Contributors: Iris Liang
What is “closing a budget” and why use budgets¶
A lot of processes are programmed and calculated inside the model. When the model runs, they collectively update the model state (temperature, nutrients, dic concentration, etc.). How to restore the contribution of each processes? That is what budgets do. “Closing a budget” means attributing the changes of some model states to the known/coded processes responsible as time proceeds, within a neglectable residual range. In the end, we will be able to get a time series showing how each process acts on the tracer field.
To help build the budgets and do analysis, we store and output diagnostics. These are additional calculated variables derived as the model runs. In this way the ocean state and processes are computationally consistent - an advantage over observations.
Links and resources¶
Documentation (from 2014) on heat and salt budgets (with linear free surface and virtual freshwater flux): link
The above documentation arose from a discussion on the MITgcm-support email thread: link to start of discussion (click through “Next message” to follow discussion)
Documentation (from 2017) on general budgets (with nonlinear free surface and real freshwater fluxes) with specific example for ECCOv4r3: link
An introductory slide on the application of budgets (in ECCO): link
ECCO tutorials on budget closure for volume, for heat, for salt, salinity and freshwater
An example notebook of dissolved carbon budget in BSOSE: link