scholarly journals Applicability of Calculation Formulae of Impact Force by Tsunami Driftage

2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
Yoshimichi Yamamoto ◽  
Yuji Kozono ◽  
Erick Mas ◽  
Fumiya Murase ◽  
Yoichi Nishioka ◽  
...  
Keyword(s):  
Large Scale ◽  
Impact Force ◽  
Numerical Models ◽  
Indian Ocean Tsunami ◽  
Tsunami Waves ◽  
Secondary Damage ◽  
The Pacific ◽  
American Society ◽  
The Impact ◽  
Civil Engineers

The aftermath of the Indian Ocean tsunami on 26 December 2004 triggered by the off Sumatra earthquake (magnitude “M” = 9.1), and the Great East Japan earthquake of 11 March 2011 off the Pacific coast of Tohoku (M = 9.0), evidence the secondary damage from driftage collision due to large tsunami waves. To prevent this type of damage, the establishment of methods for predicting driftage movement and calculating the impact force by driftage is necessary. Several numerical models have been developed to predict the driftage movement of objects. Every year, these improve in accuracy and usability. In contrast, there are many calculation formulae for calculating the impact force. However, since there are considerable differences between values calculated using these formulae, the reliability of each formula is unknown. Therefore, in this research, one team of the committee on tsunami research of the Japan Society of Civil Engineers summarizes the main calculation formulae of impact forces that have been proposed until 2019. In addition, for each type of driftage (driftwood, containers, cars, ships), we compare calculation values of these formulae with measured data of large-scale experiments. Finally, we check the range of calculation values for each formula up to 15 m/s in collision velocity and clarify then the following facts: (1) In the case of driftwood, the formulae of Matsutomi, Federal Emergency Management Agency (FEMA) and National Oceanic and Atmospheric Administration (NOAA), and American Society of Civil Engineers (ASCE) are most reliable; (2) In the case of containers, the formulae of Matsutomi, Arikawa et al., FEMA and NOAA, Ikeno et al., and ASCE are most reliable; (3) In the case of cars, the formulae of FEMA and NOAA, and ASCE are most reliable; (4) In the case of ships, the formulae of Mizutani, FEMA and NOAA, and ASCE are most reliable.

The importance of phase morphology for rheology of ferropericlase-bridgmanite mixtures

2021 ◽  
Author(s):  
Marcel Thielmann ◽  
Gregor Golabek ◽  
Hauke Marquardt
Keyword(s):  
Lower Mantle ◽  
Mantle Convection ◽  
Effective Viscosity ◽  
Large Scale ◽  
Numerical Models ◽  
Phase Morphology ◽  
Strong Impact ◽  
Analytical Approximations ◽  
The Impact ◽  
Strong Control

<p>The rheology of the Earth’s lower mantle is poorly constrained due to a lack of knowledge of the rheological behaviour of its constituent minerals. In addition, the lower mantle does not consist of only a single, but of multiple mineral phases with differing deformation behaviour. The rheology of Earth’s lower mantle is thus not only controlled by the rheology of its individual constituents (bridgmanite and ferropericlase), but also by their interplay during deformation. This is particularly important when the viscosity contrast between the different minerals is large. Experimental studies have shown that ferropericlase may be significantly weaker than bridgmanite and may thus exert a strong control on lower mantle rheology.</p><p>Here, we thus explore the impact of phase morphology on the rheology of a ferropericlase-bridgmanite mixture using numerical models. We find that elongated ferropericlase structures within the bridgmanite matrix significantly lower the effective viscosity, even in cases where no interconnected network of weak ferropericlase layers has been formed. In addition to the weakening, elongated ferropericlase layers result in a strong viscous anisotropy. Both of these effects may have a strong impact on lower mantle dynamics, which makes is necessary to develop upscaling methods to include them in large-scale mantle convection models. We develop a numerical-statistial approach to link the statistical properties of a ferropericlase-bridgmanite mixture to its effective viscosity tensor. With this approach, both effects are captured by analytical approximations that have been derived to describe the evolution of the effective viscosity (and its anisotropy) of a two-phase medium with aligned elliptical inclusions, thus allowing to include these microscale processes in large-scale mantle convection models.</p>

