Tag: acoustics

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Wesley Struble, 23 July, 2010

NOAA Teacher at Sea
Wes Struble
Onboard NOAA Ship Ka’imimoana
July 8 – August 10, 2010

Mission: Tropical Atmosphere Ocean (TAO) Cruise
Geographical area of cruise: Equatorial Pacific from 110 degrees W Longitude to 95 degrees W Longitude
Date: Friday, 23 July 2010

Weather Data from the Bridge

Current location: 4 degrees South Latitude & 110 degrees West Longitude
Cloud Cover: 5/8
Cloud Type: Stratocumulus
Visibility: 10 nautical miles
Wind Bearing: 100 degrees
Wind Speed: 20 Kt
Wave Height: 2 feet
Swell Height: 5 – 7 feet
Barometric Pressure: 1015.5 mb
Temperature: 24.8 degrees C (76.6 degrees F)

Science and Technology Log

There are a variety of buoys used by NOAA in the Pacific Ocean. One of the more interesting is the ADCP buoy. ADCP stands for Acoustic Doppler Current Profiler. This buoy is anchored to the sea floor like most of the other buoys deployed on this cruise. The major difference is that the ADCP buoy does not float at the surface but rather is tethered with a line short enough to keep it submerged approximately 300 meters below the surface of the sea. In addition, it is only deployed with the TAO buoys at the equator and not at any of the other TAO buoy locations. The buoy’s name defines its function – current profiling – using acoustic signals (similar to sonar) the buoy provides a profile (or vertical map) of the ocean currents from the depth at which the buoy is tethered to the surface. The ADCP is able to measure both the speed of the current and the direction in which it is moving. Even though the TAO buoy at the same latitude is generally visited more often, the ADCP buoy is visited only once per year. During the visit the buoy is retrieved, cleaned, damaged parts replaced or repaired, data downloaded, batteries replaced, and sensors upgraded (if necessary).

Buoy with newly attached ADCP unit – A
KA skiff at the ADCP buoy

The flotation component of the buoy is a large orange sphere just over four feet in diameter. This float is made of syntactic foam. In general, foam is a mixture of two substances: a gas phase in a solid or liquid phase. Syntactic foam should not be confused with the common foam with which we are all familiar (like the typical Styrofoam coffee cup). Most of these foams are generally composed of expanded polystyrene (a thermoplastic polymer) where the gas phase is air and the solid phase is polystyrene. Syntactic foams on the other hand use other substances for the components.

The ADCP acoustic transmitters & receivers

One of the more common syntactic foams uses small glass spheres 10 – 200 micrometers (millionths of a meter) in diameter. These glass spheres are filled with air during the manufacturing process. The spheres are then mixed in with some type of epoxy resin and allowed to cure to produce the foam. The buoyancy of the foam is affected by the size, number, and wall thickness of the glass spheres. Some of the applications that typically utilize syntactic foams are the manufacture of radar transparent materials, acoustic attenuating materials, and more specifically deep sea buoyancy floats. Our float is anchored to the sea floor with a large (several thousand pound) weight that prevents it from drifting. The material used to attach it to the anchor is very stable and exhibits little elongation under tension, thus keeping the buoy consistently at the same depth. The payload (the ADCP itself) is approximately 1 meter long and about 20 centimeters in diameter and is mounted in a circular well that is bored vertically through the center of the float. The ADCP has four sending/receiving units mounted at the top of the main body. One can see these in the photographs. These units send and receive a 75 kHz signal that reflects (echoes) off the sea/air boundary and returns to the buoy.

When we were close to the location of the ADCP buoy one of the scientists activated an acoustic trigger that released the buoy from its sea floor mooring anchor. Since it was almost 1000 feet under water it took a few minutes for the float to reach the surface. When the buoy was spotted the ship made a slow pass to visually inspect the float and to launch the skiff. The skiff towed a long and very strong line from the ship which was then attached to the top of the buoy. At this point the skiff was brought back aboard. The ship then came about so that the buoy was directly a stern. When all was ready the winch began to retrieve the line and slowly bring the buoy on board. When it reached the deck of the fantail it was made secure and the tether line (that attached the buoy to the anchor) was tied off to a chain on the ship’s deck.

