An exploratory stu dv of app roximations for the equatorial region is given to stress the rapid v... more An exploratory stu dv of app roximations for the equatorial region is given to stress the rapid variation of can alis parameter with latitude, and the consequenti al differences in the length sca les in meridional and zonal directions. The: resulting equations retain co riolis as well as non-linear inertia terms in zonal momentum balance. This approximation for dominantly zona l ftow is supplemented with anot her for a sublayer nea r the equator where the meridional flow might be dominant in case o f large interhemispheric transport, as in monsoon over the Indian Ocean.
: The report attempts to show connections between vorticity, the rotation of a line element, the ... more : The report attempts to show connections between vorticity, the rotation of a line element, the curvature of a streamline, and dissipation in viscous fluid flows. A tensor of third rank is shown to determine the angular velocity of a differential element of a filament (curve) of a moving material, if the current direction of the differential element is known. The same tensor determines the curvature of streamline at a point, if the velocity of the fluid at that point is given. Dilatation does not influence the tensor. The dissipation function of an incompressible Newtonian fluid can be expressed in terms of its second order invariants. The report also includes other properties of the tensor such as algebraic properties. (Author)
A passive device was introduced in a turbulent boundary layer to destroy its large scale structur... more A passive device was introduced in a turbulent boundary layer to destroy its large scale structure. Investigation revealed a marked increase in Clauser shape factor and decrease in skin friction. Relaxation characteristics as the boundary layer returns to equilibrium are discussed in the paper.
The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the s... more The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the simulation of the large scale circulation of the ocean. The Topex/Poseidon altimeter which has been operating since September 1992 has been providing sea surface heights (SSH) of the accuracy of 5-10 cms with a repeat cycle of 10 days. We examine in this paper, the SSH in the Indian Ocean obtained from a global simulation of MOM with a resolution of 1 ~ in the longitude, 1/3 ~ in the latitude between 30~ and 30~ and 20 levels in the vertical with climatological windforcing and restoring conditions on temperature and salinity. They are compared with the SSH from the Topex/Poseidon altimeter after suitable filtering in the time domain to remove smaller time and length scales. In addition, unfiltered data from both sources are analysed by estimating the cross-spectral density to find the coherence and crossphase at different frequencies. The agreement between the two, over most of the Northern Indian Ocean, especially the Arabian Sea and the Bay of Bengal is quite good.
An exploratory study of approximations for the equatorial region is given to stress the rapid var... more An exploratory study of approximations for the equatorial region is given to stress the rapid variation of coriolis parameter with latitude, and the consequential differences in the length scales in meridional and zonal directions. The resulting equations retain coriolis as well as non-linear inertia terms in zonal momentum balance. This approximation for dominantly zonal flow is supplemented with another for a sublayer near the equator where the meridional flow might be dominant in case of large interhemispheric transport, as in monsoon over the Indian Ocean.
Detection of small decadal-scale variation amidst larger variations on smaller timescales is carr... more Detection of small decadal-scale variation amidst larger variations on smaller timescales is carried out here by geometrical segregation rather than filtering. Sea surface temperature (SST) annual cycle is represented as a point in a 12-dimensional space and thermal history as a path connecting successive points. Drift of the domain of decadal variations in the state space is taken as a measure of change from one decade to another. Visualization of the path in the 12dimensional space is achieved by projecting it on planes. A matrix transformation gives an orthogonal decomposition of the annual cycle resembling Fourier series. The specific problem investigated here is the response of the Northern, the Tropical and the Southern Oceanic Regions (NOR, 30-90N; TOR, 30S-30N; SOR, 90-30S) to global warming during 1951-2010. The results are based on the Extended Reconstructed Sea Surface Temperature version 4 (ERSSTv4) database. Several interesting findings are obtained. The decadal scale warming has a seasonal variation, the largest being in the NOR (~0.26C to ~0.57C), in 2001-10. The consequential change in the annual cycle is increase in the amplitude of the annual mode in addition to increase in the annual mean. Decade-on-decade SST increase has peaked first in the SOR in 1971-80, and last in the NOR in 2001-10.
