Persistent magnetic vortex flow at a supergranular vertex

Context. Photospheric vortex flows are thought to play a key role in the evolution of magnetic fields. Recent studies show that these swirling motions are ubiquitous in the solar surface convection and occur in a wide range of temporal and spatial scales. Their interplay with magnetic fields is poorly characterized, however. Aims. We study the relation between a persistent photospheric vortex flow and the evolution of a network magnetic element at a supergranular vertex. Methods. We used long-duration sequences of continuum intensity images acquired with Hinode and the local correlation-tracking method to derive the horizontal photospheric flows. Supergranular cells are detected as large-scale divergence structures in the flow maps. At their vertices, and cospatial with network magnetic elements, the velocity flows converge on a central point. Results. One of these converging flows is observed as a vortex during the whole 24 h time series. It consists of three consecutive vortices that appear nearly at the same location. At their core, a network magnetic element is also detected. Its evolution is strongly correlated to that of the vortices. The magnetic feature is concentrated and evacuated when it is caught by the vortices and is weakened and fragmented after the whirls disappear. Conclusions. This evolutionary behavior supports the picture presented previously, where a small flux tube becomes stable when it is surrounded by a vortex flow.

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No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽

10.3390/data6010004 ◽

2021 ◽

Vol 6 (1) ◽

pp. 4

Author(s):

Evgeny Mikhailov ◽

Daniela Boneva ◽

Maria Pashentseva

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Large Scale ◽

Point Of View ◽

Accretion Discs ◽

Wide Range ◽

Astrophysical Objects ◽

Alpha Effect ◽

The Stability ◽

The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

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NEW CHALLENGES FACING INTEGRATIVE BIOLOGICAL SCIENCE IN THE POST-GENOMIC ERA

Journal of Biological System ◽

10.1142/s0218339006001805 ◽

2006 ◽

Vol 14 (02) ◽

pp. 275-293 ◽

Cited By ~ 2

Author(s):

CHRISTOPHER S. OEHMEN ◽

TJERK P. STRAATSMA ◽

GORDON A. ANDERSON ◽

GALYA ORR ◽

BOBBIE-JO M. WEBB-ROBERTSON ◽

...

Keyword(s):

Paradigm Shift ◽

Large Scale ◽

Experimental Testing ◽

Spatial Scales ◽

Geographical Area ◽

Biological Data ◽

Biological Research ◽

Complex Data ◽

Discovery Research ◽

Wide Range

The future of biology will be increasingly driven by the fundamental paradigm shift from hypothesis-driven research to data-driven discovery research employing the growing volume of biological data coupled to experimental testing of new discoveries. But hardware and software limitations in the current workflow infrastructure make it impossible or intractible to use real data from disparate sources for large-scale biological research. We identify key technological developments needed to enable this paradigm shift involving (1) the ability to store and manage extremely large datasets which are dispersed over a wide geographical area, (2) development of novel analysis and visualization tools which are capable of operating on enormous data resources without overwhelming researchers with unusable information, and (3) formalisms for integrating mathematical models of biosystems from the molecular level to the organism population level. This will require the development of algorithms and tools which efficiently utilize high-performance compute power and large storage infrastructures. The end result will be the ability of a researcher to integrate complex data from many different sources with simulations to analyze a given system at a wide range of temporal and spatial scales in a single conceptual model.

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Cloud Inhomogeneity from MODIS

Journal of Climate ◽

10.1175/jcli3591.1 ◽

2005 ◽

Vol 18 (23) ◽

pp. 5110-5124 ◽

Cited By ~ 37

Author(s):

Lazaros Oreopoulos ◽

Robert F. Cahalan

Keyword(s):

