The static response of the sea surface to changes in atmospheric pressure: when pressure drops by 1 hPa, sea level rises by roughly 1 cm, and the reverse for high pressure. A deep low 40 hPa below normal can lift the sea about 40 cm before any wind effect. Surge models include it, and an unvented pressure gauge with no barometer correction misses it entirely, because the drop in air pressure cancels the weight of the extra water.
Pressure's down 30 millibars, so add about 30 centimetres from the inverse barometer effect alone.
Also heard as
- inverted barometer effect
- IB effect
Related terms
Storm surge
A rise of water above the predicted tide caused by a storm's winds and low pressure.
Residual
The observed water level minus the predicted tide, showing the effect of weather, rivers and other non-tidal causes.
Pressure gauge
A submerged sensor that measures the weight of water above it, converted to water level with density and air pressure.
Storm tide
The full water level reached in a storm: astronomical tide and storm surge added together.