Intraseasonal Transitions of the Wintertime Pacific Jet Stream

2020 ◽  
Author(s):  
Maria Madsen ◽  
Jonathan Martin
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Weather Prediction ◽  
Intraseasonal Variability ◽  
Extreme Weather Events ◽  
Jet Stream ◽  
The Pacific ◽  
Basin Scale ◽  
Jet Variability ◽  
The Impact

<p>The deficiency in predictability at subseasonal-to-seasonal timescales, as compared to prediction at conventional weather prediction timescales, is significant. Intraseasonal variability of atmospheric features like the jet stream, occurring within this gap, lead to extreme weather events that present considerable hazards to society. As jets are an important feature at the interface of the large-scale general circulation and the life cycle of individual weather systems, there is strong incentive to more comprehensively understand their variability.</p><p>The wintertime Pacific jet manifests its intraseasonal variability in two predominant modes: a zonal extension or retraction and a meridional shift by as much as 20° of the jet exit region. These two leading modes are associated with basin-scale anomalies in the Pacific that directly impact weather in Hawaii and continental North America. Although recent work has demonstrated the impact intramodal changes of the Pacific jet have on large-scale structure, sensible weather phenomena, and forecast skill in and around the vast North Pacific Basin, the transitions between the leading modes have hardly been considered and, therefore, are poorly understood. Consequently, this work examines the nature and predictability of transitions between modes of wintertime Pacific jet variability as well as their associated synoptic environments.</p><p>We apply two distinct but complementary statistical analyses to 70 cold seasons (NDJFM 1948/49-2017/18) of daily 250-hPa zonal winds from the NCEP/NCAR Reanalysis to investigate such transitions. Empirical orthogonal analysis (EOF)/principal component (PC) analysis is used to depict the state of the daily Pacific jet as a point in a two dimensional phase space defined by the two leading modes.  Supporting this technique is a self-organizing maps (SOMs) analysis that identifies non-orthogonal, synoptically recurring patterns of the Pacific jet. Together, these analyses show that there are, in fact, preferred transitions between these leading modes of variability. Composite and individual case analyses of preferred transition evolutions provides new insight into the synoptic-scale environments that drive Pacific jet variability.</p>

Diverse and Transnational: Chinese (PRC) Immigrants in the United States

2007 ◽  
Vol 3 (1) ◽  
pp. 122-145 ◽  
Author(s):  
Xia-Huang Yin
Keyword(s):  
United States ◽  
Large Scale ◽  
The United States ◽  
Immigrant Group ◽  
Recent Immigrants ◽  
American Experience ◽  
The Pacific ◽  
Socioeconomic Diversity ◽  
American Society ◽  
The U.S

AbstractThis article studies characteristics of recent immigrants from China (PRC) in the United States, especially their socioeconomic status and networking with their native land. The unprecedented, large-scale, and highly diversified immigration from China to the U.S. since the late 1970s has not only turned the Chinese into the second largest immigrant group in American society, but has also created new opportunities for interpretation of the Chinese diasporic experience. By examining the socioeconomic diversity among PRC immigrants in their American life and the extensive networks they have established across the Pacific, the article shows how class, ethnicity, and transnationality work at cross purposes in the Chinese American experience and sheds light on the new dynamics in overseas Chinese communities in this rapidly changing era.

scholarly journals FINAL DESIGN OF THE NAGS HEAD BEACH NOURISHMENT PROJECT USING A LONGSHORE NUMERICAL MODEL

2012 ◽  
Vol 1 (33) ◽  
pp. 64 ◽  
Author(s):  
Haiqing Liu Kaczkowski ◽  
Timothy W Kana
Keyword(s):  
Numerical Model ◽  
Large Scale ◽  
Numerical Models ◽  
Normal Wave ◽  
Beach Nourishment ◽  
Shoreline Evolution ◽  
Longshore Transport ◽  
Final Design ◽  
Model Setup ◽  
The Impact

