Mean fields, seasonal cycles, and interannual variability are examined for fields of
satellite-derived chlorophyll pigment concentrations (CHL), sea surface height (SSH), and
sea surface temperature (SST) during 1997–2002. The analyses help to identify three
dynamic regions: an upwelling zone next to the coast, the Ensenada Front in the north,
and...
The evolution of oceanographic conditions in the upwelling region off northern Chile
(18°–24°S) between 1996 and 1998 (including the 1997–1998 El Niño) is presented using
hydrographic measurements acquired on quarterly cruises of the Chilean Fisheries Institute, with
sea surface temperature (SST), sea level, and wind speeds from Arica (18.5°S), Iquique...
Over 30 years of hydrographic data from the northern Chile (18°S-24°S) upwelling
region are used to calculate the surface and subsurface seasonal climatology extending 400 km
offshore. The data are interpolated to a grid with sufficient spatial resolution to preserve crossshelf
gradients and then presented as means within four seasons:...
Time series of satellite measurements are used to describe patterns of surface
temperature and chlorophyll associated with the 1996 cold La Nina phase and the 1997-1998
warm El Nino phase of the El Nino - Southern Oscillation cycle in the upwelling region off
northern Chile. Surface temperature data are available...
Monthly composite images from the global coastal zone color scanner
(CZCS) data set are used to provide an initial illustration and comparison of seasonal
and interannual variability of phytoplankton pigment concentration along the western
coasts of South and North America in the Peru Current system (PCS) and California
Current system...
Satellite-derived data provide the temporal means and seasonal and nonseasonal
variability of four physical and biological parameters off Oregon and Washington
(41°–48.5°N). Eight years of data (1998–2005) are available for surface chlorophyll
concentrations, sea surface temperature (SST), and sea surface height, while six years of
data (2000–2005) are available for...
Although satellite electromagnetic induction studies
have usually assumed a symmetric magnetospheric ring
current source, there is growing evidence for significant
source asymmetry. Here we apply empirical orthogonal
function methods to mid-latitude night-side hourly mean
geomagnetic observatory data to search for evidence of nonzonal
low-frequency source fields. The dominant spatial
mode...
The current satellite magnetic missions offer new
opportunities to determine the electrical conductivity of the
Earth. However, satellites are nearly stationary in local time
and therefore sample the inducing and induced fields quite
differently than geomagnetic observatories, which rotate
with the Earth. We show that estimates of induction transfer
functions...
Submersible investigations of the Cascadia accretionary
complex have identified localized venting of methane gas
bubbles in association with gas hydrate occurrence. Acoustic
profiles of these bubble plumes in the water column in the
vicinity of Hydrate Ridge offshore Oregon provide new
constraints on the spatial distribution of these gas vents...
The Gorda Escarpment is a north facing scarp immediately south of the Mendocino transform fault (the Gorda/Juan de Fuca-Pacific plate boundary) between 126°W and the Mendocino triple junction. It elevates the seafloor at the northern edge of the Vizcaino block, part of the Pacific plate, ~1.5 km above the seafloor...
As the Mendocino Triple Junction migrates northward along the California margin it is widely presumed to leave a "slab-free" or "asthenospheric" window in its wake. A 250-km-long south-north seismic refraction-reflection profile crossing the transition from transform to subduction regimes allows us to compare and contrast crust and upper mantle of...
The oceanic tidal angular momentum (OTAM) has
Been demonstrated to be the primary cause for the diurnal and
semidiurnal variations in the Earth's rotational rate, or ∆UT1.
Three ocean tide models derived from the Topex/Poseidon
altimetry mission are employed to yield predictions of ∆UT1 for
eight major diurnal/semidiurnal tides. The...
Most of the tidal energy dissipation in the ocean occurs in shallow seas, as had long been recognized. However, recent work has suggested that a significant fraction of the dissipation, perhaps 1 TW or more, occurs in the deep ocean. This paper builds further evidence for that conclusion. More than...
The most accurate determinations of the global ocean tides are currently based on altimeter measurements made by the Topex/Poseidon satellite. The error spectrum corresponding to the M₂ tidal solution is here estimated, primarily by inverse methods and secondarily by simple differencing in flatter than tidal signal spectrum, and it exceeds...
