Modelling for Science, for a better future - some recent outcomes
Wave propagation across the imperfectly bonded interface between cracked elastic solid and porous solid saturated with two immiscible viscous fluids
by Sushant Shekhar and Imtiyaz A. Parvez
The present study is aimed at understanding the effect of a vertically aligned crack, present in the elastic half space on the propagation of attenuated waves. These waves are incident at a point on the interface between the porous half space and the cracked elastic half space. The analysis is based on Snell’s law for reflection and refraction of an incident wave at the interface. A loose bonding at the interface between the porous half space and the cracked elastic half space has been considered and represented here as the tangential slip. The proposed model is solved for the propagation of harmonic plane waves. The final equations are in the form of Christoffel equations from which we find four reflected waves (three longitudinal body waves and one transverse body wave) and two refracted waves (one longitudinal body wave and one transverse body wave). The expression of reflection–refraction coefficients and energy share of each reflected and refracted waves for a given incident wave is obtained in closed form and computed numerically in the present study. Numerical examples are considered for the partition of the incident energy in which we have studied the effect of aspect ratio, crack density and loose bonding parameter.
Prediction of Indian rainfall during the summer monsoon season on the basis of links with equatorial Pacific and Indian Ocean climate indices
by Sajani Surendran, Sulochana Gadgil, P A Francis and M Rajeevan
Interannual variation of Indian summer monsoon rainfall (ISMR) is linked to El Niño-Southern Oscillation (ENSO) as well as the Equatorial Indian Ocean Oscillation (EQUINOO) with the link with the seasonal value of the ENSO index being stronger than that with the EQUINOO index. We show that the variation of a composite index determined through bivariate analysis, explains 54% of ISMR variance, suggesting a strong dependence of the skill of monsoon prediction on the skill of prediction of ENSO and EQUINOO. We explored the possibility of prediction of the Indian rainfall during the summer monsoon season on the basis of prior values of the indices. We find that such predictions are possible for July–September rainfall on the basis of June indices and for August–September rainfall based on the July indices. This will be a useful input for second and later stage forecasts made after the commencement of the monsoon season.
Citation: Sajani Surendran, Sulochana Gadgil, P A Francis and M Rajeevan (2015), Prediction of Indian rainfall during the summer monsoon season on the basis of links with equatorial Pacific and Indian Ocean climate indices, Environ. Res. Lett., 10, 094004. doi: 10.1088/1748-9326/10/9/094004
Robust signals of future projections of Indian summer monsoon rainfall by IPCC AR5 climate models: Role of seasonal cycle and interannual variability
by Jayasankar, C B, Sajani Surendran and K Rajendran
Coupled Model Intercomparison Project phase 5 (Fifth Assessment Report of Intergovernmental Panel on Climate Change) coupled global climate model Representative Concentration Pathway 8.5 simulations are analyzed to derive robust signals of projected changes in Indian summer monsoon rainfall (ISMR) and its variability. Models project clear future temperature increase but diverse changes in ISMR with substantial intermodel spread. Objective measures of interannual variability (IAV) yields nearly equal chance for future increase or decrease. This leads to discrepancy in quantifying changes in ISMR and variability. However, based primarily on the physical association between mean changes in ISMR and its IAV, and objective methods such as k-means clustering with Dunn's validity index, mean seasonal cycle, and reliability ensemble averaging, projections fall into distinct groups. Physically consistent groups of models with the highest reliability project future reduction in the frequency of light rainfall but increase in high to extreme rainfall and thereby future increase in ISMR by 0.74 ± 0.36 mm d−1, along with increased future IAV. These robust estimates of future changes are important for useful impact assessments.
Citation: Jayasankar, C. B., Sajani Surendran, and K. Rajendran (2015), Robust signals of future projections of Indian summer monsoon rainfall by IPCC AR5 climate models: Role of seasonal cycle and interannual variability, Geophys. Res. Lett., 42, 3513–3520, doi:10.1002/ 2015GL063659.
- Dichotomy in mode propagation of coseismic ionospheric disturbance: Observations from April 11, 2012 Indian Ocean earthquake
- Seismic hazard and risk assessment based on the unified scaling law for earthquakes
- Comparing statistically downscaled simulations of Indian monsoon at different spatial resolutions
- A Preliminary Study on Rainfall Pattern before and after the January 26, 2001 Bhuj Earthquake (Mw 7.7) over Kachchh Region of Western Peninsular, India.
- Ultra-high Resolution Global Model Climate Change Projection for India: Towards a Data Intensive Paradigm