scholarly journals The Ocean Version of the Lagrangian Analysis Tool LAGRANTO

2017 ◽  
Vol 34 (8) ◽  
pp. 1723-1741 ◽  
Author(s):  
Sebastian Schemm ◽  
Aleksi Nummelin ◽  
Nils Gunnar Kvamstø ◽  
Øyvind Breivik
Keyword(s):  
Case Studies ◽  
Potential Temperature ◽  
Analysis Tool ◽  
Lagrangian Analysis ◽  
Ocean Reanalysis ◽  
Near Surface ◽  
Mean Values ◽  
Spatial And Temporal Scales ◽  
First Case ◽  
Wide Range

AbstractThe Lagrangian Analysis Tool (LAGRANTO) is adopted and applied to ECMWF’s latest ocean reanalysis. The primary motivation behind this study is to introduce and document LAGRANTO Ocean (LAGRANTO.ocean) and explore its capabilities in combination with an eddy-permitting ocean reanalysis. The tool allows for flexibly defining starting points, within circles, cylinders, or any user-defined region or volume. LAGRANTO.ocean also offers a sophisticated way to refine a set of computed trajectories according to a wide range of mathematical operations that can be combined into a single refinement criterion. Tools for calculating—for example, along-trajectory cross sections or trajectory densities—are further provided. After introducing the tool, three case studies are presented, which were chosen to reflect a selection of phenomena on different spatial and temporal scales. The case studies also serve as hands-on examples. For the first case study, at the mesoscale, ocean trajectories are computed during the formation of a Gulf Stream cold-core ring to study vertical motion in the developing eddy. In the second example, source waters are traced to the East Greenland Spill Jet. This example highlights the usefulness of a Lagrangian method for identifying sources or sinks of buoyancy. The third example, on annual time scales, focuses on the temporal evolution of extreme potential temperature anomalies in the South Pacific and the memory of the involved water parcels. Near-surface trajectories reveal that it takes approximately 5 months after the highest temperature anomaly before the involved water parcels cool to their climatological mean values at their new positions. LAGRANTO.ocean will be made publicly available.

scholarly journals Ocean Emission Effects on Aerosol-Cloud Interactions: Insights from Two Case Studies

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Armin Sorooshian ◽  
Hanh T. Duong
Keyword(s):  
Case Studies ◽  
Field Experiments ◽  
Remote Sensing Data ◽  
Anthropogenic Pollution ◽  
Cloud Microphysics ◽  
Marine Aerosols ◽  
Aerosol Cloud ◽  
First Case ◽  
Wide Range ◽  
Aerosol Cloud Interactions

Two case studies are discussed that evaluate the effect of ocean emissions on aerosol-cloud interactions. A review of the first case study from the eastern Pacific Ocean shows that simultaneous aircraft and space-borne observations are valuable in detecting links between ocean biota emissions and marine aerosols, but that the effect of the former on cloud microphysics is less clear owing to interference from background anthropogenic pollution and the difficulty with field experiments in obtaining a wide range of aerosol conditions to robustly quantify ocean effects on aerosol-cloud interactions. To address these limitations, a second case was investigated using remote sensing data over the less polluted Southern Ocean region. The results indicate that cloud drop size is reduced more for a fixed increase in aerosol particles during periods of higher ocean chlorophyll A. Potential biases in the results owing to statistical issues in the data analysis are discussed.

Basin-Wide Connections of Upper-Ocean Temperature Variability in the Equatorial Indian Ocean

2021 ◽  
pp. 1-50
Author(s):  
Ge Song ◽  
Bohua Huang ◽  
Rongcai Ren ◽  
Zeng-Zhen Hu
Keyword(s):  
Indian Ocean ◽  
Equatorial Indian Ocean ◽  
Reanalysis Data ◽  
Upper Ocean ◽  
Ocean Temperature ◽  
Ocean Reanalysis ◽  
Near Surface ◽  
Surface Warming ◽  
Transition Mechanism ◽  
Wide Range

