Modelling for Science, for a better future - some recent outcomes
Precipitation-aerosol relationship over the Indian region during drought and excess summer monsoon years
by Sajani Surendran, Kavirajan Rajendran and V B Arya
This study investigates the aerosols-rainfall interaction during Indian summer monsoon and characterizes their difference in drought and excess summer monsoon years, based on MODIS (MODerate Resolution Imaging Spectro-radiometer) derived Aerosol Optical Depth (AOD) at 550 nm. AOD has been estimated using Level-2 MODIS Terra Data Version 6. AOD in drought years is found to be higher over India compared to excess monsoon years. The total effect of aerosols causes reduction of summer rainfall but with distinct differences in their impact during strong and weak summer monsoon years, due to the changes in clouds, radiation, large-scale circulation, and convection. Aerosol and cloud characteristics exhibit strong association to rainfall variability in interannual time scales. Variability in cloud effective radius and cloud optical thickness is found to be consistent with aerosol effect.
Citation: Sajani Surendran, Kavirajan Rajendran and V B Arya (2016), Precipitation-aerosol relationship over the Indian region during drought and excess summer monsoon years ", Proc. SPIE, 98820Q (May 3); doi:10.1117/12.2229447; http://dx.doi.org/10.1117/12.2229447
Reduction of uncertainty associated with future changes in Indian summer monsoon projected by climate models and assessment of monsoon teleconnections
by Kavirajan Rajendran, Sajani Surendran, Akio Kitoh and Stella Jes Varghese
Coupled Model Intercomparison Project phase 5 (CMIP5) coupled global climate model (CGCM) Representative Concentration Pathway (RCP) simulations project clear future temperature increase but diverse changes in Indian summer monsoon rainfall (ISMR) with substantial inter-model spread. Robust signals of projected changes are derived based on objective criteria and the physically consistent simulations with the highest reliability suggest future reduction in the frequency of light rainfall but increase in high to extreme rainfall. The role of equatorial Indian and Pacific Oceans on the projected changes in monsoon rainfall is investigated. The results of coupled model projections are also compared with the corresponding projections from high resolution AGCM time-slice, multi-physics and multi-forcing ensemble experiments.
Citation: Kavirajan Rajendran, Sajani Surendran, Akio Kitoh and Stella Jes Varghese (2016), Reduction of uncertainty associated with future changes in Indian summer monsoon projected by climate models and assessment of monsoon teleconnections, Proc. SPIE, 98820D (May 3) doi:10.1117/12.2229392; http://dx.doi.org/10.1117/12.2229392
Neo-deterministic Definition of Seismic and Tsunami Hazard Scenarios for the Territory of Gujarat (India)
by A. Magrin, I. A. Parvez, F. Vaccari, A. Peresan , B. K. Rastogi, S. Cozzini, D. Bisignano, F. Romanelli, Ashish, P. Choudhury, K. S. Roy, R. R. Mir and G. F. Panza
A reliable and comprehensive characterization of expected seismic ground shaking is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. So far, one of the major problems in classical methods for seismic hazard assessment consisted in the adequate characterization of the attenuation models, which may be unable to account for the complexity of the medium and of the seismic sources and are often weakly constrained by the available observations. Current computational resources and physical knowledge of the seismic waves generation and propagation processes allow nowadays for viable numerical and analytical alternatives to the use of attenuation relations. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic approach (NDSHA), which allows considering a wide range of possible seismic sources as the starting point for deriving scenarios by means of full waveforms modelling. The method does not make use of attenuation relations and, thanks to advanced computational infrastructures, permits to carry on parametric analysis and stability tests that contribute characterizing the related uncertainties, as well as to fill in the unavoidable gaps in available observations. Results from preliminary application of NDSHA method to regional scale seismic hazard assessment (ground motion at bedrock) and tsunami scenarios modelling for the Gujarat territory are illustrated. The resulting estimates are compared with available information about intensities from past earthquakes, as well as with recently developed probabilistic seismic hazard map of Gujarat.
- Probabilistic earthquake hazard assessment for Peninsular India
- An Assessment of Optimality of Observations in High-resolution Weather Forecasting
- Impact of data assimilation on high-resolution rainfall forecasts: A spatial, seasonal, and category analysis
- Evaluation of high resolution rainfall forecasts over Karnataka for the 2011 southwest and northeast monsoon seasons
- Propagation of torsional surface waves in a double porous layer lying over a Gibson half space