Paper:Watson, J and Challinor, AJ (2013
Abstract
21When projecting future crop production, the skill of regional scale (> 100km resolution) crop models 22 is limited by the spatial and temporal accuracy of the calibration and weather data used. The skill of 23 climate models in reproducing surface properties such as mean temperature and rainfall patterns is 24 of critical importance for the simulation of crop yield. However, the impact of input data errors on 25 the skill of regional scale crop models has not been systematically quantified. We evaluate the 26 impact of specific data error scenarios on the skill of regional-scale hindcasts of groundnut yield in 27 the Gujarat region of India, using observed input data with the GLAM crop model. Two methods 28 were employed to introduce error into rainfall, temperature and crop yield inputs at seasonal and 29 climatological timescales: (1) random temporal resequencing, and (2) biasing values. 30 31We find that, because the study region is rainfall limited, errors in rainfall data have the most 32 significant impact on model skill overall. More generally, we find that errors in inter-annual 33 variability of seasonal temperature and precipitation cause the greatest crop model error. Errors in 34 the crop yield data used for calibration increased Root Mean Square Error by up to 143%. Given that 35 cropping systems are subject both to a changing climate and to ongoing efforts to reduce the yield 36 gap, both potential and actual crop productivity at the regional scale need to be measured. 37 38We identify three key endeavours that can improve the ability to assess future crop productivity at 39 the regional-scale: (i) increasingly accurate representation of inter-annual climate variability in 40 climate models; (ii) similar studies with other crop models to identify their relative strengths in 41 dealing with different types of climate model error; (iii) the development of techniques to assess 42 potential and actual yields, with associated confidence ranges, at the regional scale. 43