arXiv subjects

A. Mary Selvam

Publications and source records attributed to A. Mary Selvam.

15 recordsLinked to original sources

arXiv2003

The Dynamics of Deterministic Chaos in Numerical Weather Prediction Models

Atmospheric weather systems are coherent structures consisting of discrete cloud cells forming patterns of rows/streets, mesoscale clusters and spiral bands which maintain their identity for the duration of their appreciable life times in the turbulent shear flow of the planetary Atmospheric Boundary Layer. The existence of coherent structures (seemingly systematic motion) in turbulent flows has been well established during the last 20 years of research in turbulence. Numerical weather prediction models based on the inherently non-linear Navier-Stokes equations do not give realistic forecasts because of the following inherent limitations: (1) the non-linear governing equations for atmospheric flows do not have exact analytic solutions and being sensitive to initial conditions give chaotic solutions characteristic of deterministic chaos (2) the governing equations do not incorporate the dynamical interactions and co-existence of the complete spectrum of turbulent fluctuations which form an integral part of the large coherent weather systems (3) limitations of available computer capacity necessitates severe truncation of the governing equations, thereby generating errors of approximations (4) the computer precision related roundoff errors magnify the earlier mentioned uncertainties exponentially with time and the model predictions become unrealistic. The accurate modelling of weather phenomena therefore requires alternative concepts and computational techniques. In this paper a universal theory of deterministic chaos applicable to the formation of coherent weather structures in the ABL is presented.

physics.gen-ph↗

arXiv2003

Deterministic Chaos Model for Self-Organized Adaptive Networks in Atmospheric Flows

The complex spatiotemporal patterns of atmospheric flows resulting from the cooperative existence of fluctuations ranging in size from millimeters to thousands of kilometers are found to exhibit long-range spatial and temporal correlations manifested as the selfsimilar fractal geometry to the global cloud cover pattern and the inverse power law form for the atmospheric eddy energy spectrum. Such long-range spatial and temporal correlations are ubiquitous to extended natural dynamical systems and is a signature of the strange attractor design characterizing deterministic chaos or self-organized criticality. The unified network of global atmospheric circulations is analogous to the neural networks of the human brain.

physics.gen-ph↗

arXiv2003

Deterministic Chaos: A signature of Quantumlike Mechanics in Self-Organized Adaptive Network

The observed long-range spatiotemporal correlations of real world dynamical systems is governed by quantumlike mechanics with inherent non-local connections. In summary, microscopic scale local fluctuations form a unified self-organized adaptive network manifested as the macro-scale dynamical system with implicit ordered energy flow between the larger and smaller scales. Such a concept of ladder networks may find applications in the design of artificial intelligence systems.

physics.gen-ph↗

arXiv2000

Deterministic chaos, fractals and quantumlike mechanics in atmospheric flows

The complex spaciotemporal patterns of atmospheric flows that result from the cooperative existence of fluctuations ranging in size from millimetres to thousands of kilometres are found to exhibit long-range spacial and temporal correlations. These correlations are manifested as the self-similar fractal geometry of the global cloud cover pattern and the inverse power-law form for the atmospheric eddy energy spectrum. Such long-range spaciotemporal correlations are ubiquitous in extended natural dynamical systems and are signatures of deterministic chaos or self-organized criticality. In this paper, a cell dynamical system model for atmospheric flows is developed by consideration of microscopic domain eddy dynamical processes. This nondeterministic model enables formulation of a simple closed set of governing equations for the prediction and description of observed atmospheric flow structure characteristics as follows. The strange-attractor design of the field of deterministic chaos in atmospheric flows consists of a nested continuum of logarithmic spiral circulations that trace out the quasi-periodic Penrose tiling pattern, identified as the quasi-crystalline structure in condensed matter physics. The atmospheric eddy energy structure follows laws similar to quantum mechanical laws. The apparent wave-particle duality that characterize quantum mechanical laws is attributed to the bimodal phenomenological form of energy display in the bidirectional energy flow that is intrinsic to eddy circulations, e.g., formation of clouds in updrafts and dissipation of clouds in downdrafts that result in the observed discrete cellular geometry of cloud structure.

physics.gen-ph↗

arXiv2000

Universal quantification for deterministic chaos in dynamical systems

A cell dynamical system model for deterministic chaos enables precise quantification of the round-off error growth,i.e., deterministic chaos in digital computer realizations of mathematical models of continuum dynamical systems. The model predicts the following: (a) The phase space trajectory (strange attractor) when resolved as a function of the computer accuracy has intrinsic logarithmic spiral curvature with the quasiperiodic Penrose tiling pattern for the internal structure. (b) The universal constant for deterministic chaos is identified as the steady-state fractional round-off error k for each computational step and is equal to 1 /sqr(tau) (=0.382) where tau is the golden mean. (c) The Feigenbaum's universal constants a and d are functions of k and, further, the expression 2(a**2) = (pie)*d quantifies the steady-state ordered emergence of the fractal geometry of the strange attractor. (d) The power spectra of chaotic dynamical systems follow the universal and unique inverse power law form of the statistical normal distribution.