Optical Thickness ◽

Large Scale ◽

Spatial Scales ◽

Temporal Variations ◽

Global Scale ◽

Time Of Day ◽

Wide Range ◽

Level 3 ◽

Inhomogeneity Parameter ◽

Moderate Resolution Imaging Spectroradiometer

Abstract Two full months (July 2003 and January 2004) of Moderate Resolution Imaging Spectroradiometer (MODIS) Atmosphere Level-3 data from the Terra and Aqua satellites are analyzed in order to characterize the horizontal variability of vertically integrated cloud optical thickness (“cloud inhomogeneity”) at global scales. The monthly climatology of cloud inhomogeneity is expressed in terms of standard parameters, initially calculated for each day of the month at spatial scales of 1° × 1° and subsequently averaged at monthly, zonal, and global scales. Geographical, diurnal, and seasonal changes of inhomogeneity parameters are examined separately for liquid and ice phases and separately over land and ocean. It is found that cloud inhomogeneity is overall weaker in summer than in winter. For liquid clouds, it is also consistently weaker for local morning than local afternoon and over land than ocean. Cloud inhomogeneity is comparable for liquid and ice clouds on a global scale, but with stronger spatial and temporal variations for the ice phase, and exhibits an average tendency to be weaker for near-overcast or overcast grid points of both phases. Depending on cloud phase, hemisphere, surface type, season, and time of day, hemispheric means of the inhomogeneity parameter ν (roughly the square of the ratio of optical thickness mean to standard deviation) have a wide range of ∼1.7 to 4, while for the inhomogeneity parameter χ (the ratio of the logarithmic to linear mean) the range is from ∼0.65 to 0.8. The results demonstrate that the MODIS Level-3 dataset is suitable for studying various aspects of cloud inhomogeneity and may prove invaluable for validating future cloud schemes in large-scale models capable of predicting subgrid variability.

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A large-scale forest fragmentation experiment: the Stability of Altered Forest Ecosystems Project

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2011.0049 ◽

2011 ◽

Vol 366 (1582) ◽

pp. 3292-3302 ◽

Cited By ~ 145

Author(s):

Robert M. Ewers ◽

Raphael K. Didham ◽

Lenore Fahrig ◽

Gonçalo Ferraz ◽

Andy Hector ◽

...

Keyword(s):

Forest Fragmentation ◽

Large Scale ◽

Forest Cover ◽

Forest Ecosystems ◽

Field Experiments ◽

Spatial Scales ◽

Ecological Impacts ◽

Data Types ◽

Wide Range ◽

The Stability

Opportunities to conduct large-scale field experiments are rare, but provide a unique opportunity to reveal the complex processes that operate within natural ecosystems. Here, we review the design of existing, large-scale forest fragmentation experiments. Based on this review, we develop a design for the Stability of Altered Forest Ecosystems (SAFE) Project, a new forest fragmentation experiment to be located in the lowland tropical forests of Borneo (Sabah, Malaysia). The SAFE Project represents an advance on existing experiments in that it: (i) allows discrimination of the effects of landscape-level forest cover from patch-level processes; (ii) is designed to facilitate the unification of a wide range of data types on ecological patterns and processes that operate over a wide range of spatial scales; (iii) has greater replication than existing experiments; (iv) incorporates an experimental manipulation of riparian corridors; and (v) embeds the experimentally fragmented landscape within a wider gradient of land-use intensity than do existing projects. The SAFE Project represents an opportunity for ecologists across disciplines to participate in a large initiative designed to generate a broad understanding of the ecological impacts of tropical forest modification.

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Interstellar and intergalactic dynamos

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313002573 ◽

2012 ◽

Vol 8 (S294) ◽

pp. 225-236

Author(s):

M. Hanasz ◽

D. Woltanski ◽

K. Kowalik

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Large Scale ◽

Numerical Models ◽

Rotation Period ◽

Cosmic Ray ◽

Small Scale ◽

Galactic Rotation ◽

Galaxy Mergers ◽

Wide Range

AbstractWe review recent developments of amplification models of galactic and intergalactic magnetic field. The most popular scenarios involve variety of physical mechanisms, including turbulence generation on a wide range of physical scales, effects of supernovae, buoyancy as well as the magnetorotational instability. Other models rely on galaxy interaction, which generate galactic and intergalactic magnetic fields during galaxy mergers. We present also global galactic-scale numerical models of the Cosmic Ray (CR) driven dynamo, which was originally proposed by Parker (1992). We conduct a series of direct CR+MHD numerical simulations of the dynamics of the interstellar medium (ISM), composed of gas, magnetic fields and CR components. We take into account CRs accelerated in randomly distributed supernova (SN) remnants, and assume that SNe deposit small-scale, randomly oriented, dipolar magnetic fields into the ISM. The amplification timescale of the large-scale magnetic field resulting from the CR-driven dynamo is comparable to the galactic rotation period. The process efficiently converts small-scale magnetic fields of SN-remnants into galactic-scale magnetic fields. The resulting magnetic field structure resembles the X-shaped magnetic fields observed in edge-on galaxies.

