acoustics – Page 15 – NOAA Teacher at Sea Blog

July 24, 2009April 5, 2021

Jennifer Fry, July 24, 2009

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Miller Freeman (tracker)
July 14 – 29, 2009

Mission: 2009 United States/Canada Pacific Hake Acoustic Survey
Geographical area of cruise: North Pacific Ocean from Monterey, CA to British Columbia, CA.
Date: July 24, 2009

Weather Data from the Bridge
Wind speed: 24 knots
Wind direction: 355° from the north
Visibility: clear
Temperature: 17.3°C (dry bulb); 15.5°C (wet bulb)
Sea water temperature: 9.8°C
Wave height: 3 ft.
Swell direction: 350°
Swell height: 5-6 ft.

Science and Technology Log

There is an abundance of marine life in the ocean today: sightings include a humpback whale breaching and spy-hopping. Breaching is when a whale jumps out of the water. Spy-hopping is when the whale’s head comes out of the water vertically and “takes a peek” at his surroundings. We also sighted the Pacific white-sided dolphins that appeared to be “playing” with the ship. They would swim perpendicularly to the ship’s hull and at the last minute; veer away at a 90° angle. The dolphins were also swimming alongside the bow and the side of the ship.

The sonar signals indicate an abundance of marine life under the sea and the presence of marine mammals helps us draw that conclusion. All that life is probably their prey. We made 2 fishing trawls which included hake and 2 small squid, split nose rockfish, and dark, blotched rockfish. That was the first time I had seen rockfish. They are primarily a bottom dweller. Scientists don’t want to catch too many rockfish because they tend to be over fished and their numbers need to be protected. Also, we only want to catch the fish species we are surveying, in this case, hake. The scheduled camera tow was cancelled because we did not want to catch marine mammals. The camera tow is described as a net sent down to depth that is opened on both sides. It takes video of the fish swimming by. This helps the scientists determine what species of fish are at each particular depth, during which the fish are not injured for the most part.

Personal Log

It was very exciting to see the humpback whale and dolphins today. They appeared to be very interested in the ship and it looked like they were playing with it. It was a perfect day with the sun shining and calm seas.

Question of the Day
What are ways scientists determine the health of the ocean?

Did You Know? Breaching is when a whale jumps out of the water. Spy-hopping is when the whale’s head comes out of the water vertically and “takes a peek” at his surroundings.

Animals Seen Today
Marine mammals: Pacific white-sided dolphins, California sea lion, and Humpback whale: spy hopping.
Birds: Fulmar, Shearwater, Albatross, and Skua.
Fish: Hake, Split nose rockfish, and Dark Blotched rockfish.

Ode to the Miller Freeman
As the chalky white ship, the Miller Freeman cuts through the icy blue waters of the North Pacific Ocean,
I stand in wonderment at all I see before me.
A lone Pacific white-sided dolphin suddenly surfaces over the unending mounds of waves.
A skua circles gracefully negotiating up and over each marine blue swell
Off in the distance, the band of fog lurks cautiously, waiting its turn to silently envelop the crystal blue sky.
Watching this beauty around me I have arrived, I am home.

July 23, 2009April 5, 2021

Jennifer Fry, July 23, 2009

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Miller Freeman (tracker)
July 14 – 29, 2009

Mission: 2009 United States/Canada Pacific Hake Acoustic Survey
Geographical area of cruise: North Pacific Ocean from Monterey, CA to British Columbia, CA.
Date: July 23, 2009

Here I am in the lab helping with the HAB samples.

Weather Data from the Bridge
Wind speed: 15 knots
Wind direction: 350°from the north
Visibility: clear
Temperature: 12.0°C (dry bulb); 11.8°C (wet bulb)
Sea water temperature: 9.7°C
Wave height: 2 ft.
Swell direction: 000°
Swell height: 4 ft.

Science/Technology Log

We began the day conducting 2 HAB (Harmful Algal Bloom) sample tests of the ocean. This tests the amount of plankton in the water. Scientists test this because some plankton can carry harmful toxins that can get into the fish and sea life we eat, such as clams. Later we sighted numerous marine mammals including: 2 humpback whales (breaching), 12 Pacific white-sided dolphins, and California sea lions.

We made two trawls which provided plenty of hake for us to observe, measure, and collect data. Acoustic Judging: One important aspect of the acoustic hake survey is what scientists do when not trawling. There is a process called judging that fishery biologist, Steve De Blois spends most of his day doing. While looking at acoustic data, he draws regions around schools of fish or aggregations of other marine organisms and assigns species identification to these regions based on what he sees on the acoustic display and catch information gathered from trawls. He uses 4 different frequencies to “read” the fish signals—each shows different fish characteristics. Having started at the Alaska Fishery Science Center in 1991, this is Steve’s 19^th year of participating in integrated acoustic and trawl surveys and his eighth acoustic survey studying Pacific hake. He’s learned how to read their signs with the use of sonar frequencies and his database. Steve tells us about the importance of science: “Science is a methodology by which we understand the natural world.”

