Tag: Reson

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Kathy Virdin, July 23, 2004

NOAA Teacher at Sea
Kathy Virdin
Onboard NOAA Ship Rainier
July 20 – 28, 2004

Mission: Hydrographic Survey
Geographical Area: Eastern Aleutian Islands, Alaska
Date: July 23, 2004

Latitude:55 degrees 43.34’N
Longitude: 159 degrees 10.967’ W
Visibility: 10 nautical miles
Wind direction: 175 degrees
Wind speed: 8 kts.
Sea wave height: 0-1 ft.
Swell wave height: 0-1 ft.
Sea water temperature: 11.7 C.
Sea level pressure: 1016.2 mb.
Cloud cover: Cloudy

Science and Technology Log

Today we have been in transit to the Shumagin Islands. Two launches were sent out to do Reson (shallow to mid-depth) measurements and one launch did the Elac (mid-depth to deep waters). This area really needs accurate depth measurement, since it’s an area where fishermen come frequently. The information that is received and processed on board the RAINIER is then sent to the Nautical Data Branch of NOAA where it is interpreted and made into the hydrographic sheets with added interpretative data. Then it next goes to a production team who apply it to charts. The next step for the information is to go to the Update Service branch which combines all data and puts it in the final form of nautical charts that is used by the Navy, cargo ships, tanker ships and all mariners (such as fishermen). So the RAINIER plays a vital role in getting critical information to those who use it daily to ensure their safety.

I was able to catch several of the crew for an interview. I interviewed Megan Palmer, who is a survey technician. To prepare for her job, Megan received a degree in geography and received additional training in computer systems, including the complex GIS system. She explained that NOAA is moving toward electronic nautical charts that will allow you to set your scale close or far away on the computer, depending on what you need. Alarms will go off if you get into shallow water. However, there will always be a need for nautical charts and that’s where NOAA excels. Megan enjoys her job as it gives her the opportunity to see Alaska while being on the water, and the chance to look for the unexpected in surveys. Often, she is part of the team that is charting waters that have very few depth soundings. She also enjoys the fact that NOAA tests software to see how well it works and then make recommendations to companies to improve features that the survey technicians need. She notes that there is definitely a need for more survey technicians and that it’s a rewarding and exciting career for any student who loves the ocean and wants to travel.

Personal Log

Today we had the thrill of seeing a whale swimming in the distance while we all tried to take a picture (very difficult since it moves in the water so quickly). We dropped anchor tonight in the Shumagin Is. We’ll stay here several days while the survey launches run lines in different areas. We’ve entered into an area of heavy fog and it was neat to hear the fog horn being sounded every few minutes as we move through the water. I enjoyed looking a computer file of pictures that show all the places the RAINIER has been in Alaska. Beautiful scenery!

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Kathy Virdin, July 21, 2004

NOAA Teacher at Sea
Kathy Virdin
Onboard NOAA Ship Rainier
July 20 – 28, 2004

Mission: Hydrographic Survey
Geographical Area: Eastern Aleutian Islands, Alaska
Date: July 21, 2004

Time: 6:00p.m.
Latitude: 55 degrees 49.65 N
Longitude: 157 degrees 56 W
Visibility: 11 nautical miles
Wind direction: 350 degrees NW
Wind speed: 7 kts
Sea wave height: 0-1 ft.
Swell wave height:2-3 ft.
Sea water temperature: 12.2 C.
Sea level pressure: 1013.0 mb.
Cloud cover: Partly cloudy

Science and Technology Log

Today I was able to go out on a launch (small boat) that did survey lines for eight hours. After the launch got underway, we lowered the transducer into the water where it will send out a spray of sound (approximately 131 pings) that will be measured on the launch’s computers. We also did a Reson line measurement which can accurately measure depths of 40 meters. We drove the launch in a line that was approximately 4-5 miles long, then turned and went back on the next line. Each line took about 40 minutes and we were able to cover 7 lines today. So in all, we were able to chart an area of 4-5 square miles. We stopped every four hours to put down a CDT which checks salinity, density and temperature. This information was immediately fed into the computers so that it can adjust the speed of sound through the waters by these factors. This launch also has a motion sensor that can measure the pitch and roll of the boat and that is factored into the speed the sound travels, which gives the calculated distance to the ocean floor.

