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Drought and wet episodes in Amazonia: the role of atmospheric moisture transport
* 1 , 2 , 1, 3 , 1 , 1
1  Environmental Physics Laboratory (EPhysLab), Facultade de Ciencias, Universidad de Vigo, Ourense, Spain.
2  Centro Nacional de Monitoramento e Alertas de Desastres Naturais (CEMADEN), São Jose dos Campos, Brazil
3  Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, São Paulo, Brazil.


The Amazon River basin (ARB) in Sud-America contains the world largest rainforest and biodiversity and plays an important role in the regional and global hydrological cycle. It consist of several sub-basins as the Negro River basin (NRB) in the north and the Madeira River basin (MRB) to the south, both considered of utmost importance in the Amazonia for the Amazon River. The precipitation annual cycle in both basins experiences an opposite annual cycle and as a consequence their contributions to the Amazon River are lagged in time. Here we utilized the Standardized Precipitation Index (SPEI) to identify drought and wet conditions in the NRB and MRB along the period 1980-2016. This index has the advantages over other index because considers the effect of the Atmospheric Evaporation Demand (AED) on drought severity. Besides, the Lagrangian dispersion model FLEXPART v9.0 was used to track backward in time air masses residing over the basins and to calculate along the trajectories the budget of (E-P). This permitted to identify those regions from where air masses gain humidity (E-P>0) before arriving at the basins, what we consider as moisture sources. FLEXPART has been successfully utilized for the same goal in several studies. This allowed investigating the hydrological budget of (E-P) over the NRB and MRB as well as their role as sources of moisture for surrounded continental regions. This study examines the variability of moisture uptake by the basins from these sources during drought and wet episodes in the basins. We consider this a new approach to be a useful method for understanding the causes and variability of drought and wet events in other regions worldwide.

Keywords: Drougth and wet episodes, sources of moisture, moisture transport
Comments on this paper
Dear Authors:

Congratulation on an interesting paper. I have the following comments:

1) Please discuss the characteristics (spatial resolution, etc.), as well as advantages and limitations of the incumbent data sets (P and Pet) over the entire Amazon River Basin. A recent study by Carmona et al. has investigated the triple interdependence existing among Precipitation, Actual and Potential Evapotranspiration in the Amazon River Basin (2016, A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin, Hydrol. Earth Syst. Sci., 20, 589-603,, 2016.}.

2) Please explain how do you concatenate the timescales of the SPEI (monthly, as I gather) and the timescale of the FLEXPART MODEL (daily? sub-monthly?) used to back-track the trajectories of moisture?

3) The role of precipitation reycling is not been mentioned throughout the paper. Of course, the title of the paper refers to the role of moisture advection by the winds, but let us not forget that precipitation recycling and the role of forests and of land surface-atmosphere interactions in maintaining the (E-P) term over Amazonia cannot be overstated.

Thank you very much for your contribution to the Conference.
Rogert Sorí
Dear Dr. Germán,

Thank you for your comments and suggestions !. We will take them into account to write a future paper.

Kind regards,
Rogert & Co-authors