bluuebunny/crossref_metadata_2025 huggingface dataset:
The Post-Palin Calculus: The 2012 Republican Veepstakes
Authors: Baumgartner Jody C
Published: September 2012

In this article results are presented from a conditional logit model of vice
presidential selection that correctly predicts Mitt Romney selecting Paul Ryan as
his vice presidential running mate in 2012. The model, which correctly predicts 14
of the 20 contested major party vice presidential nominations from 1960 through
2008, suggests that media exposure, political experience, having served in the
military, age, and gender/racial/ethnic diversity are significant factors in
selecting a vice presidential candidate in the modern era.
The Broad Value of a PhD in Political Science
Authors: Murakami Michael H.
Published: September 2012

Today I am a researcher at Google and one of a handful of employees, out of a
global workforce of more than 30,000, the with a PhD in political science. But less
than two years ago, I was a tenure track professor of political science at a
research university and could barely have imagined the unusual path my professional
life would take. That path has been incredibly rewarding, as well as instructive
both of the broad value a PhD in political science (and the social sciences more
generally) and of the growing role for quantitative research outside of the academy.
I recount much of that path below, with the hope that it might prove useful for
those graduate students, post-docs, and professors who might be inclined to apply
the knowledge and skills they have acquired in unconventional professional paths of
their own.
A Troika of Fellows
Authors: Dogo Harun , Sklar David , Tausanovitch Chris
Published: September 2012

This year was an unusual one for the APSA Congressional Fellowship Program—three
fellows were placed with the same congressional office. The fact that three fellows,
each with very different backgrounds, were drawn to the Senate Finance Committee,
says something about the unique role that the committee plays in congressional
policymaking. As one of the “A”s of the four “Super-A” committees, along with
Appropriations, Armed Services, and Foreign Relations, the Senate Finance Com-mittee
is one of the committee assignments most sought after by Senators. Its vast policy
jurisdiction enables members to affect many different parts of the economy, society,
and government. In addition to Chairman Baucus, the majority membership of the
committee includes chairs of six other committees: Senators John Kerry of Foreign
Relations; Jeff Bingaman of Energy and Natural Resources; John D. Rockefeller of
Commerce, Science, and Transportation; Debbie Stabenow of Agriculture and Forestry;
Kent Conrad of Budget; and Chuck Schumer who serves both as chairman of the Rules
Committee and the Democratic Policy and Communications Center. On the minority side,
in addition to the ranking member, Senator Orrin Hatch, the panel includes three
ranking members of other committees: Senators Chuck Grassley of Judiciary, Olympia
Snowe of Small Business, and Mike Enzi of Health, Education, Labor, and Pensions.
They serve alongside with the Republican Whip Senator Jon Kyl, the Republican
Conference Chair John Thune, and the Republican Senatorial Campaign Committee
Chairman John Cornyn of Texas. This concentration of senatorial experience testifies
to the importance of the work undertaken by the Finance Committee.
2013 Conference Theme Statement
Authors: Boone Catherine , Fung Archon
Published: September 2012

As the world becomes more interdependent and its governance more complex, both
within and between nation-states, the two biggest resources for human cooperation —
persuasion and legitimate coercive power — become harder to generate across cultural
and linguistic lines and sovereign boundaries. Yet the future will require more of
these resources. To help societies meet the needs for political interactions of
increasing complexity and scale, political scientists need to understand better the
uses and abuses of both persuasion and power in varying contexts and scales. This
year's program theme encourages scholars to consider the politics of persuasion and
power, along with their many intersections.
The role of language dominance in cross-linguistic syntactic influence: A Korean child's use of null subjects in attriting English
Authors: KANG SANG-GU
Published: September 2012

While Hulk and Müller (2000) predict that the direction of cross-linguistic syntactic influence is unidirectional when the construction involves syntax–pragmatics interface and surface overlap between two languages, they explicitly rule out language dominance as a factor involved. This study questions their latter claim and argues that the syntax of the dominant language can influence that of the weaker, based on a Korean–English bilingual boy's attriting English data; Korean null subjects triggered English subject drop when his Korean became more dominant. Thus, I propose a revised model of cross-linguistic influence that accounts for both Hulk and Müller's proposal and my data.
Nanometer Scale Tomographic Investigation of Fine Scale Precipitates in a CuFeNi Granular System by Three-Dimensional Field Ion Microscopy
Authors: Cazottes Sophie , Vurpillot François , Fnidiki Abdeslem , Lemarchand Dany , Baricco Marcello , Danoix Frederic
Published: October 2012

The microstructure of Cu80Fe10Ni10(at. %) granular ribbons was investigated by means of three-dimensional field ion microscopy (3D FIM). This ribbon is composed of magnetic precipitates embedded in a nonmagnetic matrix. The magnetic precipitates have a diameter smaller than 5 nm in the as-spun state and are coherent with the matrix. No accurate characterization of such a microstructure has been performed so far. A tomographic characterization of the microstructure of melt spun and annealed Cu80Fe10Ni10ribbon was achieved with 3D FIM at the atomic scale. A precise determination of the size distribution, number density, and distance between the precipitates was carried out. The mean diameter for the precipitates is 4 nm in the as-spun state. After 2 h at 350°C, there is an increase of the size of the precipitates, while after 2 h at 400°C the mean diameter of the precipitates decreases. Those data were used as inputs in models that describe the magnetic and magnetoresistive properties of this alloy.
BETWEEN THE PROBLEMS OF PÓLYA AND TURÁN
Authors: MOSSINGHOFF MICHAEL J. , TRUDGIAN TIMOTHY S.
Published: September 2012