How and where the ocean tides dissipate
their energy are longstanding questions with both
oceanographic and astronomical implications. Two
decades ago, Doake suggested that flexing of Antarctic
ice shelves by the underlying ocean tide is an important
energy sink, perhaps accounting for over half the global
dissipation rate. Observational constraints...
Tidal phenomena in the Indonesian
seas are among the most complex in the
world. Complicated coastal geometries
with narrow straits and myriad small islands,
rugged bottom topography next to
wide shelves of shallow water, and large
quantities of tidal power input from the
adjoining Indian and Pacific Oceans—all
combine to...
Altimetric data from the TOPEX/POSEIDON mission will be used for studies of global ocean circulation and marine geophysics. However, it is first necessary to remove the ocean tides, which are aliased in the raw data. The tides are constrained by two distinct types of information: the hydrodynamic equations which the...
Magnetotelluric (MT) data from two sites 150 and
300 km southeast of San Francisco, California (geomagnetic
dipole latitude: 43 degrees, L approximately 1.9) show that
the usual MT assumption of spatially uniform external magnetic
fields is violated to a significant degree in the period
range 10-30 s. Inter-station transfer functions...
Over 20 global ocean tide models have been developed since 1994, primarily as a
consequence of analysis of the precise altimetric measurements from TOPEX/POSEIDON and as a result of parallel developments numerical tidal modeling and data assimilation. This paper
provides an accuracy assessment of 10 such tide models and discusses...
Air–sea coupling during coastal upwelling was examined through idealized three-dimensional numerical simulations with a coupled atmosphere–ocean mesoscale model. Geometry, topography, and initial and
boundary conditions were chosen to be representative of summertime coastal conditions off the Oregon coast. Over the 72-h simulations, sea surface temperatures were reduced several degrees near...
In spite of an order of magnitude increase over the past 15 years in spatial sampling of the wavefield, a major uncertainty in the analysis of active source seismic data remains phase identification. This uncertainty results in part from the wide range of spatial scales of velocity heterogeneity in the...
Seismic data and seafloor samples indicate the presence of free gas, gas hydrate, and
fluid seeps south of the Gorda Escarpment, a topographic feature that marks the eastern
end of the Gorda/Pacific transform plate boundary southwest of Cape Mendocino,
California. In spite of high sedimentation rates and high biological productivity,...
In 1989, we conducted an onshore/offshore seismic experiment to image the crustal structure of the Cascadia forearc. In this paper, we discuss the processing and interpretation of a multichannel seismic reflection profile across the continental margin that was collected as part of this effort. This profile reveals several features of...
Log and core data document gas saturations as high as
90% in a coarse-grained turbidite sequence beneath the gas
hydrate stability zone (GHSZ) at south Hydrate Ridge, in the
Cascadia accretionary complex. The geometry of this gas-saturated
bed is defined by a strong, negative-polarity
reflection in 3D seismic data. Because...
The Queen Charlotte Fault is a transpressive transform plate boundary between the Pacific and North American plates offshore western Canada. Previous models for the accommodation of transpression include internal deformation of both plates adjacent to the plate boundary or oblique subduction of the oceanic plate; the latter has been the...
A simultaneous inversion for velocity and attenuation structure using multiple seismic attributes has been applied to refraction data from the 1986 GLIMPCE Lake Superior experiment. The seismic attributes considered include envelope amplitude, instantaneous frequency, and travel time of first arrival data. Instantaneous frequency is converted to t* using a matching...
The temporal and spatial variability of crescentic sandbars is analyzed with hourly
long-term (months) video observations collected at four barred sites and are qualitatively
compared to the temporal and spatial variability predicted by hypotheses underpinning
existing approaches and models for crescentic bar formation (edge-wave template model,
linear stability analysis, and...
The nonlinear dynamics of unstable alongshore currents in the nearshore
surf zone over variable barred beach topography are studied using numerical
experiments. These experiments extend the recent studies of Allen et al. [1996]
and Slnn et al. [1998], which utilized alongshore uniform beach topographies by
including sinusoidal alongshore variation to...
