pinecone/core-2020-05-10-deduplication huggingface dataset:
Technique for measuring and correcting the Taylor microscale

We discuss and develop methods to estimate and refine measurements of the Taylor microscale from discrete data sets. To study how well a method works, we construct a time series of discrete data with a known power spectrum and Taylor scale, but with various truncations of the resolution that eliminate higher frequencies in a controlled fashion. We compute the second-order structure function and correlation function, assuming that the unresolved dissipation range spectrum has various values of spectral index. A series of Taylor scale estimates are obtained from parabolic fits to subsets of the correlation function data, and these are extrapolated to the limit of zero separation. The error in this procedure, for finite time resolution sampling, depends on the spectral index in the dissipation range. When the spectral form is known, we can compute a correction factor that improves the estimate of the Taylor microscale value determined from the extrapolation method and band-limited data. Application of this technique to spacecraft observations of solar wind fluctuations is illustrated.Fil: Chuychai, P.. Mae Fah Luang University; Estados Unidos. Ministry of Education; TailandiaFil: Weygand, J. M.. University of California; Estados UnidosFil: Matthaeus, W. H.. University of Delaware; Estados UnidosFil: Dasso, Sergio Ricardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomia y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomia y Física del Espacio; ArgentinaFil: Smith, C. W.. University of New Hampshire; Estados UnidosFil: Kivelson, M. G.. University of California; Estados Unido
Delamination of southern Puna lithosphere revealed by body wave attenuation tomography

The southern Puna Plateau has been proposed to result from a major Pliocene delamination event that has previously been inferred from geochemical, geological, and some preliminary geophysical data.  Seventy-five seismic stations were deployed across the southern Puna Plateau in 2007?2009 by scientists fromthe U.S., Germany, Chile, and Argentina to test the delamination model for the region. The Puna passive seismic stations were located between 25 and 28°S. Using the seismic waveform data collected from the PUNA experiment,we employ attenuation tomography methods to resolve both compressional and shear quality factors (Qp and Qs, respectively) in the crust and uppermost mantle. The images clearly show a high-Q Nazca slab subducting eastward beneath the Puna plateau and another high-Q block with a westward dip beneath the  Eastern Cordillera. We suggest that the latter is a piece of delaminated South American lithosphere. A significant low-Q zone lies between the Nazca slab and the South American lithosphere and extends southward from the northernmargin of the seismic array at 25°S before vanishing around 27.5°S. This low-Q zone extends farther west in the crust and uppermost mantle at the southern end of the seismic array. The low-Q zone reaches ~100 km depth beneath the northern part of the array but only ~50 km depth in the south. Lateral variations of the low-Q zone reflect the possible mechanism conversion between mantle upwelling related to delamination and dehydration. The depth of the Nazca slab as defined by Q images decreases from north to south beneath the plateau, which is consistentwith the steep-flat transition of the angle of the subducting slab as defined by previous earthquake studies.Fil: Liang, Xiaofeng. Chinese Academy of Sciences. Institute of Geology and Geophysics; China. University of Missouri. Department of Geological Sciences; Estados UnidosFil: Sandvol, Eric. University of Missouri. Department of Geological Sciences; Estados UnidosFil: Kay, Suzanne. Cornell University. Department of Earth and Atmospheric Science; Estados UnidosFil: Heit, Benjamin. Deutsches GeoForschungsZentrum; AlemaniaFil: Yuan, Xiaohui. Deutsches GeoForschungsZentrum; AlemaniaFil: Mulcahy, Patrick. Cornell University. Department of Earth and Atmospheric Science; Estados UnidosFil: Chen, Chen. Cornell University. Department of Earth and Atmospheric Science; Estados UnidosFil: Brown, Larry. Cornell University. Department of Earth and Atmospheric Science; Estados UnidosFil: Comte, Diana. Universidad de Chile. Facultad de Ciencias Físicas y Matemáticas. Departamento de Geofísica; ChileFil: Alvarado, Patricia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Juan. Centro de Investigaciones de la Geosfera y Biosfera; Argentin
Distribution and mitigation of higher-order ionospheric effects on precise GNSS processing

