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Compare-Contrast-Connect: Measuring Tides

NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas



SF Fig. 6.16. A modern Sentinel tidal monitoring station operated by the US National Oceanic and Atmospheric Administration (NOAA) in the Gulf of Mexico

Image courtesy of National Oceanic and Atmospheric Administration (NOAA)

Real-time water level, water current, and weather measurement systems are used to provide mariners and port operators with the latest coastal conditions. While older tidal measuring stations used mechanical floats and recorders, modern monitoring stations use advanced acoustics and electronics (SF Fig. 6.16). To determine water level, modern recorders send an audio signal down a sounding tube and measure the time it takes for the reflected signal to travel back from the water's surface. In addition to measuring tidal heights more accurately, the modern systems also record other oceanographic and meteorological parameters such as wind speed and direction, water current speed and direction, air and water temperature, and barometric pressure.

In the United States, the National Oceanic and Atmospheric Administration (NOAA) operates over 3,000 tidal monitoring stations from Guam to Bermuda. Tidal monitoring stations offer invaluable up-to-date information to a wide variety of users from battleship captains and commercial fishermen to marine biologists and amateur tidepoolers.


Question Set
  1. Unfortunately, tide predictions are only accurate for coastlines within the immediate vicinity of monitoring stations. If you are headed to a place far away from a tide monitoring station, how can you determine what the tidal height will be?
  2. NOAA operates over 3,000 tidal monitoring stations, many of which are located on remote or rugged coastlines. It is important that each instrument is both accurate and precise.
    1. What might happen if the instrument measuring water level suddenly became inaccurate?
    2. What might happen if the instrument measuring water level suddenly lost its high precision?
    3. If you were a NOAA scientist, how would you check the accuracy and precision of the instrument measuring water level?
Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.