems can accumulate carbon over time, through the generation of highly resistant fire-altered carbon. Identifying how fuel moisture, and subsequent changes in the fire behavior, relates to the production of fire-altered...
Sea surface temperature (SST) and salinity of the Western Pacific Warm Pool (WPWP) reflect global climate effects such as the El Niño–Southern Oscillation phenomenon. However, reconstructions of past changes in the WPWP from the geologic record vary depending on the specific proxy record used. Here we develop a multiproxy record...
Much uncertainty exists about the state of the oceanic and atmospheric circulation in the tropical Pacific over the last glacial cycle. Studies have been hampered by the fact that sediment cores suitable for study were concentrated in the western and eastern parts of the tropical Pacific, with little information from...
The production of carbon and export to deep ocean sediments is linked to carbon partitioning between the ocean and atmosphere and is a key driver of climate change over the glacial-interglacial transition. Yet conflicting reconstructions create barriers to understanding changes to the carbon system over this important climate transition. Production...
Current and hydrographic observations from the Coastal Mixing and Optics
experiment moored array, deployed from August 1996 through June 1997, are used to
describe the velocity variability and evaluate the dynamics of circulation over the New
England shelf on timescales ranging from a few days to several months. Subtidal (days...
Full Text:
mean and subtidal flow on the New England shelf,’’
J. Geophys. Res., 112, C02015, doi:10.1029
Current and hydrographic observations from the Coastal Mixing and Optics
experiment moored array, deployed from August 1996 through June 1997, are used to
describe the velocity variability and evaluate the dynamics of circulation over the New
England shelf on timescales ranging from a few days to several months. Subtidal (days...
Full Text:
mean and subtidal flow on the New England shelf,’’
J. Geophys. Res., 112, C02015, doi:10.1029
We examine the thermal effects of seamount subduction. Seamount subduction may cause transient changes in oceanic crust hydrogeology and plate boundary fault position. Prior to subduction, seamounts provide high‐permeability pathways between the basaltic crustal aquifer and overlying ocean that can focus fluid flow and efficiently cool the oceanic crust. As...
We examine the thermal effects of seamount subduction. Seamount subduction may cause transient changes in oceanic crust hydrogeology and plate boundary fault position. Prior to subduction, seamounts provide high-permeability pathways between the basaltic crustal aquifer and overlying ocean that can focus fluid flow and efficiently cool the oceanic crust. As...
Here we present the first downcore results for a new paleoproxy, the Mn/Ca ratio of foraminiferal calcite, applied to sediment accumulated in the extreme Eastern Tropical North Pacific (ETNP) over the last 30,000 years. The Mn/Ca results are compared to oxygen isotopes and sea surface temperature calculated from Mg/Ca. We...
The loss of Arctic sea ice has emerged as a leading signal of global warming. This, together with acknowledged impacts on other components of the Earth system, has led to the term “the new Arctic.” Global coupled climate models predict that ice loss will continue through the twenty-first century, with...
Seamounts are a ubiquitous feature of the seafloor but relatively little is known about their internal structure. A seamount preserved in the Franciscan mélange of California suggests a sequence of formation common to all seamounts. Field mapping, geophysical measurements, and geochemical analyses are combined to interpret three stages of seamount...
At the Costa Rica margin along the Middle America Trench along‐strike variations in heat flow are well
mapped. These variations can be understood in terms of either ventilated fluid flow, where exposed basement
allows fluids to freely advect heat between the crustal aquifer and ocean, or insulated fluid flow where...
Using temperature gradients measured in 10 holes at 6 sites, we generate the first high fidelity heat flow measurements from Integrated Ocean Drilling Program drill holes across the northern and central Lesser Antilles arc and back arc Grenada basin. The implied heat flow, after correcting for bathymetry and sedimentation effects,...
The delta O-18 signal preserved in paleoarchives is widely used to reconstruct past climate conditions. In many speleothems, this signal is classically interpreted via the amount effect. However, recent work has shown that precipitation delta O-18 (delta O-18(p)) is greatly influenced by convective processes distinct from precipitation amount, and new...
Numerical solutions to the nonlinear Boussinesq equation, applied to a steeply sloping aquifer and assuming uniform hydraulic conductivity, indicate that late-time recession discharge decreases nearly linearly in time. When recession discharge is characterized by -dQ/dt=aQ[superscript b], this is equivalent to constant dQ/dt or b=0. This result suggests that a previously...