Higher-order ionospheric effects (I2+) are one of the main limiting factors in very precise Global Navigation Satellite Systems (GNSS) processing, for applications where millimeter accuracy is demanded. This paper summarizes a comprehensive study of the I2+ effects in range and in GNSS precise products such as receiver position and clock, tropospheric delay, geocenter offset, and GNSS satellite position and clock. All the relevant higher-order contributions are considered: second and third orders, geometric bending, and slant total electron content (dSTEC) bending (i.e., the difference between the STEC for straight and bent paths). Using a realistic simulation with representative solar maximum conditions on GPS signals, both the effects and mitigation errors are analyzed. The usage of the combination of multifrequency L band observations has to be rejected due to its increased noise level. The results of the study show that the main two effects in range are the second-order ionospheric and dSTEC terms, with peak values up to 2 cm. Their combined impacts on the precise GNSS satellite products affects the satellite Z coordinates (up to +1 cm) and satellite clocks (more than ±20 ps). Other precise products are affected at the millimeter level. After correction the impact on all the precise GNSS products is reduced below 5 mm. We finally show that the I2+ impact on a Precise Point Positioning (PPP) user is lower than the current uncertainties of the PPP solutions, after applying consistently the precise products (satellite orbits and clocks) obtained under I2+ correctionPeer ReviewedPostprint (author’s final draft
Compaction around a rigid, circular inclusion in partially molten rock

This is the final published version. It is also available from http://onlinelibrary.wiley.com/doi/10.1002/2013JB010906/abstract.

©2014. American Geophysical Union. All Rights Reserved.Conservation laws that describe the behavior of partially molten mantle rock have been established for several decades, but the associated rheology remains poorly understood. Constraints on the rheology may be obtained from recently published experiments involving deformation of partially molten rock around a rigid, spherical inclusion. These experiments give rise to patterns of melt segregation that exhibit the competing effects of pressure shadows and melt-rich bands. Such patterns provide an opportunity to infer rheological parameters through comparison with models based on the conservation laws and constitutive relations that hypothetically govern the system. To this end, we have developed software tools to simulate finite strain, two-phase flow around a circular inclusion in a configuration that mirrors the experiments. Simulations indicate that the evolution of porosity is predominantly controlled by the porosity-weakening exponent of the shear viscosity and the poorly known bulk viscosity. In two-dimensional simulations presented here, we find that the balance of pressure shadows and melt-rich bands observed in experiments only occurs for bulk-to-shear viscosity ratio of less than about five. However, the evolution of porosity in simulations with such low bulk viscosity exceeds physical bounds at unrealistically small strain due to the unchecked, exponential growth of the porosity variations. Processes that limit or balance porosity localization should be incorporated in the formulation of the model to produce results that are consistent with the porosity evolution in experiments.This work was supported by the Natural Environment Research Council under grants NE/I023929/1 and NE/I026995/1
The influence of an Antarctic glacier tongue on near-field ocean circulation and mixing

The article of record as published may be located at http://dx.doi.org/10.1002/2013JC009070In situ measurements of flow and stratification in the vicinity of the Erebus Glacier Tongue, a
12 km long floating Antarctic glacier, show the significant influence of the glacier. Three ADCPs (75, 300,
and 600 kHz) were deployed close (<50 m) to the sidewall of the glacier in order to capture near-field flow
distortion. Scalar (temperature and conductivity) and shear microstructure profiling captured small-scale
vertical variability. Flow magnitudes exceeded 0.3 m s21 through a combination of tidal flow ( 8 cm s21)
and a background/residual flow ( 4–10 cm s21) flowing to the NW. Turbulence was dominated by deeper
mixing during spring tide, likely indicative of the role of bathymetric variation which locally forms an obstacle
as great as the glacier. During the neap tide, near-surface mixing was as energetic as that seen in the
spring tide, suggesting the presence of buoyancy-driven near-surface flows. Estimates of integrated dissipation
rate suggest that these floating extensions of the Antarctic ice sheet alter energy budgets through
enhanced dissipation, and thus influence coastal near-surface circulation.The work was funded by The New Zealand Royal Society administered Marsden Fund, and US NSF support to Stanton and McPhee. Logistic support was provided by Antarctica New Zealand and travel funding from Air New Zealand
A physically based parameterization of gravity drainage for sea-ice modelling

