Effects of large scale advection and small scale turbulence on vertical phytoplankton dynamics

2020 ◽  
Author(s):  
Vinicius Beltram Tergolina ◽  
Stefano Berti ◽  
Gilmar Mompean
Keyword(s):  
Large Scale ◽  
Vertical Mixing ◽  
Light Availability ◽  
Point Of View ◽  
Small Scale ◽  
Turbulent Diffusivity ◽  
Factors Affecting ◽  
Spatial And Temporal Scales ◽  
Formidable Challenge ◽  
Winter Convection

<p>When studying the life cycle of phytoplankton frequently one is interested in the survival or death conditions of a population (bloom/no bloom). These dynamics have been studied extensively in the literature through a range of modelling scenarios but in summary the main factors affecting the vertical dynamics are: Water column mixing intensity, solar energy distribution, nutrients availability and predatory activity. The later two can be represented by different biological models whereas the vertical mixing is usually parameterized by a diffusive process. Even though turbulence has been recognized as a paramount factor in the survival dynamics of sinking phytoplankton species, dealing with the multi scale nature of turbulence is a formidable challenge from the modelling point of view. In addition, convective motions are being recognized to play a role in the survival of phytoplankton throughout winter stocking. With this in mind, in this work we revisit a theoretically appealing  model for phytoplankton vertical dynamics with turbulent diffusivity and numerically study how large-scale fluid motions affect its survival and extinction conditions. To achieve this and to work with realistic parameter values, we adopt a kinematic flow field to account for the different spatial and temporal scales of turbulent motions. The dynamics of the population density are described by a reaction-advection-diffusion model with a growth term proportional to sun light availability. Light depletion is modelled accounting for water turbidity and plankton self-shading; advection is represented by a sinking speed and a two-dimensional, multiscale, chaotic flow. Preliminary results show that under appropriate conditions for the flow, our model reproduces past results based on turbulent diffusivity. Furthermore, the presence of large scale vortices (such as those one might expect during winter convection) seems to hinder survival, an effect that is partially mitigated by turbulent  diffusion.</p>

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

scholarly journals Dependence of Model Energy Spectra on Vertical Resolution

2016 ◽  
Vol 144 (4) ◽  
pp. 1407-1421 ◽  
Author(s):  
Michael L. Waite
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Vertical Mixing ◽  
Energy Spectra ◽  
Small Scale ◽  
Rossby Number ◽  
Vertical Resolution ◽  
Wide Range ◽  
Qualitative Shape ◽  
Vertical Grid

Abstract Many high-resolution atmospheric models can reproduce the qualitative shape of the atmospheric kinetic energy spectrum, which has a power-law slope of −3 at large horizontal scales that shallows to approximately −5/3 in the mesoscale. This paper investigates the possible dependence of model energy spectra on the vertical grid resolution. Idealized simulations forced by relaxation to a baroclinically unstable jet are performed for a wide range of vertical grid spacings Δz. Energy spectra are converged for Δz 200 m but are very sensitive to resolution with 500 m ≤ Δz ≤ 2 km. The nature of this sensitivity depends on the vertical mixing scheme. With no vertical mixing or with weak, stability-dependent mixing, the mesoscale spectra are artificially amplified by low resolution: they are shallower and extend to larger scales than in the converged simulations. By contrast, vertical hyperviscosity with fixed grid-scale damping rate has the opposite effect: underresolved spectra are spuriously steepened. High-resolution spectra are converged except for the stability-dependent mixing case, which are damped by excessive mixing due to enhanced shear over a wide range of horizontal scales. It is shown that converged spectra require resolution of all vertical scales associated with the resolved horizontal structures: these include quasigeostrophic scales for large-scale motions with small Rossby number and the buoyancy scale for small-scale motions at large Rossby number. It is speculated that some model energy spectra may be contaminated by low vertical resolution, and it is recommended that vertical-resolution sensitivity tests always be performed.

scholarly journals Modeling the Ocean in Climate Studies

1984 ◽  
Vol 5 ◽  
pp. 133-140 ◽  
Author(s):  
Albert J. Semtner
Keyword(s):  
Turbulent Mixing ◽  
Large Scale ◽  
Deep Convection ◽  
Vertical Mixing ◽  
Mesoscale Eddies ◽  
Small Scale ◽  
Polar Regions ◽  
Sea Ice Extent ◽  
Modeling Strategy ◽  
Climate Studies

