LAGRangian analysis of the Impact  
on the global hydrological cycle of the Major Mechanisms of  
Atmospheric Moisture Transport (LAGRIMA)



Atmospheric Rivers (ARs) and Low-Level Jets (LLJs) are both major mechanisms in the atmospheric moisture transport. ARs carry large amounts of moisture together with baroclinic eddies from tropical to higher latitudes and are frequently associated with extreme precipitation worldwide. LLJs also contribute to the tropics-extratropics interaction behaving as semi-steady and well-located flows of moisture which play a key role providing advective transports that are essential to the maintenance of the hydrological cycle as we know it in different regions around the world. This project will make use of both Lagrangian and Eulerian approaches to accurately identify sources
and sinks of moisture in the most relevant ARs and LLJs of the climate system as well as in the analysis of the transport mechanisms. The proper identification of moisture sources is fundamental to the understanding of the cited mechanisms as well as in the comprehension of their impacts in the sink regions, which is particularly important in the further analysis of climate change scenarios where both ARs and LLJs are projected to undergo dramatic changes Even when both ARs and LLJs gained increased attention in the last decades, the lack of an accurate identification of the moisture sources/sinks, as well as the existence of unanswered questions regarding the transport mechanisms still pose an stumbling block in the full understanding of the phenomena. In this sense, we will address a number of scientific questions aimed to find critical answers about the mechanism and the amount of moisture transported by ARs and LLJ, the impact of eventual changes in anomalous moisture sources, and the effect of these mechanisms in both droughts and floods in the present and future conditions. A subsidiary but a relevant issue, such as the optimum water vapor resilience time in the atmosphere or the synoptic features of the advective transport will be also addressed and will result in useful contributions to the literature. Principally, although not exclusively, the Lagrangian model FLEXPART will be used in the identification and further analysis of moisture sources associated with both ARs and LLJs. Both FLEXPART and the recently developed WRF Eulerian tracers tool (WRF-TT) will be used to identify moisture sinks and to analyze their impact on local climate conditions of the studied regions. Overall, conclusions obtained in this project will help to a substantially better comprehension of the phenomena and associated impacts.This will also help to predict further effects on climate driven by possible disturbances in the moisture transport mechanisms.


Challenge 1. The role of the major mechanisms of atmospheric moisture transport in the hydrological cycle.

Challenge 2. To find the “optimal time for the integration” in the Lagrangian analysis for the best estimation of moisture sources and sinks.


There is a need for a complete analysis of the anomalous moisture transported by the LLJs and ARs at global scale over regions of high LLJs and ARs activity, as well as the global identification of their sources of moisture.


Project technical report 


List of publications:


L. GimenoR. NietoR. Sorí (2020) The growing importance of oceanic moisture sources for continental precipitationnpj Climate and Atmospheric Science 3; doi: 


J. Eiras-Barca, F. Domínguez, Z. Yang, D. Chug, R. NietoL. Gimeno, G. Miguez-Macho (2020) Changes in South American hydroclimate under projected Amazonian deforestationAnnals of the New York Academy of Sciences, Special Issue: The Year in Climate Science Research doi: 10.1111/nyas.14364


 L. GimenoM. VázquezJ. Eiras-BarcaR. SoríM. StojanovicI. AlgarraR. Nieto, A.M. Ramos, A.M. Durán-Quesada, F. Dominguez (2020) Recent progress on the sources of continental precipitation as revealed by moisture transport analysisEarth Science Reviews 201, 103070, 1-25;


I. AlgarraJ. Eiras-Barca, G. Miguez-Macho, R. NietoL. Gimeno (2019) On the assessment of the moisture transport by the Great Plains low-level jetEarth System Dynamics 10(1), 107-119,

R. NietoL. Gimeno (2019) A database of optimal integration times for Lagrangian studies of atmospheric moisture sources and sinksScientific Data 6, 1-10,

I. AlgarraJ. Eiras-BarcaR. NietoL. Gimeno (2019) Global climatology of nocturnal low-level jets and associated moisture sources and sinksAtmospheric Research 229, 39-59,

R. Nieto, D. Ciric, M. Vázquez, M.L.R. Liberato, L. Gimeno (2019) Contribution of the main moisture sources to precipitation during extreme peak precipitation monthsAdvances in Water Resources 131, 1-8, 


A.M. Ramos, R.C. Blamey, I. AlgarraR. NietoL. Gimeno, R. Tomé, C. Reason, R.M. Trigo (2019) From Amazonia to southern Africa: atmospheric moisture transport through low-level jets and atmospheric riversAnnals of the New York Academy of Sciences 1436, 217-230, doi: 10.1111/nyas.13960