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.

Modeling of aerosol induced snow albedo feedbacks over the Himalayas and its implications on regional climate

Abstract: Regional climate model (RegCM-4.6.0) coupled with Community Land Model (CLM4.5), which includes SNow, ICe and Aerosol Radiation (SNICAR) model was used to investigate the effect of aerosol-induced snow albedo feedback on the regional radiation balance and atmospheric thermodynamics. During pre-monsoon (March–April–May) season, the deposition of absorbing aerosols such as dust and Black Carbon (BC) decreases the snow albedo of Himalayan–Tibetan region by 0.15 ± 0.13 causing a positive radiative effect of 14 ± 13 W m−2. In spite of the low absorption efficiency, the contribution of dust to the total radiative effect is found to be comparable to that due to BC over this region. The snow darkening due to aerosols increases the surface temperature by 1.33 ± 1.2 K, which results in the reduction of snow cover fraction by 7 ± 11%. The snow cover reduction is more than 20% in the mid-Himalayan region and northern Tibetan slopes due to its proximity to the major source regions like Indo-Gangetic Plain and Taklimakan desert respectively. Direct radiative effect (DRE, scattering and absorption of radiation) of atmospheric aerosols is smaller compared to the snow albedo effect (SAE) over the Himalayan region. DRE increase the mid-tropospheric temperature up to 1 K, whereas SAE effects are smaller and highly localized over the Himalayan region. Due to the large geographical extend of the forcing, the change in precipitation due to the direct effect is more prominent than that of the snow albedo effect. In general, change in snow cover fraction is dominated by the SAE and precipitation is more dominated by DRE. Present work demonstrates that the snow albedo feedback process over the Himalayan–Tibetan region plays a significant role in the regional climate of South Asia and therefore is crucial for the assessment of anthropogenic impacts.

Effect of temperature and strain rate on the deformation behavior and microstructure of a homogenized AZ31 magnesium alloy

Abstract: The plastic deformation behavior and dynamic recrystallization (DRX) in homogenized AZ31 Mg alloy was investigated in uniaxial compression in the temperature range between 150 and 400 °C with strain rates ranging from 10 −3 to 10 2 s −1 . Twinning was found to contribute significantly during the early stages of deformation. The onset of twinning was examined in detail by recourse to the examination of the appearance of first local maxima before peak strain in the stress–strain responses and the second derivative of stress with strain. High strain hardening rate was observed immediately after the onset of twinning and was found to increase with the Zener–Hollomon parameter. DRX was observed at temperatures above 250 °C whereas deformation at lower temperatures (

Aerosol physical properties and Radiative forcing at the outflow region from the Indo‐Gangetic plains during typical clear and hazy periods of wintertime

Abstract: [1] Results of a campaign mode measurements of column integrated aerosol optical depths, near surface mass concentrations and LIDAR profiles during winter 2004 at Kharagpur located at the vent of the out flow region from the Indo-Gangetic plains are presented with a view to characterize the atmospheric aerosol radiative forcing during hazy and clear sky conditions. The multispectral optical depths, surface mass concentrations and black carbon are high, while a decrease in Angstrom exponent value was observed during the hazy sky days. During hazy conditions, the LIDAR profiles show a decrease in the mixed layer height leading to confinement and subsidence of aerosols. Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model along with Optical Properties of Aerosols and Clouds (OPAC) are used to perform composite aerosol forcing estimation, incorporating LIDAR derived mixed layer heights. A considerable decrease in estimated single scattering albedo has been observed during hazy sky days. The atmospheric absorption during hazy sky days increased by 75% compared to clear days. Negative forcing was observed both at the top of the atmosphere and at the surface. The forcing estimates of the present study are compared with the similar studies over other locations in the Indo-Gangetic plains during the campaign period.