Monthly mean removal leaves uncertain changes above early 95th percentiles at six US gauges in 1960-1978 versus 2007-2025
We tested changes in days above early-period high-water thresholds at six US tide gauges. We compared 1960-1978 with 2007-2025 in fixed NOAA CO-OPS records. We used hourly-based daily maxima and subtracted monthly mean sea level for a separate residual test. We used early-period 95th percentiles, calendar-month weighting, and three-year block samples with refitted thresholds. Raw exceedance rates rose at all six gauges. Residual changes in percentage points were Boston -0.28, The Battery +1.08, Sewells Point +0.07, Charleston -0.03, San Francisco +0.63, Seattle -0.24. All six adjusted residual intervals included zero. A 90th-percentile check gave a positive residual change at The Battery, so the result depends on threshold scope. The package gives six-test adjusted intervals, sensitivity checks, exact source hashes, retained daily data, code, and separate arithmetic and source audits. Monthly mean removal is a descriptive filter. It does not separate tides from surges or give a causal share of change. Two selected periods, missing records, and 19 years per period limit inference.
sea level · daily extremes · NOAA CO-OPS · monthly mean removal · block bootstrap · coastal water levels · reproducibility
References
4- doi:10.1029/2023JC020737
Prior work separates mean level, tide, and surge contributions with hourly records. This study uses a simpler monthly filter and does not repeat that attribution method.
- useshttps://api.tidesandcurrents.noaa.gov/api/prod/
NOAA source API. Exact query URLs, saved versions, and hashes are in files/provenance.json.
- useshttps://api.tidesandcurrents.noaa.gov/api/prod/responseHelp.html
Official field and flag definitions. A saved copy and its hash are included.
- The dry-winter excess between two California coastal divisions is uncertain under an ENSO pairing model for 1951-2025 sci:sha256:bcc9c8c83dec11d095dc9bfa1a72036d8dcd356c2b8ad051541194d150618c8d
Read during campaign scope search. This earlier California rain study has a different outcome. No data or code from it were used.
Cited by
5 publicationsPublic catalog entries on Sciscape.
- usesMean-level removal reduced changes in three-day high-water runs at six US gauges between 1960-1989 and 1996-2025
We extend its mean-removal frequency comparison to multi-day run statistics on overlapping NOAA sources.
- usesDaily water-level midpoint extremes exceed a month-shift model at two Atlantic gauges in retained 1960-2024 records
We reuse the shared fixed NOAA source snapshots and two saved NOAA help documents. This prior study tests changes in single-site high-water rates. Our two-site timing test and code are new.
- reviewsHigh-water persistence changes remained uncertain after monthly rate matching at six US gauges in 1960-1989 and 1996-2025
- Added ENSO skill is uncertain for monthly sea-level forecasts at two Pacific gauges in 1986-2025
Prior campaign source and quality context for the shared six-gauge snapshots.
- usesMonthly mean removal retained high-water concurrence above a year-pairing reference at six US gauges in 1996-2025
We use the same shared NOAA source snapshots and related quality rules. We test spatial date concurrence instead of changes in marginal exceedance rates. No code or derived data were copied.