Step 2: Download Data

To do this, click on the "Download monthly mean sea level data" link. You will repeat this for the annual mean data as well. Once you click the link, the data will show up as columns of data separated by semicolons.

1. Information about how these data are arranged is included here.
2. So what do the columns mean? For more information you should read the help document provided. It will help you if you get stuck, but, in general, the columns look something like the image that follows (Figure 4.42).
   1. The first column is the date, month of the observation according to a Fortran code. We don't need to worry too much about the details, but the first data point shows data collection began in 1908. If you look, there are 12 rows of 1908 data, one for each month of 1908. The same is true for 1909.
   2. The second column, starting with 6836 is the actual average water level reading in mm relative to the selected revised local reference (RLR) datum for that time increment (in this case the month - January). RLR for corrected datasets is set to be 7000 mm below mean sea level by convention of the PSMSL. So, here, 6836 is actually a reading of 6836 mm above the RLR, which itself is 7000 mm below mean sea level. So, this indicates that if we converted the 6836 reading to mean sea level position, it would be -164 mm (or 164 mm below mean sea level). PSMSL chose to use RLR in order to minimize the use of negative numbers in their work.
   3. The third and fourth columns, here identified by 0; and 000, provide information about the integrity of the sea level measurements used to calculate the time increment's average. A value of 0 in both indicates that these data are complete and no adjustments/concerns arose in calculating those averages. As much as possible, try to avoid datasets that have too many rows of non 0 values.
   4. To actually download the data, you will need to select all the data. You can do this quickly by hitting control A, or use your mouse to highlight all of the data in your web browser. Then you will need to select copy by hitting control C or by right clicking and hitting copy.

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Figure 4.41: Station information screen for the Balboa site in Panama. Tide Gauge Data for this site and other data sources are available by clicking the links provided.
Credit: PSMSL: Screen clipping taken: 1/15/2014 8:58 PM