The theme Storms and Radiation will focus on attaining realistic simulations of the top of the atmosphere (TOA) energy budget during model development.
Ensembles of short simulations combined with data assimilation techniques and observations will be used to inform parameter choices and reduce expected cloud biases. Structural limitations related to remaining sub-grid scale processes, such as cloud-microphysics and turbulent mixing, will be assessed and used to guide the development of new parametrisations of these micro and smaller-scale processes. A computationally efficient aerosol scheme designed to exploit the ability of SR-ESMs to better represent physical source and sink processes, as well as transport and interaction with cloud systems, will be developed and implemented.
This theme will study the effect of convective organization and ‘pattern-effects’ on cloud feedbacks and climate sensitivity, how clouds and precipitation affect aerosol forcing and how in turn aerosols affect the hydrological cycle through deep convection, by better representing source and sink processes, and making convection aerosol-aware, and how these processes respond to warming.
WP4 prepares the SR-ESMs for application stage simulations, targeting aerosol forcing, cloud feedback and climate sensitivity, by ensuring that the top-of-atmosphere radiation budgets of the SR-ESMs are sufficiently balanced, implementing a simplified aerosol scheme, and assessing realism of processes that remain to be sub-grid scale.
In the S&R Development phase, a primary aim of WP4 is to pave the way towards a stable climate in the nextGEMS models, with a particular focus on resolved cloud processes and the top-of-atmosphere (TOA) radiation budget. The implementation of a new simplified aerosol scheme will also be completed in the ICON model and it will be coupled to other Earth System components. Attaining a stable climate will leverage both experience in the team and new observations, as well as the development of data assimilation and perturbed physics ensemble techniques to map out the sensitivity of the model state to small scale process parameters. A particular challenge is that without a convection parametrisation in SR-ESMs the realism of other process-representations is increasingly critical. Therefore the performance of turbulence and cloud microphysics parametrisation schemes will be assessed, in particular focusing on their effects on transport and mixing in clouds. Engagement with stakeholders through Knowledge Coproduction activities, with a particular focus on renewable wind energy production, will be assured early on through the organization of the Cycle 2 hackathon, in which their proposed diagnostics will be implemented in the SR-ESMs.
Lead Beneficiary: MISU
WP5 uses the SR-ESMs to constrain key aspects of forcing, feedback and response in the climate system, and thereby contribute to imporved estimates of climate sensitivity and future warming.
In the S&R Application phase, global storm resolving simulations will be exploited to address problems regarding climate sensitivity, and aerosol impacts and their interactions with clouds, while continuing advanced model development activities. Three tasks of WP5 are focused on constraining key aspects of the forcing, feedback and response of the climate system, which are elements necessary for estimating committed global warming  and the remaining carbon budget  – the cornerstones of operationalising the Paris Agreement. WP5 will also further explore possibilities for improving descriptions of sub-grid scale processes related to cloud microphysics and turbulence, using large-eddy simulation (LES) tools, and apply advanced data assimilation techniques to constrain the model physics against observations. The performance and feasibility of NextGEMS SR- ESMs to study dust aerosol impacts will be explored in a case study, and a hackathon focusing on impacts of climate change on renewable energy production will be co-organized together with S&S (WP10).
Lead Beneficiary: MISU
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