Nags Head, located at the northeastern part of North Carolina in the U.S., has sustained chronic erosion over the past 50 years. In 2005, Coastal Science & Engineering (CSE) was retained by the town of Nags Head to develop an interim beach restoration plan. Profile volume change was used in the planning and preliminary design of the project, and longshore and cross-shore numerical models were used in the final design to refine the preliminary nourishment plan and increase potential longevity of the project. This paper focuses on the key factors of the longshore numerical model setup for the project. These include model selection, input data and parameters, model calibration, and applications under different design alternatives. The Generalized Model for Simulating Shoreline Changes (GENESIS) was used in this study to evaluate shoreline evolution under normal wave conditions during various stages of the design life following the beach nourishment project. The model was used to identify the potential occurrence of erosional hotspots and to optimize the nourishment design so that the effects of such hotspots could be avoided or minimized where possible. Model results were also used to evaluate the impact of borrow area dredging on longshore transport in the project area and the impact of nourishment on shoaling in the adjacent inlet. The project encompasses 10.11 miles (mi) (16.28 kilometers-km) of ocean shoreline, and the design nourishment volume is based on the total permitted volume of 4 million cubic yards (cy) (3 million cubic meters-m³). [Note: As-built length was 10.0 mi and volume was 4.615 million cubic yards.] The final design has fill densities varying from north to south in relation to historical erosion rates and model projections. The average fill density is 75 cubic yards per foot (cy/ft) (188 m³/m) and ranges from 38 cy/ft to 150 cy/ft (95 m³/m to 375 m³/m). In conclusion, it is shown that the numerical model selected in this study was capable of predicting the overall performance of the large scale beach nourishment project in Nags Head as well as the performance at a particular location within or adjacent to the project, and its design methods can offer guidance to future projects.

scholarly journals Cultures of light: Electric light in the United States, 1890s-1950s

2021 ◽  
Author(s):  
◽  
Margaret Maile Petty
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Large Scale ◽  
Cultural Beliefs ◽  
The United States ◽  
Light Industry ◽  
Electric Light ◽  
American Society ◽  
The Individual ◽  
The Impact

<p>Cultures of Light is set within a period that stretches from the late nineteenth to the mid-twentieth century in the United States, an era in which nearly every aspect of American life was impacted to a lesser or greater degree by the introduction, distribution and integration of electric power and light. By no means attempting to comprehensively examine the impact and effects of this expansive transformation, this thesis has a narrow but meaningful target, defined by key intersections of electric lighting and American culture. Primarily concerned with the investigation of culturally bound ideas and practices as mediated through electric light and its applications, my thesis is focused on particular instances of this interplay. These include its role in supporting nationalizing narratives and agendas through large-scale demonstrations at world’s fairs and exhibitions, in the search for and expression of modernism and its variations in the United States. Similarly electricity and electric light throughout the better part of the twentieth century was scaled to the level of the individual through a number of mechanisms and narratives. Most prominently the electric light industry employed gendered discourses, practices and beliefs in their efforts to grow the market, calling upon the assistance of a host of cultural influencers, from movie stars to architects to interior designers, instigating a renegotiation of established approaches to the design of architecture and the visual environment. Connecting common themes and persistent concerns across these seemingly disparate subject areas through the examination of cultural beliefs, practices, rituals and traditions, Cultures of Light seeks to illustrate the deep and lasting significance of electric light within American society in the twentieth century.</p>

The impact of ENSO and the Atlantic Multidecadal Variability (AMV) on the upper tropospheric large scale flow in the PRIMAVERA models.

2020 ◽  
Author(s):  
Paolo Ghinassi ◽  
Federico Fabiano ◽  
Virna L. Meccia ◽  
Susanna Corti
Keyword(s):  
Rossby Wave ◽  
Large Scale ◽  
Rossby Waves ◽  
Wave Activity ◽  
Transient Wave ◽  
Weather Regime ◽  
Weather Regimes ◽  
The Pacific ◽  
Large Scale Flow ◽  
The Impact

