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Assessing GCM Convergence for India Using the Variable Convergence Score

Ojha, Richa and Kumar, Nagesh D and Sharma, Ashish and Mehrotra, Raj (2014) Assessing GCM Convergence for India Using the Variable Convergence Score. In: JOURNAL OF HYDROLOGIC ENGINEERING, 19 (6). pp. 1237-1246.

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Official URL: http://dx.doi.org/10.1061/(ASCE)HE.1943-5584.00008...


General circulation models (GCMs) use transient climate simulations to predict climate conditions in the future. Coarse-grid resolutions and process uncertainties necessitate the use of downscaling models to simulate precipitation. However, in the downscaling models, with multiple GCMs now available, selecting an atmospheric variable from a particular model which is representative of the ensemble mean becomes an important consideration. The variable convergence score (VCS) provides a simple yet meaningful approach to address this issue, providing a mechanism to evaluate variables against each other with respect to the stability they exhibit in future climate simulations. In this study, VCS methodology is applied to 10 atmospheric variables of particular interest in downscaling precipitation over India and also on a regional basis. The nested bias-correction methodology is used to remove the systematic biases in the GCMs simulations, and a single VCS curve is developed for the entire country. The generated VCS curve is expected to assist in quantifying the variable performance across different GCMs, thus reducing the uncertainty in climate impact-assessment studies. The results indicate higher consistency across GCMs for pressure and temperature, and lower consistency for precipitation and related variables. Regional assessments, while broadly consistent with the overall results, indicate low convergence in atmospheric attributes for the Northeastern parts of India.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the ASCE-AMER SOC CIVIL ENGINEERS, 1801 ALEXANDER BELL DR, RESTON, VA 20191-4400 USA
Keywords: Precipitation; India; Climates; Simulation; General circulation models; Variable convergence score; Nested bias correction; Precipitation; Intergovernmental panel on climate change scenario; India
Department/Centre: Division of Mechanical Sciences > Centre for Earth Sciences
Division of Mechanical Sciences > Civil Engineering
Date Deposited: 24 Jun 2014 05:51
Last Modified: 24 Jun 2014 07:43
URI: http://eprints.iisc.ac.in/id/eprint/49294

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