Cyclical rise and fall of monthly mean CO2 concentra- tion occurred rather regularly at Mauna Loa... more Cyclical rise and fall of monthly mean CO2 concentra- tion occurred rather regularly at Mauna Loa, Hawaii, USA, during 1958–2008, with peaks occurring in April or May followed by troughs in September or October. However, the frequency of troughs in September in- creased from 32% in 1958–1974 to 82% in 1992–2008 and the depletion season correspondingly decreased from 4.8 months on average to 4.2 months. Does this seemingly small change in the seasonal rhythm point to changes on an inter-decadal scale in the CO2 accu- mulation rates? This question is studied here by exam- ining linear and exponential trends of seasonal and annual CO2 accumulation rates in three equal phases (1958–1974, 1975–1991 and 1992–2008). We also dis- cuss trends of average accumulation rates in the accre- tion and depletion seasons, and of the amplitude and standard deviation of the annual CO2 cycles at Mauna Loa, which can be viewed as representative of the North Central Tropical Pacific.
The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the s... more The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the simulation of the large scale circulation of the ocean. The Topex/Poseidon altimeter which has been operating since September 1992 has been providing sea surface heights (SSH) of the accuracy of 5–10 cms with a repeat cycle of 10 days. We examine in this paper,
Recent experiments on nitrogen dynamics by McCarthy et al1 in the Indian Ocean during North East ... more Recent experiments on nitrogen dynamics by McCarthy et al1 in the Indian Ocean during North East Monsoon have thrown new light on several aspects of nitrogen uptake by phytoplankton. In particular, the inhibitory effect of ammonium on the uptake of nitrate displays the properties of similarity and saturation of inhibition of nitrate uptake with increasing ammonium. Since two nutrient interaction relations currently in use in marine ecosystem models have one of these two properties but not both, a rather general theoretical formulation is presented here for a multi-nutrient environment. It is phenomenological in character with similarity and hyperbolicity taken as two fundamental properties. When it is applied to the nitrate-ammonium environment, the results are found to agree rather well with the recent observations. The implications the interaction relations on the f ratio are also discussed.
A theory is proposed in this paper to describe the behaviour of a class of turbulent shear flows ... more A theory is proposed in this paper to describe the behaviour of a class of turbulent shear flows as the Reynolds number approaches infinity. A detailed analysis is given for simple representative members of this class, such as fully developed channel and pipe flows and two-dimensional turbulent boundary layers. The theory considers an underdetermined system of equations and depends critically on the idea that these flows consist of two rather different types of regions. The method of matched asymptotic expansions is employed together with asymptotic hypotheses describing the order of various terms in the equations of mean motion and turbulent kinetic energy. As these hypotheses are not closure hypotheses, they do not impose any functional relationship between quantities determined by the mean velocity field and those determined by the Reynolds stress field. The theory leads to asymptotic laws corresponding to the law of the wall, the logarithmic law, the velocity defect law, and the law of the wake.
Extraordinary multi-seasonal episodes like El Niños of 1982–1983 and 1997–1998 and their widespre... more Extraordinary multi-seasonal episodes like El Niños of 1982–1983 and 1997–1998 and their widespread teleconnection effects have spurred varied investigations on the changes in sea surface temperature (SST) variability in the post-WWII period. Most of them have been region-specific. We investigate here change in the variance of SST anomaly (SSTA) in the world oceans from 1951–1980 to 1981–2010. Our search for quantitative patterns, in space and time, is aided by a new decomposition of SSTA annual cycle in three orthogonal components, one time-independent, one low frequency (LF, periods: 4–12 months) and one high frequency (HF, periods: 2–3 months). High SSTA variability occurs in small regions clustered near the equator, middle and high latitudes. Sixteen high variability regions (HVR) are identified on the basis of a threshold. Spread over nearly 10% of the ocean area, they occur in four clusters: two in the equatorial cluster, four each in the northern and the southern mid-latitude...