&lt;p&gt;Rossby waves play a fundamental role for both climate and weather. They are in fact associated with heat, momentum and moisture transport across large distances and with different types of weather at the surface. Assessing how they are represented in climate models is thus of primary importance to understand both predictability and the present and future climate. In this study we investigate how ENSO and the AMV affect the large scale flow pattern in the upper troposphere of the Northern Hemisphere, using reanalysis data and data from the PRIMAVERA simulations.&lt;/p&gt;&lt;p&gt;The upper tropospheric large scale flow is investigated in terms of the Rossby wave activity associated with persistent and recurrent patterns over the Pacific-North American and Euro-Atlantic regions during winter, the so called weather regimes. In order to quantify the vigour of Rossby wave activity associated with each weather regime we make use of a recently developed diagnostic based on Finite Amplitude Local Wave Activity in isentropic coordinates, partitioning the total wave activity into the stationary and transient components. The former is associated with quasi-stationary, planetary Rossby waves, whereas the latter is associated with synoptic scale Rossby wave packets. This allows one to quantify the contribution from stationary versus transient eddies in the total Rossby wave activity linked to each weather regime.&lt;/p&gt;&lt;p&gt;In this study we explore how ENSO and the AMV affect both the weather regimes frequencies and the upper tropospheric waviness in the Pacific and Atlantic storm tracks, respectively. Furthermore we analyse how both the stationary and transient wave activity component modulate the onset and transition between different regimes.&lt;/p&gt;

scholarly journals How Momentum Coupling Affects SST Variance and Large-Scale Pacific Climate Variability in CESM

2018 ◽  
Vol 31 (7) ◽  
pp. 2927-2944 ◽  
Author(s):  
Sarah M. Larson ◽  
Daniel J. Vimont ◽  
Amy C. Clement ◽  
Ben P. Kirtman
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Ocean Dynamics ◽  
Easterly Wind ◽  
Tropical Forcing ◽  
Freshwater Fluxes ◽  
The Pacific ◽  
Anomalous Wind ◽  
Momentum Coupling ◽  
The Impact

The contribution of buoyancy (thermal + freshwater fluxes) versus momentum (wind driven) coupling to SST variance in climate models is a longstanding question. Addressing this question has proven difficult because a gap in the model hierarchy exists between the fully coupled (momentum + buoyancy + ocean dynamics) and slab–mixed layer ocean coupled (thermal with no ocean dynamics) versions. The missing piece is a thermally coupled configuration that permits anomalous ocean heat transport convergence decoupled from the anomalous wind stress. A mechanically decoupled model configuration is provided to fill this gap and diagnose the impact of momentum coupling on SST variance in NCAR CESM. A major finding is that subtropical SST variance increases when momentum coupling is disengaged. An “opposing flux hypothesis” may explain why the subtropics (midlatitudes) experience increased (reduced) variance without momentum coupling. In a subtropical easterly wind regime, Ekman fluxes [Formula: see text] oppose thermal fluxes [Formula: see text], such that when the air and sea are mechanically decoupled [Formula: see text], [Formula: see text] variance increases. As a result, SST variance increases. In a midlatitude westerly regime where [Formula: see text] and [Formula: see text] typically reinforce each other, SST variance is reduced. Changes in mean surface winds with climate change could impact the [Formula: see text] and [Formula: see text] covariance relationships. A by-product of mechanically decoupling the model is the absence of ENSO variability. The Pacific decadal oscillation operates without momentum coupling or tropical forcing, although the pattern is modified with enhanced (reduced) variability in the subtropics (midlatitudes). Results show that Ekman fluxes are an important component to tropical, subtropical, and midlatitude SST variance.

Modeling of Tsunami Propagation in the Vicinity of the Southern Coasts of Iran

2007 ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Moharram D. Pirooz ◽  
Nasser H. Zaker ◽  
Mohammad Mokhtari
Keyword(s):  
Indian Ocean ◽  
Subduction Zone ◽  
Initial Conditions ◽  
Indian Ocean Tsunami ◽  
Height Distribution ◽  
Tsunami Propagation ◽  
Makran Subduction Zone ◽  
Tsunami Waves ◽  
The Indian Ocean ◽  
The Impact

The extensive death toll and sever economical damages brought by the 2004 Indian Ocean tsunami has emphasized the urgent need for assessing the hazard of tsunami in this ocean, and determining the most vulnerable coastlines to the impact of possible tsunami. In this paper the hazard of tsunami for southern coasts of Iran bordering the Indian Ocean is discussed. At first, historical data of tsunami occurrences on the Iranian southern coasts are collected, described and analyzed. Then, numerical simulation of potential tsunamis in the Makran subduction zone is performed and the tsunami wave height distribution along the Iranian coast is calculated. The Makran subduction zone is among two main tsunamigenic zones in the Indian Ocean. In this zone the Oman oceanic plate subducts beneath the Iranian Micro-plate at an estimated rate of about 19 mm/yr. Historically, there is the potential for tsunami generation in this region and several tsunamis attacked the Makran coastlines in the past. The most recent tsunami in this region has occurred on 28 November 1945 which took the lives of more than 4000 people in the coasts of Iran, Pakistan, India, and Oman. Here we examine the seafloor uplift of the Makran zone and its potential for generating destructive tsunamis in the southern coastlines of Iran. Several earthquake scenarios with moment magnitudes ranging between 6.5 and 8.5 are used as initial conditions for analysis. For scenario of an earthquake with magnitude of 8.0, propagation of tsunami waves on coastlines and wave time histories in selected reference locations are calculated.