The nonlinear dynamics of finite amplitude shear instabilities of
alongshore currents in the nearshore surf zone over barred beach topography are
studied using numerical experiments. These experiments extend the recent study
of Allen et al. [1996], which utilized plane beach (constant slope) topography by
including shore-parallel sandbars. The model involves...
A study of swash zone sediment transport was conducted at Gleneden
Beach, Oregon during February 25-28, 1994. The data collected included suspended
sediment concentration (SSC), sea surface elevation, and velocity (initially 4 and 8
cm above the bed) at three cross-shore locations within the swash zone spanning high
tides. Ensemble...
Runup kinematics on a gently sloping natural beach are examined with detailed measurements from video images, resistance wires deployed at five elevations (between 5 and 25 cm) above and parallel to the beach face, and pressure sensors located in the inner surf zone. As suggested in a previous study comparing...
We present an optical method (optical current meter) to measure the longshore
component of nearshore surface currents by measuring the alongshore drift of persistent
sea foam in the surf zone. The method uses short time series of video data collected from
an alongshore array of pixels. These space-time data are...
Because of highly dissipative conditions and strong alongshore gradients in foreshore
beach morphology, wave run-up data collected along the central Oregon coast during
February 1996 stand in contrast to run-up data currently available in the literature. During
a single data run lasting approximately 90 min, the significant vertical run-up elevation...
Sandbars are ubiquitous, yet not well understood
beach features that change their position and shape in
response to changing wave conditions. We propose and test
a simple empirical model consisting of two coupled linear
differential equations that represents bar dynamics in terms
of wave forcing and two other state variables:...
Four years of daily time exposure images from an embayed beach were examined to
study the spacing, persistence, and location preferences of rips in a natural rip channel
system. A total of 5271 rip channels was observed on 782 days. Occurrence statistics
showed no evidence of the preferred location pattern...
Alongshore-separated time series of natural swash motions were obtained over a range of environmental conditions using a video technique. Although the frequency spectra and normalized wavenumber spectra for these motions were particularly bland, wavenumber-frequency spectra of these data showed clear partitions of infragravity band energy levels associated with various wave...
Time and length scales of beach variability have been quantified using 16 years
of beach surveys sampled at the Army Corps of Engineers' Field Research Facility,
located on the U.S. Atlantic coast. Between 50% and 90% of the bathymetric variability at
this site was explained by alongshore-uniform response over the...
Field observations of turbulence and sediment suspension in the nearshore wave bottom boundary layer obtained during the Duck94 field experiment on the North Caroline coast showed the generation of near-bed turbulence to be highly intermittent. The intermittent nature of the flow was examined by applying homogeneous isotropic turbulence laws over...
Recently, models for the onshore migration of nearshore sandbars were improved by including an empirical acceleration term in the sediment transport formulation (Hoefel and Elgar, 2003). Here, field observations of the fluid-sediment interface suggest that the success of this empirical parameter may result from unsteady forcing of sediment beds by...
The path of the Antarctic Polar Front (PF) is mapped using satellite sea surface temperature data from the NOAA/NASA Pathfinder program. The mean path and variability of the PF are strongly influenced by bathymetry. Meandering intensity is weaker where the bathymetry is steeply sloped and increases in areas where the...
As the Galápagos hot spot is approached from the west along the Galápagos Spreading Center there are systematic increases in crustal thickness and in the K/Ti, Nb/Zr, ³He/⁴He, H₂O, and Na₂O content of lavas recovered from the spreading axis. These increases correlate with progressive transitions from rift valley to axial...
Helium isotopes are a robust geochemical tracer of a primordial mantle component in hot spot volcanism. The high ³He/⁴He (up to 35 RA, where RA is the atmospheric ³He/⁴He ratio of 1.39 X 10¯⁶) of some Hawaiian Island volcanism is perhaps the classic example. New results for picrites and basalts...
Hot spot–mid-ocean ridge interactions cause many of the largest structural and chemical anomalies in Earth’s ocean basins. Correlated geophysical and geochemical anomalies are widely explained by mantle plumes that deliver hot and compositionally distinct material toward and along mid-ocean ridges. Compositional anomalies are seen in trace element and isotope ratios,...