Working on the ADCP buoy on the fantail of the      KA – B

The buoy was then disconnected from its tether line and the line was attached to a large winch and all several thousand meters of it was rolled onto a number of large empty spools and stored on board. While the anchor line was being retrieved the science crew downloaded the stored data from the ADCP and prepared the buoy for redeployment. When the deck hands were ready the process was reversed. First, the tether line was attached to the buoy and it was lowered over the fantail. Then the line was slowly played out. When the ship was in the appropriate position she began to move forward as the crew played out line. When they reached the end of the line a large (several thousand pound) anchor was attached, lowered, and released. This entire process took the better part of a day.

Crew member Nemo McKay & Scientist Will Thompson retrieving the ADCP buoy

Personal Log

I have enjoyed getting to see the crew work together. One can tell that they clearly get along well and appear to enjoy working together because of all the friendly banter that passes between them. I have been impressed with how conscious they are about safety. I have been able to begin participating in some of the work deck activity during the buoy operations and it has helped in my understanding of what actually takes place. It has also helped me to get to know a number of the crew members better.

“Did You Know?”

Did you know that the greatest buoy equipment problem that occurs in this area of the ocean is vandalism? Many of the buoys are damaged, stolen/cut loose, or destroyed. This might be done either out of anger and frustration, for financial gain (the buoys have quite a large mass of aluminum framing and electronic equipment), or by accident. Regardless of the reason, much time, data, and financial resources are lost and consumed in maintaining TAO array in the Pacific Ocean.

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Story Miller, July 20, 2010

NOAA Teacher at Sea: Story Miller
NOAA Ship: Oscar Dyson

Mission: Summer Pollock III
Geographical Area: Bering Sea
Date: July 20, 2010

Time: 1240
Latitude: 53°51N
Longitude:166°34W
Wind: 7 knots (approx. 8.055mph)
Direction: 202° (SW)
Sea Temperature: 9.22°C (approx. 48.596°F)
Air Temperature: 9.82°C (approx. 49.676°F)
Barometric Pressure (mb): 1023.8

Scientific Information
Figure 1: View of the low fog, clouds and sunset in Dutch Harbor the night of the delay.

What Is NOAA and How Can You Get Involved?
NOAA stands for the National Oceanic and Atmospheric Association and is part of the United States Department of Commerce. NOAA is involved around the world and there are many different avenues one could become involved with. For example, some people are involved in forecasting the location of the next hurricane strike, which means that you could be responsible for saving the lives of people living in those areas. If climate change is of a particular interest, you could aid in the monitoring of global weather systems to make climate predictions for the future. If ecological studies suit you, a job with NOAA could involve collecting data from costal environments to continue efforts of preserving healthy ecosystems. Perhaps your studies and data analysis would aid in the critical decision making processes of businesses around the world, such as creating and enforcing policies for the fisheries industry to maintain its resources for the future.  Mapping is equally important and part of your experience with NOAA could involve creating or enhancing navigational data to aid in the protection of ships and prevent potential accidents. Finally, perhaps you are interested in commanding a NOAA ship or piloting a NOAA aircraft. In that case, you could become part of the NOAA Corps.

The Mission

The primary mission of the Oscar Dyson is the Walleye Pollock survey, which consists of conducting Acoustic Surveys and Fishery Survey Trawls. The acoustic survey relies on sonar waves that are powerful enough to detect fish at different depths. Once the fish is located on the sonar screen, the trawl net is then accurately deployed to a specific depth depending on where the targeted fish species are located. This depth can range from 16 meters from the surface all the way down to 3 meters from the bottom.  The net is then hauled onto the ship’s aft deck and the contents are spread on the table in the lab for sorting and identification. Different species, such as the Walleye Pollock, will be measured for size, sex, and age before being released overboard. Some other species like Pacific Cod and Arrowtooth Flounder will be collected for additional studies.

Delays, Delays!

Monday, July 19th appeared to be a rare, sunny day in Dutch Harbor for most of the afternoon. We were scheduled to leave Dutch Harbor at 1500h but due to baggage problems for those who recently arrived in Dutch Harbor, we were delayed until the next day. Because of the short airstrip in Dutch Harbor, the sizes of the airplanes are smaller than those of regular airports. Currently Pen Air uses SAAB Turboprop airplanes. These planes are small and hold about thirty passengers. They are typically used for small air carriers for short commutes.  Another critical factor involved with flights is weight. For every passenger, think of the additional weight of all the bags each person has. Most people fly with one or two bags, each weighing 50lbs or less and in our case, some people also had additional bags carrying scientific equipment.