AbstractIn this paper, the interannual variability of upper-ocean temperature in the equatorial Indian Ocean (IO) and its basin-wide connections are investigated using 58-year (1958-2015) comprehensive monthly mean ocean reanalysis data. Three leading modes of an empirical orthogonal function (EOF) analysis dominate the variability of upper-ocean temperature in the equatorial IO in a wide range of timescales. A coherent interannual band within the first two EOF modes identifies an oscillation between the zonally tilting thermocline across the equatorial IO in its peak phases and basin-wide displacement of the equatorial thermocline in its transitional phases. Consistent with the recharge oscillation paradigm, this oscillation is inherent of the equatorial IO with a quasi-periodicity around 15 months, in which the wind-induced off-equatorial Rossby waves near 5°S-10°S provide the phase-transition mechanism. This intrinsic IO oscillation provides the biennial component in the observed IOD variations. The third leading mode shows a nonlinear long-term trend of the upper-ocean temperature, including the near-surface warming along the equatorial Indian Ocean, accompanied by cooling trend in the lower thermocline originating further south. Such vertical contrary trends may lead to an enhanced stratification in the equatorial IO.

scholarly journals Penetration of interferometric radar signals in Antarctic snow

2021 ◽  
Vol 15 (9) ◽  
pp. 4399-4419
Author(s):  
Helmut Rott ◽  
Stefan Scheiblauer ◽  
Jan Wuite ◽  
Lukas Krieger ◽  
Dana Floricioiu ◽  
...  
Keyword(s):  
Structural Features ◽  
Snow Accumulation ◽  
Radar Signal ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Near Surface ◽  
Mean Values ◽  
Actual Surface ◽  
First Case ◽  
Radar Signals

Abstract. Synthetic aperture radar interferometry (InSAR) is an efficient technique for mapping the surface elevation and its temporal change over glaciers and ice sheets. However, due to the penetration of the SAR signal into snow and ice, the apparent elevation in uncorrected InSAR digital elevation models (DEMs) is displaced versus the actual surface. We studied relations between interferometric radar signals and physical snow properties and tested procedures for correcting the elevation bias. The work is based on satellite and in situ data over Union Glacier in the Ellsworth Mountains, West Antarctica, including interferometric data of the TanDEM-X mission, topographic data from optical satellite sensors and field measurements on snow structure, and stratigraphy undertaken in December 2016. The study area comprises ice-free surfaces, bare ice, dry snow and firn with a variety of structural features related to local differences in wind exposure and snow accumulation. Time series of laser measurements of NASA's Ice, Cloud and land Elevation Satellite (ICESat) and ICESat-2 show steady-state surface topography. For area-wide elevation reference we use the Reference Elevation Model of Antarctica (REMA). The different elevation data are vertically co-registered on a blue ice area that is not affected by radar signal penetration. Backscatter simulations with a multilayer radiative transfer model show large variations for scattering of individual snow layers, but the vertical backscatter distribution can be approximated by an exponential function representing uniform absorption and scattering properties. We obtain estimates of the elevation bias by inverting the interferometric volume correlation coefficient (coherence), applying a uniform volume model for describing the vertical loss function. Whereas the mean values of the computed elevation bias and the elevation difference between the TanDEM-X DEMs and the REMA show good agreement, a trend towards overestimation of penetration is evident for heavily wind-exposed areas with low accumulation and towards underestimation for areas with higher accumulation rates. In both cases deviations from the uniform volume structure are the main reason. In the first case the dense sequence of horizontal structures related to internal wind crust, ice layers and density stratification causes increased scattering in near-surface layers. In the second case the small grain size of the top snow layers causes a downward shift in the scattering phase centre.

Caisson Capacity in Clay: VHM Resistance Envelope: Part 3—Extension to Shallow Foundations

2011 ◽  
Author(s):  
S. Kay ◽  
E. Palix
Keyword(s):  
Shear Strength ◽  
Load Resistance ◽  
Analysis Tool ◽  
Foundation Soil ◽  
Finite Element Program ◽  
Near Surface ◽  
Wide Range ◽  
Soil Shear Strength ◽  
Non Linear ◽  
Element Program

