These web layers display discrete tidal zoning generated by the National Ocean Service (NOS) Center for Operational Oceanographic Products and Services (CO-OPS). Zoned tides, relative to a tidal datum, can be constructed by applying time and range correctors to observed water level data from a NOAA tide station. These correctors and the recommended tide stations are contained within discrete tide zones. Each zone was constructed with an ideal uncertainty of less than 0.45m at 95% Confidence Interval.Content: Discrete Tide Zones: Discrete tide zones delineate geographic areas of similar tidal characteristics. For each discrete zone, a tide curve can be constructed by applying a time (AvgTimeCorr) and range (RangeRatio) corrector to the observed water level data for the zone's assigned control water level station. Zones are grouped by geographic region. Table attributes contain tidal information for each zone:ControlStn: Operating water level station referenced by the zone AvgTimeCorr: Average of high and low tide time corrections in 6 minute intervalsRangeRatio: Range ratio (multiplier used to scale the tidal value read for the observation file)ControlStn2 (where available): Alternate operating water level station referenced by the zoneAvgTimeCorr2 (where available): Alternate average of high and low tide time corrections in 6 minute intervalsRangeRatio2 (where available): Alternate range ratio (multiplier used to scale the tidal value read for the observation file)Download Layers to Shapefile, CSV, FGDB, GeoJSON or Feature Collection by clicking on the "Export To" drop-down menu below.(Copy/paste the following link into your browser to access the authoritative data source: ftp://tidepool.nos.noaa.gov/pub/outgoing/HPT/CO-OPS_Regional_Zoning/)Note: Please be aware that you must create a free ArcGIS Online account before you can download the data.Tide Zone Water Level Correction for Hydrographic Data: To create a tide zone correction file for use with hydrographic processing software you will need the following information from the shapefiles contained in this map:Name (OBJECTID) and number of vertices for each zone that overlaps your area of coverageCoordinates of all vertices within each tide zone polygonReference/Control tide station (ControlStn or ControlStn2) for each zoneAverage tide time corrector (AvgTimeCorr or AvgTimeCorr2) and tide zone range ratio (RangeRatio or RangeRatio2)Reference/Control tide station name and coordinatesSix minute preliminary and verified water level data may be retrieved in one month increments over the internet from the CO-OPS web services at https://opendap.co-ops.nos.noaa.gov/axis/ by clicking on “Six Minute Data”.More Resources: https://tidesandcurrents.noaa.gov/hydro.html