scholarly journals Structure of the Pacific Walker Circulation Depicted by the Reanalysis and CMIP6

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1219
Author(s):  
Emmanuel Olaoluwa Eresanya ◽  
Yuping Guan
Keyword(s):  
Large Scale ◽  
Structural Changes ◽  
Numerical Models ◽  
Walker Circulation ◽  
Future Climate Change ◽  
Western Boundary ◽  
Extreme Caution ◽  
The Pacific ◽  
Mean State

The Pacific Walker circulation (PWC) is one of the most important components of large-scale tropical atmospheric circulations. The PWC and its influences have been studied extensively by numerical models and reanalysis. The newly released ERA5 and NCEP2 are the most widely used reanalysis datasets and serve as benchmarks for evaluation of model simulations. If the results of these datasets differ significantly, this could lead to a bias in projected long-term climate knowledge. For better understanding of future climate change, it is necessary to evaluate PWC reanalysis productions. As a result, we compared the PWC structures between the ERA5 and NCEP2 datasets from month to seasonal time scales. We used the zonal mass streamfunction (ZMS) over the equatorial Pacific to indicate the strength of the PWC. The PWC’s average monthly or seasonal cycle peaks around July. From February to June, the NCEP2 shows a higher PWC intensity, whereas the ERA5 shows greater intensity from July to December. The circulation center in the NCEP2 is generally stronger and wider than in the ERA5. The ERA5, however, revealed that the PWC’s west edge (zero line of ZMS over the western Pacific) had moved 10 degrees westward in comparison to the NCEP2. In addition, we compared the PWC mean state in the reanalysis and CMIP6 models; the mean state vertical structures of the tropical PWC in the CMIP6 multi-model ensemble (MME) are similar to those of the reanalyses in structure but weaker and wider than in the two reanalysis datasets. The PWC is broader in CMIP6, and the western boundary is 7 and 17 degrees farther west than in the ERA5 and NCEP2, respectively. This study suggests that, when using reanalysis datasets to evaluate PWC structural changes in intensity and western edge, extreme caution should be exercised.

scholarly journals Experimental Studies on a Powder-Snow Avalanche

1989 ◽  
Vol 13 ◽  
pp. 129-134 ◽  
Author(s):  
K. Kawada ◽  
K. Nishimura ◽  
N. Maeno
Keyword(s):  
Large Scale ◽  
Impact Force ◽  
Experimental Studies ◽  
Block Type ◽  
Impact Forces ◽  
Wave Forms ◽  
The Impact ◽  
Force Data

To make clear the structure and behaviour of a large-scale avalanche, the impact force-data obtained in the avalanche project of 1972–78 were analysed in detail. The wave forms of impact forces are classified into two types. Type 1 is composed of many separate spikes each of which represents the collision of a snow block. Type 2 has wider peaks, caused by collisons of snow blocks mixed with fluidized snow. Most of the type 1 peaks were in the width range corresponding to 0.005–0.01 s duration, and most type 2 peaks fell into the 0.02–0.1 s range.The internal velocities of an avalanche were estimated by calculating cross-correlation spectra for a time series of impact-force records. It was discovered that these internal velocities varied from 10 to 50 m/s over time. The mean distance between snow blocks was found to be in the range 1.6–5.4 m in a type 1 avalanche, and between 0.7 and 3 m in type 2 avalanches. Sizes of snow blocks or snow clouds of type 1 and type 2 were in ranges 0.26–0.52 and 0.37–1.9 m, respectively.This paper also reports on the project created to initiate artificial powder-snow avalanches in the Shiai-dani area and to make systematic observations of a variety of physical aspects. Results obtained in 1988 for both artificial and natural avalanches are given.

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