Here we study the balance of forces typical of atmospheric vortices and severe weather across scale, using the Rossby number as a guide. The activity parallels that taken in our ‘radial inflow’ laboratory experiment.
A detailed description of the activity is in weather_xtremes_atmosphere and weather_xtremes_slides.
Links to the notes and slides of the second Data class are given in the “Hurricane flow- balance of forces” section below.
Relevant theory and discussion of the balance of forces can be found in the reference materials.
Estimating the Rossby number as a function of scale
Estimate the Rossby number of various vortices in the atmosphere in a manner which is exactly analogous to that used in the laboratory experiments by tracking ‘virtual’particles in the evolving wind patterns using the EsGlobe – see EsGlobe/Atmospheric patch of particles.
- Planetary scale – the jet stream – see example movie.
- Mid-latitude cyclones – blizzards and Nor’easters – see example of the Blizzard of Jan 4, 2018.
- Tropical cyclones – hurricanes – see Harvey ( August, 2018).
Jet stream – geostrophic balance
Compare distribution of climatology of zonal wind and north-south pressure gradient for zonal averages, using the Esglobe-atmopsheric-climatology.
Hurricane flow – balance of forces
Here we analyze data from real hurricanes and compare them with the tank experiment. Check the second Data class slides and notes.
Choose a hurricane and plot the observed winds and Rossby Number in function of radius as described in the scatterometer-instructions page.
Discuss how the hurricane data compare and contrast with the radial inflow experiment.
List of interesting hurricane case studies is available here.
EXtra
Note that the surface wind tends to be cross isobaric.
Read notes on the effect of friction on the geostrophic flow.
You may use gdplot-surf to plot the surface analyzed wind and pressure.