Tuesday, August 2, 2022

Grid Spacing vs. Resolution

 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 intervalgrid 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


Monday, June 28, 2021

Exceptional heat in the Northwest

 A quick little note about the record-breaking temperatures in the Northwest this weekend. These temperatures exceed the 95th percentile HRRR analysis "climatology" by over ten degrees.


And the forecast for later today



Figure generated from HRRR Custom (utah.edu)

See this paper for details about the HRRR analysis "climatology"

Friday, January 15, 2021

New Documentation

 I finally got around to consolidating some of my more useful Python code and generated Sphinx documentation.



Please check out the following packages:

  • GOES-2-go
    • download GOES-16 or GOES-17 data from Amazon Web Services (ABI and GLM data).
    • RGB recipes for ABI images (Natural Color, Air Mass, Water Vapor, etc.)
  • SynopticPy:
    • Retrieve mesonet data from the Synoptic API
  • HRRR-B:
    • Download HRRR data from the HRRR archives at the University of Utah's Pando archive, Google Cloud Platform, and Amazon Web Services.

Wednesday, September 9, 2020

Fire and Smoke Season

Smoke from Wildfires seen by GOES-West 
September 9, 2020


MODIS (NASA Worldview)


This was a odd week. On September 9th, there was so much smoke it created an eerie Mars-like atmosphere. The solar radiation in Pacific Grove was very low, and it wasn't even foggy! This smoke certainly helps keep the temperatures down.
This picture is from my sister's friend's aunt's neighbor (do you follow??) in Salem, Oregon. That's about what it looks like here in Monterey. Any zombies hiding in those trees? Maybe the Curiosity rover?
Image