Figure 2: A typical foggy day in Dutch Harbor, Monday, July 19th, 2010

Weight in an airplane causes the plane to use more fuel and smaller airplanes cannot carry as much fuel as the other airplanes, such as Boeing 737 aircraft, commonly used for longer commutes by larger airlines. Because of the distance between Anchorage and Dutch Harbor, full flights generally need to make a stop in the small villages of King Salmon or Cold Bay to refuel. Other difficulties faced by the airport in Dutch Harbor are that the airstrip is a “daylight only” landing zone and the weather can be quite hazardous. Winds reaching up to 90 mph are not uncommon and in the summer, low fog becomes a visibility issue. If the pilots do not have a specific range of visibility, they cannot land. Therefore, the necessity of refueling in Cold Bay or King Salmon is critical because many times when the plane reaches the airport and hazardous weather conditions are preventing a safe landing, the airplane must have enough fuel to circle the airport in hope for a sliver of time when landing conditions are safe and, if necessary, enough fuel to fly all the way back to King Salmon or Cold Bay. Again, weight is an issue in the fuel consumption of an airplane and therefore, on full flights, the airplane must sometimes “bump” bags, which means that sometimes your checked bag will not make it on the flight you are on and will be scheduled on a later flight. This of course isn’t a bad plan except that the weather in Dutch can change from one extreme to the next in a matter of fifteen minutes. In our case, to add to the difficulty of getting our bags, it was explained to us that because the air had become warmer, it lessened the lift on the airplane which was another reason why the planes did not carry very many bags that day. With all these important technicalities, one could maybe understand why flying into Dutch Harbor can be difficult. Therefore, some people have successful flights and others experience the “flight to nowhere” which involves flying part or the entire three hours to Dutch Harbor, circling or waiting in Cold Bay, and then flying back to Anchorage. One could say that you are not a local until you have experienced this situation a few times!

Personal Log:

My first day on the boat proved to be interesting as I quickly learned my way around the ship. I sometimes make the analogy of myself being like a rat in a maze trying to find the cheese. In a way it is accurate because the cook on board has made some fantastic dinners and I’ve been successful at finding the mess hall by simply following my nose! For supper on Monday night, we had a buffet-style dinner and I was pleasantly surprised with the menu as I helped myself to prime rib and king crab legs!

Figure 3: Me in front of the Oscar Dyson, Monday, July 19th, 2010 (notice the extreme weather change!)

On Tuesday, we were able to get underway at approximately 1300. Before pulling away from the dock, we needed to test our FRB (Fast Rescue Boat) to make sure it was functional in the possible event of an emergency. Once we knew the FRB was functional, we hauled it back onto the boat. As soon as we began to move, I went to the flying bridge (the highest deck on the ship) to catch a glimpse of Dutch Harbor and to watch the local birds sitting on the water. Most of the birds I saw were tufted puffins. I always find them amusing because if you get near them when they have eaten too many fish, they try to fly away but their belly is too heavy. Therefore they simply skim over the water, wings flapping intensely, and bellies dragging over the top of the water!

Figure 4: Lead Fisherman Dennis Boggs and Skilled Fisherman Mike Tortorella testing the FRB

Some advances in healthcare that I am extremely excited about is that I have found a seasickness medication that does not knock me out in under 5 minutes and that works for a long period of time. Thank you Meclizine!
Currently we are underway and have approximately 381 miles northwest to travel before we make our waypoint which will take approximately 28 hours. As of right now, my job has been to get acclimated to the ship. Work will begin Thursday at sunrise, about 0700).  My current shifts will run from 0400h to 1600h each day. I cannot wait to begin the first part of my assignment!

Animals Spotted By Me Today:
Blackfooted Albatross
Tufted Puffin
Seagull
Sea Otter
Fur Seal

Something To Ponder:
Regarding NOAA fish surveys, such as the Pollock Survey I’m participating in, what impacts would the scientific information collected have on the fishery industry regarding revenue and long term success?

