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Seminar - Bayesian Model Selection of Microbial Soil Respiration Models

by

Ahmed Elshall, Postdoctoral Researcher, University of Hawaii ‘Ike Wai project.

Geoscientific models are subject to parametric and conceptual uncertainties. To accommodate these different sources of uncertainty, multimodel analysis such as model selection and model averaging are becoming popular. This talk will illustrate the theoretical and practical challenges of Bayesian model selection for microbial soil respiration modeling. We are interested in soil respiration because global soil respiration releases more than ten times more carbon dioxide to the atmosphere than all anthropogenic emissions. Improving our understanding of microbial soil respiration is thus essential for improving earth system models that are used for understanding and forecasting climate change. This presentation focuses on a poorly understood phenomena, which is the soil microbial respiration pulses in response to episodic rainfall pulses, the “Birch effect”. The hypothesis is that the “Birch effect” is generated by three mechanisms that will be discussed during the talk. To test the hypothesis, five microbial-enzyme models are developed and assessed against field measurements from a semiarid Savannah that is characterized by pulsed precipitation. These five models evolve step-wise such that the first model includes none of the three mechanism, while the fifth model includes the three mechanisms. The first part of the talk will illustrate Bayesian model selection of the five models. Bayesian inference, which involves updating a prior parameter disruption to a posterior parameter distribution using a likelihood function, will be illustrated as well as the estimation of Bayesian model evidence for model selection. The second part will discuss an important theoretical and practical challenge, which is the effect of likelihood function selection on Bayesian model selection. The techniques presented in this talk are general and can be applied to other scientific disciplines. All are welcome to attend.

Event Sponsor
WRRC, Mānoa Campus

More Information
moravcik, (808) 956-3097, morav@hawaii.edu