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I have the data of every day and time of the low and high tides from

https://tidesandcurrents.noaa.gov/noaatidepredictions/NOAATidesFacade.jsp?Stationid=8721649&bmon=01&bday=03&byear=2016&edate=&timelength=weekly&timeZone=2&dataUnits=1&datum=MLLW&timeUnits=2&interval=highlow&Threshold=greaterthanequal&format=Submit

I need to recreate the sinusoidal graph shown on the website while showing the chart in a concise order. The only way I thought of doing that is by putting time and the date together for the X-axis as I don't want the points of one day to interfere with another. Any help is appreciated.

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    You might have a confusing typo in the title. Should that be "date" rather than "data" (entirely different meanings)? If you are talking about day and time, they are already combined if the data is stored as date/time values in Excel. These are stored in the form of day counts since a reference date. The integer portion of the value is the number of days. and the decimal portion is the time as fraction of a day (0.5 = noon). You just need to format the axis as date/time.
    – fixer1234
    Commented Dec 29, 2016 at 21:20

2 Answers 2

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The answer you are looking for is probably this. It shows how to add two labels to the x-axis

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  • Please quote the essential parts of the answer from the reference link(s), as the answer can become invalid if the linked page(s) change.
    – DavidPostill ♦
    Commented Jan 12, 2017 at 13:38
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The data looks like this:

Date        Day  Time      Pred  High/Low
2016/01/03  Sun  02:07 AM  3.0   H
2016/01/03  Sun  08:19 AM  0.79  L
2016/01/03  Sun  02:11 PM  2.7   H
2016/01/03  Sun  08:33 PM  0.27  L
2016/01/04  Mon  03:04 AM  3.11  H
etc.

Remove the Day column and combine the Date and Time data into a single column (I just used simple addition and formatted accordingly), and skip the H/L column, because you can see if it's high or low:

Date                 Pred
2016/01/03 02:07 AM  3.0
2016/01/03 08:19 AM  0.79
2016/01/03 02:11 PM  2.7
2016/01/03 08:33 PM  0.27
2016/01/04 03:04 AM  3.11
etc.

Select these two columns and create an XY Scatter Chart (not a line chart). Excel only plots the high and low points of the tides (the markers in the top chart below), not the whole sinusoid curve. But if you format the line to be smoothed (and remove the markers), it looks like a sine wave (bottom chart).

Tide Chart in Excel

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