We investigate the behaviour of the function $L_{\alpha }(x) = \sum _{n\leq x}\lambda (n)/n^{\alpha }$, where $\lambda (n)$ is the Liouville function and $\alpha $ is a real parameter. The case where $\alpha =0$ was investigated by Pólya; the case $\alpha =1$, by Turán. The question of the existence of sign changes in both of these cases is related to the Riemann hypothesis. Using both analytic and computational methods, we investigate similar problems for the more general family $L_{\alpha }(x)$, where $0\leq \alpha \leq 1$, and their relationship to the Riemann hypothesis and other properties of the zeros of the Riemann zeta function. The case where $\alpha =1/2$is of particular interest.
Correlations in health status between estimates of families of people with amyotrophic lateral sclerosis and estimates of staff
Authors: Ozanne Anneli G. , Persson Lennart I.
Published: September 2012

Objective:

The aim of this study was to compare self-estimates of the physical, psychological, and general well-being of patients with amyotrophic lateral sclerosis (ALS) and their next of kin with the assessment of the nurses and physician of these participants.

Method:

The well-being of 35 pairs of patients and their next of kin was rated by themselves, and by a physician and nurses. The well-being was examined over time, using a visual analogue scale (VAS). Patients' physical function was estimated at the same time with the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised and the Norris scale.

Results:

The correlations between the staff's estimates of the well-being of patients and next of kin were similar to their own estimates, even though staff to a higher degree estimated a decrease in well-being over time among the patients. The estimates by the nurses correlated better to that of the patients and next of kin in psychological and general well-being than the physicians' estimates did.

Significance of results:

Even though the staff's estimates of participants were roughly equivalent to their self-estimates, there were some differences. This result calls attention to the importance of working in teams in which different professional roles are combined and integrated, making it possible to form a holistic view of the situation of each family. A concern overlooked by one member of staff might be covered by another, and different focuses on the family may give a better composite picture of their life situation, which could lead to better support to the family.
Sharing experiences in a support group: men's talk during the radiotherapy period for prostate cancer
Authors: Öster Inger , Hedestig Oliver , Johansson Mona , Klingstedt Nina , Lindh Jack
Published: September 2012

Objective:

Prostate cancer, one of the most common cancers in men, is often treated with radiotherapy, which strains both physical and mental health. This study aimed to describe the experiences of men living with prostate cancer shared within conversational support groups during a course of radiotherapy.

Method:

Nine men participated in one of two groups that met six or seven times, led by a professional nurse. Qualitative content analysis was used to identify themes and subthemes in the recorded group conversations.

Results:

The analysis resulted in six themes: living with a changing body, being in the hands of others, learning to live with the disease, the importance of knowledge, everyday life support, and meeting in the support group. The men discussed a wide variety of bodily experiences and described support from healthcare professionals, relatives, friends, and the support group as crucial to their recovery.

Significance of results:

Meeting men in a similar situation, sharing experiences of living with the disease, and feeling allied to each other were important to the men in our study. The conversational support group provided the patient with prostate cancer a forum where sharing was made possible.
Partisanship, political constraints, and employment protection reforms in an era of austerity
Authors: Avdagic Sabina
Published: October 2012

Why do some governments adopt unpopular reforms entailing far-reaching liberalization of the labor market, while others opt only for marginal adjustments or even regulatory reforms? This paper explains the likelihood of different types of reforms as an effect of different constellations of government partisanship and veto players. Combining the ‘blame avoidance’ and ‘veto players’ logics of politics, I argue that veto players have either a constraining or enabling effect depending on the partisan orientation of government. Liberalization is most likely to be adopted either by right parties facing few veto players, or by left parties in contexts with a high degree of power sharing. Regulatory reforms are most likely when left governments enjoy strong power concentration, but marginal regulation may also be adopted under external pressure by right governments facing many veto players. An analysis of employment protection reforms in 24 European Union countries during 1990–2007 supports the argument that the effect of political constraints and opportunities on the choice of reforms is shaped by partisan differences.
Water vapor transport for summer precipitation over the Tibetan Plateau: Multidata set analysis
Authors: Feng Lei , Zhou Tianjun
Published: September 2012

The atmospheric water vapor transport for summer precipitation over the southeastern Tibetan Plateau (hereafter TP) during 1979–2002 is examined by using five precipitation data sets and three reanalysis data sets. The multidata ensemble mean shows that under climate mean conditions, TP is a moisture sink in summer, having a net moisture convergence of 4 mm/day. The climatological water vapor transport from the southern boundary, which originates from the Indian Ocean and the Bay of Bengal, dominates the summer precipitation over the southeastern TP. It is estimated that the water vapor from the western boundary along the southern edge of the TP is about 32% of that from the southern boundary. The summer precipitation over the southeastern TP exhibits strong interannual variability, with a standard deviation of 1.3 mm/day, but no significant long‐term trend. The water vapor transport for the interannual variability of summer rainfall over the southeastern TP mainly comes from the western boundary of the TP, which is originally from lower latitudes. An excessive rainfall anomaly of 1 mm/day over the southeastern TP is associated with an anomalous water vapor input of 138 (104) kg/m/s from the western (southern) boundary. It is worth noting that the quantitative analysis in this study is determined by the setting of the domain. The interannual variability of summer precipitation over the southeastern TP is dominated by an anomalous anticyclone over the northern Indian subcontinent and the Bay of Bengal, which intensifies the water vapor transport along the southern edge of the TP and leads to more water vapor convergence over the southeastern TP, thus the excessive rainfall in the area.
The influence of snow cover thickness on the thermal regime of Tête Rousse Glacier (Mont Blanc range, 3200 m a.s.l.): Consequences for outburst flood hazards and glacier response to climate change
Authors: Gilbert A. , Vincent C. , Wagnon P. , Thibert E. , Rabatel A.
Published: September 2012

