Which types of tides are found in the United States?

The purpose of this activity is to learn how to graph tidal data from locations in the United States and to interpret your results.

In this activity, you will compare and contrast semidiurnal, diurnal, and mixed tides.

You will be able to answer these questions:

•   How are tides affected by their location?

•   Which types of tides are found in the United States?

•   What causes that pattern?

There are two acceptable methods for completing the project, one using Excel/any other spreadsheet and one using a manual approach that does not require the use of a spreadsheet. Please read the instructions carefully. It is possible to do this project without using a spreadsheet if you do all of the calculations and graphing by hand. However, Excel/spreadsheet is recommended for this assignment.

National Oceanic and Atmospheric Administration (NOAA) data sets from widely separated tide stations are included. The tidal data were obtained from the National Oceanic Survey of NOAAwebsite: tides and currents

The data sets cover hourly water level values over a one-month period from December 1 through December 31, 2014. As the data header shows, the times are Greenwich Mean Time (GMT), not local time, and the water levels are in feet.

Compare tidal information from the following sites:

Anchorage, Alaska

New London, Connecticut

Key West, Florida

Eagle Point, Texas

For each of the sites above, click on the link to open the file of data. After it opens, choose “Save Page As” (which is under File menu), then save the file to a folder on your hard drive or flash drive. Repeat this process for each of the text files.

Instructions (Using Excel):

Using the Guam tidal data as a sample, follow these instructions for importing tidal data into Excel.

Guam Tidal Data

Importing Tides Data [PDF file size 494.4 KB]

Once you are comfortable with importing tidal data into Excel, you can follow the same procedure for the other four data sets. You are graphing a 31-day period and a shorter (4- to 10-day period) for each of the four locations. Remember, to graph a shorter period, you must first select a smaller range of data.

Import all your graphs into a Word document, and complete your write up using the American Psychological Association (APA) style (6th edition).