Download Tide Data

Boston (station 8443970) tides: http://tidesonline.nos.noaa.gov/geographic.html.    You want the historical data retrieval, and then preliminary water levels.

  • Get historical data retrieval, and then preliminary water levels.   You want the predicted level and the preliminary water level, in meters, every 6 minutes, with the MSL datum and local time.  If there is weather data here, get it in case you discover challenges with integrating the tide gauge data.
  • If you export to CSV, the predicted values are not exported.
  • Best option is probably to get the predicted tides separately (see below)
    • You can select all in the table, and then copy, but that is painfully slow.
    • You can also expand the table and select all, but is also very slow.

 

Easy download of Tide predictions. 

  • At bottom of station page, pick the "NOAA Tide Predictions"
  • Get a month's worth of 6 minute readings, with MSL and local time.
  • Download as "TXT" in the upper right.
  • You should have the same number of readings as from the observations, so you can reassemble them in Excel.  They should be in the same order, oldest at the bottom.  After you cut and paste, verify that the same date is at the top and bottom.
  • While you can split the dates and times, and then reassemble them, you can also
    • Set first time as 1.00 (say this is G2)
    • Next time is  = G2 + 6/60/24
    • Copy the formula to the bottom
    • Verify the last time is 31.999999 (or whatever 6 minutes would be, subtracted from 32)
    • This works well if all readings share the same time interval.

 

My preference was to get the NAVD datum, since that is what we use for land maps (say we wanted to predict flooding with a lidar data set).  The tide predictions are not available on that datum (but the observations do have it as an option), so pick MSL.  We can later adjust by finding the offset between NAVD and the tidal datums.