The Amsterdam-St. Paul Plateau is bisected by the intermediate-rate spreading Southeast Indian Ridge, and numerous geophysical and tectonic anomalies arise from the interactions of the Amsterdam-St. Paul hotspot and the spreading center. The plate boundary geometry on the hotspot platform evolves rapidly (on timescales <1 Myr), off-axis volcanism is abundant,...
Basalts from the four southernmost segments of the subducting Chile Ridge (numbered 1-4 stepping away from the trench) display large variations in Sr, Nd, Pb, and He isotope and trace element compositions. Klein and Karsten [1995] showed that segments 1 and 3 display clear trace element evidence for recycled material...
This article presents the results of an exploratory study asking faculty in the first-year writing
program and instruction librarians about their research process focusing on results specifically
related to serendipity. Steps to prepare for serendipity are highlighted as well as a model for
incorporating serendipity into a first-year writing course.
We conduct modeling studies of the coastal circulation off northern California in the vicinity of the Eel River (40.6 degreesN, the site of the 1995-2000 Strata Formation on Margins (STRATAFORM) marine geology observational program) using a series of nested hydrostatic primitive equation models to aid in the understanding of the...
The finite amplitude nonlinear behavior of the coastal transition zone (CTZ) jet, assumed to be governed by quasi-geostrophic dynamics, is studied utilizing numerical experiments in an idealized geometry. Finite difference solutions to initial value problems are obtained for a stratified, six-layer fluid in a periodic, flat bottom, f plane channel....
We study the statistical properties of the coastal wind field along the west coast of North America for
two summers. 1981 and 1982 Coastal Ocean Dynamics Experiments 1 and 2, respectively), and the
Intervening winter using measured winds and geostrophic winds calculated from Fleet Numerical Oceanography
Center atmospheric pressure analyses....
The response of alongshore currents V over the continental shelf and of coastal sea level ζ along the
Pacific coast of North America to atmospheric forcing on large alongshore scales (100-2000 km) during
May-July 1981 (Coastal Ocean Dynamics Experiment (CODE) 1) and May-July 1982 (CODE 2) has
been studied using...
The dynamics of the coastal transition zone off Northern California during late May and early June 1987 art
examined through assimilation modeling studies. A regional baroclinic quasi-geostrophic model is driven by the
data through initial and boundary conditions. These initial and boundary conditions are specified by objective
analysis of hydrographic...
The Phoenix mission, launched on 4 August 2007, landed in the far northern
plains of Mars on 25 May 2008. In order to prepare for the landing events and the
90-sol mission, a significant amount of work has gone into characterizing the atmospheric
environment at this location on Mars for...
Mars Pathfinder successfully landed at Ares Vallis on July 4, 1997, deployed and navigated
a small rover about l00 m clockwise around the lander, and collected data from three science
instruments and ten technology experiments. The mission operated for three months and returned
2.3 Gbits of data, including over 16,500...
During the upwelling season in central California, northwesterly winds along the
coast produce a strong upwelling jet that originates at Point Año Nuevo and flows
southward across the mouth of Monterey Bay. A convergent front with a mean
temperature change of 3.77 ± 0.29°C develops between the warm interior waters...
A fluorescent dye tracer was injected into the
pycnocline on the Oregon shelf at a depth of 9–10 m. It
spread rapidly cross-shelf as two distinct layers, one above
the other in the water column, split by interleaving dye-free
water. The vertical scale of these layers, and associated
density steps,...
What is the uncertainty of climate-carbon cycle projections in response to anthropogenic greenhouse gas emissions and how can we reduce this uncertainty? We address this question by quantifying the ability of available ocean tracer observations to constrain the values of diapycnal diffusivity in the pelagic ocean (Kv), a key uncertain...
We simulated the erosion and accretion of a natural beach using a wave-resolving
eddy-diffusive model of water and suspended sediment motion in the bottom boundary
layer. Nonlinear advection was included in this one-dimensional (vertical profile) model
by assuming that waves propagated almost without change of form. Flows were forced by...