This report deals with the calculation of the development of a channel flow at Reynolds number. T... more This report deals with the calculation of the development of a channel flow at Reynolds number. The governing equations, which are of the boundary layer form, ass reduced to ordinary differential equations by an expansion in eigenfunctions of the linear problem at large downsteps distances. The roulte, which are obtained by integrating these equations for 2,5 and 5 terms for the initial condition of uniform velocity profiles at the inlet, are copmared with obtained from the boundary-layer equations as well as the nevier stoke equations by using methods. Velocity profiles the expected feature of a uniform central cor with boundary layer near the well.center line velocity, pressure gradient friction quite well with the earlier results slightly the entry, although the expansion has been truncated after very few terms, the development length and the excese pressure drop are also compared.
Experiments are conducted on the development of the turbulent boundary layer on a flat plate loca... more Experiments are conducted on the development of the turbulent boundary layer on a flat plate located in the wake of another flat plate. The mean velocity field and the Reynolds stresses of the evolving layer are measured in six cases involving different wake conditions. The study is on the evolution of the wall layer developing under zero pressure gradient. The results indicate significant influence of the wake on the evolving layer. The perturbed wall layer has a low shape factor accompanied by lower Reynolds shear stress. The perturbation intensity falls by a factor of 2 over a distance of 50-100 momentum thicknesses. The data analysis reveal multilayered structure and growth of an internal layer. The applicability of some simple correlations and turbulence models for these complex flows are also examined.
Cyclical rise and fall of monthly mean CO 2 concentration occurred rather regularly at Mauna Loa,... more Cyclical rise and fall of monthly mean CO 2 concentration occurred rather regularly at Mauna Loa, Hawaii, USA, during 1958-2008, with peaks occurring in April or May followed by troughs in September or October. However, the frequency of troughs in September increased from 32% in 1958-1974 to 82% in 1992-2008 and the depletion season correspondingly decreased from 4.8 months on average to 4.2 months. Does this seemingly small change in the seasonal rhythm point to changes on an inter-decadal scale in the CO 2 accumulation rates? This question is studied here by examining linear and exponential trends of seasonal and annual CO 2 accumulation rates in three equal phases (1958-1974, 1975-1991 and 1992-2008). We also discuss trends of average accumulation rates in the accretion and depletion seasons, and of the amplitude and standard deviation of the annual CO 2 cycles at Mauna Loa, which can be viewed as representative of the North Central Tropical Pacific.
A physical-biological-chemical model (PBCM) is used for investigating the seasonal cycle of air–s... more A physical-biological-chemical model (PBCM) is used for investigating the seasonal cycle of air–sea carbon flux and for assessing the effect of the biological processes on seasonal time scale in the Arabian Sea (AS) and Bay of Bengal (BoB), where the surface waters are subjected to contrasting physical conditions. The formulation of PBCM is given in Swathi et al (2000), and evaluation of several ammonium-inhibited nitrate uptake models is given in Sharada et al (2005). The PBCM is here first evaluated against JGOFS data on surface pCO 2 in AS, Bay of Bengal Process Studies (BoBPS) data on column integrated primary productivity in BoB, and WOCE I1 data on dissolved inorganic carbon (DIC) and alkalinity (ALK) in the upper 500 meters at 9 • N in AS and at 10 • N in BoB in September–October. There is good qualitative agreement with local quantitative discrepancies. The net effect of biological processes on air–sea carbon flux on seasonal time scale is determined with an auxiliary computational experiment, called the abiotic run, in which the biological processes are turned off. The difference between the biotic run and abiotic run is interpreted as the net effect of biological processes on the seasonal variability of chemical variables. The net biological effect on air–sea carbon flux is found to be highest in southwest monsoon season in the northwest AS, where strong upwelling drives intense new production. The biological effect is larger in AS than in BoB, as seasonal upwelling and mixing are strong in AS, especially in the northeast, while coastal upwelling and mixing are weak in BoB.
