9th Class

Zonal Mean Flow Instabilities

I) Baroclinic Instability

Two solutions for uniform PV (Qy=0) will be consider:

a)The classical Eady model, constant flow U(z) only on a f=plane,

EADY_3D001.b1.e10801_zee.nc the parameters can be found in Zeta_setup

b)The instability of a jet U(y,z) with uniform PV (Hoskins and West 1979:Baroclinic waves Frontogenesis Part II: Uniform Potential Vorticity Jet Flow. JAS Vol 36 1663-1679.)

EADY_jet002.b1.e9601_zee.nc the parameters can be found in Zeta_setup .

Since the time step for the second experiment is 90 sec, 9600 time steps is 10 days. If you will like to inspect the evolution of this wave after 10 days. The history file listed below is a continuation from 9601 (10 days) to about 13000 (~14 days). Since this run does not have eddy viscocity. the fronts became so intense that unstable lapse rates developed and the model at this stage can't handle convective instability.

EADY_jet002.b9601.e19201_zee.nc.

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A) Compare the vertical structure of the waves for the constant flow, and the jet solution (in the linear regime ~6 days)

B) Calculate for the same time; the heat fluxes and momentum fluxes for both solutions and explain the differences.

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