Geology, Ocean studies
Geology, Ocean studies
Internet Problem 5: Local and Global Tides – Sea-Level Rise Part 1: Local and Global Tides
Go to NOAA’s Tide and Current Prediction Page: Keep track of GMT (Greenwich Mean Time) and LDT (Local Time). I prefer you collect your data in metric units.
Note: at the individual station page, you can change the time and units at the bottom of the page.
https://tidesandcurrents.noaa.gov/
Look at the date for the three tidal stations Pier 21 in Galveston Bay, TX, San Francisco Bay, CA and The Bay of Fundy, ME. You can find the date for these three tidal stations by searching the map provided or entering the station number in the Find Your Local Tides and Current tab.
A) Pier 21, Galveston TX- Station # 8771450
https://tidesandcurrents.noaa.gov/map/index.html?i…
Select: Plot Data
Choose: Standard or Metric (one or the other, don’t mix units)
You are looking at two days of data.
You may also choose Station Home – Tide/Water Levels – Water Levels to see a larger version of this graph which is easier to read.
https://tidesandcurrents.noaa.gov/waterlevels.html…
Answer the following questions: 1) Date: __________________________
2) How many high tides and low tides per day are there at this location? Choose one of the options below.
a) One high and one low per day (diurnal)
b) Two high tides and two low tides of equal tidal range (semidiurnal) c) Two high and two low of varying tidal range (mixed semidiurnal)
3) What is the time and elevation of the high and low tide at this location today? (use MSL Datum)
High tide, time and height___________________
Low tide, time and height __________________
4) What is the tidal range? Hint: tidal range is the difference in elevation (water level)
between the maximum water highest (A) and minimum water height (B). Daily tidal range= A – B
B) San Francisco Bay- Station # 9414290:
Go to: https://tidesandcurrents.noaa.gov/map/index.html?i…
Select: Plot Data
Choose: Standard or Metric (one or the other, don’t mix units)
You are looking at two days of data.
You can also choose Station Home – Tide/Water Levels – Water Levels to see a larger version of this graph which is easier to read.
https://tidesandcurrents.noaa.gov/waterlevels.html…
5) Date: __________________________
6) How many high tides and low tide per day at this location? Choose one of the options below.
- a) One high and one low per day (diurnal)
- b) Two high tides and two low tides of equal tidal range (semidiurnal)
- c) Two high and two low of varying tidal range (mixed semidiurnal)
7) What is the time and elevation of high and low tide(s) at this location? (use MSL Datum)
High tide, time and height___________________
Low tide, time and height __________________
8) What is the tidal range? Hint: tidal range is the difference in elevation (water level) between the maximum water highest (A) and minimum water height (B). Daily tidal range= A – B
C) Eastport, Maine- Station # 8410140:
https://tidesandcurrents.noaa.gov/map/index.html?i…
Select: Plot Data
or https://tidesandcurrents.noaa.gov/waterlevels.html…
The Bay of Fundy is between New Brunswick and Nova Scotia: The Eastport Maine Tidal Station is located at the southern edge on the bay mouth. (The Bay of Fundy because of its unique geographic location and topographically restricted bay mouth has the highest tidal range in the world.)
9) Date: __________________________
10) How many high tides and low tide per day at this location? Choose one of the options below.
- a) One high and one low per day (diurnal)
- b) Two high tides and two low tides of equal tidal range (semidiurnal)
- c) Two high and two low of varying tidal range (mixed semidiurnal)
11) What is the time and elevation of high and low tide(s) (using MSL Datum?) High tide, time and height___________________
Low tide, time and height __________________
12) What is the tidal range? Hint: tidal range is the difference in elevation (water level) between the maximum water highest (A) and minimum water height (B).
Daily tidal range= A – B
Analysis:
13) Make some comparison between location and timing of tide along these three coastlines. Explain how the geographic area, ocean basin, the geometry of the shorelines might affect the different tidal patterns at these three locations.
Part 2: Sea Level Rise
14) Now look at the sea level trends over the last 100-170 years for the three stations: Galveston, TX:
https://tidesandcurrents.noaa.gov/sltrends/sltrend…
San Francisco:
https://tidesandcurrents.noaa.gov/sltrends/sltrend…
Eastport ME:
https://tidesandcurrents.noaa.gov/sltrends/sltrend…
Looking at the data at each station answer the following questions:
A) What is the amount of sea level rise at each station for 1900- present (for Eastport 1930- Present)?
B) Why would Galveston, with the lowest tidal range, have the highest rate of sea level rise?
Hint: It has to do with eustatic and isostatic sea level rise. https://web.whoi.edu/coastal-group/primers/sea-lev…
Additional tidal range locations to investigate (*not required*):
Other global places with unique tidal patterns are:
Cook Straits, New Zealand Anchorage Alaska The English Channel See NOAA Estuaries
