Analysis of the Moisture Transport from the Amazon to the South America Continent Using a Moisture-Tagging WRF Model

The La Plata river basin in the southern South America is a “hot-spot” for land atmosphere interaction with most of its precipitation originating from the South America continent. However, it remains unclear how land surface changes will affect precipitation in the La Plata. Possible pathways through which land surface change may affect precipitation are: 1) by changing the amount of moisture available for precipitation (moisture recycling) and 2) by changing the atmospheric thermal structure and consequently affecting the circulation. In this study, the Weather Research and Forecasting (WRF) model with coupled water vapor tracer scheme (WVT) is used to disentangle these relative contributions. The coupled model is driven with the ERA-interim data for the period 2004-2010. Satellite-based MODIS leaf area index and greenness vegetation fraction data are used as lower boundary condition. Initial results show that water vapor from the Amazon basin clearly contributes to precipitation in the southern South America continent, following the climatological wind direction. We find that this new methodology allows us to differentiate the complex eco-climate feedbacks at the continental scale.