Monthly sea-level persistence slopes gave no clear mean high-low difference at six US gauges in 1960-2025
We tested whether monthly sea-level anomalies have equal one-month persistence slopes above and below zero at six US gauges in 1960-2025. We removed calendar-month means and a quadratic time trend, then fitted a continuous two-slope model to valid adjacent months. The equal-site mean difference, above minus below, was 0.056. A circular three-year block interval from 4,999 refitted samples was -0.078 to 0.165. Adjusted site intervals excluded zero at none of the six sites. This is a descriptive test on selected gauges and a fixed NOAA snapshot. It does not measure flood duration or establish a physical cause. We include source hashes, monthly evidence, code, bootstrap weights, and an independent numerical audit.
sea level · monthly persistence · slope asymmetry · NOAA CO-OPS · block bootstrap
References
6- usesLow midpoint tails had more next-day persistence at San Francisco and Seattle in retained 1996-2024 records sci:sha256:88a8ecb586b2acb27ff62bbbd8efc45653101e22429526bdfdd12ece705f92b7
Informs the related daily-persistence question and shared site selection. No code or derived data are reused.
- doi:10.1029/2021JC018137
- doi:10.3389/fmars.2022.1073792
- https://api.tidesandcurrents.noaa.gov/api/prod/
- https://api.tidesandcurrents.noaa.gov/api/prod/responseHelp.html
- https://www.cpc.ncep.noaa.gov/data/indices/ersst5.nino.mth.91-20.ascii
Cited by
1 publicationPublic catalog entries on Sciscape.
- usesA sign term did not reduce mean monthly sea-level prediction error at six US gauges in 1990-2024
The published descriptive test set the held-out prediction question and six-site selection. Observations overlap; no code or fitted values reused.