A bounded trajectory of a continuous or discrete dynamical system is decomposed into two componen... more A bounded trajectory of a continuous or discrete dynamical system is decomposed into two components, one periodic and the other aperiodic. They have a property similar to orthogonality. This decomposition amounts to representation of the vector space of bounded trajectories into a product of two vector spaces. Applications are given for logistic map.
An exploratory stu dv of app roximations for the equatorial region is given to stress the rapid v... more An exploratory stu dv of app roximations for the equatorial region is given to stress the rapid variation of can alis parameter with latitude, and the consequenti al differences in the length sca les in meridional and zonal directions. The: resulting equations retain co riolis as well as non-linear inertia terms in zonal momentum balance. This approximation for dominantly zona l ftow is supplemented with anot her for a sublayer nea r the equator where the meridional flow might be dominant in case o f large interhemispheric transport, as in monsoon over the Indian Ocean.
: The report attempts to show connections between vorticity, the rotation of a line element, the ... more : The report attempts to show connections between vorticity, the rotation of a line element, the curvature of a streamline, and dissipation in viscous fluid flows. A tensor of third rank is shown to determine the angular velocity of a differential element of a filament (curve) of a moving material, if the current direction of the differential element is known. The same tensor determines the curvature of streamline at a point, if the velocity of the fluid at that point is given. Dilatation does not influence the tensor. The dissipation function of an incompressible Newtonian fluid can be expressed in terms of its second order invariants. The report also includes other properties of the tensor such as algebraic properties. (Author)
A passive device was introduced in a turbulent boundary layer to destroy its large scale structur... more A passive device was introduced in a turbulent boundary layer to destroy its large scale structure. Investigation revealed a marked increase in Clauser shape factor and decrease in skin friction. Relaxation characteristics as the boundary layer returns to equilibrium are discussed in the paper.
The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the s... more The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the simulation of the large scale circulation of the ocean. The Topex/Poseidon altimeter which has been operating since September 1992 has been providing sea surface heights (SSH) of the accuracy of 5-10 cms with a repeat cycle of 10 days. We examine in this paper, the SSH in the Indian Ocean obtained from a global simulation of MOM with a resolution of 1 ~ in the longitude, 1/3 ~ in the latitude between 30~ and 30~ and 20 levels in the vertical with climatological windforcing and restoring conditions on temperature and salinity. They are compared with the SSH from the Topex/Poseidon altimeter after suitable filtering in the time domain to remove smaller time and length scales. In addition, unfiltered data from both sources are analysed by estimating the cross-spectral density to find the coherence and crossphase at different frequencies. The agreement between the two, over most of the Northern Indian Ocean, especially the Arabian Sea and the Bay of Bengal is quite good.
An exploratory study of approximations for the equatorial region is given to stress the rapid var... more An exploratory study of approximations for the equatorial region is given to stress the rapid variation of coriolis parameter with latitude, and the consequential differences in the length scales in meridional and zonal directions. The resulting equations retain coriolis as well as non-linear inertia terms in zonal momentum balance. This approximation for dominantly zonal flow is supplemented with another for a sublayer near the equator where the meridional flow might be dominant in case of large interhemispheric transport, as in monsoon over the Indian Ocean.
Detection of small decadal-scale variation amidst larger variations on smaller timescales is carr... more Detection of small decadal-scale variation amidst larger variations on smaller timescales is carried out here by geometrical segregation rather than filtering. Sea surface temperature (SST) annual cycle is represented as a point in a 12-dimensional space and thermal history as a path connecting successive points. Drift of the domain of decadal variations in the state space is taken as a measure of change from one decade to another. Visualization of the path in the 12dimensional space is achieved by projecting it on planes. A matrix transformation gives an orthogonal decomposition of the annual cycle resembling Fourier series. The specific problem investigated here is the response of the Northern, the Tropical and the Southern Oceanic Regions (NOR, 30-90N; TOR, 30S-30N; SOR, 90-30S) to global warming during 1951-2010. The results are based on the Extended Reconstructed Sea Surface Temperature version 4 (ERSSTv4) database. Several interesting findings are obtained. The decadal scale warming has a seasonal variation, the largest being in the NOR (~0.26C to ~0.57C), in 2001-10. The consequential change in the annual cycle is increase in the amplitude of the annual mode in addition to increase in the annual mean. Decade-on-decade SST increase has peaked first in the SOR in 1971-80, and last in the NOR in 2001-10.
