Recent Publications

Weekly Highlighted Publication


Forensic investigation of a probable meteor sighting using USArray acoustic data
Impact: "This event demonstrates the utility of the instrumental data openly available to public, private, and academic institutions on USArray TA stations and its capabilities to assist in informing the general public regarding events unrelated to the stations’ primarily seismological focus. The presence of the TA stations in the region allowed a relatively detailed explanation of an event of great public interest to be provided from authoritative sources, in which speculation and conjecture may otherwise be rampant."

Search Recent Publications

  • Highlighted Publication
    Abstract Summary:

    Global climate and the concentration of atmospheric carbon dioxide (CO2) are correlated over recent glacial cycles(1,2). The combination of processes responsible for a rise in atmospheric CO2 at the last glacial termination(1,3) (23,000 to 9,000 years ago), however, remains uncertain(1-3). Establishing the timing and rate of CO2 changes in the past provides critical insight into the mechanisms that influence the carbon cycle and helps put...

  • Highlighted Publication The comparison between waveforms processed using a 2-D starting model and 1-D PREM
    Abstract Summary:

    A new method is developed to measure Rayleigh- and Love-wave phase velocities globally using a cluster analysis technique. This method clusters similar waveforms recorded at different stations from a single event and allows users to make measurements on hundreds of waveforms, which are filtered at a series of frequency ranges, at the same time. It also requires minimal amount of user interaction and allows easy assessment of the data quality...

  • Highlighted Publication Lumpy stratocumulus clouds. Photo courtesy of NOAA.
    Abstract Summary:

    Over the tropical North Atlantic, during boreal summer, both stratocumulus clouds and mineral aerosols are ubiquitous. We find that low cloud fraction increases in response to high mineral aerosols loadings by 3% to 10% over much of the tropical North Atlantic, in International Satellite Cloud Climatology Project (ISSCP) and Pathfinder Atmosphere Extended (PATMOSx) observations. Using the single-column mode of the Community Earth System Model...

  • Highlighted Publication
    Abstract Summary:

    Inspired by the developments of synthetic biology and the need for improved genetic tools to exploit cyanobacteria for the production of renewable bio-products, we developed a versatile platform for the construction of broad-host-range vector systems. This platform includes the following features: (i) an efficient assembly strategy in which modules released from 3 to 4 donor plasmids or produced by polymerase chain reaction are assembled by...

  • Highlighted Publication
    Abstract Summary:

    The addition of atmospheric acoustic sensors as part of the transportable stations of USArray has allowed a detailed explanation to be provided to the public and media regarding a significant meteor event observed over the region of Montreal, Canada. The meteor, obscured by cloudy conditions, was perceived by residents only as a bright blue flash followed subsequently by loud thunderous sounds and rumbling. The event quickly became a source...

  • Highlighted Publication Dunaliella
    Abstract Summary:

    According to modern oceanographic perspectives that emphasize microbial pathways, phagotrophic protists comprise one to several levels of intermediate consumers between phytoplankton and larger metazooplankton (copepods and krill). However, recent attempts to quantify pelagic trophic structure in the open ocean using nitrogen stable isotope techniques have brought into question whether such measurements adequately account for protistan...

  • Highlighted Publication Selection differential equation over image of fish
    Abstract Summary:

    An individual's phenotype will usually influence its probability of survival. However, when evaluating the dynamics of populations, the role of selective mortality is not always clear. Not all mortality is selective, patterns of selective mortality may vary, and it is often unknown how selective mortality compares or interacts with other sources of mortality. As a result, there is seldom a clear expectation for how changes in the phenotypic...

  • Highlighted Publication Central Pacific comparison of mass accumulation rates for different trophic groups
    Abstract Summary:

    Open-ocean ecosystems experienced profound disruptions to biodiversity and ecological structure during the Cretaceous/Palaeogene mass extinction about 66 million years ago(1-3). It has been suggested that during this mass extinction, a collapse of phytoplankton production rippled up the food chain, causing the wholesale loss of consumers and top predators(3-5). Pelagic fish represent a key trophic link between primary producers and top...