A number of processes in the ocean must be modeled properly in order to produce valid estimates of oceanic heat transport, sea-surface temperature, and sea-ice extent in climate studies. These include: wind-driven turbulent mixing and water transport in the surface layer, internal vertical mixing due to several small-scale mechanisms, horizontal and vertical exchanges by mesoscale eddies, mixing along isopycnals, large-scale transport by currents, deep convection in polar regions, and boundary exchanges with atmosphere, ice, and land. Techniques to model these processes are described. Prospects are given for parameterizing the effects of phenomena that cannot be resolved in climate studies, particularly mesoscale eddies. Past simulations of the ocean in climate studies are reviewed. A modeling strategy is outlined for an improved treatment of the ocean, consistent with the computational power soon to be available.

scholarly journals Experimental insights into consolidation rates during one-dimensional loading with special reference to excess pore water pressure

2020 ◽  
Vol 15 (12) ◽  
pp. 3571-3591
Author(s):  
Bartłomiej Szczepan Olek
Keyword(s):  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Small Scale ◽  
Coefficient Of Consolidation ◽  
Consolidation Process ◽  
Factors Affecting ◽  
Fine Grained ◽  
Fine Grained Soil

AbstractConsolidation rate has significant influence on the settlement of structures founded on soft fine-grained soil. This paper presents the results of a series of small-scale and large-scale Rowe cell consolidation tests with pore water pressure measurements to investigate the factors affecting the consolidation process. Permeability and creep/resistance structure factors were considered as the governing factors. Intact and reconstituted marine clay from the Polish Carpathian Foredeep basin as well as clay–sand mixtures was examined in the present study. The fundamental relationship correlating consolidation degrees based on compression and pore water pressure was assessed to indicate the nonlinear soil behaviour. It was observed that the instantaneous consolidation parameters vary as the process progresses. The instantaneous coefficient of consolidation first drastically increases or decreases with increase in the degree of consolidation and stabilises in the middle stage of the consolidation; it then decreases significantly due to viscoplastic effects occurring in the soil structure. Based on the characteristics of the relationship between coefficient of consolidation and degree of dissipation at the base, the consolidation range that complies with theoretical assumptions was established. Furthermore, the influence of coarser fraction in clay–sand mixtures in controlling the consolidation rates is discussed.

scholarly journals Impact of Japanese Post-Disaster Temporary Housing Areas’ (THAs) Design on Mental and Social Health

2019 ◽  
Vol 16 (23) ◽  
pp. 4757 ◽  
Author(s):  
Bris ◽  
Bendito
Keyword(s):  
Large Scale ◽  
Point Of View ◽  
Vulnerable Groups ◽  
Small Scale ◽  
Temporary Housing ◽  
Organization And Management ◽  
Kobe Earthquake ◽  
Management Measures ◽  
The Social ◽  
Post Disaster

The phenomenon named kodokushi, meaning death alone without the care or company of anyone inside temporary housing, appeared after the Kobe earthquake in Japan in 1995 with some 250 cases. This paper analyzes the evolution of Japanese temporary houses—to attempt to prevent the problem of kodokushi—from the point of view of management, how services and activities are organized, and design. We will use case studies as our methodological tool, analyzing the responses in 1995 Kobe (50,000 THs), 2004 Chūetsu (3000 THs), 2011 Tōhoku (50,000 THs), and 2016 Kumamoto (4000 THs). This article shows how the Japanese THAs follow a single design that has undergone very little variation in the last 25 years, a design which promotes the social isolation of their residents, making recovery—from the psychological perspective—and helping the most vulnerable members of society, more difficult. In small scale disasters (Chūetsu) applying organization and management measures was able to correct the problems caused by design and there were no cases of kodokushi: in large-scale disasters (Tōhoku), however, the difficulties to implement the same measures resulted in the reappearance of new cases at rates similar to Kobe’s. Our main conclusion is that the design of Japanese THAs must be reconsidered and changed to respond to the real needs of the most vulnerable groups.

