• A Chandrasekar

      Articles written in Journal of Earth System Science

    • A comparative study of implicit and explicit initialization for a tropical barotropic model

      Susmita Majumdar D R C Nair R S Saraswat A Chandrasekar

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      The explicit nonlinear normal mode initialization (ENMI) scheme is applied to a tropical barotropic limited area shallow water model in spherical coordinates. The model is formulated by considering potential enstrophy conserving finite difference scheme. It is seen from the results of this study that the ENMI scheme is fully capable of filtering out the spurious gravity wave oscillations. The results are compared with those using an implicit nonlinear normal mode initialization (INMI). The latter scheme gives equally satisfactory results, requiring less computational time than the explicit scheme.

    • Numerical study of the effects of urban heat island on the characteristic features of the sea breeze circulation

      Abhijit Sarkar R S Saraswat A Chandrasekar

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      A two-dimensional numerical model is employed to study the effect of the coastal urban heat island on the sea breeze front and the thermal internal boundary layer height. The temperature at the land surface is determined by solving an energy budget equation. The effect of the urban heat island is studied by varying the width of the region and its intensity. During the early afternoon, the presence of the urban heat island enhances the strength of convergence of the sea breeze front and also reduces its inland penetration. The presence of the urban heat island causes increased thermal internal boundary layer height. Larger urban width causes larger vertical velocity and higher thermal internal boundary layer. Stronger convergence and higher thermal internal boundary layer are also obtained in case of larger heat island intensity.

    • Study on the sensitivity of the vertical cooling (heat sink) on the displacements of the mid-tropospheric ridge using a linear model

      A Chandrasekar

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      A linear model of the response of a stratified atmosphere to isolated heat sources in spherical coordinates is used to study the maintenance of the mean position of the mid tropospheric ridge and its displacement. It is well known that the performance of the southwest Indian monsoon is related to the latitudinal position of the April 500 hPa ridge along 75‡E. It was demonstrated that an anomalous cooling associated with the increased snow cover in Eurasia can result in moderate southward displacement of the mid-tropospheric ridge. The results of this study indicate that the vertically integrated cooling rate (strength of heat sink) has more effect on the southward displacement of the ridge when the sink is closer to the ridge.

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