Suction embedded caissons are efficient and economic solutions to anchor floating structures. A more recent caisson application is to support seafloor structures such as manifolds, PLEMs, pumps, etc. For a deepwater hydrocarbon field, many types of seafloor structures are required, each with their own characteristics and slightly different design. Caisson designs increasingly use resistance envelope methodology. This eliminates non-linear 3D FE analyses (except for assessing responses or soil reactions), and facilitates probabilistic and optimisation analyses. In general, there is a requirement for a reliable method of assessing caisson capacity under general VHM load. Resistance envelope equations for “deep” circular caissons (1.5 < L/D < 6) have been presented by Kay and Palix (2010) for a wide range of soil undrained shear strength profiles. This paper extends the study to cover near-surface caissons (i.e. 0 ≤ L/D ≤ 1.5). As in previous studies, a quasi 3D non-linear finite element program (HARMONY) was the primary numerical analysis tool. Three soil shear strength profiles were investigated for 13 caisson embedment ratios. In the range 0 ≤ L/D ≤ 1.5, VHM envelope shapes transform from a “scallop” at L/D ≈ 0 into a “tongue” above a critical caisson embedment ratio (L/D)crit of about 0.5 The equations originally developed for the rotated ellipse/ellipsoid (i.e. “tongue”-shaped envelope) in Kay and Palix (2010) for L/D ≤ 1.5 have been extended for (L/D)crit ≥ L/D. All parameters are simple functions of L/D and soil shear strength profile. Major limitations and assumptions made were (a) foundation-soil tension was permitted and (b) no internal scoop failure (i.e. within the soil plug inside the caisson) was possible. These are important for low L/D: both may adversely affect VHM resistance.

scholarly journals Transport of Stratospheric Air Masses to the Nepal Climate Observatory–Pyramid (Himalaya; 5079 m MSL): A Synoptic-Scale Investigation

2012 ◽  
Vol 51 (8) ◽  
pp. 1489-1507 ◽  
Author(s):  
A. Bracci ◽  
P. Cristofanelli ◽  
M. Sprenger ◽  
U. Bonafè ◽  
F. Calzolari ◽  
...  
Keyword(s):  
Potential Vorticity ◽  
Monsoon Season ◽  
Jet Stream ◽  
Analysis Tool ◽  
Synoptic Scale ◽  
Ozone Monitoring Instrument ◽  
Lagrangian Analysis ◽  
Total Column Ozone ◽  
Mean Values

AbstractThis work analyzes and classifies stratospheric airmass transport events (ST) detected at the Nepal Climate Observatory–Pyramid (NCO-P; 27°57′N, 86°48′E, 5079 m MSL) Global Atmospheric Watch–World Meteorological Organization station from March 2006 to February 2008. For this purpose, in situ ozone (O3), meteorological parameters (atmospheric pressure and relative humidity), and black carbon (BC) are analyzed. The paper describes the synoptic-scale meteorological scenarios that are able to favor the development of ST over the southern Himalaya, by analyzing the meteorological fields provided by the ECMWF model (geopotential height, wind speed, and potential vorticity), satellite Ozone Monitoring Instrument data (total column ozone), and three-dimensional back trajectories calculated with the Lagrangian Analysis Tool (LAGRANTO) model. The study, which represents the first “continuous” classification of ST in the southern Himalaya, permitted classification of 94% of ST days within four synoptic-scale scenarios: stratospheric potential vorticity structures (PVS), subtropical jet stream (SJS), quasi-stationary ridges (QSR), and monsoon depressions (MD). SJS and PVS were the most frequent scenarios (48% and 30% of occurrences, respectively), QSR occurred for 12% of the ST days, and MD were detected only during the monsoon season (3%). SJS and PVS scenarios presented a peak frequency during the nonmonsoon seasons, when the jet stream and westerly disturbances influence atmospheric circulation over the southern Himalaya. During the identified ST, significant variations of O3 (+24%) and BC (−56%) were recorded relative to the averaged 2-yr mean values. On average, PVS and SJS were the most effective synoptic-scale scenarios in modifying the O3 and BC levels at NCO-P from postmonsoon to premonsoon seasons, and ST is one of the leading processes in defining the “background” BC variability at NCO-P.