Tête Rousse Glacier (French Alps) was responsible for an outburst flood in 1892 that devastated the village of St Gervais‐Le Fayet close to Chamonix, causing 175 fatalities. Changes in the hydrothermal configuration of the glacier are suspected to be the cause of this catastrophic outburst flood. In 2010, geophysical surveys of this glacier revealed a subglacial lake that was subsequently drained artificially. The processes controlling the thermal regime of the glacier have been investigated on the basis of measurements and snow/firn cover and heat flow models using meteorological data covering the last 200 years. Temperature measurements show a polythermal structure with subglacial water trapped by the cold lowest part of the glacier (−2°C). The modeling approach shows that the polythermal structure is due to temporal changes in the depth of the snow/firn cover at the glacier surface. Paradoxically, periods with negative mass balances, associated with warmer air temperature, tend to cool the glacier, whereas years with colder temperatures, associated with positive mass balances, tend to increase the glacier temperature by increasing the firnpack depth and extent. The thermal effect of the subglacial lake is evaluated and shows that the lake was formed around 1980. According to future climate scenarios, modeling shows that the glacier may cool again in the future. This study provides insights into the thermal processes responsible for water storage inside a small almost static glacier, which can lead to catastrophic outburst floods such as the 1892 event or potentially dangerous situations as in 2010.
The cooling history and the depth of detachment faulting at the Atlantis Massif oceanic core complex
Authors: Schoolmeesters Nicole , Cheadle Michael J. , John Barbara E. , Reiners Peter W. , Gee Jeffrey , Grimes Craig B.
Published: September 2012

Oceanic core complexes (OCCs) are domal exposures of oceanic crust and mantle interpreted to be denuded to the seafloor by large slip oceanic detachment faults. We combine previously reported U‐Pb zircon crystallization ages with (U‐Th)/He zircon thermochronometry and multicomponent magnetic remanence data to determine the cooling history of the footwall to the Atlantis Massif OCC (30°N, MAR) and help establish cooling rates, as well as depths of detachment faulting and gabbro emplacement. We present nine new (U‐Th)/He zircon ages for samples from IODP Hole U1309D ranging from 40 to 1415 m below seafloor. These data paired with U‐Pb zircon ages and magnetic remanence data constrain cooling rates of gabbroic rocks from the upper 800 m of the central dome at Atlantis Massif as 2895 (+1276/−1162) °C Myr−1 (from ∼780°C to ∼250°C); the lower 600 m of the borehole cooled more slowly at mean rates of ∼500 (+125/−102) °C Myr−1(from ∼780°C to present‐day temperatures). Rocks from the uppermost part of the hole also reveal a brief period of slow cooling at rates of ∼300°C Myr−1, possibly due to hydrothermal circulation to ∼4 km depth through the detachment fault zone. Assuming a fault slip rate of 20 mm/yr (from U‐Pb zircon ages of surface samples) and a rolling hinge model for the sub‐surface fault geometry, we predict that the 780°C isotherm lies at ∼7 km below the axial valley floor, likely corresponding both to the depth at which the semi‐brittle detachment fault roots and the probable upper limit of significant gabbro emplacement.
Clouds and Snowball Earth deglaciation
Authors: Abbot Dorian S. , Voigt Aiko , Branson Mark , Pierrehumbert Raymond T. , Pollard David , Le Hir Guillaume , Koll Daniel D. B.
Published: September 2012

Neoproterozoic, and possibly Paleoproterozoic, glaciations represent the most extreme climate events in post‐Hadean Earth, and may link closely with the evolution of the atmosphere and life. According to the Snowball Earth hypothesis, the entire ocean was covered with ice during these events for a few million years, during which time volcanic CO2 increased enough to cause deglaciation. Geochemical proxy data and model calculations suggest that the maximum CO2 was 0.01–0.1 by volume, but early climate modeling suggested that deglaciation was not possible at CO2 = 0.2. We use results from six different general circulation models (GCMs) to show that clouds could warm a Snowball enough to reduce the CO2required for deglaciation by a factor of 10–100. Although more work is required to rigorously validate cloud schemes in Snowball‐like conditions, our results suggest that Snowball deglaciation is consistent with observations.
Chlorophyll a in Antarctic sea ice from historical ice core data
Authors: Meiners K. M. , Vancoppenolle M. , Thanassekos S. , Dieckmann G. S. , Thomas D. N. , Tison J.‐L. , Arrigo K. R. , Garrison D. L. , McMinn A. , Lannuzel D. , van der Merwe P. , Swadling K. M. , Smith W. O. , Melnikov I. , Raymond B.
Published: September 2012