  • Highlighted Publication Spatio-temporal mapping of transporters.
    Abstract Summary:

    One quarter of eukaryotic genes encode membrane proteins. These include nearly 1,000 transporters that translocate nutrients, signaling molecules, and xenobiotics across membranes. While it is well appreciated that membrane transport is critical for development, the specific roles of many transporters have remained cryptic, in part because of their abundance and the diversity of their substrates. Multidrug resistance ATP-binding cassette (ABC...

  • Highlighted Publication NASA Visible Earth image of African dust storm
    Evan AT, Flamant C., Fiedler S., Doherty O..  2014.  An analysis of aeolian dust in climate models. Geophysical Research Letters. 41:5996-6001.
    Abstract Summary:

    Aeolian dust is a key aspect of the climate system. Dust can modify the Earth's energy budget, provide long-range transport of nutrients, and influence land surface processes via erosion. Consequently, effective modeling of the climate system, particularly at regional scales, requires a reasonably accurate representation of dust emission, transport, and deposition. Here we evaluate African dust in 23 state-of-the-art global climate models...

  • Highlighted Publication Aerial view of PII-B-1 showing the approximate deployment locations of GPS stations
    Abstract Summary:

    We study a mechanism of iceberg breakup that may act together with the recognized melt and wave-induced decay processes. Our proposal is based on observations from a recent field experiment on a large ice island in Baffin Bay, East Canada. We observed that successive collapses of the overburden from above an unsupported wavecut at the iceberg waterline created a submerged foot fringing the berg. The buoyancy stresses induced by such a foot...

  • Highlighted Publication Mussel larvae
    Abstract Summary:

    As the ocean undergoes acidification, marine organisms will become increasingly exposed to reduced pH, yet variability in many coastal settings complicates our ability to accurately estimate pH exposure for those organisms that are difficult to track. Here we present shell-based geochemical proxies that reflect pH exposure from laboratory and field settings in larvae of the mussels Mytilus californianus and M. galloprovincialis. Laboratory-...

  • Highlighted Publication Bacterial growth, cell C, and DOC consumption of three treatments
    Pedler BE, Aluwihare LI, Azam F.  2014.  Single bacterial strain capable of significant contribution to carbon cycling in the surface ocean. Proceedings of the National Academy of Sciences of the United States of America. 111:7202-7207.
    Abstract Summary:

    Marine dissolved organic carbon (DOC) encompasses one of the largest reservoirs of carbon on Earth. Heterotrophic bacteria are the primary biotic force regulating the fate of this material, yet the capacity of individual strains to significantly contribute to carbon cycling is unknown. Here we quantified the ability of a single Alteromonas strain [Alteromonas sp. strain Scripps Institution of Oceanography (AltSIO)] to drawdown ambient DOC in...

  • Highlighted Publication
    Abstract Summary:

    We present a time-dependent slip model of 12 slow slip events (SSEs) occurring in the Hikurangi margin of New Zealand during 2010 and 2011. This model is obtained by inverting daily GPS solutions from GeoNet's continuous GPS network on the North Island and northern South Island. We compare the properties of these SSEs to observations in Japan, Cascadia, and Mexico and find that Hikurangi SSEs have comparatively large amounts of slip (up to 27...

  • Highlighted Publication A likelihood analysis predicts three independent acquisition events for the cya pathway.
    Ziemert N., Lechner A., Wietz M., Millan-Aguinaga N., Chavarria K.L, Jensen PR.  2014.  Diversity and evolution of secondary metabolism in the marine actinomycete genus Salinispora. Proceedings of the National Academy of Sciences of the United States of America. 111:E1130-E1139.
    Abstract Summary:

    Access to genome sequence data has challenged traditional natural product discovery paradigms by revealing that the products of most bacterial biosynthetic pathways have yet to be discovered. Despite the insight afforded by this technology, little is known about the diversity and distributions of natural product biosynthetic pathways among bacteria and how they evolve to generate structural diversity. Here we analyze genome sequence data...