This Too is Music

2019 ◽  
Author(s):  
Rena Upitis
Keyword(s):  
Large Scale ◽  
Point Of View ◽  
Small Scale ◽  
Classroom Environments ◽  
Approaches To Teaching ◽  
Music Making ◽  
And Performance ◽  
And Mathematics ◽  
Traditional Approaches ◽  
Teaching Ideas

This Too Is Music guides and motivates teachers to foster classroom conditions that enable elementary students to thrive as improvisers, critical listeners, performers, and composers. Using anecdotes and illustrated with musical examples, the book explores how these aspects of music making are intertwined and quells any doubts teachers may have regarding their abilities to create an environment where children can improvise, dance, compose, and notate their musical offerings. While the book acknowledges the importance of traditional approaches to teaching notation and performance, its emphasis is on the student’s point of view, illustrating how young musicians can learn when their musical ideas are honored and celebrated. Various teaching ideas are presented; some are exploratory in nature, and others involve direct instruction. Regardless of their nature, all of the activities arise from research on children’s musical development in general and their development of notational systems in particular, and they have been tested in multiple elementary-classroom environments and preservice settings. The activities center on engaging with music through movement, performing, singing, improvising, composing, developing notational skills, and appealing to children across subjects, including language, drama, and mathematics. Activities encompass both small-scale classroom lessons and large-scale productions. This pedagogy has a timeless quality; even in our digital age, this musical environment appeals to children. The book invites readers to adapt the ideas to their own teaching settings, showing both preservice and established teachers that they can teach music creatively to build community and to inspire all who enter there.

Energy Use in the Japanese Copper Industry from the Meiji Period to World War I

2020 ◽  
Vol 9 (1) ◽  
pp. 82-109
Author(s):  
Asuka Yamaguchi
Keyword(s):  
World War I ◽  
Large Scale ◽  
Energy Use ◽  
Point Of View ◽  
Energy Sources ◽  
Small Scale ◽  
World War ◽  
Product Usage ◽  
Meiji Period ◽  
Financial Power

Abstract In recent years, energy constraints have been discussed from a historical point of view. This study aims at examining the copper industry’s energy use in Japan from the Meiji period to the time of World War I and clarifying the process of, and reasons for, the selection of energy sources. This study considered not only energy use in the large-scale mines but also energy use in the small-scale mines and miners’ homes. As a result, it was clarified that the mines changed into a space that was based on a diverse combination of energy sources, depending on differences in location (access to energy), natural conditions, financial power, the required amount and price of energy, energy use technologies, ore quality, and end product (usage).

scholarly journals The Production and Dissipation of Compensated Thermohaline Variance by Mesoscale Stirring

2009 ◽  
Vol 39 (10) ◽  
pp. 2477-2501 ◽  
Author(s):  
K. Shafer Smith ◽  
Raffaele Ferrari
Keyword(s):  
Large Scale ◽  
Vertical Mixing ◽  
Small Scale ◽  
Vertical Diffusion ◽  
The North ◽  
Salinity Gradients ◽  
Scale Temperature ◽  
The Mean ◽  
Geostrophic Turbulence ◽  
Quasigeostrophic Model

Abstract Temperature–salinity profiles from the region studied in the North Atlantic Tracer Release Experiment (NATRE) show large isopycnal excursions at depths just below the thermocline. It is proposed here that these thermohaline filaments result from the mesoscale stirring of large-scale temperature and salinity gradients by geostrophic turbulence, resulting in a direct cascade of thermohaline variance to small scales. This hypothesis is investigated as follows: Measurements from NATRE are used to generate mean temperature, salinity, and shear profiles. The mean stratification and shear are used as the background state in a high-resolution horizontally homogeneous quasigeostrophic model. The mean state is baroclinically unstable, and the model produces a vigorous eddy field. Temperature and salinity are stirred laterally in each density layer by the geostrophic velocity and vertical advection is by the ageostrophic velocity. The simulated temperature–salinity diagram exhibits fluctuations at depths just below the thermocline of similar magnitude to those found in the NATRE data. It is shown that vertical diffusion is sufficient to absorb the laterally driven cascade of tracer variance through an amplification of filamentary slopes by small-scale shear. These results suggest that there is a strong coupling between vertical mixing and horizontal stirring in the ocean at scales below the deformation radius.