Sea ice core chlorophyll a data are used to describe the seasonal, regional and vertical distribution of algal biomass in Southern Ocean pack ice. The Antarctic Sea Ice Processes and Climate – Biology (ASPeCt – Bio) circumpolar dataset consists of 1300 ice cores collected during 32 cruises over a period of 25 years. The analyses show that integrated sea ice chlorophyll apeaks in early spring and late austral summer, which is consistent with theories on light and nutrient limitation. The results indicate that on a circum‐Antarctic scale, surface, internal and bottom sea ice layers contribute equally to integrated biomass, but vertical distribution shows distinct differences among six regions around the continent. The vertical distribution of sea ice algal biomass depends on sea ice thickness, with surface communities most commonly associated with thin ice (<0.4 m), and ice of moderate thickness (0.4–1.0 m) having the highest probability of forming bottom communities.
P‐V‐T equation of state for ε‐iron up to 80 GPa and 1900 K using the Kawai‐type high pressure apparatus equipped with sintered diamond anvils
Authors: Yamazaki Daisuke , Ito Eiji , Yoshino Takashi , Yoneda Akira , Guo Xinzhuan , Zhang Baohua , Sun Wei , Shimojuku Akira , Tsujino Noriyoshi , Kunimoto Takehiro , Higo Yuji , Funakoshi Ken‐ichi
Published: September 2012

In order to determine the P‐V‐T equation of state of ε‐iron, in situ X‐ray observations were carried out at pressures up to 80 GPa and temperatures up to 1900 K using the Kawai‐type high pressure apparatus equipped with sintered diamond anvils which was interfaced with synchrotron radiation. The present results indicate the unit cell volume at ambient conditionsV0 = 22.15(5) Å3, the isothermal bulk modulus KT0 = 202(7) GPa and its pressure derivative K′T0 = 4.5(2), the Debye temperature θ0 = 1173(62) K, Grüneisen parameter at ambient pressure γ0 = 3.2(2), and its logarithmic volume dependence q = 0.8(3). Furthermore, thermal expansion coefficient at ambient pressure was determined to be α0(K−1) = 3.7(2) × 10−5 + 7.2(6) × 10−8(T‐300) and Anderson‐Grüneisen parameterδT = 6.2(3). Using these parameters, we have estimated the density of ε‐iron at the inner core conditions to be ∼3% denser than the value inferred from seismological observation. This result indicates that certain amount of light elements should be contained in the inner core as well as in the outer core but in definitely smaller amount.
Relationship of environmental relative humidity with North Atlantic tropical cyclone intensity and intensification rate
Authors: Wu Longtao , Su Hui , Fovell Robert G. , Wang Bin , Shen Janice T. , Kahn Brian H. , Hristova‐Veleva Svetla M. , Lambrigtsen Bjorn H. , Fetzer Eric J. , Jiang Jonathan H.
Published: September 2012

Quantifying the relationship of large‐scale environmental conditions such as relative humidity with hurricane intensity and intensity change is important for statistical hurricane intensity forecasts. Our composite analysis of 9 years of Atmospheric Infrared Sounder (AIRS) humidity data spanning 198 Atlantic tropical cyclones (TCs) shows that environmental relative humidity (ERH) above the boundary layer generally decreases with time as TCs evolve. Near the surface, ERH stays approximately constant. ERH generally increases with increasing TC intensity and intensification rate. Rapidly intensifying TCs are associated with free tropospheric ERH more than 10% (relative to the averaged ERH for all TCs) larger than that for weakening TCs. Substantial azimuthal asymmetry in ERH is also found, especially for the TCs attaining the highest intensities and largest intensification rates at distances greater than 400 km away from the TC center. In the front‐right quadrant relative to TC motion, rapid intensification is associated with a sharp gradient of ERH in the upper troposphere, with a decrease from the near to the far environment between 400 hPa and 300 hPa. The ERH gradient weakens with the decrease of intensification rate. This radial ERH gradient might be a useful predictor for the statistical forecast of TC intensification.
Stability of the Atlantic meridional overturning circulation: A model intercomparison
Authors: Weaver Andrew J. , Sedláček Jan , Eby Michael , Alexander Kaitlin , Crespin Elisabeth , Fichefet Thierry , Philippon‐Berthier Gwenaëlle , Joos Fortunat , Kawamiya Michio , Matsumoto Katsumi , Steinacher Marco , Tachiiri Kaoru , Tokos Kathy , Yoshimori Masakazu , Zickfeld Kirsten
Published: September 2012

The evolution of the Atlantic Meridional Overturning Circulation (MOC) in 30 models of varying complexity is examined under four distinct Representative Concentration Pathways. The models include 25 Atmosphere‐Ocean General Circulation Models (AOGCMs) or Earth System Models (ESMs) that submitted simulations in support of the 5th phase of the Coupled Model Intercomparison Project (CMIP5) and 5 Earth System Models of Intermediate Complexity (EMICs). While none of the models incorporated the additional effects of ice sheet melting, they all projected very similar behaviour during the 21st century. Over this period the strength of MOC reduced by a best estimate of 22% (18%–25%; 5%–95% confidence limits) for RCP2.6, 26% (23%–30%) for RCP4.5, 29% (23%–35%) for RCP6.0 and 40% (36%–44%) for RCP8.5. Two of the models eventually realized a slow shutdown of the MOC under RCP8.5, although no model exhibited an abrupt change of the MOC. Through analysis of the freshwater flux across 30°–32°S into the Atlantic, it was found that 56% of the CMIP5 models were in a bistable regime of the MOC for at least part of their RCP integrations. The results support previous assessments that it is very unlikely that the MOC will undergo an abrupt change to an off state as a consequence of global warming.
Ionospheric plasma caves under the equatorial ionization anomaly
Authors: Lee I. T. , Liu J. Y. , Lin C. H. , Oyama K.‐I. , Chen C. Y. , Chen C. H.
Published: September 2012