New Term/Phrase/Word Pelagic: relating to, living, or occurring in the waters of the ocean opposed to near the shore. In terms of fish, this means primarily living in the water column as opposed to spending most of their time on the sea floor.

Steve De Blois, NOAA Research Fishery Biologist, shares acoustic datawith Julia Clemons, NOAA Oceanographer, aboard the Miller Freeman. — Steve De Blois, NOAA Research Fishery Biologist, shares acoustic data
with Julia Clemons, NOAA Oceanographer, aboard the Miller Freeman.

Did You Know?
Northern fur seals are pelagic for 7-10 months per year. Pelagic Cormorant birds live in the ocean their entire life.

Animals Seen Today
Humpback whales (2), Pacific white-sided dolphin (12), California sea lions (6), and Northern fur seal.

In Praise of…Harmful Algal Bloom Samples
Crystal cold ocean water running through clear plastic pipes
Be patient as containers are carefully rinsed out three times.
The various sized bottles are filled with the elixir of Poseidon
Accurate measuring is essential.
Consistency ensures accurate results.
Once the water is filtered, tweezers gently lift plankton-laden filter papers.
All samples await analysis in the 20°F freezer.
Data from each test is later recorded;
Levels of domoic acid, Chlorophyll,
And types, populations, and species of phytoplankton and zooplankton.

June 18, 2009April 5, 2021

Jill Stephens, June 18, 2009

NOAA Teacher at Sea
Jill Stephens
Onboard NOAA Vessel Rainier
June 15 – July 2, 2009

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 18, 2009

Weather Data from the Bridge
Position 55° 10.089’N 161° 52.801’W
Broken cloud cover
Wind variable and light
Pressure 995.9
Temperature: Sea; 6.1°C; Dry Bulb; 8.3°C; Wet Bulb; 7.8°C

The Reson monitor displays the sonar return captured by the receiver on the bottom of the boat.

Science and Technology Log

The launch leaves the ship every day to go to spots within the survey area to collect data regarding the bottom for depth, possible anchorage sites and potential navigational hazards. Our boat was responsible for covering the long area referred to as the fairway, which is necessary in this uncharted area so that the launches can transit to and from the working areas safely, and move on to another area upon completion.

The chart of the area is “painted” with color depicting the depth of the area based upon the return form the sonar. The goal is to “paint” your assigned area. The numbers in the lower right of the screen indicate the depth in meters.

The inside of the cabin of the launch reminds me of Star Wars. There are pieces of electronic equipment everywhere! One of the survey team members sits in the command center to monitor and control the Reson collection and additional software that displays a 3-D image of the sea floor surface. As the coxswain pilots the boat over the surface of the water, low frequency sonar is emitted from the transducers. The sonar hits the sea floor and is then bounced back to a receiver on the underside of the boat. The pings are recorded by the equipment and stored in the computer.

The CTD is attached to a cable operated by a winch. The CTD acclimates to the water surface temperature before being lowered steadily to the bottom. The equipment is raised to the surface using the winch and then brought aboard. The CTD is connected to the computer for data retrieval.

There are factors that affect the accuracy and quality of the information. Boat speed, conductivity of the water, pitch and roll, yaw, and tides must be accounted for in order obtain usable data. There is equipment on board that collects the pitch, roll, yaw, and geographic position information to correct merge with the data to make corrections. The CTD apparatus is placed into the water while the boat is stopped. The cast of the CTD will collect salinity, temperature, and pressure information at depths from the surface to the bottom. This information is also sent to the computer to provide a more accurate reading of the sonar data received by the Reson system. Casts of the CTD must be made a minimum of every four hours to account for any changes between points in the survey area.

Personal Log

Here I am manning the computers onboard the launch used to collect sonar depth and bottom information in the Pavlof Islands, Alaska.

Shawn, Todd, and Dennis were on my launch today. Once the equipment was powered up and the software programs selected, I was able to sit at command center and control collection and storage of data. The raw data is merged with the corrective information and submitted to Caris, another software program that also creates models of the findings. We were using a laptop to merge the data and begin field processing of the data. I was able to assist with this process too.

Two whales surfaced near the survey launch early in the morning near Bluff Point in the Pavlof Islands.

