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Claim analyzed
Science“Storm tide is defined as the sum of base sea level, astronomical tide, and storm surge.”
Submitted by Patient Hawk 07d5
The conclusion
Open in workbench →Authoritative definitions do not support the three-part formula given here. Storm tide is consistently defined as storm surge added to the astronomical tide; “base sea level” is generally a reference datum or baseline for measurement, not a separate definitional component. As written, the claim adds an unsupported extra term.
Caveats
- Do not confuse a vertical datum or baseline sea level with a physical contributor to storm tide.
- Broader “total water level” concepts may include other factors, but that does not change the standard definition of storm tide.
- Adding “base sea level” as a separate term risks double-counting the baseline and misstates standard agency definitions.
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Sources
Sources used in the analysis
Storm surge is an abnormal water level rise generated by a storm over and above the predicted astronomical tide. Storm tide is the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas, particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases.
Storm tide is the total observed seawater level during a storm, resulting from the combination of storm surge and the astronomical tide. Astronomical tides are caused by the gravitational pull of the sun and the moon and have their greatest effects on seawater level during new and full moons—when the sun, the moon, and the Earth are in alignment.
By contrast, storm tide is defined as the water level due to the combination of storm surge and the astronomical tide, and is expressed in terms of height above a vertical or tidal datum. A vertical datum is simply a base elevation used as a reference from which to measure heights (or depths).
Storm tides is the combination of storm surge, which is water that has been pushed by a storm, with the regularly occurring tides. For example, if a hurricane makes landfall while the tide is coming in, the total water that washes ashore is called the storm tide.
Storm Tide: Is the rise in water from storm surge combined with the normal ocean tides. If storm surge arrives on land during high tide, the total water level can be much higher than if storm surge occurs at low tide when the water level may not be as high in certain areas.
A storm tide is the actual sea level as influenced by a weather disturbance. The storm tide consists of the normal astronomical tide plus the storm surge (WMO, 2017). A storm tide is the water level that results from the combination of the normal (astronomical) tide and a storm surge (an abnormal rise of water generated by a storm, over and above the predicted astronomical tide) (NOAA, 2019a).
STORM TIDE –The water level rise during a storm due to the combination of storm surge and the astronomical tide. Total water level = Storm surge + Tides + Wave runup/setup + Freshwater.
Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide.
Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases.
A storm tide is the combination of the storm surge and the normal astronomical tide. It represents the total observed sea level rise due to the combined effects of the surge and the tide. For instance, if a storm surge of 10 feet coincides with a high tide of 5 feet, the storm tide would reach 15 feet above the mean sea level.
Storm tide is the water level rise during a storm due to the combination of storm surge and the astronomical tide. The total water level = storm surge + tides + waves + freshwater input.
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Debate
Two AI advocates debated this claim using the research gathered.
Argument for
According to authoritative sources such as NOAA's National Ocean Service and Ocean Weather.Gov, storm tide is defined as the total observed water level resulting from the combination of storm surge and astronomical tide measured from a base elevation or datum (Source 2, Source 3). This total water level is mathematically expressed as the sum of its constituent components, which include the base sea level reference, the astronomical tide, and the storm surge (Source 3, Source 7).
The Proponent equivocates between a measurement reference and a definitional component: OceanWeather.gov states storm tide is surge plus astronomical tide and is merely “expressed” relative to a vertical/tidal datum, not defined as including an added “base sea level” term (Source 3 OceanWeather.gov; Source 2 NOAA National Ocean Service). The Proponent's appeal to Source 7 misreads a separate “total water level” decomposition (which adds wave and freshwater terms) as the definition of storm tide, so inserting “base sea level” is an unsupported mathematical leap that contradicts the consistent two-term definition across the authoritative sources (Source 7 National Weather Service; Source 1 NOAA).
Argument against
The motion's definition is false because authoritative references consistently define storm tide as the combination of storm surge and the astronomical tide—without adding a separate “base sea level” term (Source 1 NOAA; Source 2 NOAA National Ocean Service; Source 3 OceanWeather.gov). Moreover, OceanWeather.gov emphasizes storm tide is expressed relative to a vertical/tidal datum (i.e., the reference level is implicit in the measurement), so appending “base sea level” double-counts the datum rather than defining storm tide (Source 3 OceanWeather.gov; Source 7 National Weather Service).
The Opponent's argument relies on a false dichotomy, as measuring storm tide relative to a vertical or tidal datum inherently requires establishing a base sea level elevation from which to sum the astronomical tide and storm surge (Source 3). Furthermore, the National Weather Service explicitly defines the total water level as the sum of its constituent components, confirming that the base reference level is a fundamental mathematical part of the overall storm tide calculation (Source 7).
Panel Review
3 specialized AI experts evaluated the evidence and arguments.
Reviewer 1 — The Logic Examiner
The claim states that storm tide is defined as the sum of 'base sea level, astronomical tide, and storm surge.' The evidence pool (Sources 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) consistently and uniformly defines storm tide as the combination of storm surge and astronomical tide — a two-component definition. No authoritative source adds 'base sea level' as a separate, explicit third component in the definition of storm tide. The Opponent correctly identifies that the datum or base sea level is a measurement reference (implicit in how the result is expressed), not an additive definitional term; the Proponent's rebuttal conflates a measurement datum with a definitional component, committing an equivocation fallacy. Source 7's 'total water level' formula (which includes waves and freshwater) is a broader concept than storm tide itself, and the Proponent's use of it to justify adding 'base sea level' to the storm tide definition misreads the source. The claim therefore does not follow logically from the evidence — the evidence refutes the three-term definition and supports a two-term definition.
Reviewer 2 — The Source Auditor
The most reliable sources (NOAA Sources 1-2, USGS Sources 4-5, NWS Sources 7-8, UNDRR Source 6) uniformly define storm tide as the combination of storm surge plus astronomical tide, expressed relative to a datum rather than including base sea level as an additive component. This directly refutes the claim's three-term formulation, as the datum functions only as a measurement reference and not a definitional summand.
Reviewer 3 — The Precision Analyst
Across the evidence pool, storm tide is consistently defined as the combination (sum) of storm surge and the astronomical tide (Sources 1–3, 6, 8–11), with some sources noting it is expressed relative to a vertical/tidal datum rather than adding a separate “base sea level” component (Source 3). Therefore, the claim's added term “base sea level” over-specifies the definition beyond what the cited definitions state, making the claim false as worded.