2020-10-28 ESMD/E3SM PI Meeting -- Ocean Breakout Session

Ocean Breakout (10/28/2020)

Topic: D3S2-BR#3
Time: Oct 28, 2020 03:00 PM Eastern Time (US and Canada)

Questions for Discussion:

What are the grand challenges in ocean/ice modeling? For example:
1. What are the key missing or more uncertain processes that should be prioritized for model development?
2. What processes require more improvements in scale awareness?
3. Is there a game-changing scale for modeling processes in each component?
4. Can we develop a heirarchy of models that actually informs coupled modeling efforts?
  1. Is there something between forced ocean sea ice and fully coupled runs?
    1. “pencil atmosphere”
    2. FAFMIP
    3. other?
How can we overcome these challenges and accelerate progress?
What opportunities/recent advances can E3SM leverage?
How can we improve E3SM’s development and evaluation process? For example:
1. How could development better target known biases?
2. How can we ensure good coupled model behavior while developing component models?
3. How can development and evaluation be made more efficient?

Notes:

Laure Zanna: Turbulence Closures in Ocean Models

Goals: improve parameterization of mesoscale eddies through energetics. Link momentum, buoyancy, eddy energy closures

Sources, sinks, and transfer of energy across scales is key. Mesoscales in particular are important; extract energy from mean flow and improves model output. GM mimics baroclinic instability and reduces spurious convection and mixing, but doesn’t account for eddy energy. Eddy energy can be used to inform GM coefficient, but then you’re still missing some energy pathways, so we need to rethink momentum closures. Bachman 2019 reinjects available potential energy from GM into resolved KE. Stocastic and non-newtonian closures are also an option. Overall, recent closures have focused on targeting energy transfers; have shown a reduction in biases in ocean transport. Challenge: how do we do this across resolution and in global models? Which momentum closure is best? What is the impact of vertical structure? There is a need for observationally-constrained and unified buoyancy and momentum closures, via energetics, for a robust scale and flow aware implementation in IPCC-class models

Questions:

Does tuning and validation require high resolution models since we don’t have energy cascade observations?

We are relying on bottom drag to account for flow around topography

Have non-newtonian closures been implemented? (a few in MOM6)

How to we figure out what the eddy length scale should be? How does that relate to GM kappa? (think about what is resolved and what is not resolved, but this is not clear cut)

Discussion:

What are the grand challenges in ocean/ice modeling? For example:
1. What are the key missing or more uncertain processes that should be prioritized for model development?
2. What processes require more improvements in scale awareness?
3. Is there a game-changing scale for modeling processes in each component?
4. Can we develop a heirarchy of models that actually informs coupled modeling efforts?
  1. Is there something between forced ocean sea ice and fully coupled runs?
    1. “pencil atmosphere”
    2. FAFMIP
    3. other?
  2. Zhengyu Lui: what is minimum set? He agreed this is a good idea, going from simple to fully coupled.
How can we overcome these challenges and accelerate progress?
What opportunities/recent advances can E3SM leverage?
How can we improve E3SM’s development and evaluation process? For example:
1. How could development better target known biases?
2. How can we ensure good coupled model behavior while developing component models?
3. How can development and evaluation be made more efficient?
machine learning:
1. Zanna: used equation discovery in machine learning.
2. Anand: had a student who worked on machine learning. They found that you turn up things, like you need to have a more accurate advection scheme - you are loosing the curvature of the field, need to put that back in, as you change resolution.