Animal Sightings

This morning was a great day to see whales!! We spotted 5 blows! We were then able to see the whales breach the surface at a distance. Three of the whales moved closer to us. There were two adults and a juvenile. The juvenile was very playful and kept poking his head above the surface. The two adults came closer to the launch and we were able to get some great shots of their bodies!! On the way back to the ship, we saw four more blows. Total sightings of whales: 9 Puffins as always are out there. They are very strange, somewhat silly birds….

New Vocabulary Gain: how hard an object is listening to the sound emitted by the sonar Sound Speed: speed at which sound is able to travel (This will vary in water depending upon the factors like salinity and temperature.)

Absorption: refers to how much of the sound is absorbed by the medium and varies with the medium’s composition and other factors including temperature.

June 11, 2009April 5, 2021

Susan Smith, June 11, 2009

NOAA Teacher at Sea
Susan Smith
Onboard NOAA Ship Rainier
June 1-12, 2009

Mission: Hydrographic survey
Geographical area of cruise: Trocadero Bay, Alaska; 55°20.990’ N, 33°00.677’ W
Date: June 11, 2009

Weather at 9:45 AM
Temperature: Dry Bulb: 7.8°C (46°F); Wet Bulb: 6.7° (44°F)
Cloudcover: OVC
Visibility: 10+ nautical miles
Wind direction: 285, 7 kts.
Sea Wave Height: -0
Sea water temperature: 8.3°C (41°F)

Science and Technology Log

Today’s log is an accounting of our voyage up Glacier Bay to the Margerie Glacier. Along the way we received information about Glacier Bay from Lewis, the National Parks Service employee whose assistance we enlisted. At approximately 5:30 AM Lewis came on board. He was delivered by boat in the Sitakaday Narrows, near Bartlett Cove. We actually entered Glacier Bay a few hours later. Our destination- Margerie Glacier,at the border of the United States and Canada.

Margerie Glacier’s height is 250 feet. The glacier also extends another 100 feet below the water line. The Statue of Liberty is 307 feet tall by comparison. The Reid Glacier, south of the Tarr Inlet, is 150 above the waterline and is ••• mile across. It is the fastest moving Tidewater glacier, moving at approximately 8 feet per day. A Tidewater glacier is defined as “a glacier that terminates in the sea, where it usually ends in an ice cliff from which icebergs are discharged”.

Questions of the Day:

Why does the ice look blue? The ice in the glacier absorbs shorter red and green wavelengths.
Why is part of the glacier black? Rocky debris mixes in with the ice.
Why are the edges jagged? Because glaciers advance and recede constantly they leave jagged patterns on the ice edges.

I took several photographs through the Flying Bridge’s high powered binoculars, or “Bug Eyes”. As you can see the crevices are very deep and unstable, causing the ice to break off and drop into the water. Ice breaking away from a glacier is called calving.

Interesting patterns as seen through the high powered binoculars

Lewis explained several interesting historical things to us.

John Muir traveled this area in 1879, by canoe, giving vivid descriptions of what he had encountered. This opened up tourism like never before.
In 1925 President Coolidge, by presidential order, declared this area as Glacier Bay National Monument. It wasn’t until 1980 that it became Glacier Bay National Park.
In the 1990’s it was officially recognized as a UNESCO (The United Nations Educational, Scientific and Cultural Organization) World Heritage Site. Each World Heritage Site is the property of the state on whose territory the site is located, but it is considered in the interest of the international community to preserve each site.
Glacier Bay was covered with glaciers 100 years ago. When the glaciers receded they carved out the bay as we know it today.

Glacier Bay National Park has 3.3 million acres of land, with a park shoreline of 1,000 miles in the bay proper. Outside of the official boundary the waters three miles out cover another 300 miles. (When the Grand Pacific Glacier receded into Canada’s land area the Canadians jokingly stated they should build a deep water port because now the water was on their side of the border)

Park Regulations: No more than two cruise ships may enter the park per day. This provides less disturbance on the wildlife and environment. The park director may mandate a speed limit of 10 knots, depending on whale proximity.

Recreation

There are no trails in the backcountry.
Geikie Inlet is a kayaker’s haven
There are five areas of wilderness waters, four of which are closed to motorized traffic and sea planes during the summer, and one area with two sections, each closed half of the summer.

1. Beardslee Islands- forested with 200 year old trees

2. Adam’s Inlet- young, flat area with moose, wolves, bears

3. Rendu Inlet- raw and exposed area, not protected

4. Hugh Miller complex- including Scidmore Bay and Charpentier Inlet, west of the wilderness boundary at the mouth of the Hugh Miller Inlet.

