A New Look into the South America Precipitation Regimes: Observation and Forecast

Abstract

South America is a vast continent characterized by diverse atmospheric phenomena and climate regimes. In this context, seasonal climate predictions are helpful for decision-making in several relevant socioeconomic segments in this territory, such as agriculture and energy generation. Thus, the present work evaluates the performance of ECMWF-SEAS5 in simulating the South American precipitation regimes by applying a non-hierarchical clustering technique. In addition, the study describes the main atmospheric systems that cause precipitation in each cluster and updates a previous work performed in South America in 2010. As a result, ECMWF-SEAS5 simulates (with good correspondence) the eight climate regimes identified in the analysis of precipitation from the Climate Prediction Center (CPC). Moreover, ECMWF-SEAS5 has a satisfactory ability in representing the rainfall regime in low and medium climate predictability regions, such as central and southern South America. ECMWF-SEAS5 has good performance in the climate characterization of South America and it gives us confidence in using its seasonal climate predictions throughout the continent.

Evaluation of ECMWF-SEAS5 Seasonal Temperature and Precipitation Predictions over South America

“…better interpretation of the model predictions and indicates the satisfactory performance of ECMWF-SEAS5 seasonal temperature real-time forecasts over SA. In autumn and winter, the dry season begins in SEB [1], reducing precipitation in central SA (Figure 6a,b). In those seasons, the precipitation maxima occur in NSA and AMZ, and ECMWF-SEAS5 reasonably represents these patterns.…”

“…In those seasons, the precipitation maxima occur in NSA and AMZ, and ECMWF-SEAS5 reasonably represents these patterns. In contrast, during spring and summer, precipitation increases in most of SA [1], and the system appropriately represents the seasonal rainfall variability.…”

“…South America (SA) is a continent with a broad latitudinal extension and diversity of biomes, favoring different climates within its territory [1]. In addition, climate conditions directly influence the main socioeconomic activities developed in the region.…”

“…Global and regional climate models can reproduce and predict the main characteristics of precipitation, temperature, and circulation over SA, but they still fail to simulate regional climate over terrains with a complex topography [1,[24][25][26][27][28][29]. The global models' coarse spatial resolutions restrict their ability to simulate precipitation and represent the orography and land-atmosphere interactions [30].…”

“…The European Centre for Medium-Range Weather Forecasts-System 5 (ECMWF-SEAS5) constitutes the state-of-the-art global modeling of seasonal climate forecasts [32]. Recently, Ferreira and Reboita [1] and Gubler et al [33] applied cluster analysis to seasonal precipitation predictions from ECMWF-SEAS5 hindcasts (the system's climatological model constituted by predictions of past conditions) in order to validate the system's performance in representing the different regimes of precipitation over SA. Both works showed remarkable skill in predicting the spatial distribution of precipitation.…”