Internal Seiche Period Rectangular

Estimate the fundamental rectangular nonrotating two-layer internal seiche period 2L/c; higher harmonics are excluded as duplicated scaling variants.

Description

A two-layer lake supports an internal wave at its density interface.

A two-layer lake supports an internal wave at its density interface. For a rectangular nonrotating basin, a round trip over its length gives the fundamental internal seiche period.^[1]

The tool returns internalWaveSpeedMPerSecond, fundamentalSeichePeriodSeconds. The computation uses supplied observations and parameters rather than acquiring measurements.

When to use Internal Seiche Period Rectangular

Use this for the following task: Estimate the fundamental rectangular nonrotating two-layer internal seiche period 2L/c; higher harmonics are excluded as duplicated scaling variants. Prepare observations and calibration parameters on the same unit and reporting basis.

How to use Internal Seiche Period Rectangular and understand its results

Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
Enter lakeLengthM, upperLayerDepthM, lowerLayerDepthM, densityContrastKgPerM3, referenceDensityKgPerM3, gravityMPerSecondSquared according to the field table, then run the tool.
Read internalWaveSpeedMPerSecond, fundamentalSeichePeriodSeconds. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
Review the supplied assumptions and calibration before comparing or reporting the result.

Input field	Meaning	Value type and bounds	Requirement
lakeLengthM	Lake length m	number	Required
upperLayerDepthM	Upper layer depth m	number	Required
lowerLayerDepthM	Lower layer depth m	number	Required
densityContrastKgPerM3	Density contrast kg per m3	number	Required
referenceDensityKgPerM3	Reference density kg per m3	number	Required
gravityMPerSecondSquared	Gravity m per second squared	number	Required

Supply positive lake length, both layer depths, density contrast, reference density and gravity. Calculate wave speed and the fundamental period in seconds.

g′=g×densityContrast/referenceDensity; c=sqrt(g′×upperDepth×lowerDepth/(upperDepth+lowerDepth)); period=2×length/c

The symbols and boundary conditions refer to the supplied fields and the implementation described above.

Output field	Meaning	Value type
internalWaveSpeedMPerSecond	Internal wave speed m per second	number
fundamentalSeichePeriodSeconds	Fundamental seiche period seconds	number

json

{
  "input": {
    "lakeLengthM": 1000,
    "upperLayerDepthM": 10,
    "lowerLayerDepthM": 10,
    "densityContrastKgPerM3": 2,
    "referenceDensityKgPerM3": 1000,
    "gravityMPerSecondSquared": 10
  },
  "output": {
    "internalWaveSpeedMPerSecond": 0.31622776601683794,
    "fundamentalSeichePeriodSeconds": 6324.555320336758
  }
}

Limitations and assumptions

The model excludes rotation, irregular basin geometry and continuous stratification. Higher harmonics and damping are not returned.

Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.

Alternative or Complementary methods

Choose Internal Rossby Radius Deformation when you need its operation: Calculate two-layer internal Rossby radius c/|f| using supplied reduced gravity and signed Coriolis parameter; no latitude or coordinate transformation. Choose Wedderburn Number for the complementary operation: Evaluate W=g′h²/(u*²L) from caller two-layer density contrast, upper thickness, friction velocity and fetch; no universal upwelling or turnover criterion.

Background reference: Lake Physics Tools: rLakeAnalyzer reference manual.

References

Lake Physics Tools: rLakeAnalyzer reference manual — Winslow, Read and colleagues; GLEON

Similar or alternative tools

Internal Rossby Radius Deformation
Calculate two-layer internal Rossby radius c/|f| using supplied reduced gravity and signed Coriolis parameter; no latitude or coordinate transformation.
Wedderburn Number
Evaluate W=g′h²/(u*²L) from caller two-layer density contrast, upper thickness, friction velocity and fetch; no universal upwelling or turnover criterion.