Introduction to the special issue: the phase I CORDEX RegCM4 hyper-matrix (CREMA) experiment

Abstract

This special issue of Climatic Change gathers a series of papers detailing the first analysis of the Phase I CORDEX RegCM4 hyper-Matrix (or CREMA) experiment. CORDEX (COordinated Regional Downscaling Experiment) is a newly implemented modeling framework under the auspices of the World Climate Research Program (WCRP) whose goals are to: i) assess and improve different regional climate downscaling techniques; ii) produce a new generation of 21st century regional climate projections over regions worldwide; iii) foster the interactions between the climate science and end-user communities and in particular the involvement of scientists from developing countries (Giorgi et al. 2009; Jones et al. 2011). It is envisioned to achieve these objectives through the completion and analysis of large multi-model, multimethod simulations with different downscaling techniques (dynamical and empirical) using a common and intercomparable experiment framework. regional climate models (RCMs) are thus key components of the CORDEX initiative. During the last decades a number of RCMs systems have been developed (e.g. Giorgi 2006; Rummukainen 2010). One of these is the RegCM system developed and maintained at the Abdus Salam International Centre for Theoretical Physics (ICTP). This model has evolved through successive versions (Dickinson et al. 1989; Giorgi et al. 1993a, b; Giorgi and Mearns 1999; Pal et al. 2007) up to the most recent RegCM4 (Giorgi et al. 2012). Over the last 25 years the RegCM has been applied to a wide range of studies by a large user community coordinated through the Regional Climate research NETwork, or RegCNET (Giorgi et al. 2006). The Phase I CREMA experiment represents the first contribution of the RegCNET modeling community to the CORDEX effort. The Phase I CREMA experiment consists of a series of 34 scenario simulations completed with the RegCM4 over 5 CORDEX domains (see Table 1): Africa, Mediterranean, Central America, South America and South Asia. Each domain follows the CORDEX specifications (see Giorgi et al. 2009), with a horizontal grid spacing of 50 km, and all simulations cover the period 1970-2100. In the CREMA experiment we attempted to cover, albeit in a limited way,

Inter-annual variability of precipitation over Southern Mexico and Central America and its relationship to sea surface temperature from a set of future projections from CMIP5 GCMs and RegCM4 CORDEX simulations

“…Two GCMs from the CMIP5 experiment (Taylor et al 2012) provide initial and lateral boundary conditions: the Hadley Center HadGEM-ES2 (HadGEM) and the MPI-ES-MR model (MPI) from the Max Planck Institute for Meteorology. These GCMs were selected because they provided a relatively good simulation of present-day climate when driving the RegCM4 (see Giorgi et al 2014;Elguindi et al 2013). Although still relatively coarse, the 50 km resolution used for this study (which was selected to simplify comparisons among CORDEX experiments) improves the representation of the land areas in the SMECAM region compared to the GCMs; the latter show only a few land-points over the region (Fig.…”

“…As a contribution to CORDEX, the regional climate model RegCM4 ) was run for a series of 21st century scenario simulations over five CORDEX domains in what is called the Phase I CREMA (CORDEX RegCM hyper-MAtrix) experiment described by Giorgi et al (2014). In particular we completed six simulations extending from 1970 to 2100 over the Central America CORDEX domain, with two RegCM4 configurations driven by two GCMs from the CMIP5 (Climate Model Intercomparison Project 5), for two GHG emission scenarios (see Sect.…”

“…Other aspects of these simulations (such as mean climatological biases and changes, extreme daily events and tropical storms) are discussed elsewhere in the Special Issue on The Phase I CORDEX RegCM4 Experiment MAtrix (CREMA) (i.e. Coppola et al 2014;Giorgi et al 2014;Diro et al 2014). …”

Doubling of U.S. Population Exposure to Climate Extremes by 2050

“…There are a number of well‐documented barriers to the reliable estimation of population exposure to changes in climate extremes at regional‐ to local‐scales, including the heterogeneity in social‐ecological systems and the uncertainty in the projections of General Circulation Models (GCMs) (Giorgi, 2014; Giorgi et al, 2008). The complexities within social‐ecological systems, which are a combination of interacting social and ecological subsystems, result in a spatially heterogenous distribution of the human population (Liu et al, 2007).…”

Projected seasonal mean summer monsoon over India and adjoining regions for the twenty-first century

“…The RegCM4 is driven by the GFDL-ESM2M GCM, and the focus of the analysis is on the evolution of the summer monsoon over the Indian subcontinent and adjacent ocean areas. The simulation is also part of a broader project, the phase I CORDEX RegCM4 hypermatrix, or CREMA (Giorgi 2014), in which the RegCM4 is run over multiple CORDEX domains as a first contribution of the RegCM4 user community to CORDEX. The model and simulation details are provided in Section 2, while validation of the model simulated climate is carried out in Section 3.…”