DAILY WATER-LEVEL SUMMARY: NORTH SPIT (NOAA CO-OPS STATION 9418767)
Record: 1977-08-16 to 2026-11-07. Generated: 2026-11-07 12:07 PST.

FILES
  ns_daily_summary_ft.csv  values in feet (2 decimals)
  ns_daily_summary_m.csv   values in meters (3 decimals)
  Each file starts with a few comment lines beginning with #. In R:
  read_csv(file, comment = "#"); in Python: pandas.read_csv(file, comment="#").

DAYS
  One row per local (Pacific) calendar day, on Pacific Standard Time or
  Pacific Daylight Time (PST/PDT) as in effect on each day. Days without
  data are included, with NA values.

COLUMNS
  station, noaa_station   Station name and NOAA CO-OPS station number.
  date_local              Local (Pacific) day.
  day_status              verified (NOAA verified data), preliminary (data
                          not yet verified by NOAA), or no data.
  data_type               hourly (NOAA verified hourly heights, before
                          1996) or 6-min (NOAA 6-minute data, 1996 on).
  max_water_level_navd88  Highest observed high water of the day (NAVD88),
                          adjusted for vertical land motion (VLM).
  max_predicted_navd88    Highest predicted high water of the day (NAVD88),
                          adjusted for regional sea-level (ReSL) change.
  mean_tidal_residual     Daily mean tidal residual: adjusted observed minus
                          adjusted predicted water level (days with at least
                          80% of the day's data).
  mean_7td_residual       Centered 7-tidal-day (about 7.2-day) running mean
                          of the residual, at local noon.
  monthly_anomaly         Monthly sea-level anomaly: monthly mean sea level
                          after removing the long-term relative sea-level
                          trend and the average seasonal cycle. One value
                          per calendar month, repeated on each day.
  anomaly_status          verified (NOAA verified monthly mean) or
                          preliminary (from NOAA 6-minute data).
  max_skew_surge          Largest skew surge of the day: highest observed
                          water level in a tidal cycle minus the predicted
                          high water of that cycle.
  tsunami                 Tsunami event on that day (NOAA NCEI Global
                          Historical Tsunami Database); blank otherwise.
                          Skew surge on these days includes the tsunami.

METHODS
  Observed water levels are adjusted for VLM and predictions for ReSL change,
  both relative to 1992.5 (middle of the 1983-2001 National Tidal Datum
  Epoch), so the residual removes the station's long-term relative sea-level
  trend (Patton et al., 2023; NHE, 2026). Because of the adjustment, water
  levels for past years differ slightly from NOAA's published NAVD88 values.
  For hourly years, each high-water peak is estimated with a parabola fit
  through the highest hourly value and its two neighbors. Hourly skew surge
  tends to run slightly lower than 6-minute skew surge, which also captures
  short-period oscillations (seiche).

DISCLAIMER
  Preliminary NOAA data have not undergone quality assurance or quality
  control (QAQC) and are subject to change. Use with appropriate caution.

DATA SOURCES
  NOAA CO-OPS: hourly heights, 6-minute water levels, tide predictions and
  monthly means. NOAA NCEI: Global Historical Tsunami Database.

Developed by: Jeff Anderson (NHE).
