Criscimagna_Ellie_Lab2
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MSC 112 Lab 2, Charts and Navigation Lab September 5, 2023 Ellie Criscimagna Exercise 1: Purpose: The first exercise was carried out in order to chart the ocean floor. Underwater topography is critical in understanding more about the ocean, its history, and much more. Knowing more about the ocean floor can help scientists determine what and where is safe (US Department of Commerce, 2012). Ocean floor mapping is also important to know for ship maneuvering and help us track and protect marine life (US Department of Commerce, 2012). While seafloor mapping is important, it is an underlooked aspect of oceanography. In fact, only about 25% of the ocean floor has been mapped (
Our mission 2023). Methods: In the first exercise, a seafloor chart of the North Pacific Ocean was provided. A rhumb line around 8 inches long was then randomly drawn across a visually interesting section of the chart. The two ends were then labeled Point A and Point B. The depth in meters was recorded at each isobath along the rhumb line, which was then measured with the latitude scale on the side of the chart. (The latitude scale was used rather than the longitude scale, as 1˚ in latitude is equivalent to 60 minutes.) When graphed, the length in minutes between each point was recorded cumulatively as to accurately depict the changes in depth on the ocean floor from point A to point B. Results: Figure 1 depicts the deep valleys, higher ridges, and overall variation, along the ocean floor in the North Pacific Ocean right below the Andreanof Islands in Alaska. The depth varied between point A, measuring 80 meters deep, right off the coast, and went as deep as 6254 meters, only about 111 kilometers from point A. This means the average slope down from point A to the deepest point was about -40 meters per kilometer. However, the ocean floor then rose slightly back up to the 5000s and almost flattened.
Conclusion: The seafloor near the Andreanof Islands in Alaska is varied with ridges and trenches. There are many possible explanations for the extreme variations in this area. First, Point A is measured at 80 meters because it is right off the coast of these islands on a continental shelf created from built up sediment. The depth then falls down to 6254 meters down the continental slope formed by a collapse of sediments. Then the seafloor rises slightly and begins to plateau with the continental rise, a collection of these collapsed sediments. Table 1. Raw data of length between points and processed data of cumulative length in minutes, as well as distance in kilometers calculated from the equation of 1˚ of latitude = 60 minutes = 1.852 km. Length between points (minutes) Total Length (minutes) Distance (km) Depth (m) 0 0 0 80 12 12 22.224 1326 15 27 50.004 4657 27 54 100.008 4892 6 60 111.12 6254 12 72 133.344 5979 21 93 172.236 5405 20 113 209.276 5069 20 133 246.316 5305 15 148 274.096 5227 27 175 324.1 4892 16 191 353.732 5260 30 221 409.292 5523
Figure 1. Depth of Ocean Floor in the North Pacific Ocean
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Exercise 2: Purpose: Ocean navigation is very important for ocean research. It is necessary to locate oneself in the ocean, as well as travel from Point A to Point B without complication. Many improvements have been made to ocean navigation since its primitive beginnings in celestial navigation. However, GPS and autonomous navigation is not always reliable when one is out at sea. It is important to know how to use longitude and latitude for navigation as well. Methods: In this exercise, two different leading scenarios and questions were provided. The first scenario was to find the distance between two points on a map. Point A was Black Point Marina, and Point B was Elliot Harbor. In this case, the distance was measured in mm and then referenced with the latitude scale on the side. Then, the course needed to be determined, so a parallel ruler and a compass rose was used to find the proper heading. With the given speed, it was also necessary to calculate the time it would take to take this course. This was done with a simple equation of speed = distance over time, or in this case, time = distance over speed. In the second scenario, two points were again provided. Point A was Miami, and Point B was Bimini. However, the addition of a current speed meant the method used must vary from the first scenario. The distance between the two points was again measured in mm and then referenced with the latitude scale. However, due to the current, it was necessary to use the formula D 2 = D 1 (speed of current/speed of boat), where D 1 refers to the distance between the two points, and D 2 refers to the distance between the destination and the point to which one must set sail, to determine the course. Results: The distance between Black Point Marina in South Dade and Elliot Harbor on Elliot Key is 8.4 nautical miles. The most efficient route was straight from Black Point Marina to Elliot Harbor on a course of 130˚SE. At a speed of 5 knots, this route would take around 100 minutes or an hour and 40 minutes. Though Miami and Bimini are close to parallel, the current of 4 knots north means that one should set sail at around 132˚ SE to reach Bimini from Miami.
