Friday, August 12, 2011

Bores

The last few days have seen what I hope to be the start of a drought buster the drought get busted here in Central OK and it started off with the transition to Northwesterly flow aloft. Convection developed up in Kansas and produced outflow which propagated south and resulted in the production of a bore which transitioned to a series of solitons. The latter are atmospheric gravity waves (amplitude ordered) which propagate on the interface of the inversion aloft. You can see the waves on radar (below).
What I find interesting is that these waves passed over the Oklahoma mesonet and were well resolved with the 5 minute interval data collection. As the waves approached Norman there were 3 or 4, and passing through Norman there were 5, and afterward possibly a sixth wave.

The following day we had two waves which may be another set of bores. These waves contributed to the development of convection in eastern OK which gave the area some much needed rainfall and kept temperatures down for the whole day.

On the 10th, the radar depiction above, the NSSL WRF model did a good job depicting the convection and outflow, but I doubt there was a bore as it might not be well resolved spatially on a 4km grid. One thing I know that will be beneficial in model development is to output time series so we can see what kind of waves (density currents, gravity waves, bores, solitons, etc) emanate from model generated convection. In this way we can test whether the models are capable of simulating these features. This will probably be more valuable at finer resolution as has been shown in research grade real-data simulations down into the sub 1km grid spacing range.

These waves can be implicated in all kinds of processes, from pre-conditioning the environment to being the cause of convection initiation, to doing nothing. Exploring these fine scale features and quantifying their impacts on the model simulations (through physics sensitivity) is just another way to help understand the fine resolution models (and maybe contribute to our understanding of the real world).