This paper reports the existence of plasma caves, minima in the electron density located at 5–10° to the magnetic equator, in the bottomside ionosphere based on electron densities simulations from the International Reference Ionosphere (IRI‐2007) and clear evidences given by plasma density and drift measurements of the Dynamic Explorer 2 (DE 2) satellite during 1981–1983. The IRI simulations suggest plasma caves as daytime features (08:00–19:00 LT; length of 18,158 km in the longitudinal direction), that range from theE region up to about 300 km altitude with 10° (or 1100 km) width in the latitudinal direction. In situ measurements of the ion and electron densities probed by the DE 2 confirm the existence of the plasma caves at low altitudes of the EIA ionosphere. The unexpected downward and upward (or weakly and strongly upward) ion drifts at the magnetic equator and the two off equators seem to play an important role responsible for the plasma cave formation.
Hot and cold ion outflow: Spatial distribution of ion heating
Authors: Nilsson H. , Barghouthi I. A. , Slapak R. , Eriksson A. I. , André M.
Published: September 2012

Ions apparently emanating from the same source, the ionospheric polar cap, can either end up as energized to keV energies in the high‐altitude cusp/mantle, or appear as cold ions in the magnetotail lobes. We use Cluster observations of ions and wave electric fields to study the spatial variation of ion heating in the cusp/mantle and polar cap. The average flow direction in a simplified cylindrical coordinate system is used to show approximate average ion flight trajectories, and discuss the temperatures, fluxes and wave activity along some typical trajectories. It is found that it is suitable to distinguish between cusp, central and nightside polar cap ion outflow trajectories, though O+ heating is mainly a function of altitude. Furthermore we use typical cold ion parallel velocities and the observed average perpendicular drift to obtain average cold ion flight trajectories. The data show that the cusp is the main source of oxygen ion outflow, whereas a polar cap source would be consistent with our average outflow paths for cold ions observed in the lobes. A majority of the cusp O+ flux is sufficiently accelerated to escape into interplanetary space. A scenario with significant oxygen ion heating in regions with strong magnetosheath origin ion fluxes, cold proton plasma dominating at altitudes below about 8 RE in the polar cap, and most of the cusp oxygen outflow overcoming gravity and flowing out in the cusp and mantle is consistent with our observations.
Thermochronological dating of brittle structures in basement rocks: A case study from the onshore passive margin of SW Sri Lanka
Authors: Emmel B. , Lisker F. , Hewawasam T.
Published: September 2012

The brittle structural inventory of southern and southwestern Sri Lanka has been studied by kinematic, mineralogical and thermochronological techniques. Thermochronological analyses of faults comprise apatite and zircon fission track (FT) data and apatite (U‐Th‐Sm)/He ages from fault planes and undisturbed host rocks, and range between ∼65 and ∼230 Ma. The ages of both settings are undistinguishable for topographic altitudes below ∼100 m, while fault planes from higher elevations are significantly younger than the corresponding host rocks. Thermal history modeling and qualitative interpretation of the thermochronological data identify at least five episodes of thermal overprint associated with faulting activity occurring at 159 ± 18, 144 ± 14, 120 ± 10, 94 ± 8, and 70 ± 10 Ma. The kinematic, mineralogical and thermochronological data collectively show that Sri Lanka was subjected to major N‐S oriented extension subsequent to the Gondwana breakup. The resulting brittle structures exert primary control on the island's geomorphology, especially on the Southern Escarpment of the Sri Lankan Highlands.
Simultaneous long‐term and short‐term slow slip events at the Hikurangi subduction margin, New Zealand: Implications for processes that control slow slip event occurrence, duration, and migration
Authors: Wallace Laura M. , Beavan John , Bannister Stephen , Williams Charles
Published: September 2012

We document a sequence of simultaneous short‐term and long‐term slow slip events (SSEs) at the Hikurangi subduction zone during the 2010/2011 period. The sequence of short‐term events (each ∼2–3 weeks in duration) ruptured much of the shallow plate interface (<15 km) at central and northern Hikurangi over a 6‐month period, was accompanied by microseismicity and involved patchy, irregular migration of SSE slip. We suggest that the patchy migration of the short‐term SSE is due to large‐scale (∼100–3500 km2) heterogeneities on the plate interface related to seamount subduction and sediment subduction and/or underplating. This is in contrast to a 2010/2011 long‐term SSE at the central Hikurangi margin, which evolved steadily over ∼1.5 years and ruptured much of the plate interface between 20 and 70 km depth. We suggest that the occurrence of long‐term versus short‐term SSEs at Hikurangi is related to differences in effective normal stresses and relative heterogeneity of the subduction interface. The long‐term SSE sequence began 1 year before the short‐term sequence. Coulomb stress change models suggest that the long‐term SSE may have triggered initiation of the subsequent short‐term SSE sequence. Initiation of the short‐term sequence occurred in a region just updip of or within an interseismically locked portion of the plate interface and may be located within the updip transition from seismic to aseismic behavior. Alternatively, it could be characteristic of a region undergoing partial interseismic coupling. This is in contrast to SSEs observed elsewhere in the world that typically occur within the downdip transition from seismic to aseismic behavior.
Diurnal variability of upper ocean temperatures from microwave satellite measurements and Argo profiles
Authors: Gille S. T.
Published: September 2012

