Astronomical Tide and Storm Surge Non-Linearity

Arielle Alpert

Astronomical Tide

• Gravity-induced

• Diurnal, semi-diurnal, and mixed semi-diurnal

Storm Surge vs. Storm Tide

Storm tide (water level) = storm surge + astronomical tide

non-linearity

Tide-Surge Interaction

• Not necessarily a linear supposition of the two

• Reduces water level below that obtained by linearly adding simulated tide and surge

• Not necessary in observational data

Bernier 2007

• If the tide-surge interaction is linear, the probability of an extreme will be approximately equal for each tidal stage.

• Tide-surge interaction will only contribute significantly to the total sea level when the surges are large enough to interact.

• In NYC area, storm surge tends to be reduced when it happens at the high tide or during the rising tide, while it tends to be increased at the low tide or during the receding tide.

Analysis

High Tide: within 1.5 hours of tidal maximum

Low Tide: within 1.5 hours of tidal minimum

Receding Tide: from the high to low tidal stage

Rising Tide: from the low to high tidal stage

Lin et al., 2012

Low Tide

High Tide

References

• Bernier, N. B., and K. R. Thompson (2007), Tide-surge interaction off the east coast of Canada and northeastern United States, J. Geophys. Res., 112, C06008, doi:10.1029/2006JC003793.

• Tang, Y. M., R. Grimshaw, B. Sanderson, and G. Holland (1995), A Numerical Study of Storm Surges and Tides, with Application to the North Queensland Coast, J. Phys. Oceanography, 26, 2700–2711.

• Lin, N., K Emanuel, M Oppenheimer, and E. Vanmarcke (2012), Physically Based Assessment of Hurricane Surge Threat Under Climate Change, Nature Clim. Change, 462–467.