Modelling for Science, for a better future - some recent outcomes
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
by Catherine, J. K., M. S. M. Vijayan, U. B. Syeda Rabiya, K. Shimna, V. K. Gahalaut, and D. S. Ramesh
The ionosphere response to the great intraplate Indian Ocean earthquake of April 11, 2012 (Mw 8.6) and its largest aftershock (Mw 8.2), is analysed using GPS aided Total Electron Content (TEC) measurements. Data from the dense GPS networks, SuGAR (Sumatran GPS Array) and the permanent Andaman-Nicobar array, formed the near-field observations at distances 250–1200 km from the epicenter. Stations such as IISC, DGAR and few others provided measurements over 2000 km from the epicenter. The CIDs with a propagation velocity of 930–1262 m/s, equal the speeds of the shock acoustic waves, arrive within 10–18 min after the earthquake occurrence. The observed phenomenon of CID splitting into two modes, north and south of the epicenter is akin to the well documented effects of anisotropy on wave propagation. Closer to the epicenter, to its south, the propagation velocity of CID is ~1 km/sec and further south east of the network the velocity reduces to 500–600 m/s. In contrast, towards Andaman in the north, the CID propagation velocity increases to 2–3.5 km/s. The zenith angle of the line-of-sight between the GPS receiver and satellite appears to influences the amplitude of the TEC fluctuations. The anomalous azimuthal variation of the Rayleigh wave radiation pattern best explains the observed N-S asymmetry of CID.
2015), Dichotomy in mode propagation of coseismic ionospheric disturbance: Observations from April 11, 2012 Indian Ocean earthquake., J. Geophys. Res. Space Physics, 120, doi:10.1002/2014JA020621., , , , , and (
Seismic hazard and risk assessment based on the unified scaling law for earthquakes
by A. Nekrasova, V. G. Kossobokov, I. A. Parvez, X. Tao
The Unified Scaling Law for Earthquakes (USLE), that generalizes the Gutenberg–Richter recurrence relation, has evident implications since any estimate of seismic hazard depends on the size of territory that is used for investigation, averaging, and extrapolation into the future. Therefore, the hazard may differ dramatically when scaled down to the proportion of the area of interest (e.g. a city) from the enveloping area of investigation. In fact, given the observed patterns of distributed seismic activity the results of multi-scale analysis embedded in USLE approach demonstrate that traditional estimations of seismic hazard and risks for cities and urban agglomerations are usually underestimated. Moreover, the USLE approach provides a significant improvement when compared to the results of probabilistic seismic hazard analysis, e.g. the maps resulted from the Global Seismic Hazard Assessment Project (GSHAP). In this paper, we apply the USLE approach to evaluating seismic hazard and risks to population of the three territories of different size representing a sub-continental and two different regional scales of analysis, i.e. the Himalayas and surroundings, Lake Baikal, and Central China regions.
- 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
- The Role of Microzonation in Estimating Earthquake Risk
- Seismotectonic implications of strike–slip earthquakes in the Darjiling–Sikkim Himalaya