RFA3: Tropical forests and coupled Earth system processes.
How do precipitation recycling and the seasonal timing of precipitation respond to changes in forest structure and Earth’s climate?
Over continental scales precipitation recycling, defined as the contribution of local evaporation to local precipitation, and the seasonal timing of precipitation are sensitive to changes in climate forcing and forest structure. RFA3 explores and improves modeling of the role soil hydrology plays in plant response to climate forcing, develops new data products to serve as model benchmarks, and implements fully coupled E3SM-FATES interactions at regional and global scales. Because of its strong sensitivities to climate and land-use forcing, the work in RFA3 will focus on the Amazon Basin.
Hillslope-to-continental scale soil hydrology and water table dynamics. We will improve modeling of soil hydrology and perform basin-wide hydrological simulations to better assess the role of landscape heterogeneity in governing evapotranspiration, with a crucial focus on understanding how much of the Amazon evapotranspiration is sourced from the vadose zone versus from groundwater. A comprehensive suite of field measurements and satellite data will be used in development and benchmarking of E3SM-FATES.
Large-scale observations of forest structure and dynamics, and atmospheric coupling. We are building new detailed data products to test and initialize FATES simulations including pantropical representations of heterogeneous forest structure and regionally variable phenology. We are reprocessing data from our partners in Brazil (LBA) to improve local quantification of water and energy fluxes and hillslope hydrology.
Model experiment with FATES coupled to E3SM. We are exploring the role of plant hydraulic traits and water available to plants in governing diurnal, seasonal, and interannual patterns in forest evapotranspiration, and how variation in these patterns affect precipitation across the Amazon. Fully coupled simulations taking advantage of advances in our hydrological models and new data will address the question of how climate change and land use change affect precipitation recycling and seasonality in the Amazon Basin.