5. Upper Muir and Wachusett Inlets- a. Muir, a large and exposed area, is closed from June 1-15; and b. Wachusett is closed July 16-August 31

Grand Pacific Glacier, brown area — Launch up close with the glacier

Research Projects-There are many research projects going on in Glacier Bay National Park. Academic research is continually being done by universities. There are long term weather stations set up within the park and 24 CTD (Conductivity, Temperature, Depth) stations to check. Three specific populations being studied are the brown bears, whales, and birds. These populations are being monitored to determine the extent they are affected by motor vessels, tourism, and land management. There is also huge research (approximately 40 projects each summer) on plant succession. Simply by the multitude of research projects occurring you can easily see why Glacier Bay National Park is known as a research park. For more photographs and information, go here.

Grand Pacific Glacier- The mountains are Canadian.

Teacher at Sea Experience Summary

This trip has given me such insight on all the work done to insure the safety of all who utilize Alaska’s waterways. Before coming on board I had no idea of the volume of intricate data which must be collected and processed to make navigational charts. I had no knowledge of how a NOAA ship as large as Rainier operates and the myriad of jobs necessary to make it all run smoothly. After 11 days on the Rainier I can honestly say there is no other ship I would have enjoyed being on more- the hospitality shown me from day one was remarkable, the patience required to answer the same questions over and over was stellar, I got to take the helm, and I learned more science and nautical vocabulary than even I anticipated. Thank you, NOAA, for this opportunity and thank you, the people of Rainier S-221, who allowed me to spend part of my summer vacation living and working with you. Bravo Zulu!

June 9, 2009April 5, 2021

Susan Smith, June 9, 2009

NOAA Teacher at Sea
Susan Smith
Onboard NOAA Ship Rainier
June 1-12, 2009

Mission: Hydrographic survey
Geographical area of cruise: Trocadero Bay, Alaska; 55°20.990’ N, 33°00.677’ W
Date: June 9, 2009

Weather Data from the Bridge
Temperature: Dry Bulb: 12.2° (54°F); Wet Bulb: 11.1° (52°F)
Cloud Cover: Overcast 8/8
Visibility: 10 Nautical Miles
Wind direction: 315, 08 kts.
Sea Wave Height: 0-1
Sea Water Temperature: 12.8°C (55°F)

Science and Technology Log

Question: What might an empty bottom sampler indicate? There might be a hard bottom, so it is not a good place to try to anchor.

Today we took bottom samples in ten locations. The objective of bottom sampling is to update historical data and look for good anchor locations. This chart has five locations where we took bottom samples. They are shown where the stars are. The red symbol depicts our launch driving from one point to the next.

There are many houses, and what appeared to be summer hotels, in this area, so they must have accurately charted information. When we performed our bottom sampling, the bottom sampler was affixed to a rope which we dropped over the side of the launch. Some times a weight is put on the rope so it will hit bottom with more force. After we tried three times and the claw was not closed we put a weight on and it closed from then on.When the sampler hit the bottom the claw of the sampler shut, trapping whatever was in that locale. We then brought the rope back up and opened the sampler to observe its contents.

Susan sending the sampler down with Shawn’s help

We found the following materials:

43 feet deep: nothing in three tries- must be a hard bottom
50 feet deep: very densely packed green, sticky mud
47 feet deep: same as number 4
168 feet deep: big rocks only
130 feet deep: fine, green, sticky mud
47 feet deep: piece of black plastic (like a coffee stirrer), very fine black silt
37.5 feet deep: black sand with kelp
2. 168 feet deep: black, sticky mud
1. 100 feet deep: grey sand, three rocks of varying sizes
small rocks Of these samples, green, sticky mud indicated the best locations for anchoring.

Personal Log

We departed Trocadero Bay in the late morning. As we headed toward Glacier Bay for our tour on Wednesday we had our abandon ship and fire drills. When we did not complete the series of three drills (man overboard drill is the third one), I asked what the chances were of having this third drill. As it was explained to me we generally have the man overboard drill if we are ahead of our dead reckoning. When asked what that is I was told, “If we are where we are supposed to be when we are supposed to be there”. Here’s the dictionary definition of dead reckoning- Dead Reckoning: 1. calculation of one’s position on the basis of distance run on various headings since the last precisely observed position, with as accurate allowance as possible being made for wind, currents, compass errors, etc.; 2.one’s position as so calculated.

On the chart times of arrival are written in pencil so adjustments can be made.

This was important because were to pick up a National Park Service guide for our tour into Glacier Bay and we could not be early. A man overboard drill takes a great deal of time, because the ship must go back to its position when someone fell overboard. This entails making a huge circle with a ship that is 231 feet long, 42 feet wide, and has a displacement of 1,800 tons. As you can imagine just the turning around alone takes a considerable amount of time.

For more information on the NOAA Ship Rainier (S-221) go here.