  • Highlighted Publication Unfiltered NO3, DIC, and O2 dynamics at CCE-2 during 2011
    Abstract Summary:

    We use autonomous nitrate (NO3-), oxygen (O-2), and dissolved inorganic carbon (DIC) observations to examine the relationship between ratios of C:N:O at an upwelling site in the Southern California Current System. Mean ratios and 95% confidence intervals observed by sensors over 8 months were NO3-:O-2=-0.110.002, NO3-:DIC=0.140.001, and DIC:O-2=-0.830.01, in good agreement with Redfield ratios. Variability in the ratios on the weekly time...

  • Highlighted Publication
    Abstract Summary:

    Harmful algal blooms (HABs) pose a significant threat to human and marine organism health, and negatively impact coastal economies around the world. An improved understanding of HAB formation and transport is required to improve forecasting skill. A realistic numerical simulation of the US Pacific Northwest region is used to investigate transport pathways from known HAB formation hot spots, specifically for Pseudo-nitzschia (Pn), to the coast...

  • Highlighted Publication Annual mean OLR (W/m2) for a the twentieth century forcing
    Abstract Summary:

    The change in Madden-Julian oscillation (MJO) amplitude and variance in response to anthropogenic climate change is assessed in the 1A degrees nominal resolution community climate system model, version 4 (CCSM4), which has a reasonable representation of the MJO characteristics both dynamically and statistically. The twentieth century CCSM4 run is compared with the warmest twenty-first century projection (representative concentration pathway 8...

  • Highlighted Publication Example of objectively mapped fields (vectors and line contours) and dimensional errors
    Abstract Summary:

    Current and pressure-recording inverted echo sounders (CPIES) were deployed in an eddy-resolving local dynamics array (LDA) in the eddy-rich polar frontal zone (PFZ) in Drake Passage as part of the cDrake experiment. Methods are described for calculating barotropic and baroclinic geostrophic streamfunction and its first, second, and third derivatives by objective mapping of current, pressure, or geopotential height anomaly data from a two-...

  • Highlighted Publication ´╗┐´╗┐´╗┐Stacked, variance-preserving power spectral density estimates of (a) alongshore velocity, (b) cross-shore velocity
    Abstract Summary:

    At a coastal upwelling zone near 30 degrees S latitude, diurnal wind variability forced energetic inertial current oscillations (>0.5 m s(-1)) that materially influenced phytoplankton distribution and productivity. The diurnal-inertial band resonance found at this latitude in the Benguela upwelling system allowed rapid, efficient transfer of energy from counterclockwise rotating winds into anticyclonic currents upon the onset of the...

  • Highlighted Publication (A) Sea ice concentration and (B) CERES clear-sky albedo
    Pistone K., Eisenman I, Ramanathan V.  2014.  Observational determination of albedo decrease caused by vanishing Arctic sea ice. Proceedings of the National Academy of Sciences of the United States of America. 111:3322-3326.
    Abstract Summary:

    The decline of Arctic sea ice has been documented in over 30 y of satellite passive microwave observations. The resulting darkening of the Arctic and its amplification of global warming was hypothesized almost 50 y ago but has yet to be verified with direct observations. This study uses satellite radiation budget measurements along with satellite microwave sea ice data to document the Arctic-wide decrease in planetary albedo and its...

  • Highlighted Publication         Power spectra (20 Hz) of the difference in along track height between passes retracked with the 3-parameter model and the 2-parameter model after smoothing
    Abstract Summary:

    Improving the accuracy of the marine gravity field requires both improved altimeter range precision and dense track coverage. After a hiatus of more than 15 yr, a wealth of suitable data is now available from the CryoSat-2, Envisat and Jason-1 satellites. The range precision of these data is significantly improved with respect to the conventional techniques used in operational oceanography by retracking the altimeter waveforms using an...

