Harmonic representation of a local tide
A bounded harmonic model represents astronomical water-level tide as η(t)=η₀+Σ_jA_jcos(ω_jt+φ_j).
Key knowledge
A bounded harmonic model represents astronomical water-level tide as η(t)=η₀+Σ_jA_jcos(ω_jt+φ_j). Astronomically specified frequencies and fitted local amplitudes/phases describe a station's response over the modeled interval. The harmonic sum is not a prediction of wind-driven surge or every change in mean sea level.
Values and equations
η(t)=η₀+Σ_jA_jcos(ω_jt+φ_j)
- η,η₀,A_j
- water level,reference offset and constituent amplitudes m
- ω_j
- specified constituent angular frequencies rad s⁻¹
- φ_j
- phase at the documented time origin rad
- t
- time from the chosen origin s
Conditions and scope
- Define time origin,phase convention,vertical datum and chosen constituents. Adequate sampling and duration are needed to separate nearby frequencies; missing data and time-dependent/nodal corrections require treatment.
- Fit coefficients using a documented error model and validation. A short or changing record can confound constituents, trends and weather; one site's fitted amplitudes cannot simply be transferred to another basin.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read actual harmonic-constituent fitting/prediction paragraph. The explicit cosine sum is a disclosed mathematical representation of those constituents, linked to existing Fourier/regression methods; no unread operational NOAA nodal algorithm or universal thirty-day adequacy claim.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-tidal-harmonic-model
- Revision
- core.1
- Structured reference record
- University core expansion