Abstract
Abstract Observational and modeling studies show that a deeper soil water uptake by tree roots is required for evapotranspiration in the Amazon Basin. Therefore, this study performed three numerical modeling experiments with different depths of soil water uptake by Amazonian tree roots using the Eta/CPTEC regional climate model. In the “Control” and “Deep Soil Shallow Root” experiments the depth of soil water uptake by tree roots is set up with 2 m, while in the “Deep Soil Deep Root” experiment this depth is set up with 7.2 m, according to the observational studies. The energy balance at the LBA flux towers is better simulated in the “Deep Soil Deep Root” experiment than in other experiments. Moreover, with the “Deep Soil Deep Root” experiment the seasonality of evapotranspiration is reduced in the regions where there is strong seasonality of precipitation, while the seasonality of moisture is reduced in shallow soil layers and increases in the deeper soil layers. In addition, in the regions with strong seasonality of precipitation the deeper soil layers have an inter-annual hydrological memory, and in all regions the soil moisture memory is inversely related to the amount of precipitation, with different behaviors in each soil layer. In conclusion, the deeper soil water uptake by the Amazonian trees is important for the energy balance and soil moisture dynamics in the Amazon Basin.
Highlights
Soil moisture significantly influences the estimation of the water balance in climate models
It is important to observe that with the increases in the depth of the soil water uptake by the Amazonian tree roots, the latent heat flux is largely overestimated in the Amazon Forest
This overestimate in the Deep Soil and Deep Root (DSDR) experiment is due to the association of the greater soil water availability to trees throughout the year in this experiment, with the parametrization of the “Soil Moisture Factor Controlling Stomatal Resistance”, named “β Factor”
Summary
Soil moisture significantly influences the estimation of the water balance in climate models. This is mainly due to its capacity to maintain the hydroclimatic characteristics of past events, to influence evapotranspiration, runoff and recycling of precipitation (Koster and Suarez, 2001). Dirmeyer et al (2009) found that in the regions under the influence of monsoon rains, a feedback mechanism occurs between soil moisture and precipitation recycling in the post-monsoon phase. During the austral winter season, the process described above is widespread in the Amazon Basin south of the Equator. In this region, Dirmeyer et al (2009) found that the memory of water in the soil lasts approximately 40 days. This study used gridded moisture products which take into account only the first meters of soil depth
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