Developing site-specific future temperature scenarios for Northern Ireland: addressing key issues employing a statistical downscaling approach

作者：Mullan Donal^*; Fealy Rowan; Favis Mortlock Dave

来源：International Journal of Climatology, 2012, 32(13): 2007-2019.

DOI：10.1002/joc.2414

• climate change
• statistical downscaling
• Northern Ireland
• temperature
• calibration period
• grid box
• predictor selection
• spatial offsets

Modelling future temperature changes is a crucial step in the climate change impacts analysis stage for a wide range of environmental and socioeconomic sectors. A scale mismatch exists, however, between the coarse spatial resolution at which general circulation models (GCMs) project future climate change scenarios, and the finer spatial resolution at which impact modellers require such projections. Various downscaling techniques can be used to bridge this gap, with statistical downscaling methods emerging as a popular, low-cost and accessible means of developing site-specific future scenarios. Despite its widespread use, little attention has been paid to some of the key issues in statistical downscaling which are central to the development of the future scenarios, including GCM grid-box choice and the effects of modifying the calibration period. In this study, such issues are examined with respect to the development of site-specific future temperature scenarios for nine climatological stations across Northern Ireland. Results indicate that the more remote grid box of the two analysed is most strongly correlated with maximum and minimum temperatures, illustrating the importance of examining potential spatial offsets in the predictor-predictand relationship. In addition, modifications to the calibration period result in only minor differences to seasonal calibration and validation values as well as resultant future projections, indicating that longer calibration periods do not always offer improvements over shorter periods. Future downscaled scenarios reveal considerable warming across all sites and seasons, with large inter-GCM differences apparent. This underlines the importance of employing multiple GCMs and emissions scenarios to help address the uncertainties inherent in global climate modelling. This study illustrates the potential of statistical downscaling methods in generating high-resolution future climate change scenarios appropriate to the requirements of impact modellers, provided a thorough analysis of some of the key issues that shape the character of the future scenarios are fully explored.

• 出版日期2012-11