physics.gen-ph↗

arXiv2000

Simulation of Urban Effects of Cloud Physical Parameters

A scale invariant, selfsimilar atmospheric eddy continuum exists in the planetary atmospheric boundary layer spanning several orders of magnitude in scales and gives rise to the observed fractal geometry for the global cloud cover pattern. The global weather systems are manifestations of the unified atmospheric eddy continuum with inherent mutual global-local energy exchange and therefore local urban energy/pollution sources have long-range global effects leading to climate change and environmental degradation. It is shown that the observed scale invariant atmospheric eddy continuum originates from the turbulence scale by the universal period doubling route to chaos eddy growth phenomenon in the planetary atmospheric boundary layer. The cloud dynamical, microphysical and electrical parameters are shown to be simple unique functions of turbulence scale energy generation.

physics.gen-ph↗

arXiv2000

Remote Sensing of Geomagnetic Field and Applications to Climate Prediction

Observations show that geomagnetic field lines follow closely the atmospheric circulation patterns and that geomagnetic field variations are precursors to climate change . The exact mechanism for the observed close relationship between global geomagnetic field and the tropospheric weather patterns is not clear. In this paper a universal theory of atmospheric eddy dynamics is presented which shows that the global geomagnetic field, atmospheric electric field and weather systems are manifestations of a semi permanent scale invariant hierarchical atmospheric eddy continuum. Quantitative equations are derived to show that the full continuum of atmospheric eddies exist as a unified whole and originate from buoyant energy supply from frictional turbulence at the planetary surface . Large eddy growth occurs from turbulence scale by the universal period doubling route to chaos . The turbulent eddies are carried upwards on the large eddy envelopes and vertical mixing occurs by the turbulent eddy fluctuations resulting in downward transport of negative space charges from higher levels and simultaneous upward transport of positive space charges from surface levels. The eddy circulations therefore generate a large-scale vertical aerosol current, which is of the correct sign and magnitude to generate the horizontal component of the geomagnetic field. Therefore, atmospheric circulation patterns leave signature on the geomagnetic field lines whose global variations can be easily monitored by satellite borne sensors and thus assist in weather and climate prediction.

physics.gen-ph↗

arXiv1999

A New Hypothesis for the Vertical Distribution of Atmospheric Aerosols

A simple model which can explain the observed vertical distribution and size spectrum of atmospheric aerosol has been proposed. The model is based on a new physical hypothesis for the vertical mass exchange between the troposphere and the stratosphere. The vertical mass excange takes place through a gravity wave feedback mechanism. There is a close agreement between the model predicted aerosol distribution and size spectrum and the observed distributions.

physics.gen-ph↗

arXiv1999

Numerical Simulation Of Warm Rain Process

Extensive aircraft cloud physical observations made in more than 2000 tropical cumulus clouds indicated new observational evidence viz., (1) horizontal structure of the air flow inside the cloud has consistent variations with successive positive and negative values of vertical velocity representative of ascending and descending currents, (2) regions of ascending currents are associated with higher liquid water content (LWC) and negative cloud drop charges and the descending currents are associated with lower LWC and positive cloud drop charge, (3) width of the ascending and descending currents is about 100 m, (4) ratio of the measured LWC (q) to that of the adiabatic value (qa) = 0.60 at cloud-base levels, (5) increase in the cloud electrical activity with LWC, (6) cloud drop size spectra is unimodal near the cloud-base and multimodal at higher levels, (7) in-cloud temperatures are colder than the environment, (8) environmental lapse rates are equal to the saturated adiabatic value while inside the cloud they are lower, (9) positive increments in the LWC are associated with the increments in temperature inside the cloud and the immediate environment and (10) variances of in-cloud temperature and humidity are larger in the regions where the values of the LWC are higher. The observed dynamical and physical characteristics of clouds cannot be explained by the presently available cloud models. An alternative cell dynamical system cloud model which predicts the observed cloud characteristics is discussed in this paper.

physics.gen-ph↗

arXiv1999

A New Mechanism for the Maintenance of Fair Weather Electric Field and Cloud Electrification

Wilson's hypothesis of the global electric circuit with the thunderstorms as generators has not been proven up to now. The exact physical mechanism responsible for the generation of fair weather electric field is not clearly understood. Some of the recent remarkable observations showed evidence for the horizontal fields in the magnetosphere and ionosphere which penetrate atleast into the stratosphere and perhaps into the troposphere. In the present paper a gravity wave feed back mechanism (cell dynamical system model) for the coupling of the troposphere and the ionosphere has been discussed. The physical mechanism proposed can offer an alternate explanation for the atmospheric electrical phenomena during fair and disturbed weather.

