Name : Ms.M.K.SHARADA

Date of birth : 6th January 1964

Status : Married

Address :

Office : CSIR Centre for Mathematical Modelling And Computer Simulation,
Belur Campus, BANGALORE - 560037.

Tel : (+91)(80) 5274649
Fax : (+91)(80) 5260392

e-mail : sharada@cmmacs.ernet.in

Residence : SA 98, N A L Colony,
Kodihalli, Vimanapura P.O.,
BANGALORE - 560017.

Educational Qualification
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Degree    University     Year     Subjects     Class/Rank Percentage
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M.Sc        Bangalore     1987     Mathematics     First Class 88.5

                University                                         First Rank

B.Sc         Bangalore     1984     Physics            First Class 89.0

                University                  Chemistry        Fourth Rank

                                                Mathematics

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Awards

(1) Shri S.Nijalingappa 62nd Birth-day Commemoration Gold Medal, 1988

(2) Shri Bellegere Seetharama Shastry Gold Medal, 1988

(3) Prof.C.N.Srinivasa Iyengar Gold Medal, 1988

(4) Karnataka Government Cash Awards to Rank holders for the year 1986-87
 

RESEARCH ACTIVITIES

(1) MODELLING OF MARINE ECOSYSTEMS

Modelling of marine biological systems is of interest from several different viewpoints. Marine biota play an important role in the global carbon cycle. The biological pump transfers a considerable amount of carbon from euphotic zone to the deep ocean as organic matter, the basic mechanism being fixation of inorganic carbon into organic molecules during photosynthesis. Ocean carbon cycle models coupled with ocean-atmosphere general circulation models, can describe the long-term responses of ocean system to global change scenarios. Since the growth of fish larvae depends on the available phytoplankton, the estimation of biomass of primary production leads to the estimation of marine productivity. Biological processes also play an important component in the heat flux across the ocean as a whole since phytoplankton are absorbers and scatterers of solar radiation. Plankton are responsible for the production of organic compounds such as dimethyl sulphide which helps in the formation of clouds.

As a first step towards the development of the coupled, basin scale models of ocean circulation and biogeochemical cycles, a study is being carried out on a class of dynamical models of marine ecosystems. These models are in general intrinsically nonlinear, since the growth and grazing terms are nonlinear functions of species population, nutrients, mixed layer depth and solar radiation. Study of dynamics of such nonlinear models call for use of numerical methods. Furthermore, the number of parameters is rather large, typically 20 to 50. Therefore, it seems advisable to focus attention on a specific region and rely on available experimental and other information in choice of these parameters.

Initially, the dynamics of a basic three component model of marine ecosystem based on the uptake law of Michaelis-Menten and grazing laws of Ivlev and Mayzaud & Poulet was studied using phase plane analysis (Yajnik et al, 1992). The present study aims at the marine ecosystem in the Arabian Sea. The scientific interest in this region is considerable since the marine productivity is very high and the blooms of primary productivity exist in both monsoons. An interactive software package was developed to study the dynamics of the nonlinear 7-component model (Fasham et al, 1990) for the marine ecosystems including the effect of the time varying mixed layer depth, solar radiation and upwelling velocity and to carry out parameter sensitivity analysis. Two parameters affecting the nutrient supply, namely, subsurface nitrate concentration and diffusion parameter were varied. In addition, three ecosystem parameters, namely, asymptotic grazing rate of zooplankton, grazing preference of zooplankton and detritus sinking rate were varied. Annual averages and monthly averages of each component as well as fluxes have been obtained to give a quantitative picture of sensitivity of the ecosystem from carbon-flux point of view to few of the model parameters (M K Sharada and K S Yajnik, 1997). Several modifications of the model formulation and model parameter values have been tried to obtain the monthly average values of chlorophyll from the model simulation comparable to satellite data and JGOFS cruise data. Also, the effect of nonlinear mortality and self-grazing terms for zooplankton on the dynamics of a basic marine ecosystem model is being studied (M.K.Sharada and K.S.Yajnik, In press).

(2) STUDY OF MODELS OF OSCILLATORS

Interactive software packages were developed to solve linear, nonlinear and coupled ordinary differential equations. They were written in PASCAL. The results were displayed graphically on the monitor as the calculation progressed. They convey the basic concepts such as equilibrium, stability, limit cycles, sensitivity to initial conditions, etc. in certain dynamical systems like Van der Pol oscillator, Duffing oscillator. Another interactive software package was developed to communicate the ideas of bifurcation and stability of the deterministic systems governed by general nonlinear maps. The package displays graphically the behaviour of these maps for large times.

(3) CLIMATE MODEL

The climate over timescales of ten thousand to a million years shows strong periodicities and complicated behaviour. The model due to Saltzman and coworkers deals with nonlinear dynamics in which nonlinearity is motivated by the greenhouse effect of carbondioxide and the insulating effect of the ice cover. A variant of this type of model with four state variables (ocean temperatures and ice cover extents in the two hemispheres) which describes the spatial variability by having two coupled Saltzman oscillators was studied through numerical simulation to examine the large time behaviour near and far away from the bifurcation point. This simulation also helps to delineate the domains of different types of behaviour in the parameter space.

