An update of IPCC climate reference regions for subcontinental analysis of climate model data: definition and aggregated datasets

Abstract

Abstract. Several sets of reference regions have been used in the literature for the regional synthesis of observed and modelled climate and climate change information. A popular example is the series of reference regions used in the Intergovernmental Panel on Climate Change (IPCC) Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Adaptation (SREX). The SREX regions were slightly modified for the Fifth Assessment Report of the IPCC and used for reporting subcontinental observed and projected changes over a reduced number (33) of climatologically consistent regions encompassing a representative number of grid boxes. These regions are intended to allow analysis of atmospheric data over broad land or ocean regions and have been used as the basis for several popular spatially aggregated datasets, such as the Seasonal Mean Temperature and Precipitation in IPCC Regions for CMIP5 dataset. We present an updated version of the reference regions for the analysis of new observed and simulated datasets (including CMIP6) which offer an opportunity for refinement due to the higher atmospheric model resolution. As a result, the number of land and ocean regions is increased to 46 and 15, respectively, better representing consistent regional climate features. The paper describes the rationale for the definition of the new regions and analyses their homogeneity. The regions are defined as polygons and are provided as coordinates and a shapefile together with companion R and Python notebooks to illustrate their use in practical problems (e.g. calculating regional averages). We also describe the generation of a new dataset with monthly temperature and precipitation, spatially aggregated in the new regions, currently for CMIP5 and CMIP6, to be extended to other datasets in the future (including observations). The use of these reference regions, dataset and code is illustrated through a worked example using scatter plots to offer guidance on the likely range of future climate change at the scale of the reference regions. The regions, datasets and code (R and Python notebooks) are freely available at the ATLAS GitHub repository: https://github.com/SantanderMetGroup/ATLAS (last access: 24 August 2020), https://doi.org/10.5281/zenodo.3998463 (Iturbide et al., 2020).

Changes in drought features at the European level over the last 120 years

“…Europe has experienced a number of extremely dry summers within the last decade (i.e., 2015, 2018, and 2019), which have already been documented in previous studies (Bakke et al, 2020;Hari et al, 2020;Ionita et al, 2017;Laaha et al, 2017). To put the last decade drought events into a longer perspective, we computed the drought area for MED, CEU, and NEU, affected by three types of drought: moderate (SPEI12/ SPI12 between −1 and −1.5, and scPDSI between −2 and −3), severe (SPEI12/ SPI12 between −1.5 and −2, and scPDSI between −3 and −4), and extreme (SPEI12/SPI12 smaller than −2, and scPDSI smaller than −4), considering the 12-month SPEI (December SPEI12) and SPI (December SPI12) and the annual scPDSI.…”

“…In the two past decades, drought has been a recurrent feature at the European level with long-lasting drought events affecting different parts of the continent (Bakke et al, 2020;Hanel et al, 2018;Laaha et al, 2017;Naumann et al, 2018). In 2015, more than 50 % of Europe was affected by severe drought, while over the period 2018-2019 more than 60 % of the continent was affected by moderate and severe dryness (Bakke et al, 2020;Hari et al, 2020;Van Lanen et al, 2016).…”

“…M. Ionita and V. Nagavciuc: Changes in drought features at the European level over the last 120 years 1687 2 Data and methods As stated before, the main region of analysis for this study is Europe, but for most of the analyses employed through the paper we split the European domain into three separate macroregions (Iturbide et al, 2020). These regions, which were chosen following the recommendation from the 5th Assessment Reports of the IPCC (IPCC, 2014) are (a) the South Europe/Mediterranean region (MED), (b) Central Europe (CEU), and (c) North Europe (NEU) (Fig.…”

Projected future daily characteristics of African precipitation based on global (CMIP5, CMIP6) and regional (CORDEX, CORDEX-CORE) climate models

“…A new set of reference regions has been designed for the upcoming Intergovernmental Panel on Climate Change (IPCC) 6th Assessment Report (AR6) (Iturbide et al 2020) and used in studies with both global (e.g. Almazroui et al 2020) and regional (e.g.…”

The ExtremeX global climate model experiment: Investigating thermodynamic and dynamic processes contributing to weather and climate extremes

“…The top section shows the global RMSE for land grid points and seasonal and annual (ANN) averages. The bottom section shows the average annual RMSE for the reference regions from the Sixth Assessment Report (AR6) on climate change(Iturbide et al, 2020). For an overview of the AR6 reference regions seeFig.…”