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Analysis and Reduction of Systematic Errors through a Seamless Approach to Modeling Weather and Climate

Journal of Climate ◽

10.1175/2010jcli3541.1 ◽

2010 ◽

Vol 23 (22) ◽

pp. 5933-5957 ◽

Cited By ~ 123

Author(s):

G. M. Martin ◽

S. F. Milton ◽

C. A. Senior ◽

M. E. Brooks ◽

S. Ineson ◽

...

Keyword(s):

Time Scales ◽

Land Surface ◽

Large Scale ◽

Climate Models ◽

Spatial Scales ◽

Full Range ◽

Model Development ◽

Model Performance ◽

Systematic Errors ◽

Wide Range

Abstract The reduction of systematic errors is a continuing challenge for model development. Feedbacks and compensating errors in climate models often make finding the source of a systematic error difficult. In this paper, it is shown how model development can benefit from the use of the same model across a range of temporal and spatial scales. Two particular systematic errors are examined: tropical circulation and precipitation distribution, and summer land surface temperature and moisture biases over Northern Hemisphere continental regions. Each of these errors affects the model performance on time scales ranging from a few days to several decades. In both cases, the characteristics of the long-time-scale errors are found to develop during the first few days of simulation, before any large-scale feedbacks have taken place. The ability to compare the model diagnostics from the first few days of a forecast, initialized from a realistic atmospheric state, directly with observations has allowed physical deficiencies in the physical parameterizations to be identified that, when corrected, lead to improvements across the full range of time scales. This study highlights the benefits of a seamless prediction system across a wide range of time scales.

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Functional MRI of large scale activity in behaving mice

10.1101/2020.04.16.044941 ◽

2020 ◽

Author(s):

Madalena S. Fonseca ◽

Mattia G. Bergomi ◽

Zachary F. Mainen ◽

Noam Shemesh

Keyword(s):

Large Scale ◽

Brain Activity ◽

Spatial Scales ◽

Distributed Processing ◽

Brain Regions ◽

Visually Guided ◽

Dynamic Interactions ◽

Complex Behaviour ◽

Wide Range ◽

Circuit Techniques

ABSTRACTBehaviour involves complex dynamic interactions across many brain regions. Detecting whole-brain activity in mice performing sophisticated behavioural tasks could facilitate insights into distributed processing underlying behaviour, guide local targeting, and help bridge the disparate spatial scales between rodent and human studies. Here, we present a comprehensive approach for recording brain-wide activity with functional magnetic resonance imaging (fMRI) compatible with a wide range of behavioural paradigms and neuroscience questions. We introduce hardware and procedural advances to allow multi-sensory, multi-action behavioural paradigms in the scanner. We identify signal artifacts arising from task-related body movements and propose novel strategies to suppress them. We validate and explore our approach in a 4-odour classical conditioning and a visually-guided operant task, illustrating how it can be used to extract information insofar intangible to rodent behaviour studies. Our work paves the way for future studies combining fMRI and local circuit techniques during complex behaviour to tackle multi-scale behavioural neuroscience questions.

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Turbulence in Large-Scale Two-Dimensional Balanced Hard Sphere Gas Flow

Atmosphere ◽

10.3390/atmos12111520 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1520

Author(s):

Rafail V. Abramov

Keyword(s):

