✦AESTUS GRAVITATIONALIS
OBSERVED
COASTAL HYDRODYNAMICS · LUNAR GRAVITATIONAL TIDAL HARMONICS

NOAA Tide & Gravity Observatory

Empirical coastal ocean tide harmonics decomposing principal lunar semidiurnal (M2), solar semidiurnal (S2), and lunar elliptic (N2) constituents against verified water level gauges.

NOAA Center for Operational Oceanographic ProductsDiscipline: 02 // ASTRONOMIC

AESTUS GRAVITATIONALIS · GUIDED HYDROGRAPH

The Moon pulls. The coast answers.

Watch lunar, solar, and local coastal clocks resolve into one measured water level.

01 · LUNAR FORCE

The Moon pulls. The coast answers.

A tide is not a single wave arriving from space. It is the local water response to a changing gravitational field, shaped by the basin beneath it.

Station responseSemidiurnal
King tide range2.34 m
SELECT GAUGE · 8665530Charleston, Cooper River
DECOMPOSE METEOROLOGICAL RESIDUAL+0.20 m
ASTRONOMICAL ONLYSTORM RESIDUAL
Harmonic receiverCharleston, Cooper River
00:0012:0024:0000:00 · -0.03 m OBSERVED
M₂12.42 h
lunar clock
S₂12.00 h
solar clock
N₂12.66 h
elliptic clock

Local amplification

Charleston, Cooper River

1.44×

Moon's principal gravitational bulge

The selected station and surge value are the source of truth for both curves.

The NOAA Tide & Gravity Observatory

Empirical coupling of lunar gravitational harmonics (M₂, N₂) against real-time hydrodynamic gauge measurements.

OBSERVED
Tide Classification
Semidiurnal
Mean Tidal Range
1.62 meters
Spring Syzygy Range
1.95 meters
Perigean King Tide
2.34 m (1.44x)
24-Hour Hydrograph: Astronomical Tide vs. Observed Water Level (Meters)
Astronomical Prediction Measured Water Level
00:0004:0008:0012:0016:0020:0024:00
Simulate Storm Surge Residual:+0.20 m
NOAA CO-OPS Live Station #8665530