We incorporate a physically derived parameterization of gravity drainage,
in terms of a convective upwelling velocity, into a one-dimensional, thermodynamic sea-
ice model of the kind currently used in coupled climate models. Our parameterization
uses a local Rayleigh number to represent the important feedback between ice salinity,
porosity, permeability and desalination rate. It allows us to determine salt fluxes from
sea ice and the corresponding evolution of the bulk salinity of the ice, in contrast to older,
established models that prescribe the ice salinity. This improves the predictive power of
climate models in terms of buoyancy fluxes to the polar oceans, and also the thermal
properties of sea ice, which depend on its salinity. We analyze the behaviour of exist-
ing fixed-salinity models, elucidate the physics by which changing salinity affects ice growth
and compare against our dynamic-salinity model, both in terms of laboratory experiments
and also deep-ocean calculations. These comparisons explain why the direct effect of ice
salinity on growth is relatively small (though not always negligible, and sometimes dif-
ferent from previous studies), and also highlight substantial differences in the qualita-
tive pattern and quantitative magnitude of salt fluxes into the polar oceans. Our study
is particularly relevant to growing first-year ice, when gravity drainage is the dominant
mechanism by which ice desalinates. We expect that our dynamic model, which respects
the underlying physics of brine drainage, should be more robust to changes in polar cli-
mate and more responsive to rapid changes in oceanic and atmospheric forcing.This is the accepted manuscript. The final version is available from Wiley/American Geophysical Union at http://onlinelibrary.wiley.com/doi/10.1002/2013JC009296/abstract
Suspended particulate layers and internal waves over the southern Monterey Bay continental shelf: An important control on shelf mud belts?

The article of record as published may be located at http://dx.doi.org/10.1002/2013JC009360Physical and optical measurements taken over the mud belt on the southern continental
shelf of Monterey Bay, California documented the frequent occurrence of suspended
particulate matter features, the majority of which were detached from the seafloor, centered
9–33 m above the bed. In fall 2011, an automated profiling mooring and fixed
instrumentation, including a thermistor chain and upward-looking acoustic Doppler current
profiler, were deployed at 70 m depth for 5 weeks, and from 12 to 16 October a long-range
autonomous underwater vehicle performed across-shelf transects. Individual SPM events
were uncorrelated with local bed shear stress caused by surface waves and bottom currents.
Nearly half of all observed SPM layers occurred during 1 week of the study, 9–16 October
2011, and were advected past the fixed profiling mooring by the onshore phase of
semidiurnal internal tide bottom currents. At the start of the 9–16 October period, we
observed intense near-bed vertical velocities capable of lifting particulates into the middle
of the water column. This ‘‘updraft’’ event appears to have been associated with nonlinear
adjustment of high-amplitude internal tides over the mid and outer shelf. These findings
suggest that nonlinear internal tidal motions can erode material over the outer shelf and that,
once suspended, this SPM can then be transported shoreward to the middle and shallow
sections of the mud belt. This represents a fundamental broadening of our understanding of
how shelf mud belts may be built up and sustained.This project was funded by the National Science Foundation (grant OCE0961810 to McPhee-Shaw, Bellingham, Shaw, and Stanton), and by the U.S. Geological Survey
Ice-Ocean Interactions in North West Greenland