  • Highlighted Publication Map of western United States showing atmospheric river impacts.
    Abstract Summary:

    Narrow corridors of water vapor transport known as atmospheric rivers (ARs) contribute to extreme precipitation and flooding along the West Coast of the United States, but knowledge of their influence over the interior is limited. Here, the authors use Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data, Climate Prediction Center (CPC) precipitation analyses, and Snowpack Telemetry (SNOTEL)...

  • Highlighted Publication
    Abstract Summary:

    We use CryoSat-2 interferometric satellite radar altimetry over the Mercer and Whillans ice streams, West Antarctica, to derive surface elevation changes due to subglacial lake activity at monthly resolution for the period 2010 to 2013. We validate CryoSat-2 elevation measurements, trends, and spatial patterns of change using satellite image differencing and in situ vertical movement from Global Positioning System (GPS) data. Two subglacial...

  • Highlighted Publication Spatial pattern of the first two EOFs of MADA and NADA.
    Abstract Summary:

    The amplitude of El Nil-ID-Southern Oscillation (ENSO) varies substantially at each phase of its evolution, affecting the timing and patterns of atmospheric teleconnections around the globe. Instrumental records are too short to capture the full behavior of ENSO variability. Here we use the well-validated Monsoon Asia Drought Atlas (MADA) and North America Drought Atlas (NADA) for the past 700 years, and show that tree-ring records from...

  • Highlighted Publication Horizontal snapshot of modeled sea surface elevation and perturbation vorticity
    Feddersen F.  2014.  The generation of surfzone eddies in a strong alongshore current. Journal of Physical Oceanography. 44:600-617.
    Abstract Summary:

    The surfzone contains energetic two-dimensional horizontal eddies with length scale larger than the water depth. Yet, the dominant eddy generation mechanism is not understood. The wave-resolving model funwaveC is used to simulate surfzone eddies in four case examples, from the SandyDuck field experiment, that had alongshore uniform bathymetry. The funwaveC model is initialized with the observed bathymetry and the incident wave field in 8-m...

  • Highlighted Publication Predicted global distribution of four community metrics
    Abstract Summary:

    In line with global targets agreed under the Convention on Biological Diversity, the number of marine protected areas (MPAs) is increasing rapidly, yet socio-economic benefits generated by MPAs remain difficult to predict and under debate(1,2). MPAs often fail to reach their full potential as a consequence of factors such as illegal harvesting, regulations that legally allow detrimental harvesting, or emigration of animals outside boundaries...

  • Highlighted Publication Maximum correlation between SLA and INSTANT transport
    Sprintall J, Revelard A..  2014.  The Indonesian Throughflow response to Indo-Pacific climate variability. Journal of Geophysical Research-Oceans. 119:1161-1175.
    Abstract Summary:

    The Indonesian Throughflow (ITF) is the only open pathway for interocean exchange between the Pacific and Indian Ocean basins at tropical latitudes. A proxy time series of ITF transport variability is developed using remotely sensed altimeter data. The focus is on the three outflow passages of Lombok, Ombai, and Timor that collectively transport the entire ITF into the Indian Ocean, and where direct velocity measurements are available to help...

  • Highlighted Publication A school of yellow fin tuna.
    Abstract Summary:

    Spatial variability can confound accurate estimates of catch per unit effort (CPUE), especially in highly migratory species. The incorporation of spatial structure into fishery stock assessment models should ultimately improve forecasts of stock biomass. Here, we describe a nonlinear time series model for producing spatially explicit forecasts of CPUE that does not require ancillary environmental or demographic data, or specification of a...

  • Highlighted Publication Number of open water days of each season.
    Abstract Summary:

    The climate-driven collapses of the Larsen A and B ice shelves have opened up new regions of the coastal Antarctic to the influence of sea ice resulting in increases in seasonal primary production. In this study, passive microwave remote sensing of sea ice concentration and satellite imagery of ocean color are employed to quantify the magnitude of and variability in open water area and net primary productivity (NPP) in the Larsen embayments...