The sensitivity of model-produced time-dependent wind-driven circulation on the
continental shelf to the turbulent closure scheme employed is studied with a twodimensional
approximation (variations across-shelf and in depth) using the Princeton
Ocean Model. The level 2.5 Mellor-Yamada closure (MY), k-ε closure, and K-Profile
Parameterization schemes are used to evaluate the...
A two-part modeling study of the wind-forced flow on the continental shelf off
northern California in the region (37°–40°N) of the Coastal Ocean Dynamics Experiment
(CODE) is pursued. This paper involves a process-oriented study with idealized wind
stress forcing. Gan and Allen [2002] involves forcing with observed winds and heat...
Knowledge of the physical oceanography of continental shelves has increased tremendously in recent years, primarily as a result of new current and hydrographic measurements made in locations where no comparable measurements existed previously. In general, observations from geographically distinct continental shelves have shown that the nature of the flow may...
The linear stability of a coastal transition zone (CTZ) jet is analyzed using a six-layer quasi-geostrophic model with observed basic state velocity profiles. The velocity profiles are obtained from objectively analyzed hydrographic and acoustic doppler data from the 1987 CTZ pilot experiment. Along-jet perturbation wave-lengths of 260-265 km are found...
An Eulerian analysis for wave forcing of three-dimensional (3D) wave-averaged mean
circulation in the surf zone is presented. The objective is to develop a dynamically
consistent formulation for applications in a 3D primitive equation model. The analysis is
carried out for the case of shallow-water linear waves interacting with wave-averaged...
The Gulf of Aqaba, northern Red Sea, is an ideal natural laboratory for studying the
impact of atmospheric dry deposition of iron to the ocean surface. We have measured
atmospheric iron deposition weekly for 18 months, and dissolved and total dissolvable
iron concentrations in the stratified summer (August) and well-mixed...
We study the stability properties of, and the phase error present in, a finite element scheme for Maxwell’s
equations coupled with a Debye or Lorentz polarization model. In one dimension we consider a second order
formulation for the electric field with an ordinary differential equation for the electric polarization added...
Advective skew dispersion is a natural Markov process defined ned
by a di ffusion with drift across an interface of jump discontinuity in
a piecewise constant diff usion coeffcient. In the absence of drift this
process may be represented as a function of -skew Brownian motion
for a uniquely determined...
Sea surface temperature (SST) is measured from space by advanced very high resolution radiometer (AVHRR), scanning multichannel microwave radiometer (SMMR), high resolution infrared sounder (HIRS) and VISSR atmospheric sounder (VAS). Typical accuraces have been reported from 0.5°C regionally to 2.0°C on a global basis. To evaluate the accuracy of the...
A mean reference surface and time-dependent orbit errors are estimated simultaneously for
each exact-repeat ground track from the first two years of Geosat sea level estimates based on
the Goddard Earth model (GEM)-T2 orbits. Motivated by orbit theory and empirical analysis of
Geosat data, the time-dependent orbit errors are modeled...
Tide gauges are designed to measure changes in water level relative to land. However, vertical motions of the earth's crust manifest themselves as apparent water level changes in tide gauge records. These crustally induced changes are often small in amplitude relative to the wide range of oceanic processes which affect...
Currents and winds measured over the continental shelf and upper continental slope during the first
half of 1984 are analyzed to determine the character of the flow off central California (Point Conception
to San Francisco). The mean flow was poleward from Point Conception to Point Sur, in opposition to
the...
A previous altimeter wind speed retrieval algorithm was developed on the basis of wind speeds in the the limited range from about 4 to 14 ms¯¹. In this paper, we use a new approach which gives a wind speed model function applicable over the range 0 to 21 ms¯¹. The...
The variability of sea level and surface geostrophic currents in the Southern Ocean is investigated from the first 26 months of unclassified Geosat altimeter data (November 1986 to December 1988). Because of problems unique to Geosat, it has been necessary to develop new techniques for analyzing the height data. These...
A new method is developed for studying large-scale temporal variability of ocean currents from
satellite altimetric sea level measurements at intersections (crossovers) of ascending and descending orbit
ground tracks. Using this method, sea level time series can be constructed from crossover sea level
differences in small sample areas where altimetric...
