Instructions on creating tidal plots:
2. In the Search bar on the left side of the screen, type in the Galveston, TX ID 8771450 and select the Galveston Pier 21 option.
3. Click on the top bar “More Data” and select Tide Predictions. This will open up a new browser from NOAA.
4. Change the date in the bottom from October 17, 2020 to October 17, 2020. Keep all other options the same.
5. Click the blue Plot Daily button to update the plot.
6. At the top right of the chart, click on the three vertical lines and select an option to download the plot. Paste an image of the chart into your Lab Handout.
7. Now change the date to Oct. 1, 2020 to Oct. 31, 2020 and click the blue Plot Daily to update the plot. Save and past the image into your Lab Handout.
8. Repeat for Boston (8443970) and San Francisco (9414290).Use the short-term (72 hour plots) that you just made to answer the following questions (on your Lab Handout):
1. What is the range (vertical distance) between high and low tides at each location? Is it always the same?
2. Do high and low tides occur at the same time each day? If not, by how much do the times change each day?
3. What is the tidal period (time between successive high tides or between successive low tides)? (1 pt)Use the long term (one-month) records you just made to answer the following questions (on your lab handout):
4. What happens to the tidal range over this longer period at each site?
5. Is there a regular cycle to these changes – if so what is the period of these changes?
6. What process might be responsible for these longer term changes in the tides?
PART 2. Comparing local tidal trends with sea level trendsVisit the NOAA tide gauge stations at the following address:
Navigate to Virginia link to explore the present tidal conditions and the Sea Level Trends link for historical tidal records for Colonial Beach, Lewisetta, and Sewell’s Point. Use this data to answer the following questions (please fill in the table):
1) What is the tidal range for each station (difference in height from low to high tide)? What are the mean sea level trends recorded for these tidal stations? (At the bottom of the page you will see a link that will take you to Sea Level Trends. Click here and then on U.S. Stations.) (1/2 pt each)Tide StationTidal RangeMean Sea Level TrendsColonial BeachLewisettaHampton Roads (Sewell’s Point)
3) Visit the NOAA Sea Level Trends site at the following address: http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml. Investigate the sea level trends for our Atlantic coast and answer the following questions (Note, just Zoom around on the map to the appropriate city and click on the arrow to see the sea level trends) :
What are the rates of sea level rise for Portland ME, Boston MA, Washington DC, Wilmington NC, and Miami Beach FL? What is the overall range and average rate for all of the sites? Why do you think there so much variability in the data? (1/2 pt each)CitiesSea Level RisePortland, MEBoston, MAWashington D.C.Wilmington, NCMiami Beach , FLTotal Range of Sea Level Rise of all cities: Average of Sea Level Rise of all cities:
4) Compare the rates of sea level rise obtained for your sites in Virginia and those from Washington DC to those other sites on the east coast. Are the rates of rates of sea level rise in the Chesapeake Bay higher or lower? What factors might be contributing to the apparent disparity in the data?