Diurnal temperature variability in the top 50 m of the ocean is assessed by pairing Argo temperature profiles with geographically colocated Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E) sea surface temperatures (SSTs) collected within ±24 h of each other. Data pairs with time separations of up to ±3 h are used to evaluate systematic differences between the two data sets. Daytime SSTs are warmer than Argo 5 m temperatures in low‐wind conditions, as expected due to diurnal surface warming effects. SSTs also tend to be warmer than Argo 5 m temperatures when columnar water vapor is less than ∼7 mm. These effects are removed empirically. For Argo data collected within ±24 h of satellite overpass times, temperature differences between Argo and AMSR‐E show evidence of a diurnal cycle detectable at 5 m depth and below. The diurnal amplitude decreases with increasing latitude and increasing depth to the base of the mixed layer and is stronger in summer than in winter. At 5 m depth, the amplitude of the summer diurnal cycle ranges from about 0.1°C at the equator to 0.05°C near 60° latitude. At latitudes where the diurnal amplitude exceeds about 0.04°C, maximum temperatures occur at about 16:50 ±0:40 local time, and minimum temperatures occur at about 07:50 ±0:40 local time. Above the base of the mixed layer, the time of the diurnal maximum increases with depth, consistent with downward propagation of the diurnal signal, while the time of the minimum implies an upward propagation.
Historical changes in El Niño and La Niña characteristics in an ocean reanalysis
Authors: Ray Sulagna , Giese Benjamin S.
Published: September 2012

The variation of El Niño Southern Oscillation (ENSO) events from the mid‐nineteenth century until the beginning of the twenty‐first century is explored using an ocean reanalysis. A comparison of the reanalysis with three sea surface temperature reconstructions shows that the timing of events is similar in all four products, however there are important differences in the strength and location of events. The difference between the reconstructions is sometimes larger than the difference between the reanalysis and a given reconstruction. These differences are larger in the first half of the record, a period for which there are relatively sparse observations. The reanalysis is used to explore decadal variability and trends in the frequency, duration, and propagation direction of ENSO events. There is considerable decadal variability of these ENSO characteristics with the time between events ranging from several months to ten years and the duration of ENSO varying from 5 to 27 months. As has been previously shown for the strength and location of ENSO there is little overall trend in the characteristics. Having a three dimensional representation of the ocean from the reanalysis allows exploration of subsurface changes during ENSO. An analysis of subsurface anomalies shows that during ENSO events the subsurface anomalies are highly correlated with the strength of surface anomalies over the 140 year period. Overall, there is no evidence that there are changes in the strength, frequency, duration, location or direction of propagation of El Niño and La Niña anomalies caused by global warming during the period from 1871 to 2008.
Persistent upwelling and front over the Sulu Ridge and their variations
Authors: Jing Zhiyou , Qi Yiquan , Du Yan
Published: September 2012

The persistent upwelling and front isolated over the Sulu Ridge are newly detected by a suite of satellite measurements and confirmed by historical cruise observations. A three‐dimensional tide‐circulation coupled model is employed to investigate the dynamic mechanisms. The intense vertical velocity shear induced by the vigorous internal tidal mixing is identified as the vital dynamic factor to trigger the upwelling and nutrient pumping, through the strong tide‐topography interactions. Satellite observations indicate that the pronounced surface cooling and phytoplankton bloom are isolated over the Sulu Ridge throughout the year. The steady front characterizes 10–20 km width and strength over 0.3°C/km near the southern edge. The feature is further confirmed by the numerical simulation and in situ hydrological observation. Modeling experiment suggests that a quasi‐symmetrical vertical circulation bifurcation across the Sulu Ridge due to the asymmetry of tidal currents is the main mechanism to maintain the persistent upwelling and front. Moreover, the local wind forcing plays an important regulating role in the seasonal and interannual variations. The surface cooling and thermal front intensity reach the maximum in winter under the forcing of strong northeasterly monsoons. Due to prolonged El Niño–Southern Oscillation (ENSO) effects, the surface cooling was significantly weakened during 1998 and 2010 summer. Further analysis indicates the fact that the southwesterly monsoon is weakened dramatically as part of the anticyclonic atmospheric circulation anomalies over the northwest Pacific. The latter results from the significant influence of tropical Indian Ocean capacitor effect associated with El Niño–Southern Oscillation.
Inverse carbon dioxide flux estimates for the Netherlands
Authors: Meesters A. G. C. A. , Tolk L. F. , Peters W. , Hutjes R. W. A. , Vellinga O. S. , Elbers J. A. , Vermeulen A. T. , van der Laan S. , Neubert R. E. M. , Meijer H. A. J. , Dolman A. J.
Published: September 2012

