OC201_Lab6_Waves
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Oregon State University, Corvallis *
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201
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Dec 6, 2023
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OC201, Oceanography
Lab 6: Using Buoys & Models to Study Waves
Surface waves are an important way that the ocean intersects with humans. If waves are large, then they become hazards to people at the coast or ships at sea. Then again if you are an expert surfer you might want to seek out large waves. In either case, you would want to know what the waves are like
now and how they are forecast to change in the future. Oceanographers have put a lot of time and energy into measuring and predicting waves. Wave measurements such as height, period and direction are mainly made using various types of surface buoys that are fixed in a particular location. Wave predictions are made using data from buoys, as well as meteorological information such as sea-level pressure and wind speed and direction. In this lab, which partially addresses Physical Science Learning Outcomes 1 and 2, we will use wave data and models from around the globe, focusing on the Northeast Pacific Ocean. General directions:
Each student will turn-in a lab report, so be sure each of you is collecting the requested data and writing your own responses.
It may help when you are writing up your lab report to have taken additional notes regarding the data (other than the specific information
asked below). For example, it may help you to note significant changes in data.
Part 1: Accessing the Coastal Data Information project’s buoy data:
Access the internet, then go to http://cdip.ucsd.edu
Follow the directions below to specific locations within this site.
Plotting and interpreting wave data
Real-time Wave Data Table (12 pts)
Click on the “Recent Observations” tab below the “Welcome to CDIP.”
You should now see 7 “Parameter Summary” buttons, a Map of the Pacific and Western Atlantic on the right and a Table of Recent Buoy Observations organized by stations below.
Change the time zone to “Pacific” by accessing the pull-down menu on the upper right of the table.
Record the following data for each buoy station in the Excel spreadsheet that
accompanies this lab. The table on the CDIP site has the buoys arranged from south (Pacific islands, including Hawaii) to north in the Pacific and then the Gulf and Atlantic. Ask the GTA if you’re having trouble finding a particular buoy.
Click on the station name
and record from the “Observed Data” box:
a.
Date and time
b.
Significant Wave Height (in meters
)
c.
Peak Period (in seconds)
d.
Direction (in degrees)
Now refer to the graph of Wave Hs
(significant wave height) on the right and record the observed high and low waves (
in meters
) for the previous week which is denoted by the green line in the shaded area of
the graph. Next, record the forecasted (purple line) highest wave for the next week and the date it is predicted to occur. Hint
: you can get pretty accurate numbers by moving the cursor to the high and low values of the graphs. Don’t worry about getting it perfect, just get close to the highs and lows.
Make sure you save and upload the Excel file with your last name and first initial!! e.g., “smith_r.xlsx”
Part 2: Plotting Wave Data (8 pts, 4 pts for each figure)
Using the data collected in the Excel file to make two figures.
Plot significant wave height (m) vs. latitude (x-axis). This is Figure 1. Make sure all axes are labeled.
Plot peak period (seconds) vs. latitude. This is Figure 2. Again, make sure each axis is labeled with units. AND the figure should have a title.
Import these 2 figures into Word and give them brief captions that describe what each figure shows. Remember each figure has its own caption. Figure captions go below the figure. Figure 1: (insert below with caption)
Figure 2: (insert below with caption)
Answer the following questions regarding data in Table 1 and Figs. 1 & 2. (12 pts, 4 pts for each answer below)
1.
How does significant wave height and period vary along the US West Coast? If there are latitudinal (i.e., N-S) trends in the variation of these 2 parameters, do they agree?
2.
How does wave direction vary along the coast? If it is different along the coast, what does that imply about the source of waves?
3.
Compare the southernmost station (Point Loma, CA) to the northernmost station (Grays Harbor, WA). What are the forecasted highest waves at each of these sites over the next week? When are they supposed to occur
at each station? (Remember these forecasts for comparison to results from Part 3.)
Part 3: Model forecasts (18 pts)
Next go to the web site: www.stormsurf.com
This is a third-party commercial
site (hence the ads) that takes data collected by a variety of government agencies (e.g., NOAA) and replots it in a more user-friendly manner.
Start by clicking “Wave” near the top of the page. This will open up a page called “Wave Models” and a colorful figure of the world ocean with significant
wave height. The data shown in the figure are from a model called WaveWatch III that is run by NOAA. Spend a few minutes looking at the figure.
4.
Write a short paragraph describing what you see
. For example, in what parts of the global ocean are the waves the largest? Where are the waves
smallest? From this pattern, describe the main processes that control wave heights. Are the patterns you see consistent with what you’ve learned in class. Why or why not? (
6 pts
)
Next scroll down to the section entitled: “Full Screen Hi-Def Wave Model
” and
click on the red button below “N. Pacific.” This will open a map with the entire North Pacific from 5S to 65N and a series of images that represent forecasts of wave heights (in feet) and wave directions over a 7-day period in
6-hour increments. The heights are denoted by colors and the directions by arrows. Note that you can pause the images by clicking in the middle and hitting the stop button that appears. Use the forward and backward arrows to move through the images. To restart the movie hit the “fast-forward” button.
5.
Write a short paragraph describing the patterns you see
. How do the WaveWatch III predictions match what you observed from the US West Coast buoys (~30 to 50N) that you studied in Part 1? Are the heights roughly the same? How about the directions? (
6 pts
)
6.
Repeat for the S Atlantic. Describe what you see.
Pay particular attention
to the wave heights on the west and east sides of South America south of
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40S. Explain why there are differences between the wave heights on these two coasts. (
6pts
)
Extra Credit (5 pts)
:
Lastly, let’s go to Hawaii. Wouldn’t that be nice!?
Rather than actually going
to Hawaii, scroll down to “Local Wave Models for the Pacific Ocean”
and find Hawaii. Click on the second button from the left: “Significant Sea Height.” Watch the movie and scroll through it using the stop and go buttons. Describe what you see.
How do the wave heights vary over entire the week?
Are they the same on all sides of the islands? If not, how do they vary spatially? Based on the big picture you saw in Part 3, where in Hawaii would you expect the largest surf to be found?