(4) MODELLING THE SEDIMENTARY BASINS

Development of models for the sedimentary basins is of practical interest in phenomena such as petroleum migration and ore genesis. The oil potential of the basin can be obtained from the temperature history of the basins. The one-dimensional model of the ocean basin incorporating the effects of consolidation, subsidence etc., is studied to describe the temperature distribution and the corresponding conversion of organic compound to petroleum.
 

Publications

(1) S.C.Manjula Vani, M.K.Sharada & K.T.Madhavan, Development of a signal processing software for NAL Laser Doppler Velocimeter, Journal of Instrumentation Society of India, 1989.

(2) K.S.Yajnik & M.K.Sharada, Dynamics of a basic phytoplankton model, Oceanography of the Indian Ocean, B.N.Desai(ed.), 91-98, 1992.

(3) M.K.Sharada & K.S.Yajnik, Seasonal variation of chlorophyll and primary productivity in central Arabian Sea: A macrocalibrated upper ocean ecosystem model, Proc. Indian Acad. Sci. (Earth Planet. Sci.), 106, Nos 1 & 2, June 1997, pp.33-42

Conference Presentations

(1) K.S.Yajnik, M.I.James & M.K.Sharada, Parametric study of the global climate model, 26th Convention of the Geological Society of India, Hyderabad, March 1990.

(2) M.K.Sharada, G.Reddaiah, V.Gopal & K.S.Yajnik, Dynamics of a nonlinear 7- component model of a marine ecosystem, National Seminar on Applications of Mathematical Modelling to Biology and Chemistry, Hyderabad, December 1991.

(3) M.K.Sharada & K.S.Yajnik, Dynamics of a nonlinear model of marine ecosystems for tropical conditions, IMACS International Symposium on Mathematical Modelling and Scientific Computing, Bangalore, December 1992.

(4) K.S.Yajnik & M.K.Sharada, Modelling of primary productivity in the Arabian Sea, C-25, GAIM First Science Conference, Gramisch-Parten Kirchen, Germany, September 1995.

(5) M.K.Sharada & K.S.Yajnik, Marine ecosystem model, JGOFS work shop on 0- and 1-D models of carbon cycles in the upper ocean, Toulouse, France, December 1995.

(6) P.S.Swathi, M.K.Sharada and K.S.Yajnik, A coupled physical-biological model for the Indian ocean, Tropmet-97, February 1997

(7) M.K.Sharada & K.S.Yajnik, Comparison of simulations of a mixed-layer FDM type model with CZCS data in north Indian Ocean, Workshop on Inverse Modelling in Global Biogeochemical Cycles, Heraklion, Greece, 16-20 March, 1998
 
 

Participation in Conferences/Training Programmes

(1) Conference on Mathematical Modelling, NAL, Bangalore, March 1988.

(2) Workshop on Mathematical Modelling and Computer Simulation, NAL, Bangalore, October 1988.

(3) Workshop on Geomechanics, NAL, Bangalore, January 1989.

(4) Geomechanics of Lithosphere, NGRI, Hyderabad, February 1989.

(5) 26th Convention of the Geological Society of India, NGRI, Hyderabad, March 1990.

(6) Intensive Course on C and UNIX, C-MMACS, Bangalore, April 1990.

(7) International Symposium on the Oceanography of the Indian Ocean, NIO, Goa, January 1991.

(8) A short course on Numerical Turbulent Flows, NAL, Bangalore, February 1991.

(9) Discussion meeting on Scientific Visualization, IISc, Bangalore, March 1991.

(10) Training Programme on IDEAS, C-MMACS, Bangalore, September 1991.

(11) IMACS International Symposium on Mathematical Modelling and Scientific Computing, Bangalore, December 1992.

(12) Intensive Course on Recent Developments in Large Scale and Parallel Matrix Computations and their applications, C-MMACS, Bangalore, December 1992.

(13) Intensive Course on Inverse Problems in Science and Engineering, C-MMACS, Bangalore, February 1993.

(14) Graphical User Interface, Using X Windows and Motif, C-DAC, Bangalore, May 1993.

(15) Workshop on Monitoring and Modelling of Coastal Ocean, C-MMACS, Bangalore, August 1993.

(16) MONTCLIM Discussion Meeting on Development of Coupled Models for monsoon and Tropical Climate, C-MMACS, Bangalore, February 1994.

(17) Intensive Course on Modelling of Oceanic and Atmospheric Processes,

C-MMACS, Bangalore, November 1994.

(18) Intensive Course on Application of Remotely-Sensed Data on Ocean Colour,

C-MMACS, Bangalore, April 1995.

(19) JGOFS Workshop on 0- and 1-D models of carbon cycles in theupper ocean, Toulouse, France, December 1995

(20) Intensive course on formal methods in software development, IISc., Bangalore, April1996.

(21) Workshop on complex systems (Chaos), C-MMACS, Bangalore, June 1996.

(22) Workshop on Virtual Reality, CAIR, Bangalore, September, 1997.

(22) Workshop on Inverse Modelling in Global Biogeochemical Cycles, Heraklion, Greece, 16-20 March, 1998.