Vertical multi-frequency FDEM loop-loop soundings for sub-surface conductivity imaging: comparison of HCP and PERP configurations for different environments 

2021 ◽  
Author(s):  
Julien Guillemoteau ◽  
Mauricio Arboleda Zapata ◽  
François-Xavier Simon ◽  
Guillaume Hulin ◽  
Laurent Deschodt ◽  
...  
Keyword(s):  
Case Studies ◽  
Joint Inversion ◽  
Layered Media ◽  
Sensor Data ◽  
Near Surface ◽  
First Case ◽  
Electrical Imaging ◽  
Sensitivity Pattern ◽  
Lateral Variations

&lt;p&gt;Frequency domain loop-loop electromagnetic induction (FDEM) soundings using decametric coil-separations and multi-frequency sources have been used for decades to investigate the electrical conductivity of top 100 m of the subsurface. The most common coil configurations include horizontal and vertical co-planar (HCP and VCP) setups, and the data recorded with a rather large station spacing are typically processed assuming 1D layered media. In many geological situations, the subsurface shows significant lateral contrasts in the electrical material properties, especially, in regoliths close to earth&amp;#8217;s surface. Here, the HCP and VCP 2D/3D sensitivity functions show complex and rather extended lateral sensitivity patterns. Therefore, in presence of high lateral variations in the uppermost layers, assuming 1D layered media for interpreting HCP and VCP profiles is often not valid. Furthermore, using rather large lateral station spacings often hinders the identification (and removal) of 2D/3D effects. In consequence, the overall 1D FDEM profiling procedure is often considered to be less robust than other electrical imaging techniques (e.g., DC tomography) to depict near-surface horizontal variations of the subsurface.&lt;/p&gt;&lt;p&gt;In shallower FDEM applications focusing on the characterization of the uppermost soil layers, portable loop-loop FDEM sensors (e.g. rigid boom systems with coil separations &lt; 6 m) are used to explore the subsurface electrical properties. Here, it is commonly known that the PERP configuration shows better lateral resolution and apparent conductivity maps closer to the actual conductivity distribution. The latter feature is in fact crucial for the validity and applicability of the 1D approximation. The robustness of the PERP configuration regarding the 1D assumption can be explained by its sensitivity pattern showing a preponderant sign and a rather focused pattern, centered approximately below the receiver.&lt;/p&gt;&lt;p&gt;In order to evaluate the benefit of the PERP configuration for systems with decametric coil separation, we present two case studies, where densely sampled profiles of 1D inversions of multi-frequency FDEM HCP and PERP data are compared to 2D ERT inverted models and additional independent borehole and rigid-boom FDEM sensor data. In the first case study, we explore a coastal environment near Bourbourg, France, where only minor lateral variations in the subsurface are expected. Here, our results demonstrate that a 1D inversion of HCP and PERP data result in similar models. In the second case study, we explore debris flow deposits close to Braunsbach, Germany, which are characterized by significant near-surface lateral variability. In this case, only the 1D inversion of our PERP data results in a pseudo 2D model being in agreement with the inverted 2D ERT data. These two case studies confirm that the 1D inversion of PERP data (only) yields results that are more robust regarding 2D/3D artifacts than the 1D inversion of HCP data, or a joint inversion of HCP/PERP data. In conclusion, we propose that the 1D inversion of spatially densely sampled multi-frequency PERP data should be further evaluated in view of characterizing the lateral variations within the first 20 m of the subsurface because it could represent an efficient alternative to ERT methods in selected applications.&amp;#160;&amp;#160;&lt;/p&gt;

scholarly journals Observations of near surface wind speed, temperature and radiative budget at Dome C, Antarctic Plateau during 2005

2013 ◽  
Vol 26 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Stefania Argentini ◽  
Ilaria Pietroni ◽  
Giangiuseppe Mastrantonio ◽  
Angelo P. Viola ◽  
Guillaume Dargaud ◽  
...  
Keyword(s):  
Wind Speed ◽  
Potential Temperature ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Layer Growth ◽  
Near Surface ◽  
Mean Values ◽  
Thermal Inversion ◽  
Different Seasons ◽  
Almost All

AbstractThe annual and diurnal behaviours of near surface wind speed, temperature, and the radiative budget at Concordia Station (Dome C) in different seasons are shown. The wind speed was lowest in summer when a daily cycle was also observed. The largest mean values were concurrent with boundary layer growth in the afternoon. In winter and spring the wind speed reached the highest mean values. Perturbations in the wind flow were due to warming events which occurred periodically at Dome C. The lowest temperatures were in April and at the end of August. The coreless winter behaviour was perturbed by warming events which in many cases produced an increase in temperature of c. 20°C. The average temperature profiles show permanent thermal inversion, with the exception of a few hours in the afternoons during the summer. The strongest ground-based thermal inversions were observed in the polar winter. The largest potential temperature gradients were limited to a 30–40 m deep layer close to the surface. The net radiation was negative almost all the time with the exception of the period from mid-December to mid-January.

