Planetary Rossby waves on a beta plane
For small-amplitude low-frequency nearly geostrophic perturbations of a resting uniform layer, f=f₀+βy gives planetary Rossby-wave dispersion ω=−βk_x/(k_x²+k_y²+L_d⁻²).
Key knowledge
For small-amplitude low-frequency nearly geostrophic perturbations of a resting uniform layer, f=f₀+βy gives planetary Rossby-wave dispersion ω=−βk_x/(k_x²+k_y²+L_d⁻²). Forβ>0 and nonzero k_x,the zonal phase speed ω/k_x is westward. This describes a vorticity-wave mechanism, while group propagation and fluid-particle motion can differ.
Values and equations
ω=−βk_x/(k_x²+k_y²+L_d⁻²)
- ω
- signed angular frequency in exp[i(k·x−ωt)] s⁻¹
- β
- northward gradient df/dy m⁻¹ s⁻¹
- k_x,k_y
- east/north angular wavenumbers m⁻¹
- L_d
- layer deformation length m
Conditions and scope
- Local midlatitude beta-plane expansion,f₀≠0,constant background depth/restoring coefficient,small Rossby number and specified positive deformation length. Neglect forcing,dissipation and background mean flow in this expression.
- A mean zonal flow adds advection and can alter the PV gradient; boundaries, nonlinearity and equatorial dynamics need adapted models. A plane-wave limit is not an exact description of every observed eddy.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual linear PV balance9, geostrophic substitution10 and plane-wave dispersion11–12 plus westward-phase/group qualifications. Retained a signed ω rather than the source's chosen positive-frequency/negative-k convention; no numerical basin or latitude example adopted.
2026-10-10 · Independent AI editorial review: All73 exact supplement compact statements, conditions, displayed equations and247 origin semantic links read; all109 combined original36+supplement73 author-source rows, exact locators, hypotheses, exclusions and disclosed derivations assessed. Original36 exact scientific content is independently approved in the linked receipt. All18 inherited Earth compact references and shared Math/Physics/Measurement methods were considered in the full practical Earth inventory. Targeted actual primary sections listed below; not every source body/proof or every possible university elective independently reread. AI editorial reference review, not human certification, full-degree proficiency, new experimental validation or a claim of whole combined Earth-and-Cosmos approval. Receipt: earth-completion-independent-content-inventory-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-rossby-wave-dispersion
- Revision
- core.1
- Structured reference record
- University core expansion