Turbulent Flows ◽

Hard Sphere ◽

Large Scale ◽

Gas Flow ◽

Spatial Scales ◽

Mean Field ◽

Current Work ◽

Two Dimensional ◽

Dynamical Mechanism ◽

Wide Range

In recent works, we developed a model of balanced gas flow, where the momentum equation possesses an additional mean field forcing term, which originates from the hard sphere interaction potential between the gas particles. We demonstrated that, in our model, a turbulent gas flow with a Kolmogorov kinetic energy spectrum develops from an otherwise laminar initial jet. In the current work, we investigate the possibility of a similar turbulent flow developing in a large-scale two-dimensional setting, where a strong external acceleration compresses the gas into a relatively thin slab along the third dimension. The main motivation behind the current work is the following. According to observations, horizontal turbulent motions in the Earth atmosphere manifest in a wide range of spatial scales, from hundreds of meters to thousands of kilometers. However, the air density rapidly decays with altitude, roughly by an order of magnitude each 15–20 km. This naturally raises the question as to whether or not there exists a dynamical mechanism which can produce large-scale turbulence within a purely two-dimensional gas flow. To our surprise, we discover that our model indeed produces turbulent flows and the corresponding Kolmogorov energy spectra in such a two-dimensional setting.

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Parameterization of the Spatial Variability of Rain for Large-Scale Models and Remote Sensing

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-15-0066.1 ◽

2015 ◽

Vol 54 (10) ◽

pp. 2027-2046 ◽

Cited By ~ 4

Author(s):

Z. J. Lebo ◽

C. R. Williams ◽

G. Feingold ◽

V. E. Larson

Keyword(s):

Spatial Variability ◽

Large Scale ◽

Rain Rate ◽

Numerical Models ◽

Spatial Scales ◽

Warm Pool ◽

Radar Data ◽

Model Output ◽

Wide Range ◽

Averaged Model

AbstractThe spatial variability of rain rate R is evaluated by using both radar observations and cloud-resolving model output, focusing on the Tropical Warm Pool–International Cloud Experiment (TWP-ICE) period. In general, the model-predicted rain-rate probability distributions agree well with those estimated from the radar data across a wide range of spatial scales. The spatial variability in R, which is defined according to the standard deviation of R (for R greater than a predefined threshold Rmin) σ(R), is found to vary according to both the average of R over a given footprint μ(R) and the footprint size or averaging scale Δ. There is good agreement between area-averaged model output and radar data at a height of 2.5 km. The model output at the surface is used to construct a scale-dependent parameterization of σ(R) as a function of μ(R) and Δ that can be readily implemented into large-scale numerical models. The variability in both the rainwater mixing ratio qr and R as a function of height is also explored. From the statistical analysis, a scale- and height-dependent formulation for the spatial variability of both qr and R is provided for the analyzed tropical scenario. Last, it is shown how this parameterization can be used to assist in constraining parameters that are often used to describe the surface rain-rate distribution.

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Interacting abiotic, biochemical and management factors explain soil organic carbon in Pyrenean grasslands

10.5194/egusphere-egu2020-19993 ◽

2020 ◽

Author(s):

Antonio Rodríguez ◽

Rosa Maria Canals ◽

Josefina Plaixats ◽

Elena Albanell ◽

Haifa Debouk ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Large Scale ◽

Plant Biomass ◽

Spatial Scales ◽

Grazing Management ◽

Quality Factors ◽

Wide Range ◽

Herbage Quality ◽

Management Factors

<p>Grasslands are one of the major sinks of terrestrial soil organic carbon (SOC). Understanding how environmental and management factors drive SOC is challenging because there are scale-dependent effects, and large scale drivers affecting SOC both directly and through drivers working at fine spatial scales. Here we address how regional and landscape factors, and grazing management, soil properties and nutrients, and herbage quality factors affect SOC in mountain grasslands in the Pyrenees. Taking advantage of the high variety of environmental heterogeneity in the Pyrenees, we fitted a set of models with explicative purposes including variables that comprise a wide range of environmental and management conditions. We found that temperature seasonality (MMT) was the most important abiotic driver of SOC in our study. MMT was positively related to SOC but only under certain conditions: exposed hillsides, steep slopes and relatively highly grazed areas. High MMT conditions probably are more favourable for plant biomass production, but landscape and grazing management factors buffer the conversion of this biomass into SOC. Concerning biochemical SOC predictors, we obtained some unexpected interaction effects between grazer type, soil nutrients and herbage quality. Soil N was a crucial factor modulated by effects of livestock species and neutral-detergent fibre content of vegetation. Herbage recalcitrance effects varied depending on grazer species. These results highlight the need to expand knowledge about grassland SOC drivers under different environmental and management conditions.</p><p>&#160;</p>

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