OC201_F2022_Lab6_Waves_Emily_Petrilla
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Oregon State University, Corvallis *
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Course
201
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Geography
Date
Apr 3, 2024
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5
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OC201, Oceanography Winter 2022 Lab 6: Using Buoys & Models to Study Waves –
Quinten Struyk-Bonn 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. I.
Plotting and interpreting wave data Part 1: Real-time Wave Data Table (12 pts) •
Click on the “Recent
Observations
” tab below the “Welcome to CDIP
.
”
•
You should now see 4 “
Parameter Summary
”
buttons, a Map of the Pacific and Western Atlantic on the right and a Table of Recent Buoy Observations organized by stations. •
Change the time zone to “
Pacific
”
by accessing the button on the lower right (below map) 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 i
f you’re having trouble finding a particular buoy. •
Click on the station name and record 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 high and low waves for the previous week which is denoted by light purple shading. Next record the largest waves forecast for the next week and the date that high wave is forecast to occur. Hint
: you can get pretty accurate numbers by clicking on the figure and 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 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 there should be figure captions both figures. Figure captions go below the figure. Figure 1: (insert here) Figure 2: (insert here) 1.54
1.02
2.72
2.73
2.14
1.75
2.43
2.69
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
30.0
32.0
34.0
36.0
38.0
40.0
42.0
44.0
46.0
48.0
Wave Height (m)
Latitude
Latitude vs Wave Height
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? For wave height, the lowest is 1.02 m and the highest is 2.73 m. The peak periods varied with fastest being 5.56 and the slowest being 11.76 s, with many of the data points being 11.11 s. They agreed at first, however the Wave Height graph began to dip down at a point where the Peak Period data continued to remain higher for a bit before a steep incline down. 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? Many of them were in an Eastward or Southeast direction, however one of them (Astoria Canyon in Oregon) was more Northward direction wise. The source of waves could be travelling in different ways due to currents and wind patterns, since we have data ranging from CA, Or, and WA. 3.
Compare the southernmost station (Point Loma, CA) to the northernmost station (Grays Harbor, WA). What are the forecast high 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 2B.) For Point Loma, Ca, the forecast for the highest waves this week is an estimated 2.5 m, while Grays Harbor, WA is an estimated 4.4 m. For Point Loma, CA, its highest wave is supposed to happen on 11/2/22 and for Grays Harbor, WA, it’s supposed to happen on
10/31/22. 9.09
6.25
11.11
11.76
11.11
11.11
5.56
7.14
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
30.0
32.0
34.0
36.0
38.0
40.0
42.0
44.0
46.0
48.0
Peak Period
Latitude
Latitude vs Peak Period
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II. 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) I noticed that the waves are the biggest near the South pole, however there’s some large hotspots in between Japan and Alaksa, as well as in the Indian Ocean and between the East Coast of the U.S. and the UK. It seems to be the lowest near the equator. The patterns seem to be pretty consistent to what we’ve learned in class
, especially because of the polar vortex that remains all year round. 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) I noticed that the bigger waves eventually move their way towards the shore a bit before fizzling out, especially along the thin stretch of land of Alaska. The heights of the waves are roughly the same, being relatively large. The direction in this map shows a more Southwest direction, however the waves eventually are pushed more Eastward just like other data shows.
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 40S. Explain why there are differences between the wave heights on these two coasts. (6pts) Most of the largest waves are in the South near the pole, and wrapping around the bottom of South America. The waves look to be getting smaller one they have to wrap around the southern tip of South America, bending downward/south in direction. They seem to get bigger on the East side of Australia and on the West side of South America on the very edge of the South pole near the 50-60S line. 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 in space? Based on the big picture you saw in Part B, where in Hawaii would you expect the largest surf to be found? The waves actually seem to be smaller in wave height when closer to each island in comparison to the open ocean where they look to be between 6-8 feet tall, however when we look at the islands, they only seem to be around 2-4 feet in height. They vary slightly per day, but keep a relatively consistent pattern of having shorter waves near the islands, especially near Maui in particular. They also seem to keep a pattern of having shorter waves on the Southeast side of the islands, as that’s where most of the direction is headed anyways. I would expect the largest surf to be found near the Northeast side of the islands.