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Rebecca Kimport, JULY 12, 2010 part2

NOAA Teacher at Sea Rebecca Kimport
NOAA Ship Oscar Dyson
June 30, 2010 – July 19, 2010

Mission: Summer Pollock survey
Geograpical Area:Bering Sea, Alaska
Date: July 12,  2010

A Floating City

A modern city has a network of companies that provide us with modern conveniences (water, electricity, sewage and trash removal). A NOAA research vessel provides those same conveniences to its crew through the complex engineering network. We wouldn’t be able to eat, drink, take showers, or conduct research without the expertise of our engineers.
Sea water is taken in by an intake valve about 6 m below the surface. It goes through a variety of cleaning processes to filter, distill and purify the water for human consumption. First, small sea creatures are removed by a filter known as the “sea chest.” Here is a picture of some of the creatures captured by the sea chest in the Oscar Dyson. Next, the water is distilled using the heat from the engine under a vacuum to remove dissolved ions. The water is then purified using bromine and UV light before it is pumped into the piping system (running throughout the ship in pipes labeled “potable water”). The water is so pure that we have to add salt for the espresso machine to recognize the water level (the science of the espresso machine will have to wait for a later entry).

Contents of the Sea Chest

Lights, Camera, Acoustics
The Oscar Dyson requires electricity to run the ships instruments, the scientific equipment and the lights which allow us to keep the ship operational 24/7. Our power is generated by the engines which also propel the ship forward. The Oscar Dyson runs on diesel fuel and uses larger, more powerful versions of the engines we find in cars. We use about 110 gallons of fuel each hour to maintain scientific and navigational operations.

Engine

Taking out the trash
Kitchen and food waste are the main sources of trash on the Oscar Dyson. Trash is sorted and disposed of based on how it breaks down. Food, which decomposes, is released into the ocean to re-enter the ecosystem. Combustible items (such as paper, napkins, etc) are burned in the ship’s incinerator which is run every night. Non-combustible items, such as aluminum cans, are recycled and brought back to land.

And out the other end
Although a less than pleasant topic to discuss over dinner, it is important to remember that a ship must track its human waste as well. Per NOAA regulations, human waste is treated through a complex process before being released into the ocean (to re-enter the eco-system). This process, like those of water treatment plants and septic systems on land, break down the waste through multiple steps involving biological, physical and chemical reactions. Ask me for more information if you really want the dirty details.

Who’s watching the engines?
The Oscar Dyson employs an engineering staff of seven, who have specialized training and job responsibilities to ensure proper functioning and maintenance of the vessel. Like all good engineers, they usually work behind the scenes so it was great to get an inside look at the inter-workings of the ship.

New Vocabulary
hull: watertight body of a ship
distill: remove impurities
ions: an atom with a positive or negative charge. Ions are created when elements gain or lose electrons. They can be in the form of a solid or a liquid (dissolved)
UV light: ultraviolet light

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Rebecca Kimport, JULY 3, 2010

NOAA Teacher at Sea Rebecca Kimport
NOAA Ship Oscar Dyson
June 30, 2010 – July 19, 2010

Mission: Summer Pollock survey
Geograpical Area:Bering Sea, Alaska
Date: July 3,  2010

Here fishy fishy

In a previous post, I briefly mentioned that acoustics helps Oscar Dyson scientists locate aggregations of pollock. I didn’t know much about acoustics surveying before I arrived on board but think its pretty cool.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”. At right you will see a picture of the acoustic data picked up by the transducers. 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.

Acoustic Data
Acoustic 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.

Sonar
Sonar

Looking in more than one direction
Along with the transducers, there is also a multibeam SONAR that produces the same information as the transducers but with a wider angle range. Scientists use this program to help separate species in the water column. The multibeam ME70 sends its signal out after the transducers information is sent and returned. They alternate about 1.5 seconds apart. Scientists around the world are working to improve this technology and we use information from a group at University of New Hampshire along with a program from Tasmania to analyze these data. 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.

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.Thought Question: What could happen if we didn’t regulate the amount of fish that could be caught? Bonus points for anyone who can identify an area where overfishing has impacted the ecosystem.
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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