what is gfd? - department of atmospheric sciencesdargan/509/509_lecture1.pdf · the gfd toolkit •...
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What is GFD?
ATM S 509/OCEAN 512 Geophysical Fluid Dynamics I
1-4-17
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Key aspects of geophysical flows
• Rotation • Stratification
Also: • Topography/bathymetry/
inhomogeneous surface • Latent heating/other diabatic terms
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The GFD Toolkit
• Development of equations for the atmosphere and ocean – Fluid properties of air and water – Ways to talk about stratification – Mathematical formulation of rotating
reference frame
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The GFD Toolkit
• Conservation equations – Energy – Vorticity – Potential vorticity
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The GFD Toolkit
• Scaling arguments – To rule out particular terms and find
dominant balances – Deriving simplified equations – Sometimes based on order of magnitudes – Sometimes formal asymptotic expansions
in small nondimensional parameters
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The GFD Toolkit
• Examination of transient and steady response to forcing – Waves
• Linear theory, Fourier analysis
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The GFD Toolkit
• Instabilities – Convective – Barotropic, baroclinic, inertial
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The GFD Toolkit
• Idealized physical systems – To illustrate phenomena most succinctly
and elegantly • Lab experiments/numerical experiments
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Equations of Motion
• Conserved tracer • Momentum equation • Mass equation • Equation of state
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Equation of state for seawater
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Equation of state for seawater
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Equation of state for seawater
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More on nonlinear eqn of state
Mix these two parcels
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More on nonlinear eqn of state
Mix these:
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Density of Air vs Ocean
Air is much less dense than water (3 orders of mag or more)
Also air density changes much more than sea water (orders of mag vs 2%)