Abstract
ABSTRACTRanking the performance of global climate models (GCMs) is a notoriously difficult exercise. Multi‐model comparison studies nearly always show that each model has strengths and weaknesses relative to others, and for many purposes the multi‐model ensemble mean delivers better estimates than any individual model. Nevertheless, in regions like East Africa, where there is little consensus between models on the magnitude or sign of 21st century precipitation change, the multi‐model ensemble mean approach to climate projection provides little value for adaptation planning. Here, we consider several possible frameworks for model evaluation and ranking, and assess the differences in performance of a subset of models participating in the 5th Coupled Model Intercomparison Project (CMIP5) according to each framework. Our test case is precipitation in the Nile River headwaters regions. We find that there is little consistency in the relative performance of models across frameworks based on amount and seasonality of precipitation, interannual precipitation variability, precipitation teleconnections, and continental scale climate patterns. These analyses offer some guidance on which GCMs are most likely to provide meaningful results for specific applications, but they caution that any effort to select ‘best performing’ GCMs for the Nile River basin must carefully consider the purposes for which GCMs are being selected.
Highlights
Global climate models (GCMs) are regularly applied to study past, present, and future climate in Africa (Braconnot et al, 2012; Biasutti, 2013; Otieno and Anyah, 2013; Rowell, 2013; Tierney et al, 2013; Müller et al, 2014)
This lack of consensus projects onto simulations of future climate: while models generally agree on the direction of precipitation change in parts of Africa directly affected by Hadley Cell strengthening [e.g. North Africa, some portions of Equatorial Africa (IPCC, 2013)], there is wide model disagreement in climatically complex regions such as the Greater Horn of Africa (GHA), parts of southern Africa, and the Sahel (Williams and Funk, 2011; Biasutti, 2013; Otieno and Anyah, 2013)
Related statistics have been used for GCM selection in the Ethiopian Highlands (Jury, 2015), the GHA (Otieno and Anyah, 2013), and for presentation of GCM projections worldwide (IPCC, 2013)
Summary
Global climate models (GCMs) are regularly applied to study past, present, and future climate in Africa (Braconnot et al, 2012; Biasutti, 2013; Otieno and Anyah, 2013; Rowell, 2013; Tierney et al, 2013; Müller et al, 2014). A number of recent studies have sought to evaluate the relative performance of GCMs participating in the 3rd and 5th phases of the Coupled Model Intercomparison Project (CMIP3 and CMIP5; Taylor et al, 2012) for selected regions of Africa Some of these studies have focused on process representation (Williams and Funk, 2011; Dirmeyer et al, 2013; Roehrig et al, 2013) while others have implicitly or explicitly ranked GCMs based on their ability to replicate statistics of precipitation (Otieno and Anyah, 2013; Jury, 2015), teleconnections (Rowell, 2013; Martin et al, 2014), or large scale atmospheric fields (Brands et al, 2013) in simulations of 20th century climate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