Ice shelves play an important role in the mass balance of an ice sheet, by providing a link between the ocean and ice. Melting at the base of an ice shelf can play a vital role in its mass balance and stability. Topographic channel features have been found on the base of ice shelves, and have been found to alter melting, however the mechanism behind this alteration is unknown. Petermann Glacier is a major outlet glacier in North West Greenland, draining approximately 6% of Greenland Ice Sheet. It terminates in a long, thin ice shelf, constrained within a high-walled fjord. The ice shelf has pronounced longitudinal channel features on its base, which limited observations suggest direct ocean currents in a mixed layer of ocean and melt waters, focusing melt in these regions. Petermann Glacier underwent two large calving events in 2010 and 2012, and the impact of these events, or possible further calving events, on basal melting is unknown.\ud
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Using the MITgcm to model the ocean cavity beneath an idealised ice shelf, this thesis discusses the impact of basal channels on interactions at the ice base and circulation within the cavity. This is supplemented with a modelling investigation into the interactions beneath Petermann Glacier, and the impact of recent calving events. The inclusion of channels was found to have a stabilising effect on the ice shelf by decreasing the mean basal melt rate, caused by the refocusing, and decrease in intensity of, the meltwater layer flow beneath the ice shelf. This stabilisation and resulting `survivor bias' explains why channels are commonly found on the base of warm water ice shelves. The model of Petermann Glacier found similar melt patterns to observational studies, however with a lesser magnitude. The calving events of 2010 and 2012 removed areas of ice shelf with low melt rates, resulting in little impact on the overall volume of ice removed through ocean melting, though further calving would vastly reduce the volume of ice melted. One consequence of calving is the increase in melting-induced undercutting at the ice front, leading to the potential for enhanced secondary calving.\ud
\ud
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Part of the results contained within this thesis are published as: Millgate, T., P.R. Holland, A. Jenkins and H.L. Johnson (2013), The effect of basal channels on oceanic ice-shelf melting, Journal of Geophysical Research Oceans, 118, doi:10.1002/2013JC009402
Relating Lagrangian and Eulerian horizontal eddy statistics in the surfzone

The article of record as published may be located at http://dx.doi.org/10.1002/2013JC009415Concurrent Lagrangian and Eulerian observations of rotational, low-frequency (1024 to 1022 Hz)
surfzone eddies are compared. Surface drifters were tracked for a few hours on each of 11 days at two
alongshore uniform beaches. A cross-shore array of near-bottom current meters extended from near the
shoreline to seaward of the surfzone (typically 100 m wide in these moderate wave conditions). Lagrangian
and Eulerian mean alongshore velocities V are similar, with a midsurfzone maximum. Cross-shore dependent
Lagrangian (rL) and Eulerian (rE) rotational eddy velocities, estimated from low-pass filtered drifter and current
meter velocities, respectively, also generally agree. Cross-shore rotational velocities have a midsurfzone maximum
whereas alongshore rotational velocities are distributed more broadly. Daily estimates of the Lagrangian
time scale, the time for drifter velocities to decorrelate, vary between 40 and 300 s, with alongshore time
scales greater than cross-shore time scales. The ratio of Lagrangian to apparent Eulerian current meter
decorrelation times TL/TA varies considerably, between about 0.5 and 3. Consistent with theory, some of the
TL/TA variation is ascribable to alongshore advection and TL/TA is proportional to V/r, which ranges between
about 0.6 and 2.5. Estimates of TL/TA vary between days with similar V/r suggesting that surfzone Lagrangian
particle dynamics vary between days, spanning the range from ‘‘fixed-float’’ to ‘‘frozen-field’’ [Lumpkin et al.,
2002], although conclusions are limited by the statistical sampling errors in both TL/TA and V/r.This analysis was supported by NSF, ONR, and CA Sea Grant. The HB06 field work was supported by CA Coastal Conservancy, NOAA, NSF, ONR, and CA Sea Grant. R. T. Guza was a co-PI on the HB06 experiment. Staff and students from the Integrative Oceanography Division (B. Woodward, B. Boyd, K. Smith, D. Darnell, I. Nagy, D. Clark, M. Omand, M. Yates, M. McKenna, M. Rippy, and S. Henderson) and the Naval Postgraduate School (J. Brown and B. Swick) were instrumental in acquiring the field observations. The comments from three reviewers improved this manuscript and are greatly appreciated
Sea surface temperature and salinity seasonal changes in the western Solomon and Bismarck Seas