Variable discharge alters habitat suitability for benthic algae and cyanobacteria in a forested Mediterranean stream

2010 ◽  
Vol 61 (4) ◽  
pp. 441 ◽  
Author(s):  
Elisabet Tornés ◽  
Sergi Sabater
Keyword(s):  
Water Flow ◽  
Large Scale ◽  
Light Availability ◽  
Benthic Algae ◽  
High Water ◽  
Algal Community ◽  
Small Scale ◽  
Low Velocity ◽  
Substratum Type ◽  
Mediterranean Stream

Large-scale algal community patterns can be understood by studying organisation within patches. Spatial heterogeneity in light and substratum type may affect the biomass and community composition of benthic algae and cyanobacteria. We compared the effects of these factors at the species level in two reaches differing in canopy cover in a forested Mediterranean stream in winter (high water flow) and late spring (low water flow). Partial redundancy analyses revealed that the major determinants of species distribution were strongly associated with variations in measured environmental variables. Light availability, the Reynolds number and substratum type were the main factors accounting for the algal and cyanobacterial distribution. Factors affecting algal distribution varied between hydrological periods, suggesting that some species had specific requirements whereas others had a wider tolerance to environmental conditions. Our results demonstrated that the hydraulic conditions (low velocity v. high velocity) influence small-scale heterogeneity in streams, and that this affects benthic community distribution.

scholarly journals The first century of Phalaris aquatica L. cultivation and genetic improvement: a review

2009 ◽  
Vol 60 (1) ◽  
pp. 1 ◽  
Author(s):  
R. N. Oram ◽  
V. Ferreira ◽  
R. A. Culvenor ◽  
A. A. Hopkins ◽  
A. Stewart
Keyword(s):  
South Africa ◽  
New Zealand ◽  
Large Scale ◽  
Small Scale ◽  
Scale Production ◽  
Department Of Agriculture ◽  
Factors Affecting ◽  
Phalaris Aquatica ◽  
Seed Retention ◽  
The Usa

2006 marked the centenary of the commercial propagation of phalaris (Phalaris aquatica L.) as a cultivated pasture plant, firstly in Australia, and soon after in New Zealand, South Africa, and North and South America. Small-scale evaluation of cv. Australian began in the Toowoomba Botanic Gardens, Queensland, in 1884. The first recorded large-scale production of seed was at the Glen Innes Research Farm of the NSW Department of Agriculture in February 1906. By 1908–15, several graziers in Australia and New Zealand sold seed widely within Australia, New Zealand, USA, Argentina, and South Africa. Factors affecting the utilisation of the original cultivar in Australia over the first half-century are reviewed. Thereafter, the need to extend the area of perennial pastures into regions unsuitable for cv. Australian led CSIRO and the US Department of Agriculture to collect germplasm widely in the Mediterranean region. Selection between and within Moroccan populations produced cvv. Sirocco and El Golea in Australia, and cv. Perla koleagrass in the USA. In Argentina, selection within cv. Australian produced the very successful, seed-retaining cv. Pergamino El Gaucho INTA, which was re-selected in Australia to produce cv. Seedmaster. The discovery of a single seed-retaining plant within a certified line of cv. Australian gave cv. Uneta, which had excellent seed retention because the rachillae of most seeds remained intact at maturity. In Australia, selection in populations derived from crosses between cv. Australian and Mediterranean ecotypes gave a succession of winter-active cultivars: Sirosa, Sirolan, Holdfast, Landmaster, Atlas PG, Advanced AT, and Holdfast GT. The latter 5 have Uneta-type seed retention, reduced tryptamine and tyramine alkaloids, and adaptation to different soil and climatic niches. Populations for the hotter, drier inland slopes of NSW are being field-tested. Also, a promising but unstable semi-dwarf line has been found: dwarfism appears to be caused by a transposable element. Breeding and selection programs in Argentina, several states of the USA, New Zealand, Israel, Tunisia, and Greece also produced cultivars with specific adaptations. Active breeding programs are continuing at Ardmore, OK, USA, and Pergamino, Argentina. A major remaining obstacle to the further improvement and utilisation of phalaris is the unknown chemical nature of the toxin(s) causing ‘sudden death’, which temporarily interfere with nitrogen metabolism in the brains of herbivores, especially ruminants.

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