Melt inclusions trapped in phenocrysts provide a unique picture of magma systems prior to modification by crustal processes. However, post-entrapment crystallization complicates their interpretation. Re-heating the phenocryst to the temperature of entrapment is a commonly applied method to recover the original melt composition. To understand the effects of re-homogenization, we...
During summer 2007, perennial sea ice in the Beaufort Sea, Arctic Ocean, experienced an unprecedented amount of basal melt. It has previously been shown that this basal melt was linked to an increase in open-water fraction, increasing absorption of solar radiation into the ocean. GPS ice drifters, deployed around the...
The output of gas and tephra from volcanoes is an inherently disorganized process that makes reliable flux estimates challenging to obtain. Continuous monitoring of gas flux has been achieved in only a few instances at subaerial volcanoes, but never for submarine volcanoes. Here we use the first sustained (yearlong) hydroacoustic...
During the last glacial period atmospheric carbon dioxide and temperature in Antarctica varied in a similar fashion on millennial time scales, but previous work indicates that these changes were gradual. In a detailed analysis of one event we now find that approximately half of the CO₂ increase that occurred during...
We investigate the freshwater composition of the shelf
and slope of the Arctic Ocean north of the New Siberian
Islands using geochemical tracer data (δ¹⁸O, Ba, and PO₄*)
collected following the extreme summer of 2007. We find
that the anomalous wind patterns that partly explained the sea
ice minimum at...
We estimate the depth of the 120°C isotherm by constructing crustal thermal gradients based on theoretical and observed conductive heat flux as a function of lithospheric age. We chose the 120°C isotherm because it is close to the upper limit for prokaryotic life, and therefore, the isotherm approximates the maximum...
It is widely accepted that plate divergence at mid-ocean ridges drives mantle flow, mantle melting, and the formation of new oceanic crust. However, many of the details of this process remain obscure because of the inaccessibility of the mantle to direct observation. Thus, geodynamic models are needed to provide insight...
Error in distributed temperature sensing (DTS) water temperature measurements may be introduced by contact of the fiber optic cable sensor with bed materials (e.g., seafloor, lakebed, streambed). Heat conduction from the bed materials can affect cable temperature and the resulting DTS measurements. In the Middle Fork John Day River, apparent...
Large rivers represent gateways for the transport of
terrigenous and anthropogenic material to the coastal ocean.
Here we document a ∼700 km2 recirculation or bulge associated
with the Columbia River plume that retains recently discharged
river water sufficiently to create a regional bioreactor.
Fueled by a fluvial nitrate source, this...
An interlaboratory study of Mg/Ca and Sr/Ca ratios in three commercially available carbonate reference
materials (BAM RS3, CMSI 1767, and ECRM 752-1) was performed with the participation of
25 laboratories that determine foraminiferal Mg/Ca ratios worldwide. These reference materials containing
Mg/Ca in the range of foraminiferal calcite (0.8 mmol/mol to...
Vailulu’u seamount is an active underwater volcano that marks the end of the Samoan hotspot trail (Hart et al., 2000). Vailulu’u has a simple conical morphology (Figure 1) with a largely enclosed volcanic crater at relatively shallow water depths, ranging from 590 m (highest point on the crater rim) to...
We present a new high-precision, high-resolution record of atmospheric methane from the West Antarctic Ice Sheet (WAIS) Divide ice core covering 1000–1800 C.E., a time period known as the late preindustrial Holocene (LPIH). The results are consistent with previous measurements from the Law Dome ice core, the only other high-resolution...
New apatite and zircon (U-Th)/He cooling ages quantify late Cenozoic exhumation patterns associated with fault activity across the Kashmir Himalaya. Apatite (U-Th)/He (AHe) cooling ages of detrital grains from the Sub-Himalayan foreland sediments indicate significant resetting. AHe data and thermal modeling reveal cooling and exhumation initiated by 4Ma at the...
The Pacific Arctic is undergoing rapid biogeochemical changes in response to warming air temperatures caused by climate forcing. This is manifesting as changes in seasonal sea ice thickness and sea ice extent, as well as changes in primary production within surface waters. The data and samples analyzed here were collected...