Conclusions: Though ocean navigation seems straightforward, specifically in the first scenario, it is not always that easy. Simply adding a small current made the calculations and planning that much harder. In reality, there are not many scenarios where no current exists, or even where a current remains constant. These scenarios exhibit that ocean navigation is harder than it may seem, and is much different than navigation on land due to the somewhat unpredictable environment and
Exercise 3: Purpose: In this exercise, the tracking data for different marine animals was provided. Tracking marine animals is becoming increasingly important for marine megafauna conservation. The more learned about these animals and their behaviors, the better scientists can protect them (The Pew Charitable Trusts, 2022). As a byproduct, tracking these marine animals also provides more data on ocean salinity and temperature (The Pew Charitable Trusts, 2022). This is especially helpful in areas in which it is difficult for researchers to reach (The Pew Charitable Trusts, 2022). This data is very important to broaden our understanding of the ocean itself. Methods: Using every three points from the provided data, a map of the Loggerhead/Green turtle named Bower’s movement was created. The nature of Loggerheads, Green turtles, and hybrids was then studied online to formulate a better understanding of Bower and his movements. Results: The resulting graph, (see Figure 2 below), begins near the coast of Florida and moves South from November of 2002 to January of 2003 before the data stops, reappearing in the center of the Atlantic Ocean in May of 2003. Conclusions: The data points from January 24th and May 15th are drastically different, jumping from 28˚N, 80˚W to 41˚N, 53˚W. Though these two data points are months away, differing from the other gaps between data of only about two weeks, this travel could have a couple explanations. The first is that, like any other object or animal in the ocean, Bower may have gotten caught up in the Gulf Stream, as his movement between January and May follows the same course as the Gulf Stream current. Loggerhead migration typically follows a circular path going up the Gulf Stream and continuing the circle, until back off the coast of the southern United States (Whiteman, 2012). This migration, however, typically takes from 6 to 12 years to complete. Green sea turtles are less migratory, and when found in the Atlantic, are typically found off the coast of Florida (
Atlantic Green Sea Turtle
). While it is not uncommon to see Green sea turtles off the coast of Massachusetts, it is not often that they are found in the middle of the Atlantic Ocean (
Atlantic Green Sea Turtle
). This means that while it is possible that migration played a role in Bower’s travel, he was most likely swept into the strong current of the Gulf Stream.
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Table 2. Raw Data of Bower’s Movement from November, 2002 to August, 2003. Date (m.d.y) Latitude (˚N) Longitude (˚W) 11.15.02 32.564 79.703 11.30.02 32.074 79.321 12.15.02 30.740 80.626 12.30.02 29.398 80.992 01.24.03 28.066 80.291 05.15.03 41.036 53.160 06.01.03 41.369 51.170 06.18.03 41.310 45.965 07.25.03 38.573 42.608 08.10.03 34.993 46.051 Figure 2. Bower, “the Logger/Green” turtle’s movement from November of 2002 to August of 2003.
References Atlantic Green Sea Turtle
. CT.gov. (n.d.). https://portal.ct.gov/DEEP/Wildlife/Fact-Sheets/Atlantic-Green-Sea-Turtle Our mission
. Seabed 2030. (2023, June 29). https://seabed2030.org/our-mission/ The Pew Charitable Trusts, M. F. (2022, February 4). Tracking marine megafauna can guide more effective ocean conservation
. https://www.pewtrusts.org/en/research-and-analysis/articles/2022/02/04/tracking-marine- megafauna-can-guide-more-effective-ocean-conservation#:~:text=So%20tracking%20the m%20means%20we,our%20understanding%20of%20the%20ocean. US Department of Commerce, N. O. and A. A. (2012, September 18). Seafloor Mapping: The Foundation for Healthy Oceans and a Healthy Planet
. OceanExplorer.NOAA.gov. https://oceanexplorer.noaa.gov/world-oceans-day-2015/why-map-the-seafloor-to-keep-us -and-natural-resources-safe.html#:~:text=High%2Dresolution%20seafloor%20mapping% 20is,structures%20on%20the%20ocean%20bottom. Whiteman, L. (2012, June 20). Loggerhead turtle migration follows Magnetic Map
. LiveScience. https://www.livescience.com/21080-loggerhead-turtle-migration.html