Climate change and precipitation variability over the western ‘Pampas’ in Argentina

Abstract

This work focuses on the analysis of spatial and temporal variability of precipitation in the central region of southern Central Argentina (SCA), a climate transition area which has experienced an important agricultural expansion. For this purpose, gauge station precipitation datasets available in the area were extensively used. The annual cycle shows a defined dry season (May–August) and wet season (September–April). Wet season represents over 85% of annual totals. A regionalization analysis of wet‐season precipitation suggests five subregions with spatially homogeneous precipitation variability in SCA. Three out the five subregions are located in central SCA. Conveniently devised precipitation indices for the latter subregions show the presence of significant precipitation jumps by the early 1970s, and to a minor extent, the mid‐1960s. Precipitation jumps are responsible for the observed long‐term trends in central SCA, which explain positive precipitation changes over 30–40% of regional averages in the period 1922–2012. The presence of stationary and non‐stationary components in SCA precipitation variability remotely connects the region mainly with variations in equatorial Pacific SSTs. The assessment of greenhouse gases concentration effects on future projections of wet‐season precipitation over central SCA is investigated by means of multi‐model analysis of historical experiment, and the representative concentration pathways 4.5 (RCP 4.5) and 8.5 (RCP 8.5), provided by the Coupled Model Intercomparison Project Phase 5. Results suggest an overall increased precipitation, roughly 15% respect to present climate, under most severe future scenario.

Statistical downscaling of daily precipitation and temperatures in southern La Plata Basin

“…Meanwhile, the change to drier conditions in General Pico station is clearly represented by the analogue method and consistent with the results of Maenza et al . ().…”

“…Several authors have documented the rainfall and temperature trends in southeastern South America, overlapped to a large decadal variability (Penalba and Vargas, ; Rusticucci, ; Maenza et al, ). In the eastern margin of the domain analysed, there is a strong consensus concerning the progressive increase up to the present of annual rainfall mainly due to the increases in rainfall during the summer (de Barros Soares et al, ; Saurral et al, ).…”

Evaluation of CMIP5 retrospective simulations of temperature and precipitation in northeastern Argentina

“…For instance, the RMSE values are lower than in Africa but greater than in North America (see also Sheffield et al, ). The MBE metric suggests that most GCMs (18 out of 25) tend to underestimate precipitation, consistently with the results reported by Díaz and Vera () for the La Plata Basin and Maenza et al () for the western Pampas of Argentina (south of the study region).…”

“…Penalba and Rivera () found a similar result in the eastern portion of southern South America, reporting that CMIP5 models reproduce the shape of the annual cycle of precipitation but underestimate monthly totals during all year. A similar finding was reported by Maenza et al () in the western Pampas of Argentina. It is also evident in Figure (b) that most individual members underestimate the observed annual cycle in northeastern Argentina.…”

“…Consistent with these findings, Maenza et al . () found that while 15 CMIP5 models and their ensemble capture the low‐frequency variations of wet season precipitation, they underestimate precipitation values over the western Pampas of Argentina. Trends in precipitation for the period 1902–2005 have been discussed by Vera and Díaz () who reported that an ensemble of CMIP5 models identified the positive change of precipitation, but with a weaker magnitude than that in observations.…”