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Earth System Dynamics An interactive open-access journal of the European Geosciences Union

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Earth Syst. Dynam., 8, 147-161, 2017
http://www.earth-syst-dynam.net/8/147/2017/
doi:10.5194/esd-8-147-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
28 Feb 2017
Role of moisture transport for Central American precipitation
Ana María Durán-Quesada1,2, Luis Gimeno3, and Jorge Amador1,2 1Department of Atmospheric, Oceanic and Planetary Physics, University of Costa Rica, San José, Costa Rica
2Center for Geophysical Research, University of Costa Rica, San José, Costa Rica
3Environmental Physics Laboratory, University of Vigo, Vigo, Spain
Abstract. A climatology of moisture sources linked with Central American precipitation was computed based upon Lagrangian trajectories for the analysis period 1980–2013. The response of the annual cycle of precipitation in terms of moisture supply from the sources was analysed. Regional precipitation patterns are mostly driven by moisture transport from the Caribbean Sea (CS). Moisture supply from the eastern tropical Pacific (ETPac) and northern South America (NSA) exhibits a strong seasonal pattern but weaker compared to CS. The regional distribution of rainfall is largely influenced by a local signal associated with surface fluxes during the first part of the rainy season, whereas large-scale dynamics forces rainfall during the second part of the rainy season. The Caribbean Low Level Jet (CLLJ) and the Chocó Jet (CJ) are the main conveyors of regional moisture, being key to define the seasonality of large-scale forced rainfall. Therefore, interannual variability of rainfall is highly dependent of the regional LLJs to the atmospheric variability modes. The El Niño–Southern Oscillation (ENSO) was found to be the dominant mode affecting moisture supply for Central American precipitation via the modulation of regional phenomena. Evaporative sources show opposite anomaly patterns during warm and cold ENSO phases, as a result of the strengthening and weakening, respectively, of the CLLJ during the summer months. Trends in both moisture supply and precipitation over the last three decades were computed, results suggest that precipitation trends are not homogeneous for Central America. Trends in moisture supply from the sources identified show a marked north–south seesaw, with an increasing supply from the CS Sea to northern Central America. Long-term trends in moisture supply are larger for the transition months (March and October). This might have important implications given that any changes in the conditions seen during the transition to the rainy season may induce stronger precipitation trends.

Citation: Durán-Quesada, A. M., Gimeno, L., and Amador, J.: Role of moisture transport for Central American precipitation, Earth Syst. Dynam., 8, 147-161, doi:10.5194/esd-8-147-2017, 2017.
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Short summary
This work aims to leverage the understanding of precipitation distribution with a long-term analysis of moisture transport from oceanic and continental sources and its relevance for regional precipitation features, variability and trends. Combining reanalysis, model output, in situ observations and satellite products we provide a robust survey that is useful for, for example, modelling, water resource management, flood and drought monitoring, rain-linked disease spread and ecosystem studies.
This work aims to leverage the understanding of precipitation distribution with a long-term...
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