We analyze mean and seasonal change of Sea Surface Temperature (SST) and Salinity (SSS) in the Solomon and Bismarck Seas, using 1977–2009 in situ data collected from Voluntary Observing Ships. Covariability of these two variables with surface wind, altimeter-derived and model-derived horizontal currents, precipitation, and Sepik River discharge are examined. SST and SSS show large annual oscillations in the Solomon Sea, with the coldest and saltiest waters occurring in July/August mainly due to horizontal advection. In contrast, they show large semiannual oscillations in the Bismarck Sea. There, the coldest and saltiest waters happen in January/February, when the northwest monsoon winds drive coastal upwelling,and in July/August, when the New Guinea Coastal Current advects cold and high-salinity waters from the Solomon Sea through Vitiaz Strait. The low SSS values observed in April/May, stuck between the January/\ud
February and July/August SSS maxima, are further enhanced by the Sepik River discharge annual maximum.\ud
A high-resolution model strengthens the conclusions we derive from observations. The impacts of ENSO on\ud
SST and SSS are also discussed with, for instance, saltier-than-average and fresher-than-average waters during the 2002–2003 El Nino and 2007–2008 La Ni ~ na, respectivel
A comparison of satellite- and ground-based measurements of SO2 emissions from Tungurahua volcano, Ecuador

Satellite-measured SO2 mass loadings and ground-based measurements of SO2 emission rate
are not directly comparable, with ∼40% differences between mean emissions reported by each technique
from Tungurahua volcano, Ecuador, during late 2007. Numerical simulations of postemission processing and
dispersal of Tungurahua’s SO2 emissions enable more effective comparison of ground- and satellite-based
SO2 data sets, reducing the difference between them and constraining the impact of plume processing on
satellite SO2 observations. Ground-based measurements of SO2 emission rate are used as the model input,
and simulated SO2 mass loadings are compared to those measured by the Ozone Monitoring Instrument
(OMI). The changing extent of SO2 processing has a significant impact on daily variation in SO2 mass loading
for a fixed volcanic emission rate. However, variations in emission rate at Tungurahua are large, suggesting
that overall volcanic source strength and not subsequent processing is more likely to be the dominant
control on atmospheric mass loading. SO2 emission rate estimates are derived directly from the OMI
observations using modeled SO2 lifetime. Good agreement is achieved between both observed and
simulated mass loadings (∼21%) and satellite-derived and ground-measured SO2 emission rates (∼18%),
with a factor of 2 improvement over the differences found by simple direct comparison. While the balance
of emission source strength and postemission processing will differ between volcanoes and regions, under
good observation conditions and where SO2 lifetime is ∼24 hours, satellite-based sensors like OMI may
provide daily observations of SO2 mass loading which are a good proxy for volcanic source strength.B.T.M. acknowledges funding from the
National Centre for Earth Observation,
part of the UK’s Natural Environment
Research Council, and latterly the
Deep Carbon Observatory and
the Smithsonian Institution. B.T.M.,
M.E., and T.A.M. are supported by
and contribute to the NERC NCEO
Dynamic Earth and Geohazards group.
S.A.C. acknowledges funding from
NASA through grants NNX09AJ40G
(Aura Validation), NNX10AG60G
(Atmospheric Chemistry Modeling and
Analysis Program), and NNX11AF42G
(Aura Science Team). J.Y. was funded
by the Isaac Newton Trust at the
University of Cambridge for the
duration of this project. The authors
thank Anja Schmidt and two anonymous
reviewers for their thorough
and constructive comments. We
acknowledge the Goddard Earth
Sciences Data and Information
Services Center for making OMI SO2
data publicly available.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/2013JD019771/abstract