RESEARCH ARTICLE Analysis of atmospheric moisture transport to the Upper Paraná River basin Leonardo Zandonadi Moura | Carlos Henrique Ribeiro Lima Universidade de Brasília, Brasília, Brazil Correspondence Leonardo Zandonadi Moura, Universidade de Brasília, Brasília 70910-900, DF, Brazil. Email: lzmoura@unb.br The understanding of the atmospheric phase of the hydrological cycle is an impor- tant step forward in improving our abilities to predict droughts and floods, as well as the impacts of climate change on water resources. Here we focus on the study of the atmospheric moisture transport to the Upper Paraná River basin, Brazil, through the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) dispersion model, which is used to generate air masses trajectories based on the 1970–2010 National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. In terms of moisture source regions, we found that the tropical South Atlantic is the main contributor to the Upper Paraná River basin, exporting about 175 mm/month of water vapour during the rainy sea- son. The North Atlantic contribution is relevant in February (about 38 mm/month). Other regions over the Atlantic Ocean (North and subtropical South) are also iden- tified as sources, and moisture evaporated from these places has a significant impact on the streamflow variability at the Itaipu streamflow gauge, located at the basin outlet. The continental sources play a more relevant role during the dry sea- son (May–October). The Amazon region is more relevant as a moisture source dur- ing the dry season, exporting an average of 45 mm/month. A similar pattern is observed in other continental sources, such as Chaco/Pantanal/Cerrado, which together export about 99 mm/month to the Paraná River basin during the dry sea- son. An extreme event analysis reveals that changes in moisture advection from the tropical South Atlantic are related to floods and droughts in the region. Particularly, we observe that flood events are preceded by positive anomalies of moisture advec- tion up to 2 months in advance, while persistent, negative anomalies of moisture transport lead seasonal droughts by up to 8 months beforehand. KEYWORDS drought, flood, HYSPLIT, Lagrangian water balance, storm tracks, upper Paraná River basin, water vapour tracer 1 | INTRODUCTION The dynamics of moisture transport in the atmosphere has often been related to extreme events of droughts (e.g., Pampuch et al., 2016) and floods (e.g., Nakamura et al., 2013) and the understanding of such teleconnection patterns has important implications for the advance of water resources management all over the world, particularly in a changing climate. The establishment of source–receptor rela- tionships for the moisture transport in the atmosphere, for instance, has been a way to investigate the dynamics of the moisture advection to a specific region or water basin (sink region), shedding some light on the large-scale oceanic and atmospheric processes connected to regional floods and droughts. Such studies usually rely on three main approaches: physical water vapour tracers (WVTs; Received: 14 May 2017 Revised: 10 April 2018 Accepted: 11 May 2018 Published on: 14 August 2018 DOI: 10.1002/joc.5718 Int J Climatol. 2018;38:5153–5167. wileyonlinelibrary.com/journal/joc © 2018 Royal Meteorological Society 5153