physics.gen-ph↗

arXiv1999

The Dynamics of Fullerene Structure Formation : Order out of Chaos Phenomenon

C60 molecules form spontaneously during vaporization of carbon associated with intense heating and turbulence such as in electrical arcs or flames. Self-organization of fluctuations in the highly turbulent (chaotic) atomized carbon vapor appears to result in the formation of the stable structure of C60 and therefore may be visualized as order out of chaos phenomenon. The geometry of C60, namely, the self-similar quasiperiodic Penrose tiling pattern implies long-range spatiotemporal correlations. Such non-local connections in space and time are ubiquitous to dynamical systems in nature and is recently identified as signatures of self-organized criticality . A cell dynamical system model for turbulent fluid flows developed by the author is summarized and it is shown that the observed quasiperiodic Penrose tiling pattern is a signature of quantum-like mechanics governing flow dynamics.

physics.gen-ph↗

arXiv1998

Possible Solar Influence On Atmospheric Electric Field

A cell dynamical system model for the troposphere - ionosphere coupling is proposed . Vertical mass exchange in the troposphere-ionosphere-magnetosphere takes place through a chain of eddy systems. Any perturbation in the troposphere would be transmitted to ionosphere and vice versa. A global perturbation in ionosphere, as the one caused by solar variability, is transmitted to troposphere influencing weather systems/geomagnetic/atmospheric electrification processes.

chao-dyn↗

arXiv1998

Quasicrystalline Pattern Formation in Fluid Substrates and Phyllotaxis

Phyllotactic patterns possess the quasicrystalline structure of the quasiperiodic Penrose tiling pattern. The author has shown that quasicrystalline structure of the quasiperiodic Penrose tiling pattern underlie iterative growth processes such as turbulent(small scale) fluctuations in fluid flows and round-off error growth in numerical integration schemes. Selfsimilarity in spatial structure extends down to the level of DNA molecules in plants . It is possible that plant growth processes may be coupled to the turbulent fluid environments of air and water respectively in the exterior and interior of the plant body down to sub-cellular levels resulting in the spontaneous generation of the quasicrystalline structure in plant growth pattern.

chao-dyn↗

arXiv1997

Chaos and Quantumlike Mechanics in Atmospheric Flows : A Superstring Theory for Supergravity

The author has identified quantumlike mechanics in atmospheric flows with intrinsic nonlocal space-time connections manifested as the selfsimilar fractal geometry to the global cloud cover pattern concomitant with inverse power law form for power spectra of temporal fluctuations. Such long-range spatiotemporal correlations are generic to dynamical systems in nature and are recently identified as signatures of selforganized criticality, a field of study belonging to the newly emerging discipline of nonlinear dynamics and chaos. The author has presented a universal thory of chaos which postulates that spatial integration of enclosed small scale fluctuations result in the generation of a hierarchical scale invariant eddy continuum(network) with ordered two-way energy flow between the scales. The model concepts lead to the following results. (1) The eddy energy spectrum follows normal distribution characteristics,i.e.,the square of the eddy amplitude represents the probability density,a result which is observed in the subatomic dynamics of quantum systems. (2) Wave-particle duality is attributed to the bimodal (formation and dissipation) phenomenological form for manifestation of energy in the bidirectional energy flow intrinsic to eddy circulations,e.g., formation and dissipation respectively of clouds in updrafts and downdrafts of atmospheric eddies. (3) The nested continuum of eddy flow trajectories follow Kepler's third law of planetary motion. Therefore,inverse square law form for centripetal force, representing inertial or gravitational force is intrinsic to the hierarchical eddy continuum. The above model is analogous to a superstring model where manifestation of matter is visualised as vibrational modes in stringlike energy flow patterns.

chao-dyn↗

arXiv1997

Universal Quantification for Self-Organized Criticality in Atmospheric Flows

Atmospheric flows exhibit selfsimilar fluctuations on all scales(space-time) ranging from climate(kilometers/years) to turbulence(millimeters/seconds) manifested as fractal geometry to the global cloud cover pattern concomitant with inverse power law form for power spectra of temporal fluctuations. Selfsimilar fluctuations implying long-range correlations are ubiquitous to dynamical systems in nature and are identified as signatures of self-organized criticality in atmospheric flows. Also, mathematical models for simulation and prediction of atmospheric flows are nonlinear and computer realizations give unrealistic solutions because of deterministic chaos, a direct consequence of finite precision round-off error doubling for each iteration of iterative computations incorporated in long-term numerical integration schemes used for model solutions An alternative non-deterministic cell dynamical system model predicts, (a): the observed self organized criticality as a consequence of quantumlike mechanics governing flow dynamics,.(b):atmospheric flows trace an overall logarithmic spiral trajectory with the quasiperiodic Penrose tiling pattern for the internal structure,(c): eddy circulation structure follows Kepler's third law of planetary motion and results in inverse square law form for centripetal acceleration. The inertial masses representing the eddy circulation therefore follow laws analogous to the Newton's inverse square law for gravitation. The model is similar to a superstring model for subatomic dynamics which unifies quantum mechanical and classical concept and incorporates gravitational forces along with nuclear and electromagnetic forces.

chao-dyn↗