Vector Average Current Components

Distinguish duration-weighted vector resultant from scalar mean current speed, retaining reversals; does not infer coordinates or drifter displacements.

Description

Opposing currents may cancel in a vector average while maintaining a substantial average scalar speed.

Opposing currents may cancel in a vector average while maintaining a substantial average scalar speed. Duration weighting preserves their different meanings.

Distinguish duration-weighted vector resultant from scalar mean current speed, retaining reversals; does not infer coordinates or drifter displacements.

When to use Vector Average Current Components

Use this tool to distinguish duration-weighted vector resultant from scalar mean current speed, retaining reversals; does not infer coordinates or drifter displacements.

Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.

How to use Vector Average Current Components and understand its results

Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.
Enter eastwardCurrentsMPerSecond, northwardCurrentsMPerSecond, sampleDurationWeights using the field table and calculation rules, then run the tool.
Read meanEastwardCurrentMPerSecond, meanNorthwardCurrentMPerSecond, resultantMeanSpeedMPerSecond, scalarMeanSpeedMPerSecond. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
eastwardCurrentsMPerSecond	Eastward currents m per second	list of number	Required
northwardCurrentsMPerSecond	Northward currents m per second	list of number	Required
sampleDurationWeights	Sample duration weights	list of number	Required

Align signed current components with nonnegative weights of positive total. Return mean components, resultant speed and weighted mean of individual speeds.^[1]

Paired lists must be nonempty and have equal lengths.

resultant speed = hypot(weighted mean east,weighted mean north)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
meanEastwardCurrentMPerSecond	Mean eastward current m per second	number
meanNorthwardCurrentMPerSecond	Mean northward current m per second	number
resultantMeanSpeedMPerSecond	Resultant mean speed m per second	number
scalarMeanSpeedMPerSecond	Scalar mean speed m per second	number

json

{
  "input": {
    "eastwardCurrentsMPerSecond": [
      1,
      -1
    ],
    "northwardCurrentsMPerSecond": [
      0,
      0
    ],
    "sampleDurationWeights": [
      1,
      3
    ]
  },
  "output": {
    "meanEastwardCurrentMPerSecond": -0.5,
    "meanNorthwardCurrentMPerSecond": 0,
    "resultantMeanSpeedMPerSecond": 0.5,
    "scalarMeanSpeedMPerSecond": 1
  }
}

Limitations and assumptions

No drifter displacement or coordinates are inferred.

Numbers and computed results must be finite; overflow produces an error. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Ekman Spiral Surface Deflection Angle: Calculate a constant-viscosity steady Ekman current vector at depth, including hemisphere-dependent rotation and exponential decay; not a universal observed 45-degree surface rule. For a complementary task, use Stokes Drift Surface Velocity: Evaluate monochromatic deep-water Stokes drift at caller depth below surface, not Eulerian mean current; supplied amplitude is half wave height.

References

Vector Average Current Components — tool.io

Similar or alternative tools

Ekman Spiral Surface Deflection Angle
Calculate a constant-viscosity steady Ekman current vector at depth, including hemisphere-dependent rotation and exponential decay; not a universal observed 45-degree surface rule.
Stokes Drift Surface Velocity
Evaluate monochromatic deep-water Stokes drift at caller depth below surface, not Eulerian mean current; supplied amplitude is half wave height.