Tag: transducer

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Michele Brustolon, July 1, 2010

NOAA Teacher at Sea
Michele Brustolon
Onboard NOAA Oscar Dyson
June 28 – July, 2010

NOAA Teacher at Sea: Michele
NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Eastern Bering Sea (Dutch Harbor)
Date: July 1, 2010

Weather Data from the Bridge

Time: 1400
Latitude: 58.19 N
Longitude: 170.01 W
Cloud Cover: 100%, dense fog
Wind: 11.49 knots
Air Temperature: 3.800 C/ 38.840 F
Water Temperature: 3.960 C/ 39.1280 F
Barometric Pressure: 1003.10 mb

Science and Technology Log

Here fishy fishy!
July 1st began by spending time in the Acoustics Lab learning about the equipment used to analyze the data. The Oscar Dyson has 5 transducers on its center board and 1 temporary transducer on the side of the center board that looks horizontally. The transducers allow us to see where the fish are. Because of where the transducers are placed, we can only see the pollock from 16m to the bottom. This means that if there are any fish between the surface and 16m they will not be detected. This is the near surface “dead zone”. Why this happens? The transducers are mounted on the bottom of the centerboard about 9 m below the water line, and near the transducer face (first 7 m), no good data are collected. Why it’s okay? Pollock tend to hang out in mid-water. Although a few baby pollock might be in the near surface “dead zone,” the majority of pollock will be in the area we are watching. There is also a bit of a “dead zone” at the other end near the ocean floor. Yesterday the bottom was around 69.35m.

Transducer data

Why acoustics?
Ideally, the acoustic data collection would allow us to track aggregations of pollock without actually having to fish them out of the water. All parties involved (scientists, fish, bank accounts) would benefit from this change but scientists are still in the process of perfecting this process. The Oscar Dyson is part of a fleet of five boats that was specifically designed for acoustics. Specifically, it is considered a “quiet boat” where the engine noise is decreased to prevent scaring the fish. Other Acoustic projects include: Pacific hake off the coast from California to Vancouver Island (run as a joint project with Canada), herring in the northwest Atlantic, and krill in the Antarctic. Acoustics are used throughout the globe and many countries depend on acoustics for their fish surveys.

A little help from UNH!
Along with the transducers, there is also a multibeam SONAR that produces the same information as the transducers but with a wider angle range. The multibeam ME70 sends its signal out after the transducers information is sent and returned. They alternate about 1.5 seconds apart. The University of New Hampshire (UNH) is helping to use the tool and also to analyze the data. To analyze the transducer data collected, a program is in place from Tasmania to help determine what the boat is seeing. The scientists use the program to help separate species in the water column. Scientists utilize the multibeam ME 70 along with the transducers and fish trawling to ensure they are capturing an accurate picture of the mid-waters.

Multibeam ME70 data

How the survey data we collect are used. The data we collect on the Oscar Dyson during the summer pollock surveys are used by scientists and policy makers to determine the fishing quota (the “take”) of pollock for the next season. Quotas are important for maintaining the population of pollock (and other species) for this generation and generations to come. The data we collect on the Oscar Dyson help ensure that maximum stock can be taken without negatively impacting the Eastern Bering Sea pollock population.

Here I am deploying the XBT (eXpendable bathymetric thermograph)

Personal Log

Although there was no fishing yesterday, I certainly was able to be involved. I launched the XBT off the Hero Deck just as we began our fire drill. Once that was completed I returned to the Acoustics Lab until we were cleared from the drill. We then had our abandon ship drill where we get our survival suits and head to our assigned position. My meeting location is at life raft 3 and 4. Once we learned how to deploy our life raft, we headed inside to the conference/lounge to practice donning our suits. While this is very serious, it is also worth a laugh or two watching people struggle and become orange gumbies! The goal is to be able to don your suit in under 60 seconds!

Zodiac ride into the cove of St. Paul’s Island

Yesterday I had the opportunity to head into St. Paul’s Island; the largest of the Pribilof Islands. St. Paul’s is also called the Galápagos of the north. The Zodiac was driven by Joel Kellogg and Amber Payne, and our CO (Commanding Officer Mike Hoshlyk) allowed Katie, Rebecca, and I the opportunity to take the trip inland. Our mission while on land was to bring science equipment (ice-flow detector) to the airport that needed to be sent to Anchorage. Stepping foot onto St. Paul’s Island seemed eerie and mysterious. There was the lurking fog along with a very industrial feel to the island. Because most of the island consists of coalescing small volcanoes, the sediment’s dark color is due to lava flow which didn’t brighten the land at all. We did not see many people other than those working on dredging the new causeway or the people in the airport. Our taxi driver said that they hadn’t gotten mail since Monday and it was Thursday which explained why the people waiting for flights at the airport seemed a bit anxious. On our way back to the boat, we were able to see sea lions and some puffins hanging out in the water and around the break wall. As we approached the boat, it was like an apparition appearing before us. Just another once in a lifetime chance that I have had this cruise!

Want more information about the Pribilofs? Check out http://www.amiq.org/aleuts.html

Oscar Dyson coming back from Pribilofs

Animals Seen

Auklets
Murre (2 different types differentiated by bill type)
Fox
Puffins
Sea lions

(but no fur seals…everyone told me I would see them but they were missing. It seems to be a question everyone is asking.)

Word of the day

Desmadre: troublemaker

New Vocabulary

Transducer: instrument used to send out signals that return and show where fish are located
Ground fishing: trawling on the ocean floor

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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.