CLIMATE/EARTH 401�Geophysical Fluid Dynamics�Dynamical Meteorology

Richard B. Rood

rbrood@umich.edu

https://clasp.engin.umich.edu/people/richard-b-rood/

https://openclimate.org/

Vorticity 6: Solenoidal / Baroclinic Term

Vorticity and Divergence

• Related to shear �of the velocity field.

∂v/∂x-∂u/∂y

• Related to stretching �of the velocity field.

∂u/∂x+∂v/∂y

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Let’s go through this term by term

Solenoidal / Baroclinic Term

Solenoidal or Baroclinic Terms

Related to the horizontal gradient of thermodynamic variables

Two important definitions

• barotropic – density depends only on pressure.
• And by the ideal gas equation, surfaces of constant pressure, are surfaces of constant density, are surfaces of constant temperature.
• baroclinic – density depends on pressure and temperature.
• Suggests that there is some thermal energy in the system that could be tapped.

“Solenoidal” or “Baroclinic” Terms

Baroclinic: surfaces of constant density

intersect surfaces of constant pressure

“Solenoidal” or “Baroclinic” Terms

ρ-2Δρ

ρ-Δρ

ρ

Barotropic: surfaces of constant density

parallel to surfaces of constant pressure

Baroclinicity and growth of weather systems

• Baroclinicity is a large part of what drives the development of low-level, low-pressure systems in middle-latitudes
• It is also important in understanding circulations around fronts.

Solenoidal or baroclinic terms around a front

Baroclinic: surfaces of constant density

intersect surfaces of constant pressure

End: Vorticity 6: Solenoidal / Baroclinic Term

Richard B. Rood

rbrood@umich.edu

https://clasp.engin.umich.edu/people/richard-b-rood/

https://openclimate.org/