Climate model simulations and paleoclimate proxies are two tools that enable an understanding of the climate history of the Earth. When utilized together, they form a powerful paradigm for understanding past changes. Proxies are the only physical link to the past conditions on Earth, and models “fill in the gaps”...
This work advances a unified approach to process-based hydrologic modeling to enable controlled and systematic evaluation of multiple model representations (hypotheses) of hydrologic processes and scaling behavior. Our approach, which we term the Structure for Unifying Multiple Modeling Alternatives (SUMMA), formulates a general set of conservation equations, providing the flexibility...
The primary impacts of anthropogenic CO2 emissions on marine biogeochemical cycles predicted so far include ocean acidification, global warming induced shifts in biogeographical provinces, and a possible negative feedback on atmospheric CO2 levels by CO2-fertilized biological production. Here we report a new potentially significant impact on the oxygen-minimum zones of...
New major and trace element and Sr, Nd, and Pb isotope data, together with ³⁹ Ar-⁴⁰Ar ages for lavas from the extinct Galapagos Rise spreading center in the eastern Pacific reveal the evolution in magma compositions erupted during slowdown and after the end of active spreading at a mid-ocean ridge....
Swash hydrodynamics were investigated on an intermediate beach using runup data obtained from video images. Under mild, near-constant, offshore wave conditions, the presence of a sandbar and the tidally controlled water depth over its crest determined whether most of the incoming waves broke before reaching the shoreline. This forced a...
Boreal summer insolation during the last interglaciation (LIG) generally warmed the subpolar to polar Northern Hemisphere more than during the early Holocene, yet regional climate variations between the two periods remain. We investigate northeast Labrador Sea subsurface temperature and hydrography across terminations (T) I and II and during the LIG...
Surface and subsurface flow dynamics govern residence time or water age until discharge, which is a key metric of storage and water availability for human use and ecosystem function. Although observations in small catchments have shown a fractal distribution of ages, residence times are difficult to directly quantify or measure...
Full Text:
moisture dynamics, and the
old water paradox, Water Resour. Res., 46, W03514, doi:10.1029/2009WR008371
Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the
deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area,
the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling
results, integrated with observations from...
The Coastal Ocean Advances in Shelf Transport (COAST) program conducted an
interdisciplinary study of coastal upwelling off central Oregon during summer 2001.
Two intensive field efforts during May–June and August 2001 were coordinated with
ocean circulation, ecosystem, and atmospheric modeling of the region. A primary
goal was to contrast the...
Volcanic eruptions are important events in Earth’s cycle of magma generation and crustal construction. Over durations of hours to years, eruptions produce new deposits of lava and/or fragmentary ejecta, transfer heat and magmatic volatiles from Earth’s interior to the overlying air or seawater, and significantly modify the landscape and perturb...
Mid-ocean ridge volcanism and extensional faulting are the fundamental processes that lead to the creation and rifting of oceanic crust, yet these events go largely undetected in the deep ocean. Currently, the only means available to observe seafloor-spreading events in real time is via the remote detection of the seismicity...
In this paper, we present an approach to extracting mineralogic information from thermal infrared (TIR) spectra that is not based on an input library of pure mineral spectra nor tries to extract spectral end-members from the data. Instead, existing modal mineralogy for a number of samples are used to build...
Davidson Seamount, a volcano located about 80 km off the central California coast, has a volume of
~320 km³ and consists of a series of parallel ridges serrated with steep cones. Davidson was sampled and
its morphology observed during 27 ROV Tiburon dives. During those dives, 286 samples of lava,...
One important role of anthropogenic aerosol particles is their influence on climate by acting as cloud condensation nuclei. However, these particles are diverse in composition and mixing state, and our knowledge of which particle types act as cloud condensation nuclei is incomplete. Here we present direct measurements of individual organic...
Underground temperatures contain a record of past changes in the energy balance at the Earth's surface, such that borehole temperature data can be used to reconstruct long‐term trends of ground surface temperature (GST) changes. In addition to surface air temperature, however, GST is the response of the ground to other...
The thermal structure of convergent margins provides information related to the tectonics, geodynamics,
metamorphism, and fluid flow of active plate boundaries. We report 176 heat flow measurements
made with a violin bow style probe across the Costa Rican margin at the Middle America Trench. The
probe measurements are collocated with...
