SO503, Spring 2005
Tide Gauge Records
You should look at the paper by Douglas and Peltier (March 2002, Physics Today), which you can get through the Nimitz Library.
The Permanent Service for Mean Sea Level (once at http://www.pol.ac.uk/psmsl/) contains world wide tide gauge records:
http://ilikai.soest.hawaii.edu/uhslc/iotd/index.html?136,65 --tsunami records
Get one of the long term records from PSMSL (Amseterdam, Liverpool, or Stockholm), and run a regression to determine the rate of sea level change here. What are the units? (This is an Excel task; find the data, import it, and get the regression).
Discuss the pattern of global sea level rise from tide gauge data, and how you can use a GIS to discover this. This is intended to be a coherent, thought out response, into which you can incorporate figures, maps, or diagrams (including even the answer to Part I). It is not supposed to be a shotgun answer to a number of questions, for instance those on this page lower down. We have two databases with sea level rise data, in c:\mapdata\database\tides. The Hawaii data links to actual tidal records (daily averages) for each station.
To help you in part II, the following questions are designed to force you to see how the GIS works (make sure you understand what filters and queries are). You can answer as few or as many as you want; you do NOT have to turn in these answers.
We have data for 419 tide stations, courtesy
of the University of Hawaii ( http://uhslc.soest.hawaii.edu/ ) and
1141 stations from PSMSL. The duration of the
Hawaii records ranges from 1 to
99 years. The values are average sea level height by day.
The average rate of sea level rise is indicated for the stations
whose record exceeds 18 years.
MICRODEM program will now plot the locations of
the tide stations, and then let you plot the tide records. Follow
the following steps to plot a tide station:
· Start MICRODEM program.
Open a base map.
· Open the tides data base.
A map will appear with the locations of the 419 stations.
You can force the map to redraw with the blue arrow button over
You can color code by duration of the record by selecting the
Plot button on the database, and then picking
"color code by numeric field", and picking Duration.
You can also color code by the computed Rise.
You can Filter the data set using the Filter button.
This letter set a parameter and conditions, and only see those
stations that match the filter conditions.
You can graph a station by
Picking the TS button on the map toolbar, and then clicking on the station.
Return to all stations using the All stations button.
Look at the record for San Francisco.
Use the Analyze, Linear Fit menu choice to see the best fit line.
The reported slope is in meters per day (the window title
converts it to mm/year).
How much did sea level rise at San Francisco in this time
What happened to sea level from 1940 to 1950 (convert the rate
from the Linear fit to mm/yr)?
How much do you trust this record to accurately reflect what is
happening, and how long a record would you want to see?
Look at the stations for the Galapagos
Islands (on the equator at W90).
What unusual patterns can you see?
Do you trust the trends?
Look at the stations for Galveston TX and
Grand Isle LA.
What characterizes these stations, and how good are their
What is the longest period at these stations that would appear to
record dropping sea level?
How long do you think the record has to be to accurately reflect
the sea level change in this region?
How many stations have a record:
How many southern hemisphere stations
have a record:
Of the stations with a record > 18
years, how many have seen
What 3 stations have seen the largest
sea level rise, and where are they located? What factors
there could account for this rise?
3 stations have seen the largest sea level drop, and where are
they located? What factors there could account for this
What is the average rate of sea level
rise for all the stations? (Look at the Stats button before you
What is the average rate of sea level
rise for all the stations that are seeing a rise?
What is the average rate of sea level rise for all the stations that are seeing a drop?