NOAA has about 8 or 9 ships that do hydrography work which is extremely important to scientific research, as well as commerce. About 90-95% of all goods used in the U.S. are brought to us by ships! So it’s vital that they have accurate information to chart their path through our waters. The RAINIER is the only ship in the world that can do all the hydrographic survey work that it does. It’s an honor to work on a NOAA vessel and all members of the NOAA corps must have a degree in one of the sciences. The swath or path of the sonar beam that our launch is sending out covers about 200 meters. We’re seeing the data that tells us that the depths in this area are 100 meters. We have successfully measured our plot of the chart today with multi-beam swaths that intersect at the outskirts with one another. This is another measure taken to ensure accuracy.

Personal Log

I asked a lot of questions today while we were surveying, as the field operations officer with us had time to answer them. The work was mostly being done by the computers, so we were watching and checking them periodically. I learned that the launches are expensive boats because of all the high-tech equipment they carry (all of it necessary to get the job done). When we came back to the RAINIER, the sun came out and we went up on the deck to enjoy the view. I saw puffins flying over the water, and one of them flapped its wings across the water as it skimmed along the surface. This was a treat to watch the puffins as they entertained us with their antics. Tomorrow, I’m looking forward to following up on the data that was gathered from the two launches that went out today. It will be scrutinized and evaluated by the survey technicians and then stored in the folder for the day.

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Kathy Virdin, July 20, 2004

NOAA Teacher at Sea
Kathy Virdin
Onboard NOAA Ship Rainier
July 20 – 28, 2004

Mission: Hydrographic Survey
Geographical Area: Eastern Aleutian Islands, Alaska
Date: July 20, 2004

Time: 2:20 p.m.
Latitude: 55 degrees 39.4 N
Longitude: 158 degrees 00.3 W
Visibility: 10 nautical miles (nm)
Wind direction: Northwest
Wind speed: 7 kts
Sea wave height: 0-1 ft.
Swell wave height:2-3 ft.
Sea water temperature:13.3 degrees Celsius
Sea level pressure:1010.1mb.
Cloud cover:3/8 partly cloudy

Science and Technology Log

Today we reached the point where we would begin our surveys. I watched the survey technicians lower a Seabird (sound velocity profile unit) into the water, then raise it back up and hook it into a computer, where they could download the information. This will give them the salinity (salt content), temperature and pressure of the water. They lowered the Seabird 117 meters down into the water, before retrieval. At the same time, from the hull of the ship, a transducer sound wave emitter is sending sound waves to the bottom and measuring the time it takes for their return. From this information, they will calculate the distance to the floor of the ocean. They use this data from the Seabird to help them make corrections in the sound wave speeds from the transducer. The salinity, temperature and pressure will cause variations in the speed of sound, so they need to correct for this effect to gain an accurate depth measurement.

This information is being processed and viewed by cartographers (map designers) who will take what data the RAINIER gives them to update old maps or develop new maps and charts. These maps are used by fishermen, geologists or anyone who navigates through these Alaskan waters. We are headed for the Shumagin Islands where we will send out launches (smaller boats) to measure depths in places where the Rainier might not otherwise go. I found it interesting to note that environmentalists would also use this information, since they know where certain species of fish are likely to live, and they can decide how best to protect them if they are endangered. We will go back and forth three times in one plotted line to make sure our data is accurate and complete. When we send out a launch in more shallow water, they will use a different sonar device, called a Reson. It emits higher sound waves which will give a more accurate reading. For middle to deep depth measurement, they will use the Elac sonar and a vertical beam echo sounder which goes straight down that can be used for shoreline measurements. Because Alaska has such rough terrain, it’s important to get accurate measurements for those who use her waters.

Personal Log

I am amazed by how specific the data is that the survey technicians collect and how well everyone knows their job. This is truly a finely tuned, professional organization. Everyone has been so kind to answer my many questions even though I’m sure I’ve gotten in their way. I’ve spent a lot of time in the Plot room, where the data is logged into the computers and then interpreted by the technicians. Outside, it’s a beautiful, sunny day, which is the first pretty weather we’ve had. We saw a pod of whales, recognizable by the blow of water coming from their nostrils. I could see them really well through the high-powered binoculars that belong to the ship. I am working on a list of questions that I will use to interview different members of the crew, as well as the scientists so I can take this information back to my students, as they learn what the roles are on a NOAA vessel. Someday, I want my students to be the next generation of scientists that use the knowledge we are gaining today to frame the discoveries they will make in the future.