CO2 fluxes for the Netherlands and surroundings are estimated for the year 2008, from concentration measurements at four towers, using an inverse model. The results are compared to direct CO2flux measurements by aircraft, for 6 flight tracks over the Netherlands, flown multiple times in each season. We applied the Regional Atmospheric Mesoscale Modeling system (RAMS) coupled to a simple carbon flux scheme (including fossil fuel), which was run at 10 km resolution, and inverted with an Ensemble Kalman Filter. The domain had 6 eco‐regions, and inversions were performed for the four seasons separately. Inversion methods with pixel‐dependent and ‐independent parameters for each eco‐region were compared. The two inversion methods, in general, yield comparable flux averages for each eco‐region and season, whereas the difference from the prior flux may be large. Posterior fluxes co‐sampled along the aircraft flight tracks are usually much closer to the observations than the priors, with a comparable performance for both inversion methods, and with best performance for summer and autumn. The inversions showed more negative CO2 fluxes than the priors, though the latter are obtained from a biosphere model optimized using the Fluxnet database, containing observations from more than 200 locations worldwide. The two different crop ecotypes showed very different CO2uptakes, which was unknown from the priors. The annual‐average uptake is practically zero for the grassland class and for one of the cropland classes, whereas the other cropland class had a large net uptake, possibly because of the abundance of maize there.
A new approach for simulating the redistribution of soil particles by water erosion: A marker‐in‐cell model
Authors: Cooper James R. , Wainwright John , Parsons Anthony J. , Onda Yuichi , Fukuwara Tomomi , Obana Eiichiro , Kitchener Ben , Long Edward J. , Hargrave Graham H.
Published: September 2012

There are currently no process‐based approaches that allow detailed spatial information on soil redistribution on hillslopes to be modeled at spatial scales that are appropriate for studying slope processes. In response, we developed a new type of soil‐erosion model, a marker‐in‐cell model, which simulates the redistribution of soil during rainfall events. The model is a hybrid of cell‐ and particle‐based techniques. A cell‐based model is used to determine the hydrology and hydraulics occurring at the cellular scale on the hillslope. Markers, representing sediment, are then moved through the grid according to these properties. The spatial pattern of erosion is determined directly by the properties of the markers. The model allows two‐dimensional spatial patterns of individual particle movement on a hillslope to be simulated within a computationally efficient framework. We have tested the model using data collected from a plot‐scale, rainfall‐simulation experiment. We measured the redistribution of137Cs‐rich tracer soil to resolve the spatial patterns of erosion caused by a single, high‐intensity, rainfall event. The model was able to recreate the key temporal and spatial aspects of the hydrology and hydraulics occurring on the plot, as well as the spatial redistribution of137Cs‐rich tracer soil. The development of the model was used to probe our understanding of how to investigate soil‐erosion processes. The lack of empirical underpinnings of the different model components highlighted the need to understand the spatiotemporal dynamics of soil erosion processes at the grain‐scale so to provide a better process‐based understanding of detachment and transport can be sought.
Assessment of the spatial distributions of total‐ and methyl‐mercury and their relationship to sediment geochemistry from a whole‐lake perspective
Authors: Rydberg J. , Rosén P. , Lambertsson L. , De Vleeschouwer F. , Tomasdotter S. , Bindler R.
Published: September 2012

The aim of this study was to determine the spatial variability for total‐ and methylmercury in surface sediments (0–2 cm) across a single whole‐lake basin, and to relate this variability to the sediment's geochemical composition. 83 surface sediment samples from Stor‐Strömsjön – a lake with multiple sub‐basins located in northern Sweden – were analyzed for geochemical composition as well as total‐mercury (total‐Hg) and methylmercury (methyl‐Hg; 35 samples) concentrations. Our results indicate that variations in fine‐grained mineral matter (36%) and organic matter (34%) explain an equal amount of the total‐Hg variation, but that their relative importance varies between different parts of the lake. Total‐Hg concentrations were similar in locations controlled by organic matter or fine‐grained mineral matter (average 109 ng g−1); however, total‐Hg inventories (mass per unit area) were significantly higher in the latter (35 and 53 μg m−2, respectively). Methyl‐Hg concentrations are largely (55% of variance) controlled by water depth and sulfur concentration, which supports the importance of within lake methylation reported from other studies. Both for concentrations and inventories the spatial distribution for methyl‐Hg in surface sediments is patchy, and interestingly the highest methyl‐Hg inventory (1.4 μg m−2) was found in a shallow location with coarse‐grained minerogenic sediment (very low organic matter). A large spatial variability, even within a single lake, is something that needs to be recognized, e.g., when studying processes affecting mercury cycling, mercury loadings and when using lake sediments to reconstruct historic mercury deposition.
A design and an application of a regional coupled atmosphere‐ocean model for tropical cyclone prediction
Authors: Winterbottom Henry R. , Uhlhorn Eric W. , Chassignet Eric P.
Published: September 2012