In the northern California Current, the onset of the 2005
upwelling season was five weeks later than usual, and well established
upwelling with a cold surface signature did not
occur until about seven weeks after this. As part of the joint
US-Canada Pacific hake survey, from 14–16 July 2005 we...
This special section discusses a rare phenomenon: strong enhancement of Subarctic influence in the California Current system in the summer of 2002. This cold, fresh anomaly in the upper halocline was more extreme than any prior observation, though historical records extend back for several decades. The Subarctic anomaly extended more...
NW Rota-1 is a submarine volcano in the Mariana volcanic arc that is notable as the site where underwater explosive eruptions were first witnessed in A. D. 2004. After years of continuous low-level eruptive activity, a major landslide occurred at NW Rota-1 in August 2009, triggered by an unusually large...
In the future, Earth will be warmer, precipitation events will be more extreme, global mean sea level will rise, and many arid and semiarid regions will be drier. Human modifications of landscapes will also occur at an accelerated rate as developed areas increase in size and population density. We now...
The volcanic origin of the Samoan archipelago can be explained by one of three models, specifically, by a hot spot forming over a mantle plume, by lithospheric extension resulting from complex subduction tectonics in the region, or by a combination of these two processes, either acting sequentially or synchronously. In...
Summertime low clouds are common in the Pacific Northwest (PNW), but spatiotemporal patterns have not been characterized. We show the first maps of low cloudiness for the western PNW and North Pacific Ocean using a 22‐year satellite‐derived record of monthly mean low cloudiness frequency for May through September and supplemented...
We examine the relation between δ¹⁸O in rainwater collected in southwestern Oregon
and climate variables including temperature, parcel trajectory, precipitation amount, and
specific humidity. Local surface air temperature at the time of sample collection explains a
large proportion of δ¹⁸O variability, suggesting that paleoclimatic archives that are related
to rainfall...
We construct an extratropical reduced temperature–depth profile for land areas north
of 20°N latitude from the global borehole temperature database compiled for climate
reconstruction. The mean reduced temperature profile compares well with a time series
constructed from an initial baseline temperature (0.6° ± 0.1°C) and the last 140 years
of...
Observations of temperature, winds, and atmospheric trace gases suggest that the transition from troposphere to stratosphere occurs in a layer, rather than at a sharp ‘‘tropopause.’’ In the tropics, this layer is often called the ‘‘tropical tropopause layer’’ (TTL). We present an overview of observations in the TTL and discuss...
In this study we present 42 new ⁴⁰Ar/³⁹Ar incremental heating age determinations updated age progression for the Louisville seamount trail. Louisville is the South Hawaiian‐Emperor seamount trail, both trails representing intraplate volcanism (~80 Ma to present) and being examples of primary hot spot lineaments. Our age‐progressive trend from 71 to...
Although geodetic measurements of interseismic deformation in interior Tibet suggest slow
strain accumulation, active slip along the right-lateral Gyaring Co Fault is suggested to be between 8
and 21 mm/yr. Reliable geologic constraints on the slip rate along this fault are sparse. Here we document
12 ± 2 m of...
Full Text:
, B04403, doi:10.1029/2011JB009071.
Armijo, R., P. Tapponnier, J. L. Mercier, and H. Tong-Lin (1986
Sea surface temperatures (SST) and inorganic continental input over the last 25,000 years (25 ka) are reconstructed in the far eastern equatorial Pacific (EEP) based on three cores stretching from the equatorial front (~0.01°N, ME0005-24JC) into the cold tongue region (~3.6°S; TR163-31P and V19-30). We revisit previously published alkenone-derived SST...
[1] We report detailed thermal measurements undertaken during Integrated Ocean Drilling Program (IODP)
Expeditions 315 and 316 along the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) transect
offshore the Kii Peninsula, Japan. Geothermal objectives included determining thermophysical rock properties
of the cored material and characterizing the background thermal regime along this...
We assimilate localized mass anomalies inferred from
GRACE ranging measurements into a hydrodynamic model
to improve tidal solutions around Antarctica for the M2, S2,
and O1 constituents. The variational approach used accounts
for the spatial averaging of tidal elevations implicit in the
mass anomaly parametrization used for the GRACE tidal...
