Work Package 2

"Earth system models": Constraints to reduce ESM uncertainties and biases

Projects 3 and 4 will directly build upon knowledge acquired in WP1. They are scheduled to start at Month 10, so that they can use initial diagnostics identified in the first year of Projects 1 and 2, and at the same time also provide feedback on best avenues to isolate observational diagnostics specifically suited to evaluating and constraining ESMs. Both Projects will combine own model experiments (with ESMs and LSMs, with support from the model developer) and analyses of multi-model experiments. They will focus on the following topics:

• Drought processes and drought-ecosystem feedbacks, including feedbacks to land water, energy and carbon fluxes, and the role of soil moisture-precipitation feedbacks (Project 3)
• Land surface-temperature feedbacks, considering effects from soil moisture, albedo, land use/land cover, soil types, and topography (Project 4)

The two PhD projects will address the following main questions:

• Evaluating ESMs and their LSMs for present-day climate: What are the main uncertainties and shortcomings of current ESMs, including shared biases, and underlying causes? Do current ESM-based seasonal forecasting systems correctly capture land-mediated predictability for droughts and heatwaves?
• Mapping between present-day behaviour and projections: What are the relevant diagnostics for predicting the future behaviour of drought and heat extremes, which are suitable for the application of observational constraints to ESMs? (In coordination with WP1 and WP3)