Recent progress on the sources of continental precipitation as revealed by moisture transport analysis

The assessment of sources of moisture is key to the understanding of the hydrological cycle at different time scales, because it enables the establishment of source-sink relationships and the identification of the main moisture transport conveyors and associated processes, the result of which is precipitation. Gimeno et al. (2012) provided a comprehensive review of the state-of-the-art in the assessment of moisture source-sinks and how different approaches can contribute to improving our knowledge of this component of the Earth's Climate System. Since then, a variety of studies have focused on more specific aspects of the moisture budget and the source-sink distribution across the globe by integrating observations, satellite-derived products, physical tracers and numerical modelling. Here, we summarise the main advances in the field related to the impact of the moisture source-sink relationship on rainfall distribution, and add to the scientific debate on the question of the residence time of water vapour. We also revisit some of the recent advances in the role of the major mechanisms of moisture transport at a global scale, mainly Atmospheric Rivers and Low-Level Jet systems (Gimeno et al., 2016), in terms of their effects on precipitation extremes. Finally, we set out some of the main challenges for future research.