Thermal wind in height coordinates
Hydrostatic and nearly geostrophic balances imply vertical geostrophic shear from horizontal density gradients: ∂u_g/∂z=gρ_y/(fρ₀), ∂v_g/∂z=−gρ_x/(fρ₀).
Key knowledge
Hydrostatic and nearly geostrophic balances imply vertical geostrophic shear from horizontal density gradients: ∂u_g/∂z=gρ_y/(fρ₀), ∂v_g/∂z=−gρ_x/(fρ₀). Equivalently ∂u_g-vector/∂z=−[g/(fρ₀)]e_z×∇_hρ. Thermal wind is a shear relation, so a reference velocity at one level is still required to infer an absolute velocity profile.
Values and equations
u_{g,z}=gρ_y/(fρ₀); v_{g,z}=−gρ_x/(fρ₀)
- u_g,v_g
- east/north geostrophic velocities m s⁻¹
- x,y,z
- east, north and upward coordinates m
- ρ,ρ₀
- density and constant reference density kg m⁻³
- f
- signed Coriolis parameter s⁻¹
- g
- gravitational acceleration m s⁻²
Conditions and scope
- Local east x,north y,upward z,nonzero f,small Rossby number,hydrostatic balance and small density deviations from constantρ₀. Horizontal gradients are taken at fixed height.
- Friction, strong accelerations, equatorial f≈0, nonhydrostatic motion and spatially varying coefficients need adapted equations. Density depends on temperature, salinity/composition and the consistent equation of state.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual hydrostatic/geostrophic differentiation and Boussinesq height equations4–5, including signs and the small-Rossby criterion. Retained the reference-velocity ambiguity explicitly; no assumption that temperature alone determines seawater density.
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Entry details
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- uni-earth-thermal-wind-height
- Revision
- core.1
- Structured reference record
- University core expansion