Vishal Dixit

Vishal Dixit
Indian Institute of Technology Bombay | IIT Bombay

PhD, Atmospheric Science

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15
Publications
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78
Citations

Publications

Publications (15)
Article
Full-text available
It is well known that subtropical shallow convection transports heat and water vapor upwards from the surface. It is less clear if it also transports horizontal momentum upwards to significantly affect the trade winds in which it is embedded. We utilize unique multiday large‐eddy simulations run over the tropical Atlantic with ICON‐LEM to investiga...
Article
Motivated by the abundance of low clouds in the subtropics, where the easterly trade winds prevail, we study the role of shallow convection in the momentum budget of the trades. To this end, we use ICON‐LEM hindcasts run over the North Atlantic for twelve days corresponding to the NARVAL1 (winter) and NARVAL2 (summer) flight campaigns. The simulati...
Article
Full-text available
The simulation of Saharan mid tropospheric clouds is investigated with the weather research and forecasting (WRF) regional atmospheric model at convection permitting (4 km) horizontal grid-spacing. We identify two potential problems in such simulations: one that affects cloud cover, and another that affects the mean and geographic patterns of both...
Article
Full-text available
Water vapour is the most abundant and powerful greenhouse gas in Earth's atmosphere, and is emitted by human activities. Yet the global warming potential (GWP) and radiative forcing (RF) of emitted water vapour have not been formally quantified in the literature. Here these quantities are estimated for surface emission using idealised experiments c...
Article
Atmospheric cloud radiative effects (ACRE) narrow the Intertropical Convergence Zones (ITCZs) in climate models. Some studies have attributed this to the upper tropospheric heating by deep clouds. We report two types of idealized aquaplanet experiments, one where ACRE in specific altitude ranges is removed and another where the ACRE associated with...
Article
Full-text available
Recent studies have shown that the shallow meridional circulation (SMC) coexists with the deep circulation in the marine ITCZ. The SMC has been assumed to be forced by strong meridional gradients of Sea Surface Temperature (SST) which affect the atmosphere under hydrostatic balance. In this paper, we present a new viewpoint that the shallow meridio...
Article
Paleoclimatic proxies indicate that significant summertime rainfall reached the Sahara region during the mid-Holocene, presumably in response to stronger summertime heating in the Northern Hemisphere. Climate models generally do not replicate the enhanced precipitation. As a step toward understanding the response and possible role of model errors,...
Article
Full-text available
The behavior of tropical extreme precipitation under changes in sea surface temperatures (SSTs) is investigated with the Weather Research and Forecasting Model (WRF) in three sets of idealized simulations: small-domain tropical radiative-convective equilibrium (RCE), quasi-global "aquapatch", and RCE with prescribed mean ascent from the tropical ba...
Article
Full-text available
The inter-tropical convergence zones (ITCZ) form closer to the equator during equinoxes while they form well away from the equator during the boreal summer. A simple three-way balance between the pressure gradients, Coriolis force and effective Rayleigh friction has been classically used to diagnose the location of maximum boundary layer convergenc...
Conference Paper
Full-text available
The Bay of Bengal shows a unique feature during boreal summer in the tropics. The Sea surface temperatures (SST) in the basin is found to have a weak gradient in the northern hemisphere and a strong gradient in the southern hemisphere. There are two favorable locations for the ITCZ, one near equator (5 • S) and other off-equator (15 • N). In this p...
Article
Full-text available
A simple linear model was proposed by Jiang et al. (2004) to highlight the mechanism of scale selection during the northward propagation of cloud bands over Bay of Bengal. The easterly shear in zonal winds was shown to be an essential parameter in scale selection. This model was criticized for the use of unrealistic values of the friction and diffu...
Article
Full-text available
A Community Atmosphere Model (CAM 3.0) has been used in a zonally symmetric aqua-planet configuration to study the sensitivity of the location of ITCZ and associated Hadley circulation to the latitudinal distribution of sea surface temperature (SST) and convective relaxation time scale. In simulations with SST similar to boreal summer SST in Indian...

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Projects

Projects (2)
Project
Effect of convective organisation
Project
To understand the processes that lead to mid-Holocene greening of Sahara desert.