A Geosat altimeter wind speed algorithm is derived by cross-calibrating Geosat and Seasat
altimeter estimates of the normalized radar cross section σ₀ and modifying an existing Seasat
altimeter wind speed model function to obtain a model function appropriate for Geosat observations.
It is argued that the σ₀ distribution measured by...
The sea-state bias in Geosat altimeter range measurements expressed as a percentage of significant
wave height (SWH) is examined as a function of SWH. The bias is shown to be approximately
a fixed -3.5% of SWH for SWH smaller than about 4 m. For larger SWH, the bias decreases in...
Seasonal variability of alongshore geostrophic velocity relative to 500 dbar is examined from 23 years
of hydrographic data along two sections off central California (one off Point Sur and the other off Point
Conception). The seasonal cycles are determined by least square fits of the gappy data records to
harmonics...
The scheduled February 1985 launch of a radar altimeter aboard the U.S. Navy satellite Geosat has
motivated an in-depth investigation of wind speed retrieval from satellite altimeters. The accuracy of sea
surface wind speed estimated by the Seasat altimeter is examined by comparison with wind speed
estimated by the Seasat...
Research has found an upward trend in impulse buying in general, and impulse buying is frequently foreseen among mall shoppers. Impulse purchases account for over $4 billion in annual sales in the U.S. (Mogelonsky, 1998). Retailers have found that over 50 percent of mall shoppers purchase on impulse (Nichols et...
In the North Atlantic, cold, relatively salty water sinks in the icy Labrador and Greenland seas, forming North Atlantic Deep Water (NADW). This circulates through the global ocean, driving ocean overturning and global heat transport and, thus, impacting global climate. As one of the most climatically sensitive regions on Earth,...
The southern portion of the Kodiak-Bowie seamonnt chain in the southeastern
Gulf of Alaska presents a unique opportunity to investigate loading on young oceanic
lithosphere. Oceanic lithosphere younger than 25 Ma is loaded both by sediments in a deep
offshore trough and by seamount 100-200 km offshore. Free-air gravity anomaly...
There has been a renaissance of interest in marine heat flow in the past 10–15 years, coinciding with fundamental achievements in understanding the Earth’s thermal state and quantifying the dynamics and impacts of material and energy fluxes within and between the lithosphere and hydrosphere. At the same time, technical capabilities...
Temperature profiles from boreholes on the Colorado Plateau of southeastern Utah
have been examined for evidence of climate change. Because these boreholes penetrate layered
sedimentary rocks with different thermal conductivities, Bullard plots (Temperature versus
integrated thermal resistance) are used to estimate background heat flow and surface temperature
intercepts. Reduced temperatures,...
Long-period ground surface temperature variations contained in borehole
temperature-depth profiles form a complementary climate change record to high-frequency,
but noisy surface air temperature (SAT) records at weather stations. We illustrate the
benefits of jointly analyzing geothermal and meteorological data for two regions in Utah
where both high-quality temperature-depth measurements and...
We perform numerical simulations of buoyancy-driven, pore fluid flow in the
Hawaiian archipelagic apron and underlying oceanic crust in order to determine the extent to
which heat redistributed by such flow might cause conductive heat flow measurements to
underrepresent the true mantle heat flux. We also seek an understanding of...
We present two profiles of collocated single-channel seismic reflection and heat flow determinations across Hawaiian flexural moat: one north of Oahu and the other north of Maro Reef. Seismic reflection data are used as an aid in determining depth to basement and interpreting moat stratigraphy. Moat sediments are locally up...
We present the first comprehensive investigation of the concentrations, fluxes and sources of aerosol trace elements over the Gulf of Aqaba. We found that the mean atmospheric concentrations of crustally derived elements such as Al, Fe and Mn (1081, 683, and 16.7 ng m¯³) are about 2–3 times higher than...
The relationship between iron and nitrate concentrations was examined off the coast of
Oregon during the upwelling season. Surface Fe and N (nitrate + nitrite) concentrations
measured underway by flow injection analysis ranged from <0.3 to 20 nmol L¯¹ and <0.1 to
30 mmol L¯¹, respectively. Total dissolvable Fe concentrations,...
