Fast All-season Soil STrength (FASST) Model Alterations for Efficient Regional Simulation

The Army Fast All-season Soil STrength (FASST) model was developed to predict soil strength for vehicle mobility applications in areas with undeveloped road networks. FASST also serves as a 1-D, land surface model (LSM) for soil state characterization and land-atmosphere energy and moisture exchange simulation. Originally, FASST was designed as a single-point model but was later modified for regional simulation using vector-based terrain datasets. Although this modified version of FASST was capable of producing regional land surface state simulations, the I/O processes still mimicked the original single-point model design and would run the model from start to finish for a single vector point before moving onto an adjacent location. This type of processing restricted the ability of the model to efficiently interface with other modeling frameworks (e.g., fully coupling FASST to an atmospheric mesoscale model) or data assimilation capabilities (e.g., NASA's Land Information System (LIS)). Modelers and software engineers from Atmospheric and Environmental Research (AER) altered the FASST driver and I/O processes to calculate environmental conditions for the entire grid space before moving onto the next time step. This presentation provides details on model modifications and product development advancement due to these alterations. In addition, details on the integration of FASST into the LIS framework will be provided.