If you spend enough time with meteorologist, you'll inevitably hear criticism against using the non-interchangeable terms "grid spacing" and "resolution" to describe the spacing between grid points in a numerical weather model. Just last week I reviewed a paper where one of the other reviewers blasted the authors for incorrectly using the terms interchangeably. I cringed at the comment. What drives me nuts about this is that the reviewer didn't even explain why the terms are not interchangeable. The supposed incorrect use of the term model "resolution" in place of "grid spacing" will go on forever because those who are deeply offended by those who interchange the term rarely explain how the two terms are different.
What is the difference?
In a March 2000 BAMS commentary, Lewis D. Grasso explains:
The two terms grid spacing and resolution refer to two different length scales that characterize a grid configuration. Because of this, they are not interchangeable in linear and nonlinear numerical models. It is not possible to resolve a wave on the scale of one grid spacing in any spatial direction. Since 2Δx and 3Δx waves are removed to prevent nonlinear instability, waves on the scale of at least 4Δx may be resolved. Other terms that may be used in place of grid spacing are grid interval, grid length, and grid increment.
There you have it; resolution is not the correct term to describe a model's grid spacing because resolution refers to the length scale that waves are resolved in the model.
More resources on the topic
- https://weather.mailasail.com/Franks-Weather/Grid-Length-Resolution
- https://www.meted.ucar.edu/nwp/model_structure/navmenu.php?tab=1&page=3-0-0