River Influences on Shelf Ecosystems (RISE) is the first comprehensive
interdisciplinary study of the rates and dynamics governing the mixing of river and coastal
waters in an eastern boundary current system, as well as the effects of the resultant plume
on phytoplankton standing stocks, growth and grazing rates, and community...
Over the last three decades the first-order correlation in morphology and orientation of seamount trails
has been called upon to support the concept of a ‘‘fixed’’ Pacific hot spot frame of reference and to explain
the Hawaii-Emperor bend (HEB) by a dramatic change in Pacific plate motion. In this paper,...
The overflow of deep water from the Nordic seas
into the North Atlantic plays a critical role in global ocean
circulation and climate. Approximately half of this overflow
occurs via the Iceland–Scotland (I–S) overflow, yet the history
of its strength throughout the Holocene (~0–11 700 yr
ago, ka) is poorly...
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Cycles,
16(4): 1139- doi:10.1029/2001GB001662.
Campin, J.-M., Goosse, H. (1999) Parameterization of
The 8.2 ka event was the last deglacial abrupt climate event. A reduction in the Atlantic meridional overturning circulation (AMOC) attributed to the drainage of glacial Lake Agassiz may have caused the event, but the freshwater signature of Lake Agassiz discharge has yet to be identified in δ¹⁸O of foraminiferal...
Full Text:
the Labrador Sea” by Hoffman et al. (Geophysical
Research Letters, 39, L18703, doi: 10.1029
Mineral dust particles have been shown to act as cloud condensation nuclei, and they are known to interact
with developing tropical storms over the Atlantic downwind of the Sahara. Once present within liquid
droplets, they have the potential to act as freezing ice nuclei and further affect the microphysics, dynamics,...
Abstract: Coastal upwelling zones may be at enhanced risk from ocean acidification as upwelling brings low aragonite saturation state (Ω[subscript Ar]) waters to the surface that are further suppressed by anthropogenic CO₂. Ω[subscript Ar] was calculated with pH, pCO₂, and salinity-derived alkalinity time series data from autonomous pH and pCO₂...
The Northwest Lau Backarc Basin, consisting of the Northwest Lau Spreading Center (NWLSC) and the Rochambeau Rifts (RR), is unique in having elevated ³He/⁴He ratios (up to 28 R[subscript a]) in the erupted lavas, clearly indicating a hot spot or ocean island basalt (OIB)-type signature. This OIB-type helium signature does...
Moored current measurements from the Oregon shelf
during 1998–2003 are used to estimate time series of
anomalous alongshore currents and pseudo-displacements,
after accounting for the mean and seasonal cycle. From
early January through mid-June, 2002, currents at 10 m
were anomalously strong toward the south by an average
12 cm/s,...
Upper ocean hydrography in the central Arctic Ocean
has relaxed since 2000 to near-climatological conditions
that pertained before the dramatic changes of the 1990s. The
behavior of the anomalies of temperature and salinity in the
central Arctic Ocean follow a first-order linear response to
the AO with time constant of...
Many Earth science disciplines are currently experiencing the emergence of new ways of data
publication and the establishment of an information technology infrastructure for data archiving and
exchange. Building on efforts to standardize data and metadata publication in geochemistry [Staudigel et
al., 2002], here we discuss options for data publication,...
Volcanic samples collected with the Monterey Bay Aquarium Research Institute's ROV Tiburon from eight seamounts at the continental margin offshore central to southern California comprise a diverse suite of mainly alkalic basalt to trachyte but also include rare tholeiitic basalt and basanite. All samples experienced complex crystal fractionation probably near...
We report a decadally resolved record of atmospheric CO₂ concentration for the last 1000 years, obtained from the West Antarctic Ice Sheet (WAIS) Divide shallow ice core. The most prominent feature of the pre-industrial period is a rapid ∼7 ppm decrease of CO₂ in a span of ∼20–50 years at...
Oxygen isotope data from planktonic and benthic foraminifera, on a high-resolution age model (44 ¹⁴C dates spanning 17,400 years), document deglacial environmental change on the southeast Alaska margin (59°33.32′N, 144°9.21′W, 682 m water depth). Surface freshening (i.e., δ¹⁸O reduction of 0.8‰) began at 16,650 ± 170 cal years B.P. during...
