Tuesday, April 5, 2016
330 Gross Hall - Noon
William Riley, PhD
Earth Sciences Division, Berkeley National Laboratory
Abstract:
Predicting the role of terrestrial processes in ongoing and future climate remains challenging after several decades of dedicated effort. Terrestrial ecosystems affect (and are affected by) climate through interactions with carbon, water, radiation, nutrients (e.g., nitrogen (N), phosphorus (P)), and others. Further, these dynamics are often tightly linked, have large spatial heterogeneities, and vary over a wide range of temporal scales. Although our group works on various aspects of these problems, I will focus here on representations of nutrient dynamics in soils, microbes, and plants, and how these interactions affect carbon exchanges with the atmosphere.
There is no consensus in Earth System Models (ESMs) regarding representation of nutrient competition, and theoretical support for current implementations is weak. To resolve these inconsistencies, we developed a new theory (called the Equilibrium Chemistry Approximation, ECA) based on enzyme kinetics, physical constraints, and competitor and substrate characteristics. This approach applies the Law of Mass Action and the quasi-steady-state approximation to develop a generalizable set of equations for multi-competitor and multi-consumer interactions. We integrate the resulting reaction network with a vertically-resolved multi-phase reactive transport solver integrated in the US DOE ESM (called the ACME Land Model, ALM).
Biographical Sketch:
Bill focuses on modeling terrestrial ecosystems and their interactions with climate and climate change. His educational background includes a B.S. degree in mechanical and aerospace engineering, an M.S. degree in physics, and a Ph.D. in civil and environmental engineering. His published work includes development, testing, and application of numerical models that represent soil microbial dynamics, abiotic processes, nutrient competition between microbes and plants, watershed-scale hydrological and biogeochemical processes, and climate-scale carbon and nutrient cycle processes. Bill is currently a scientist at the Lawrence Berkeley National Laboratory and serves as the co-chair for the National Center for Atmospheric Research (NCAR) Land Model Working Group and the co-lead of land model development in the U.S. DOE Earth System Model (ACME).