Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/xmlui/handle/123456789/18639
Title: Credibility of statistical downscaling under nonstationary climate
Authors: SALVI, K
GHOSH, S
GANGULY, AR
Keywords: Asian Summer Monsoon
General-Circulation Model
Radiative-Transfer Model
Daily Precipitation
Atmospheric Circulation
Interannual Variability
Stochastic Simulation
Scale Circulation
Unresolved Clouds
Solar-Radiation
Issue Date: 2016
Publisher: SPRINGER
Citation: CLIMATE DYNAMICS,46(42891)1991-2023
Abstract: Statistical downscaling (SD) establishes empirical relationships between coarse-resolution climate model simulations with higher-resolution climate variables of interest to stakeholders. These statistical relations are estimated based on historical observations at the finer resolutions and used for future projections. The implicit assumption is that the SD relations, extracted from data are stationary or remain unaltered, despite non-stationary change in climate. The validity of this assumption relates directly to the credibility of SD. Falsifiability of climate projections is a challenging proposition. Calibration and verification, while necessary for SD, are unlikely to be able to reproduce the full range of behavior that could manifest at decadal to century scale lead times. We propose a design-of-experiments (DOE) strategy to assess SD performance under nonstationary climate and evaluate the strategy via a transfer-function based SD approach. The strategy relies on selection of calibration and validation periods such that they represent contrasting climatic conditions like hot-versus-cold and ENSO-versus-non-ENSO years. The underlying assumption is that conditions such as warming or predominance of El Nio may be more prevalent under climate change. In addition, two different historical time periods are identified, which resemble pre-industrial and the most severe future emissions scenarios. The ability of the empirical relations to generalize under these proxy conditions is considered an indicator of their performance under future nonstationarity. Case studies over two climatologically disjoint study regions, specifically India and Northeast United States, reveal robustness of DOE in identifying the locations where nonstationarity prevails as well as the role of effective predictor selection under nonstationarity.
URI: http://dx.doi.org/10.1007/s00382-015-2688-9
http://localhost:8080/xmlui/handle/123456789/18639
ISSN: 0930-7575
1432-0894
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