Interpreting Laser-Based Fault Localization Results: Case Studies

2019 ◽  
Author(s):  
Sukho Lee ◽  
John van den Biggelaar ◽  
Marc van Veenhuizen
Keyword(s):  
Case Studies ◽  
Circuit Design ◽  
High Sensitivity ◽  
Failure Behavior ◽  
Process Technology ◽  
Resistance Change ◽  
Voltage Imaging ◽  
Root Cause ◽  
First Case ◽  
Proper Interpretation

Abstract Laser-based dynamic analysis has become a very important tool for analyzing advanced process technology and complex circuit design. Thus, many good reference papers discuss high resolution, high sensitivity, and useful applications. However, proper interpretation of the measurement is important as well to understand the failure behavior and find the root cause. This paper demonstrates this importance by describing two insightful case studies with unique observations from laser voltage imaging/laser voltage probing (LVP), optical beam induced resistance change, and soft defect localization (SDL) analysis, which required an in-depth interpretation of the failure analysis (FA) results. The first case is a sawtooth LVP signal induced by a metal short. The second case, a mismatched result between an LVP and SDL analysis, is a good case of unusual LVP data induced by a very sensitive response to laser light. The two cases provide a good reference on how to properly explain FA results.

A Silicon Debugging Methodology on Customer Prototype for Wafer Foundries

2012 ◽  
Author(s):  
Mai Zhihong ◽  
Ng Tsu Hau ◽  
Dawood M. Khalid ◽  
Tan Pik Kee ◽  
Jeffrey Lam
Keyword(s):  
Case Studies ◽  
Semiconductor Industry ◽  
Full Information ◽  
Limited Information ◽  
Ip Protection ◽  
First Case ◽  
Silicon Debugging ◽  
Failure Location ◽  
Device Chip ◽  
Latch Up

Abstract IP protection is of major importance for a semiconductor company and only limited information is made available for device debugging for the product outsourced to a foundry. In order to position ourselves better in the ever competitive semiconductor industry, with the consideration of IP protection, we have to provide the customers with the Si debugging capability and device/chip verification services in foundry. This paper explores the Si debugging methodology and technique in a foundry. Two case studies are presented and discussed. The first case illustrates the isolation of the failure location by InGaAs microscopy, upon which the failure was identified to be caused by a latch-up issue. In the second case, due to confidentiality considerations from the customer, full information could not be provided to the foundry for silicon debugging. The paper illustrates the ability to effectively debug a failure despite being constrained by limited information from the customer.

Myths of the Underworld in Contemporary Culture

2019 ◽  
Author(s):  
Judith Fletcher
Keyword(s):  
Short Stories ◽  
Case Studies ◽  
Joseph Conrad ◽  
Ezra Pound ◽  
Border Crossing ◽  
First Century ◽  
Contemporary Culture ◽  
Cinematic Adaptation ◽  
Narrative Tradition ◽  
Wide Range

Stories of a visit to the realm of the dead and a return to the upper world are among the oldest narratives in European literature, beginning with Homer’s Odyssey and extending to contemporary culture. This volume examines a series of fictional works by twentieth- and twenty-first century authors, such Toni Morrison and Elena Ferrante, which deal in various ways with the descent to Hades. Myths of the Underworld in Contemporary Culture surveys a wide range of genres, including novels, short stories, comics, a cinematic adaptation, poetry, and juvenile fiction. It examines not only those texts that feature a literal catabasis, such as Neil Gaiman’s Sandman series, but also those where the descent to the underworld is evoked in more metaphorical ways as a kind of border crossing, for instance Salman Rushdie’s use of the Orpheus myth to signify the trauma of migration. The analyses examine how these retellings relate to earlier versions of the mythical theme, including their ancient precedents by Homer and Vergil, but also to post-classical receptions of underworld narratives by authors such as Dante, Ezra Pound, and Joseph Conrad. Arguing that the underworld has come to connote a cultural archive of narrative tradition, the book offers a series of case studies that examine the adaptation of underworld myths in contemporary culture in relation to the discourses of postmodernism, feminism, and postcolonialism.

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