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Normal Gravity at Sea Level Equator 978032 mGal Lookup

Return rounded GRS80 equatorial sea-level normal gravity; the milestone title 978032 mGal is approximate, not an exact universal observed gravity.

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Description

Look up rounded GRS80 equatorial normal gravity in m/s² and mGal.

Geodesy distinguishes a mathematical reference ellipsoid, a realized coordinate datum and the physical gravity field. Geodetic latitude follows the ellipsoid normal; geocentric latitude follows a radius from the center. Ellipsoidal height, orthometric height and geoid undulation are separate signed quantities. Keep the declared ellipsoid, coordinate axes, angular units and time scale with a result.

Look up rounded GRS80 equatorial normal gravity in m/s² and mGal.

GRS80 provides a reference ellipsoid and a normal gravity model. Geometric flattening and model normal gravity are reference quantities; neither identifies a measured local gravity or a datum realization by itself.1

When to use this tool

Use this tool when you need to look up rounded GRS80 equatorial normal gravity in m/s² and mGal.

How to use the tool and how it works

  1. Enter model using the definitions below.
  2. Run the operation. Resolve input-format errors before interpreting an output.
  3. Read result.equatorialGravityMgal, result.equatorialGravityMetersPerSecondSquared, result.model, using the stated boundary, ordering, sign and absence conventions.

Require the exact model string GRS80 and return rounded equatorial normal gravity, in both m/s² and mGal. Convert m/s² to mGal by multiplying by 10⁵.2

Input fieldMeaning and unitsAccepted input
modelExact supported normal-gravity model identifier: GRS80.Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply.
Output fieldInterpretation
resultObject containing the fields below.
result.equatorialGravityMgalStored rounded GRS80 equatorial normal gravity in mGal.
result.equatorialGravityMetersPerSecondSquaredThe same stored rounded normal gravity in m/s².
result.modelName of the stated historical/spherical model, retained as context.
json
{
  "input": {
    "model": "GRS80"
  },
  "output": {
    "result": {
      "equatorialGravityMgal": 978032.67715,
      "equatorialGravityMetersPerSecondSquared": 9.7803267715,
      "model": "GRS80 normal gravity, rounded"
    }
  }
}

Limitations and assumptions

  • The stored value is 9.7803267715 m/s². It is model normal gravity at the equator on the ellipsoid, not measured local gravity or a claim about every sea-level location.
  • All quantities are finite and retain the units stated for this operation. Ellipsoid-parameter tools use semi-major axis 1–10⁸ m and dimensionless flattening 0–0.02; explicit-axis tools use 0.9a≤b≤a unless a tighter bound is stated. These tools do not fetch datums, geoid grids, satellite observations or Earth-orientation updates.
  • Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
  • Numeric results must be finite. Large physical magnitudes are allowed by the output evidence checks, while integer fields and source schemas retain their exactness rules. Source indexes are zero-based. Floating-point residues can remain even where an ideal formula gives an exact zero.

Alternative or Complementary methods

Use a coordinate transform for a change of representation and explicit datum parameters for a change of reference frame. Preserve model and convergence metadata, and use observation and datum information appropriate to a real survey before interpreting a computed tolerance as accuracy.

References

  1. Geodetic Reference System 1980 (corrected reference) — H. Moritz; International Association of Geodesy, hosted by MIT

  2. Tool behavior and example: Normal Gravity at Sea Level Equator 978032 mGal Lookup — tool.io

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