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tides and waterlevels iconTides Roadmap to Resources


These online resources are meant to guide students and educators to topics presented in the online tides and water levels tutorial. The following links will take you to specific Web pages created and managed by NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS). CO-OPS predicts, records and distributes oceanographic and meteorological data from thousands of monitoring stations in U.S. coastal and territorial waters.

Please note: The Web links provided have been checked at the time of this page's publication, but the linking sites may become outdated or non-operational over time. If you should come across a non operational link please contact NOAA Ocean Service Education at
"Our Restless Tides" provides comprehensive information about the astronomical and physical forces that cause and affect the world's tides. Detailed diagrams and mathematical formulae illustrating the forces acting on the world's oceans are presented. (28 pages, pdf, 600Kb)
The "Glossary of Tide and Current Terminology" is and indispensable reference tool lists and defines more than 400 terms and concepts concerned with the tidal phenomena and its measurement.
The "NOS Water Level Observation Network" lets you to access graphic presentations of predicted and observed water levels, air and water temperatures, wind speed and direction, and air pressure in real time from U.S. coastal and territorial waters. After clicking on a state, select a tidal monitoring station and click on it. Predicted readings for an area will appear in blue, and actual observations will appear in red. To view a good example of a diurnal tidal cycle, select a tidal station in Louisiana, Mississippi or Alabama. To see semi-diurnal tides, select a coastal monitoring station from a northeastern state such as Delaware or Maine. Note that the tidal range increases as you move further north. To observe mixed semidiurnal tides, select any one of the tidal stations on the west coast.
The "Physical Oceanographic Real Time System" (PORTS®) Web site provides real-time oceanographic and meteorological data for 15 major U.S. harbors. After selecting a particular harbor, you can view the types and geographic placement of different sensors in that area by clicking on the sensor locations highlighted on the area maps. To zoom in on a particular area where an instrument is stationed, click on the "plus" symbol in the upper left hand side of the image. You can reorient the image by "dragging" it with your mouse or using the arrow buttons on the upper left hand side of the image. To view specific data for a particular sensor in graphic format click on the image of data graph you wish to view. To view the data in ASCII, or text format, scroll down the page of the graphic presentation and click on the link to the data set you want to see.
The "NOS Water Level Observation Network - Great Lakes" Web site provides real-time observations of water levels for seven of the eight states bordering the five Great Lakes. You can select a particular monitoring station by choosing a state and clicking on it. A map will appear showing the geographic locations of all the monitoring stations in the state. Select one of these stations to view a graph of water levels in real time at that site for a 24-hour period. To view the data in ASCII, or text format, scroll down the page and click on the link to the data listing.
This Web site provides you with tidal predictions computed by CO-OPS for more than 3000 tidal current stations. Click on the year for which you want tidal prediction data. This opens a new page with a list of states and other areas for which there are tide stations on the left side of the page. Clicking on a state name displays a list of regions within that state. Clicking on a region name will present a list of the tidal current stations in the area. These stations are listed geographically. This will make finding the location you are interested in, or a nearby station, simpler.

Unlike tide stations, which are normally located along the shoreline, most tidal current stations are located offshore in channels, rivers, and bays. These stations are often named for the channel, river, or bay in which they are located or for a nearby navigational reference point. A map or some personal knowledge of the area may help you identify stations.

To access tidal current data from 2004 through 2006 go to: On the left hand side of the page look beneath "Predictions" and then beneath "Published Current Tables" click the year for which you wish to view tidal current data.

Similar to the tidal current prediction Web site above, this site provides you with water level predictions for more than 3000 water level stations. The list of stations may be selected from a listing on the main part of the page, or from a sub-listing of stations broken down by state which can be accessed on the left hand side of the page. You can also use the interactive map feature accessible from the page to search for a tidal station geographically.

To access tidal data from 2004 through 2006 point go to: On the left hand side of the page look beneath "Predictions" and then beneath "Published Tide Tables" click the year that you wish to view tidal current data for.
"About Water Levels, Tides & Currents" provides links to additional information including Tide Predicting Machines, How Does One Measure Water Levels, Why Does One Measure Water Levels, and The Challenge of Measuring Water Currents.
(83 pp, 1.9M)
"Understanding Tides" is a technical publication authored by Stacy Dopp Hicks, provides in-depth explanations of many aspects of tides, including Gravitational Attraction, Sun-Earth and Moon-Earth Systems, Spring and Neap Tides, Tide-Generating Forces, Tidal Waves in Gulfs and Estuaries, Tidal Bores, and Tidal Harmonic Constituents.


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