The biosonar system of dolphins and porpoises has been studied for about 5 decades and much has
been learned [Au,W.W. L. )1993). The Sonar of Dolphins (Springer, New York)]. Most experiments
have involved human-made targets; little is known about odontocetes’ echolocation of prey. To
address this issue, acoustic backscatter from...
Bench scale column studies were used to examine the partitioning of microorganisms between groundwater
and a geologic medium and to examine the effect of hydrogeology (i.e., porous- versus fracture-flow) on
organism partitioning. Replicated columns were constructed with intact basalt core segments that contained
natural fractures and with the same basalt...
PCR amplification, restriction fragment length polymorphism, and phylogenetic analysis of oxygenase genes
were used for the characterization of in situ methane- and ammonia-oxidizing bacteria from free-living and
attached communities in the Eastern Snake River Plain aquifer. The following three methane monooxygenase
(MMO) PCR primer sets were used: A189-A682, which amplifies...
Methane hydrate found in marine sediments is thought to contain gigaton quantities of methane and is
considered an important potential fuel source and climate-forcing agent. Much of the methane in hydrates is
biogenic, so models that predict the presence and distribution of hydrates require accurate rates of in situ
methanogenesis....
We isolated a methanogen from deep in the sediments of the Nankai Trough off the eastern coast of Japan.
At the sampling site, the water was 950 m deep and the sediment core was collected at 247 m below the sediment
surface. The isolated methanogen was named Nankai-1. Cells of...
Genomic libraries derived from environmental DNA (metagenomic libraries) are useful for characterizing
uncultured microorganisms. However, conventional library-screening techniques permit characterization of
relatively few environmental clones. Here we describe a novel approach for characterization of a metagenomic
library by hybridizing the library with DNA from a set of groundwater isolates, reference...
Surface heat flux components are estimated at a midshelf site over the northern California shelf using moored measurements from the 1981-1982 Coastal Ocean Dynamics Experiment (CODE) and the 1988-1989 Shelf Mixed Layer Experiment (SMILE). Time series of estimated fluxes extend from early winter through summer upwelling conditions, allowing examination of...
Heat and salt balances are estimated over the northern California shelf from
early December 1988 through late February 1989 (winter) and from early March
through early May 1989 (spring) from moored meteorological and oceanographic time
series taken in 93 m of water 6.3 km from the coast. We find a...
Marine renewable energy promises to assist in the effort to reduce
carbon emissions worldwide. As with any large-scale development in the marine
environment, however, it comes with uncertainty about potential environmental
impacts, most of which have not been adequately evaluated—in part because many of
the devices have yet to be...
Realistic hindcast of the Columbia River estuarine-plume-shelf circulation in summer
2004 using the Regional Ocean Modeling System nested within the Navy Coastal Ocean
Model (NCOM) is quantitatively evaluated with an extensive set of observations. The
model has about equal skill at tidal and subtidal properties. Tidal circulation and water
properties...
Argos-tracked drifters are used to study the near-surface circulation in
the Santa Barbara Channel. The mean consists of a cyclonic cell in the western
Santa Barbara Channel with weaker flow in the eastern Channel. Drifter mean
velocities agree well with record means from near-surface current meters. At
the eastern entrance...
The near-surface circulation in the Santa Barbara Channel and off the coast of central and southern California is described based on 20 releases of drifters
drogued 1 m beneath the surface from 12 sites within the channel at bimonthly
intervals. This description includes small-scale features of the circulation which are...
In north and central California, equatorward winds drive equatorward flows
and the upwelling of cold dense water over the shelf during the midspring and summer
upwelling season. When the winds temporarily weaken, the upwelling flows between
Point Reyes and Point Arena ‘‘relax,’’ becoming strongly poleward over the shelf.
Analytical and...
Along- and cross-shelf correlation scales of subtidal cross-shelf (u) and alongshelf
(ν) velocities are estimated using moored records from several field programs over
the northern California shelf. Over record lengths of 4-6 months, along-shelf correlation
scales of ν are greater than maximum mooring separations (60 km). In the cross-shelf
direction...