Vikram Sarabhai Space Centre

About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.

First observations of turbulence parameters in the troposphere over the Bay of Bengal and the Arabian Sea using radiosonde

Abstract: [1] This paper discusses the turbulence characteristics of the free atmosphere over the Bay of Bengal and the Arabian Sea during the premonsoon season of 2006. The turbulence scaling concepts, developed over the past decades for application to oceanic mixing, are used for retrieving turbulence properties in the free atmosphere from high-resolution soundings, as described by Clayson and Kantha (2008). The variability in the vertical turbulence structure over a large spatial region is studied using this novel method for the first time. Investigations revealed the presence of a highly turbulent band at upper troposphere below the cold point tropopause (CPT) with significant enhancements in Thorpe length and eddy diffusion coefficient. This increased turbulence is studied in conjunction with the observations of the tropical tropopause layer (TTL). It is seen that the lower and upper boundaries of this turbulence band nearly coincide with the height where the potential temperature lapse rate begins to show a decrease (LRHmin) and cold point tropopause, respectively. The TTL is the transition regime from convectively dominated troposphere to radiatively dominated stratosphere, and is characterized by a decrease in the static stability. The enhanced zonal and meridional wind shear observed in this region shows that the stability in this region is further weakened because of the breaking of Kelvin–Helmholtz waves, which results in the enhancement of turbulence. The study reveals the potential of high-resolution soundings to be used in the investigations of turbulence in the free atmosphere.

Syntactic foam composites of epoxy‐allyl phenol‐bismaleimide ternary blend—Processing and properties

Abstract: Syntactic foams based on a reactive polymer blend of Epoxy-Allyl Phenol-Bismaleimide were processed using hollow glass microballoons The effect of microballoon concentration on the mechanical and thermophysical properties of the foam composites was investigated The mechanical properties, specific strength, coefficient of linear expansion, and density of the foam composites showed decreasing trend with increase in microballoon concentration whereas the specific heat showed a marginal increase The temperature dependence of the thermophysical properties revealed an increase in coefficient of linear expansion, whereas the specific heat was more or less insensitive to the test temperature Syntactic foams of fixed filler loading (50% by weight) were processed using a blend of two types of microballoons of different shell thickness The mechanical properties increased proportional to the concentration of the higher shell thickness microballoon At moderate filler load microballoon breakage dominated the failure mode The compositional dependency of the mechanical properties was corroborated by SEM analysis of the fracture surfaces © 2007 Wiley Periodicals, Inc J Appl Polym Sci, 2007

Surface changes in solar irradiance due to aerosols over central Himalayas

Abstract: During a comprehensive aerosol field campaign as a part of the ISRO-GBP, extensive measurements of radiative fluxes at the surface were made during December 2004 at Manora Peak, in the Shivalik ranges of the Central Himalayas. The surface radiative fluxes were used to estimate aerosol radiative forcing. Our analysis clearly shows that during the clean atmospheric conditions over Manora Peak, the observed aerosol radiative forcing is in good agreement to those of modeled ones, while for the higher aerosol optical depths (AODs), modeled values are significantly smaller than the observed ones. It was observed that at Manora Peak, the anthropogenic aerosols (from valley below) transported upwards by evolution of boundary layer during the daytime provide an atmosphere conducive for ‘mixed’ aerosols. Focused efforts are needed to address this issue for which simultaneous observations at high altitude site with those in nearby valley are essential.