The prediction of tropical cyclone (TC) track has improved greatly in recent decades due in part to the implementation and improvement of numerical weather prediction (NWP) models. However, the prediction of TC intensity using NWP models remains difficult. Several hypotheses have been proposed to explain the factors contributing to the TC intensity prediction errors and one of the leading candidates is the implication of an evolving sea‐surface temperature (SST) boundary condition beneath the TC. In this study, a regional scale coupled atmosphere‐ocean model is developed using the Advanced Research Weather Research and Forecasting (ARW) model and the HYbrid Coordinate Ocean Model (HYCOM). A coupling algorithm and a methodology to define appropriate ocean initial conditions are provided. Experiments are conducted, during the lifecycle of TC Ike (2008), using both the coupled‐model and static (e.g., temporally fixed) SST to illustrate the impacts of the coupled‐model for the TC track, intensity, and structure, as well as upon the larger (synoptic) scale. The results from this study suggest that the impact of the evolving SST (e.g., from a coupled atmosphere‐ocean model) begin to impact the intensity, size, and thermodynamic structure for TC Ike (2008) at forecast lead‐times beyond 48‐hours. Further, the forecast trajectories (i.e., tracks) do not illustrate large differences between the non‐coupled and coupled‐models. Finally, the impact of the SST boundary condition upon TC Ike (2008) appears to be a function of the strength of the atmospheric forcing – in particular the size and intensity of the TC wind field.
Deep time foraminifera Mg/Ca paleothermometry: Nonlinear correction for secular change in seawater Mg/Ca
Authors: Evans David , Müller Wolfgang
Published: September 2012

The Mg/Ca ratio of foraminifera tests is increasingly being utilized as a paleotemperature proxy. Deep time (pre‐Pleistocene) Mg/Ca paleothermometry is complicated by the fact that the Mg/Ca ratio of seawater (Mg/Casw) has undergone considerable secular variation over the Cenozoic. Previous studies have corrected for this by assuming an invariant Mg distribution coefficient (DMg) with Mg/Casw. More recent laboratory culturing has shown that this is not the case, demonstrating that a power relationship best describes the variation in test Mg/Ca (Mg/Catest) with Mg/Casw. Therefore, previous corrections are likely to have led to inaccurate temperature reconstructions. Here, we show how the systematics of such a correction should be applied and demonstrate why this provides good evidence that the Mg/Ca ratio of Paleogene seawater was lower than previously implied by foraminiferal constraints, in agreement with the majority of the proxy Mg/Casw evidence. We also demonstrate how it is indirectly possible to constrain the value of H, the power component of a Mg/Catest–Mg/Casw calibration, potentially enabling the appropriate correction of results derived from species where this relationship has not been calibrated. However, this technique should not be treated as a substitute for culturing. The previous erroneous assumptions regarding both (1) the relationship between Mg/Catest and Mg/Caswand (2) the Mg/Ca ratio of seawater at a given time in the past may counteract each other to differing extents. As a result, previous absolute pre‐Pleistocene paleotemperature estimates derived from Mg/Ca ratios in foraminifera should be treated with caution, although relative temperature changes over short (<1 Ma timescales) are likely to be reliable.
Second‐kind integral solvers for TE and TM problems of diffraction by open arcs
Authors: Bruno Oscar P. , Lintner Stéphane K.
Published: September 2012

We present a novel approach for the numerical solution of problems of diffraction by open arcs in two dimensional space. Our methodology relies on composition of weighted versions of the classical integral operators associated with the Dirichlet and Neumann problems (TE and TM polarizations, respectively) together with a generalization to the open‐arc case of the well known closed‐surface Calderón formulae. When used in conjunction with spectrally accurate discretization rules and Krylov‐subspace linear algebra solvers such as GMRES, the new second‐kind TE and TM formulations for open arcs produce results of high accuracy in small numbers of iterations—for low and high frequencies alike.
Changes in snowpack accumulation and ablation in the intermountain west
Authors: Harpold Adrian , Brooks Paul , Rajagopal Seshadri , Heidbuchel Ingo , Jardine Angela , Stielstra Clare
Published: September 2012

Recent observations have documented declining snow water equivalent (SWE) and earlier melt in the coastal Cascade and Sierra Nevada mountain ranges, and climate models suggest that warming temperatures will decrease snowpack storage in the higher‐elevation mountain ranges of interior western North America. To date, however, observations of changing SWE or snowmelt have been limited to the state of Colorado in the intermountain west (IMW), defined here as the Rio Grande, Colorado River, and Great Basins, which supply water to the driest regions of North America. We used daily SNOTEL data collected between 1984 and 2009 combined with the nonparametric regional Kendall test to demonstrate significant and widespread changes in the duration of snow cover in these river basins. Daily SNOTEL data demonstrated that basin average maximum SWE occurred as early as 7 March (Lower Colorado River Basin) and as late as 13 April (Upper Colorado, Yampa, and White River Basins). Although significant increases in winter temperature (T) were widespread, there were minimal changes in the day of maximum accumulation and no indications from SWE to winter precipitation ratios (SWE:P) and winter T observations that a transition from snow to rain had occurred. While there was little change in day of maximum accumulation, the duration of snow cover decreased in 11 of 13 drainage regions, and snowmelt center of mass (SM50) advanced 1 to 4 days per decade in 6 of 13 regions. There were significant trends toward a faster SM50 and shorter duration of snow cover in the highest‐elevation regions (>2800 m) of the Colorado River Basin, suggesting that winter T and P may not be the primary driver of change. Our results show that the IMW hydroclimate is both spatially and temporally variable, with few changes in winter T and P in the Great Basin and drier and warmer winters in the Colorado River and Rio Grande Basins. The changes in snowmelt timing also were variable, with a shorter SM50 and less maximum SWE in the Colorado River and Rio Grande Basins. The variable response of snowpacks in the IMW to widespread warming highlights the need for additional research into the mass and energy balance of these continental snowpacks.