Vol.:(0123456789) 1 3 Climate Dynamics https://doi.org/10.1007/s00382-018-4172-9 Variability of regional atmospheric moisture over Northern South America: patterns and underlying phenomena I. Hoyos 1,2  · J. Cañón‑Barriga 1  · T. Arenas‑Suárez 2  · F. Dominguez 3  · B. A. Rodríguez 2 Received: 14 July 2017 / Accepted: 9 March 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract We evaluate the spatio-temporal variability of atmospheric moisture in northern South America. The spatial structure of moisture is discussed in seasonal and interannual time scales. We combine the principal component analysis of moisture fux divergence and the physical information fow to measure the relative infuence of global climate phenomena in the leading modes of regional variability. Our results highlight the inherent complexity of spatial structure in this region due to the interaction of the Tropical Andes, the regional circulation changes related to the annual migration of the ITCZ, the low-level jet structures of regional atmospheric transport and the moisture transport from surrounding marine areas. Modes of variability related to oscillations in the tropical and extratropical Atlantic and Tropical Pacifc are the most important sources of variability underlying the regional atmospheric moisture. To emphasize ENSO related variability, we propose a seasonal state classification index that unambiguously classifes the local evolution of precipitation in El Niño and La Niña years, showing the occurrence of marked diferences in local moisture content in each of these phases. Keywords Teleconnections · Information transference · Regional ENSO infuence · Seasonal state index 1 Introduction Northern South America encompasses an eco-region of global environmental importance due to its widely recog- nized biodiversity (Tejedor-Garavito et al. 2012; Josse et al. 2009; Myers et al. 2000). Land forms in the region transi- tion from steep mountains to extended plain areas with a wide variety of land covers. The complexity of moisture transport processes in this area comprises intra-Americas transport and ecosystem service transferences from sur- rounding areas of the Amazon, the Orinoco basin and the Atlantic and Pacifc oceans (Hoyos et al. 2017, 2014; Pov- eda et al. 2014; Durán-Quesada et al. 2012; Sakamoto et al. 2012; Durán-Quesada et al. 2010; Garreaud 2009; Amador 2008; Poveda et al. 2006). The annual migration of the Inter Tropical Convergence Zone (ITCZ) and the complex orog- raphy of the Tropical Andes are natural drivers of spatial variability in rainfall patterns (Insel et al. 2009) and much of the subregional seasonality of precipitation is character- ized by orographic rainfall regulated by meso-scale convec- tive systems that interact with the orography (Poveda et al. 2014; Bhushan and Barros 2007; Roe 2005; Lin et al. 2001; Velasco and Fritsch 1987). The oceanic infuences in regional climate are character- ized by the transport of moisture from the Caribbean Sea, and the Atlantic and Pacifc oceans (Hoyos et al. 2017; Arias et al. 2015). The region is sensitive to coupled global climate phenomena with multiple time-scales of interaction, such as Tropical Easterly Waves [TEWs, IDEAM (2005); Serra et al. (2010)], the North Atlantic Oscillation (NAO, Mesa et al. 1997) and the El Niño-Southern Oscillation (Arias et al. 2015; Córdoba-Machado et al. 2015, 2014; Pabón 2003; Waylen and Poveda 2002; Poveda et al. 2001; Restrepo and Kjerfve 2000; Carvajal et al. 1998), among others. ENSO is the most widely recognized ocean-atmosphere coupled phenomenon with infuence over the region. The regional hydroclimatic efects are commonly related to dryer * I. Hoyos isabel.hoyos@udea.edu.co 1 Facultad de Ingeniería, Grupo GAIA. Universidad de Antioquia, SIU/UdeA, Calle 70 N 52-21, Medellín, Colombia 2 Instituto de Física, Grupo de Fundamentos y Enseñanza de la Física y los Sistemas Dinámicos, Universidad de Antioquia, Medellín, Colombia 3 Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Champaign, USA