National Institute of Oceanography, India

About: National Institute of Oceanography, India is a facility organization based out in Panjim, Goa, India. It is known for research contribution in the topics: Monsoon & Population. The organization has 4713 authors who have published 6927 publications receiving 174272 citations.

Planetary waves on a rotating sphere. II

Abstract: Simple solutions are found for barotropic planetary oscillations of a fluid in a $\beta$-plane, both in the unbounded plane and in enclosed basins of various shapes. These are compared with analogous motions of fluid on the surface of a sphere. The motions in a $\beta$-plane are considered in part I. It is shown that waves can exist which may be oriented in any horizontal direction; they drift westwards with a velocity $\beta$/$\kappa^2$, where $\kappa$ = 2$\pi$/wavelength is the absolute wave number. The group velocity of these waves makes an angle 2$\alpha$ with the eastward direction, where $\alpha$ is the angle made by the vector wave number. The reflexion of such waves from a fixed boundary is studied; both the wavelength and orientation of the reflected wave differs from that of the incident wave in general. Westward-drifting motions are typical of motions on an unbounded $\beta$-plane. On the other hand, motions in an enclosed basin can be described as a carrier wave modulated by a real amplitude function f(x, y). The equation for f is equivalent to the equation for a vibrating membrane clamped at the boundaries; normal mode solutions can be obtained explicitly for a variety of shapes of basin, including the rectangle, circle and equilateral triangle. Motions on a sphere are considered in part II. On an unbounded sphere the general solutions are spherical harmonics S$_n$($\theta$', $\phi$') where ($\theta$', $\phi$') denote spherical co-ordinates with respect to some pole P', not necessarily on the axis of rotation. The motions are propagated by a westward drift of the pole P' round a circle of latitude, with angular velocity 2$\Omega$/n(n+1). Solutions in enclosed basins have been found not only when the boundaries of the basin are circles of latitude, but also when the boundaries are meridians of longitude. The validity of the $\beta$-plane approximation is investigated, first by determining the asymptotic forms of the surface harmonics when the wave number n is high; secondly by comparing the periods of the lower modes in an enclosed basin on a sphere with the corresponding periods for the $\beta$-plane. At high wave numbers the solutions in terms of spherical harmonics do generally reduce to motions satisfying the $\beta$-plane equations: but exceptions occur in the neighbourhood of certain caustic lines, where the variation of $\beta$ must be taken into account. Thus it is possible for a wave motion to be trapped in the neighbourhood of a great-circle, the amplitude falling off rapidly to either side. The plane of this great-circle rotates slowly round the axis of rotation of the sphere. On the other hand, in an enclosed basin centred on the equator some of the lower modes of oscillation agree very well with those derived from the $\beta$-plane approximation. Even when the radius of the basin is as great as one quadrant, the periods of the four lowest symmetric modes agree within 10%.

Recent Developments in the Synthesis of Five‐ and Six‐Membered Heterocycles Using Molecular Iodine

Abstract: Heterocyclic scaffolds represent the key structural subunits of many biologically active compounds. Over the last few years iodine-mediated reactions have been extensively studied due to their low cost and eco-friendliness. This Review covers advances in the field of iodine-mediated synthesis of heterocyclic compounds since 2006, especially with an emphasis on mechanisms of ring formation. In this article, syntheses of different heterocycles are classified based on the manipulation of functional groups.

Ocean primary production and available light: further algorithms for remote sensing

Abstract: In the context of remote sensing of the ocean, the general problem of estimating water column production from surface irradiance and column chlorophyll concentration is examined, and some refinements are made to the linear theory presented by Platt (1986, Deep-Sea Research , 33 , 149–163). Further empirical evidence is presented to show the stability of the relationship between surface light and biomass-normalized primary production of the ocean water column. A theoretical explanation is given for the non-zero intercept often obtained when these two variables are regressed. The systematic errors in the estimation of primary production by remote sensing, due to non-uniformity in the biomass profile, are examined through sensitivity analyses on a generalized biomass profile. The errors are shown to be functions of the parameters of the biomass profile, of the photosynthetic parameters and of the optical properties of the water. The probable random errors in the estimation of water column primary production using remotely sensed data are evaluated. Some general issues related to the collection and assimilation of data on ocean primary production are addressed.

Litter Fall and Energy Flux in a Mangrove Ecosystem

Abstract: Production, elemental composition andin situdecomposition of litter ofRhizophora apiculata,R. mucronata,Sonneratia albaandAvicenna officinaliswere studied in a mangrove ecosystem fringing Madovi–Zuari Estuaries on the Central West Coast of India. Litter yield ranged from 10.2 tonnes ha-1year-1inA. officinalisthrough 11.8 (R. apiculataandR. mucronata) to 17 tonnes ha-1year-1inS. alba. Seasonally maximum litter fall was in pre- and post-monsoon monthe, with the lowest production in the monsoon. Modelling of litter fall as a function of Julian day and six environmental parameters showed that the observed changes can be explained in terms of dry/wet season and wind speed, with a 1000. Total decomposition (98–100% loss in dry weight and C, and >90% loss in N and P) of yellow leaves was within 15 weeks in the twoRhizosporaspp. andS. alba, and within 8 weeks inA. officinalis. In all four species, mass changes during decomposition obeyed first-order kinetics. Comparison of C, N and P fluxes from the decomposing mangrove litter with phytoplankton, bacterial and secondary production in the estuarine waters showed that mangrove production is important mainly for the C budget of the Estuaries and in sustaining the microbial food chain and nutrient regeneration, rather than the particulate food chain directly.