Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/hess-2016-547
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
26 Oct 2016
Review status
This discussion paper has been under review for the journal Hydrology and Earth System Sciences (HESS). A final paper in HESS is not foreseen.
Hotspots of sensitivity to GCM biases in global modelling of mean and extreme runoff
Lamprini V. Papadimitriou1, Aristeidis G. Koutroulis1, Manolis G. Grillakis1, and Ioannis K. Tsanis1,2 1Technical University of Crete, School of Environmental Engineering, Chania, Greece
2McMaster University, Department of Civil Engineering, Hamilton, ON, Canada
Abstract. Climate model outputs feature systematic errors and biases that render them unsuitable for direct use by the impact models, especially when hydrological parameters are studied. To deal with this issue many bias correction techniques have been developed to adjust the modelled variables against observations. For the most common applications, adjustment concerns only precipitation and temperature whilst for others more driving parameters (including radiation, wind speed, humidity, air pressure) are bias adjusted. Bias adjusting only a part of the variables required as biophysical model input could affect the physical consistency among input variables and is poorly studied. In this work we quantify the individual effect of bias correction of each climate variable on global scale hydrological simulations of the recent past. To this end, a partial correction bias assessment experiment is conducted. Six climate parameters (precipitation, temperature, radiation, humidity, surface pressure and wind speed) from a set of three Global Climate Models are tested. The examined hydrological indicators are mean and extreme (low and high) runoff production. A methodology for the classification of the bias correction effects is developed and applied. Global hotspots of hydrological sensitivity to GCM biases at the global scale are derived, for both mean and extreme runoff. Our results show that runoff is mostly affected by the biases in precipitation, temperature, specific humidity and radiation (in this order) and suggest that bias correction should be applied in priority to these parameters. Surface pressure and wind speed had a minor effect on runoff simulations for the majority of the land surface. Low runoff has an increased sensitivity to the GCM biases compared to mean and high runoff, underlying the importance of bias correction for the study of low flow conditions and relevant hydrological extremes, such as droughts.

Citation: Papadimitriou, L. V., Koutroulis, A. G., Grillakis, M. G., and Tsanis, I. K.: Hotspots of sensitivity to GCM biases in global modelling of mean and extreme runoff, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-547, 2016.
Lamprini V. Papadimitriou et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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RC1: 'review "Hotspots of sensitivity to GCM biases in global modeling of mean and extreme runoff"', Anonymous Referee #1, 22 Nov 2016 Printer-friendly Version 
 
RC2: 'Review of HESS-2016-547', Anonymous Referee #2, 02 Dec 2016 Printer-friendly Version 
Lamprini V. Papadimitriou et al.
Lamprini V. Papadimitriou et al.

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Short summary
Bias correction of climate model outputs has become a standard procedure that accompanies biophysical impact studies. However, bias correction introduces a new level of uncertainty in the modelling chain which remains relatively unexplored. In this work we present a new framework for the quantification and categorization of the effect of bias correction on biophysical impact simulations and we apply it on hydrological simulations deriving hotspots of sensitivity to GCM biases at the global scale
Bias correction of climate model outputs has become a standard procedure that accompanies...
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