Cyclical rise and fall of monthly mean CO2 concentra- tion occurred rather regularly at Mauna Loa... more Cyclical rise and fall of monthly mean CO2 concentra- tion occurred rather regularly at Mauna Loa, Hawaii, USA, during 1958–2008, with peaks occurring in April or May followed by troughs in September or October. However, the frequency of troughs in September in- creased from 32% in 1958–1974 to 82% in 1992–2008 and the depletion season correspondingly decreased from 4.8 months on average to 4.2 months. Does this seemingly small change in the seasonal rhythm point to changes on an inter-decadal scale in the CO2 accu- mulation rates? This question is studied here by exam- ining linear and exponential trends of seasonal and annual CO2 accumulation rates in three equal phases (1958–1974, 1975–1991 and 1992–2008). We also dis- cuss trends of average accumulation rates in the accre- tion and depletion seasons, and of the amplitude and standard deviation of the annual CO2 cycles at Mauna Loa, which can be viewed as representative of the North Central Tropical Pacific.
The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the s... more The Modular Ocean Model (MOM) is perhaps the most versatile ocean model available today for the simulation of the large scale circulation of the ocean. The Topex/Poseidon altimeter which has been operating since September 1992 has been providing sea surface heights (SSH) of the accuracy of 5–10 cms with a repeat cycle of 10 days. We examine in this paper,
Recent experiments on nitrogen dynamics by McCarthy et al1 in the Indian Ocean during North East ... more Recent experiments on nitrogen dynamics by McCarthy et al1 in the Indian Ocean during North East Monsoon have thrown new light on several aspects of nitrogen uptake by phytoplankton. In particular, the inhibitory effect of ammonium on the uptake of nitrate displays the properties of similarity and saturation of inhibition of nitrate uptake with increasing ammonium. Since two nutrient interaction relations currently in use in marine ecosystem models have one of these two properties but not both, a rather general theoretical formulation is presented here for a multi-nutrient environment. It is phenomenological in character with similarity and hyperbolicity taken as two fundamental properties. When it is applied to the nitrate-ammonium environment, the results are found to agree rather well with the recent observations. The implications the interaction relations on the f ratio are also discussed.
A theory is proposed in this paper to describe the behaviour of a class of turbulent shear flows ... more A theory is proposed in this paper to describe the behaviour of a class of turbulent shear flows as the Reynolds number approaches infinity. A detailed analysis is given for simple representative members of this class, such as fully developed channel and pipe flows and two-dimensional turbulent boundary layers. The theory considers an underdetermined system of equations and depends critically on the idea that these flows consist of two rather different types of regions. The method of matched asymptotic expansions is employed together with asymptotic hypotheses describing the order of various terms in the equations of mean motion and turbulent kinetic energy. As these hypotheses are not closure hypotheses, they do not impose any functional relationship between quantities determined by the mean velocity field and those determined by the Reynolds stress field. The theory leads to asymptotic laws corresponding to the law of the wall, the logarithmic law, the velocity defect law, and the law of the wake.
