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.

Spatial and temporal heterogeneity in aerosol properties and radiative forcing over Bay of Bengal: Sources and role of aerosol transport

Abstract: The Bay of Bengal (BoB) region is a small oceanic region surrounded by landmasses with distinct natural and anthropogenic aerosol sources. Despite this and the significant influence of BoB on the Indian monsoon and weather, information on aerosols and its spatial and temporal heterogeneity is sparse. The observations onboard several cruises and on an island location have been used in this paper along with satellite (MODIS onboard TERRA satellite) data (2000–2004) to study the spatial and temporal heterogeneity in aerosol properties. Our studies show that seasonal variation in aerosol optical depths over northern BoB are similar to that of east coast of India and west China, whereas variations over the southern BoB region are similar to that of Arabian Sea. The aerosol optical depths (AODs) and black carbon (BC) mass fraction (MF) over northern BoB reach their maximum value during April/May $(AOD ~0.48 {\pm} 0.06; BCMF ~6%)$ and minimum during October/November $(AOD ~0.19 {\pm} 0.02; BCMF ∼3%)$ in contrast to the seasonal pattern reported over Arabian Sea by earlier investigations. Over equatorial Indian Ocean south of BoB, AODs were low $(∼0.11 {\pm} 0.03)$ and seasonal variations were not very significant. The whole-sky (including clouds) aerosol surface radiative forcing (0.2 to 40 ${\mu}$ m)4 over northern BoB was in the range of −9 to −30 $W m^{-2}$, whereas that over southern BoB was in the range of −3 to −12 $W m^{-2}$. The corresponding atmospheric forcing was in the range of +6 to +20 $W m^{-2}$ and +1 to +6 $W m^{-2}$. The atmospheric absorption translates to a heating rate of 0.5 to 1.0 K/day.

Preparation, characterization and microwave dielectric properties of Ba(B1/2′Nb1/2)O3 [B′ = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb and In] ceramics

Abstract: Microwave dielectric resonators (DRs) based on Ba(B 1/2 ′Nb 1/2 )O 3 [B′=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In] complex perovskites have been prepared by conventional solid state ceramic route. The dielectric properties (relative permittivity, e r ; quality factor, Q ; and resonant frequency, τ f ) of the ceramics have been measured in the frequency range 4–6 GHz using resonance methods. The resonators have relatively high dielectric constant in the range 36–45, high quality factor and small temperature variation of resonant frequency. The dielectric properties are found to depend on the tolerance factor ( t ), ionic radius ( r ), and lattice parameter ( a p ).

Penetration of magnetospheric convective electric field to the equatorial ionosphere during the substorm of March 22, 1979

Abstract: The possible penetration of magnetospheric convective electric field to low latitudes is investigated with the help of VHF radar measurements of equatorial electrojet electric fields during the 1054 UT substorm of March 22, 1979. The observed time relationship of these electric fields with the southward component of the interplanetary magnetic field and the polar-auroral magnetic activity suggests that the magnetospheric convective electric fields may penetrate to low latitudes, at least on certain occasions during the growth phase of a substorm before screening by ring current becomes effective.