Assessment of CORDEX simulations over South America: added value on seasonal climatology and resolution considerations

Abstract

A new set of CORDEX simulations over South America, together with their coarserresolution driving Global Climate Models (GCMs) are used to investigate added value of Regional Climate Models (RCMs) in reproducing mean climate conditions over the continent. There are two types of simulations with different lateral boundary conditions: five hindcast simulations use re-analysis as boundary conditions, and five other historical simulations use GCMs outputs. Multi-model ensemble means and individual simulations are evaluated against two or three observation-based gridded datasets for 2-meter surface air temperature and total precipitation. The analysis is performed for summer and winter, over a common period from 1990 to 2004. Results indicate that added value of RCMs is dependent on driving fields, surface properties of the area, season and variable considered. A robust added value for RCMs driven by ERA-Interim is obtained in reproducing the summer climatology of surface air temperature over tropical and subtropical latitudes. Mixed results can be seen, however, for summer precipitation climatology in both hindcast and historical experiments. For winter, there is no noticeable improvement by the RCMs for the large-scale precipitation and surface air temperature climatology. To further understand the added value of RCMs, models deviations from observation are decomposed according to different terms that reflect the observational uncertainty, the representativeness error, the interpolation error, and the actual performance of the model. Regions where these errors are

The diurnal cycle of precipitation over South America represented by five gridded datasets

“…(). The two models have been used extensively over South America in different international projects such as CLARIS, CLARIS‐LPB and CORDEX (Menéndez et al ., , , ; Carril et al ., ; Ruscica et al ., , , ; Sánchez et al ., ; Falco et al ., ; Spennemann et al ., ; Zaninelli et al ., ). The spatial domain includes the South American continent and adjacent oceans at approximately 50 km resolution and the models were driven every 6 hr with boundary conditions from ERA‐Interim reanalysis (Dee et al ., ).…”

Warm‐season precipitation drivers in northeastern Argentina: Diurnal cycle of the atmospheric moisture balance and land–atmosphere coupling

“…ERA5 has a finer spatial and temporal resolution and a better global balance of precipitation and evaporation than ERA‐Interim, among other improvements (Copernicus Climate Change Service (C3S), 2017). The version of RCA4 considered in this study is currently used within CORDEX (http://www.cordex.org) and has been used over South America in previous studies (Spennemann et al ., 2018; Falco et al ., 2019; Giles et al ., 2019; Menéndez et al ., 2019; Zaninelli et al ., 2019), to which the reader can refer for more information about the model's configuration and performance. The spatial resolution is 25 and 50 km for ERA5 and RCA4, respectively.…”

Observed and Projected Hydroclimate Changes in the Andes

“…The origin of these biases lies, at least partly, in unresolved topographical forcing which remains too smoothed over the complex terrain of the Andes, limiting the simulation of regional processes such as the interactions between local circulation and orography, a key factor in climate modulation at meso-scale levels. However, even considering these systematic biases, recent studies have confirmed that CORDEX-type RCMs (e.g., with a spatial resolution of 20-50 km) have the potential to add value in the representation of extreme precipitation and mean surface temperature over the Andes (Falco et al, 2018(Falco et al, , 2019Bozkurt et al, 2019).…”