Extraordinary multi-seasonal episodes like El Niños of 1982–1983 and 1997–1998 and their widespre... more Extraordinary multi-seasonal episodes like El Niños of 1982–1983 and 1997–1998 and their widespread teleconnection effects have spurred varied investigations on the changes in sea surface temperature (SST) variability in the post-WWII period. Most of them have been region-specific. We investigate here change in the variance of SST anomaly (SSTA) in the world oceans from 1951–1980 to 1981–2010. Our search for quantitative patterns, in space and time, is aided by a new decomposition of SSTA annual cycle in three orthogonal components, one time-independent, one low frequency (LF, periods: 4–12 months) and one high frequency (HF, periods: 2–3 months). High SSTA variability occurs in small regions clustered near the equator, middle and high latitudes. Sixteen high variability regions (HVR) are identified on the basis of a threshold. Spread over nearly 10% of the ocean area, they occur in four clusters: two in the equatorial cluster, four each in the northern and the southern mid-latitude...
This report deals with the calculation of the development of a channel flow at Reynolds number. T... more This report deals with the calculation of the development of a channel flow at Reynolds number. The governing equations, which are of the boundary layer form, ass reduced to ordinary differential equations by an expansion in eigenfunctions of the linear problem at large downsteps distances. The roulte, which are obtained by integrating these equations for 2,5 and 5 terms for the initial condition of uniform velocity profiles at the inlet, are copmared with obtained from the boundary-layer equations as well as the nevier stoke equations by using methods. Velocity profiles the expected feature of a uniform central cor with boundary layer near the well.center line velocity, pressure gradient friction quite well with the earlier results slightly the entry, although the expansion has been truncated after very few terms, the development length and the excese pressure drop are also compared.
Experiments are conducted on the development of the turbulent boundary layer on a flat plate loca... more Experiments are conducted on the development of the turbulent boundary layer on a flat plate located in the wake of another flat plate. The mean velocity field and the Reynolds stresses of the evolving layer are measured in six cases involving different wake conditions. The study is on the evolution of the wall layer developing under zero pressure gradient. The results indicate significant influence of the wake on the evolving layer. The perturbed wall layer has a low shape factor accompanied by lower Reynolds shear stress. The perturbation intensity falls by a factor of 2 over a distance of 50-100 momentum thicknesses. The data analysis reveal multilayered structure and growth of an internal layer. The applicability of some simple correlations and turbulence models for these complex flows are also examined.
Cyclical rise and fall of monthly mean CO 2 concentration occurred rather regularly at Mauna Loa,... more Cyclical rise and fall of monthly mean CO 2 concentration occurred rather regularly at Mauna Loa, Hawaii, USA, during 1958-2008, with peaks occurring in April or May followed by troughs in September or October. However, the frequency of troughs in September increased from 32% in 1958-1974 to 82% in 1992-2008 and the depletion season correspondingly decreased from 4.8 months on average to 4.2 months. Does this seemingly small change in the seasonal rhythm point to changes on an inter-decadal scale in the CO 2 accumulation rates? This question is studied here by examining linear and exponential trends of seasonal and annual CO 2 accumulation rates in three equal phases (1958-1974, 1975-1991 and 1992-2008). We also discuss trends of average accumulation rates in the accretion and depletion seasons, and of the amplitude and standard deviation of the annual CO 2 cycles at Mauna Loa, which can be viewed as representative of the North Central Tropical Pacific.
A physical-biological-chemical model (PBCM) is used for investigating the seasonal cycle of air–s... more A physical-biological-chemical model (PBCM) is used for investigating the seasonal cycle of air–sea carbon flux and for assessing the effect of the biological processes on seasonal time scale in the Arabian Sea (AS) and Bay of Bengal (BoB), where the surface waters are subjected to contrasting physical conditions. The formulation of PBCM is given in Swathi et al (2000), and evaluation of several ammonium-inhibited nitrate uptake models is given in Sharada et al (2005). The PBCM is here first evaluated against JGOFS data on surface pCO 2 in AS, Bay of Bengal Process Studies (BoBPS) data on column integrated primary productivity in BoB, and WOCE I1 data on dissolved inorganic carbon (DIC) and alkalinity (ALK) in the upper 500 meters at 9 • N in AS and at 10 • N in BoB in September–October. There is good qualitative agreement with local quantitative discrepancies. The net effect of biological processes on air–sea carbon flux on seasonal time scale is determined with an auxiliary computational experiment, called the abiotic run, in which the biological processes are turned off. The difference between the biotic run and abiotic run is interpreted as the net effect of biological processes on the seasonal variability of chemical variables. The net biological effect on air–sea carbon flux is found to be highest in southwest monsoon season in the northwest AS, where strong upwelling drives intense new production. The biological effect is larger in AS than in BoB, as seasonal upwelling and mixing are strong in AS, especially in the northeast, while coastal upwelling and mixing are weak in BoB.