  • Highlighted Publication Green bloom spreading into blue water surrounded by white ice
    Abstract Summary:

    We examined the within-day variability in seawater optical properties and biogeochemical constituents for a high-latitude location in the Ross Sea, Antarctica, during development of the annual spring phytoplankton bloom. Measurements of particulate organic carbon concentration (POC), chlorophyll-a concentration (Chl), and particle size distribution were conducted at 4-6 hour intervals in parallel with determinations of the spectral absorption...

  • Highlighted Publication
    Abstract Summary:

    Iceberg calving from ice shelves accounts for nearly half of the mass loss from the Antarctic Ice Sheet, yet our understanding of this process is limited. The precursor to iceberg calving is large through-cutting fractures, called rifts, that can propagate for decades after they have initiated until they become iceberg detachment boundaries. To improve our knowledge of rift propagation, we monitored the lengths of 78 rifts in 13 Antarctic ice...

  • Highlighted Publication Illustration of three phases of geodynamo generation:
    Abstract Summary:

    Observations of Earth's magnetic field extending back to 3.45 billion years ago indicate that generation by a core dynamo must be sustained over most of Earth's history. However, recent estimates of thermal and electrical conductivity of liquid iron at core conditions from mineral physics experiments indicate that adiabatic heat flux is approximately 15 TW, nearly three times larger than previously thought, exacerbating difficulties for...

  • Highlighted Publication Basal drag reconstruction for the Antarctic ice sheet
    Abstract Summary:

    The recovery of a 1.5 million yr long ice core from Antarctica represents a keystone of our understanding of Quaternary climate, the progression of glaciation over this time period and the role of greenhouse gas cycles in this progression. Here we tackle the question of where such ice may still be found in the Antarctic ice sheet. We can show that such old ice is most likely to exist in the plateau area of the East Antarctic ice sheet (EAIS)...

  • Highlighted Publication Figure 2: Mean basal mass-loss rates of Antarctic ice shelves
    Abstract Summary:

    Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year(1,2). More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front(3-5). So far, however, no study has reliably quantified the calving flux and the basal mass balance (the balance between...

  • Highlighted Publication Standard deviation of ERSST and MME along the equator.
    Abstract Summary:

    This study evaluates the simulation of the Indian Ocean Basin (IOB) mode and relevant physical processes in models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Historical runs from 20 CMIP5 models are available for the analysis. They reproduce the IOB mode and its close relationship to El Nino-Southern Oscillation (ENSO). Half of the models capture key IOB processes: a downwelling oceanic Rossby wave in the southern...

  • Highlighted Publication Raindrops
    Abstract Summary:

    Climate model simulations disagree on whether future precipitation will increase or decrease over California, which has impeded efforts to anticipate and adapt to human-induced climate change. This disagreement is explored in terms of daily precipitation frequency and intensity. It is found that divergent model projections of changes in the incidence of rare heavy (>60 mm day(-1)) daily precipitation events explain much of the model...

  • Highlighted Publication Observed and simulated global mean surface temperature.
    Abstract Summary:

    Under present growth rates of greenhouse gas and black carbon aerosol emissions, global mean temperatures can warm by as much as 2 degrees C from pre-industrial temperatures by about 2050(1,2). Mitigation of the four short-lived climate pollutants (SLCPs), methane, tropospheric ozone, hydrofluorocarbons and black carbon, has been shown to reduce the warming trend by about 50% (refs 1,2) by 2050. Here we focus on the potential impact of this...

  • Highlighted Publication Transmitted and reflected light photomicrographs of an alteration region
    Abstract Summary:

    There are numerous indications that subseafloor basalts may currently host a huge quantity of active microbial cells and contain biosignatures of ancient life in the form of physical and chemical basalt glass alteration. Unfortunately, technological challenges prevent us from observing the formation and mineralization of these alteration features in situ, or reproducing tubular basalt alteration processes in the laboratory. Therefore,...