Multiplicative random cascades (MRCs) can parsimoniously generate highly intermittent patterns similar to those in rainfall. The elemental MRC model parameter is the cascade weight, which determines how rainfall at one scale is partitioned at the next smallest scale in the cascade. While it is known that the probability density of...
Water circulating through oceanic lithosphere extracts large quantities of heat, affecting magmatic, tectonic, geochemical, and microbial processes. Numerous estimates for the amount of hydrothermal heat extraction have been made on the basis of the difference between the predicted and observed heat flux across the seafloor. These methods have assumed a...
Many investigations using satellite data have determined that aerosol optical depth and cloud cover are correlated and some have interpreted the correlation as evidence of an aerosol indirect effect on clouds. This study uses in situ aircraft observations taken during the Indian Ocean Experiment (INDOEX), February–March 1999, and mostly over...
We present observations from deployments of a microstructure turbulence instrument
(the Towed Microstructure and Auxiliary Sensor Instrument) aboard a pumping profiling
vehicle (the Lamont Pumping SeaSoar) towed behind a research vessel at the New
England shelf break front in August 2002. From these we determined coincident fine-scale
vertical eddy diffusivity...
This article investigates the origins of the variability of the Malvinas Current (MC)
transport using the results of an eddy-permitting ocean general circulation model. First, the
dynamical links between the variabilities of the MC and the Antarctic Circumpolar
Current (ACC) transports at the Drake Passage are established. Time series analyses...
Bathymetry and magnetic anomalies indicate that a seamount on the Juan de Fuca plate has been subducted beneath the central Cascadia accretionary complex and is now located similar to 45 km landward of the deformation front. Passage of this seamount through the accretionary complex has resulted in a pattern of...
The Blanco Transform Fault Zone (BTFZ) forms the ~350 km long Pacific–Juan de
Fuca plate boundary between the Gorda and Juan de Fuca ridges. Nearby broadband seismic networks provide a unique framework for a detailed, long-term seismotectonic study of an entire oceanic transform fault (OTF) system. We use regional waveforms...
General circulation models (GCMs) predict that the global hydrological cycle will change in response to anthropogenic warming. However, these predictions remain uncertain, in particular, for precipitation (Intergovernmental Panel on Climate Change, 2013, https://doi .org/10.1017/CB09781107415324.004). Held and Soden (2006, https://doi.org/10.1175/JCLI3990.1) suggest that as lower tropospheric water vapor concentration increases in a...
Aerosols and clouds have important effects on Earth's climate through their effects on the radiation budget and the cycling of water between the atmosphere and Earth's surface. Limitations in our understanding of the global distribution and properties of aerosols and clouds are partly responsible for the current uncertainties in modeling...
Submarine volcanic eruptions and intrusions construct new oceanic crust and build long chains of volcanic islands and vast submarine plateaus. Magmatic events are a primary agent for the transfer of heat, chemicals, and even microbes from the crust to the ocean, but the processes that control these transfers are poorly...
The seasonal cycle of the near-surface circulation off central Chile was analyzed using satellite altimetry and an oceanic model. To evaluate the role of the wind stress curl on the circulation we performed two identical simulations except for the wind-forcing: the "control run" used long-term monthly mean wind stress and...
The seismicity of the North Atlantic was monitored from May 2002 to September 2003 by the ‘SIRENA array’ of autonomous hydrophones. The hydroacoustic signals provide a unique data set documenting numerous low-magnitude earthquakes along the section of the Mid-Atlantic Ridge (MAR) located in a ridge-hot spot interaction context. During the...
A melt pond model is presented that predicts pond size and depth changes, given an
initial ice thickness field and representative surface fluxes. The model is based on the
assumption that as sea ice melts, fresh water builds up in the ice pore space and eventually
saturates the ice. Under...
This work advances a unified approach to process-based hydrologic modeling, which we term the ‘‘Structure for Unifying Multiple Modeling Alternatives (SUMMA).’’ The modeling framework, introduced in the companion paper, uses a general set of conservation equations with flexibility in the choice of process parameterizations (closure relationships) and spatial architecture. This...
Halogens are primarily located within surface reservoirs of the Earth; as such they have proven to be effective tracers for the identification of subducted volatiles within the mantle. Subducting lithologies exhibit a wide variety of halogen compositions, yet the mantle maintains a fairly uniform signature, suggesting halogens may be homogenized...