A bounded trajectory of a continuous or discrete dynamical system is decomposed into two componen... more A bounded trajectory of a continuous or discrete dynamical system is decomposed into two components, one periodic and the other aperiodic. They have a property similar to orthogonality. This decomposition amounts to representation of the vector space of bounded trajectories into a product of two vector spaces. Applications are given for logistic map.
This lecture reviews the developments in the study of convection that led to Lorenz oscillator, n... more This lecture reviews the developments in the study of convection that led to Lorenz oscillator, nonlinear dissipative systems and chaos. The lecture seeks to emphasise making of connections between diverse problems.
This is a lecture given to R & D personnel in medical sciences. It introduces concepts of mathema... more This is a lecture given to R & D personnel in medical sciences. It introduces concepts of mathematical modelling and describes epidemiological models, especially one for TB and one for cataract in some detail.
This lecture seeks to introduce to students and young research workers on engineering and geophys... more This lecture seeks to introduce to students and young research workers on engineering and geophysical problems basic notions of turbulence starting from fundamentals and leads them to some of the widely used turbulence models.
This lecture gives a method of separating semi-annually periodic quantities from the rest. It als... more This lecture gives a method of separating semi-annually periodic quantities from the rest. It also gives applications of the method to the tropical Indian Ocean.
A lecture delivered on the occasion of 75th anniversary of Prof. Vinod Gaur at CSIR Centre for ma... more A lecture delivered on the occasion of 75th anniversary of Prof. Vinod Gaur at CSIR Centre for mathematical modelling and computer simulation in 2011
This lecture gives a brief introduction to mathematical modelling. It also gives a summary of eve... more This lecture gives a brief introduction to mathematical modelling. It also gives a summary of events that led to the establishment of CSIR Centre for Mathematical Modelling and Computer Simulation (C-MMACS, later renamed as CSIR Fourth Paradigm Institute) at Bangalore (now called Bengaluru), India in 1988 and gives a few highlights of its activities.
This presentation deals with decadal scale variations in atmospheric CO2 and sea surface temperat... more This presentation deals with decadal scale variations in atmospheric CO2 and sea surface temperature. The exposition is based on my two papers. It also explains the Fourier-like decomposition based on representation of annual cycle as a 12-dimensional vector.
This is a lecture given at a World bank Project review meeting on progress of World bank supporte... more This is a lecture given at a World bank Project review meeting on progress of World bank supported project on cataract in seven states of India. It gives a new model of cataract blindness incidence and prevalence to evaluate the effectiveness of the intervention programme.
A new method of analysis is presented for the analysis of sea surface temperature data. It is an ... more A new method of analysis is presented for the analysis of sea surface temperature data. It is an orthogonal decomposition similar to Fourier Series, but the coefficients can vary from year to year. ERSSTv3b data are used. Detailed results are given for the variation of amplitude and phase of annual and semi-annual modes for low latitudes (30S-30N) and middle-to-high latitudes (90S-30S and 30N-90N)..
This is a review of a book based on lectures delivered at a two-week spring school on "Fluid Dyna... more This is a review of a book based on lectures delivered at a two-week spring school on "Fluid Dynamics and Geophysics of Environmental Hazards" organised by IUTAM and IUGG at Institute of Mathematical Sciences, National University of Singapore in 1999.
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Papers by Kirit S Yajnik
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