Tag Archives: sonar

Denise Harrington: Tenacity – May 7, 2016

Posted on by deniseharrington
NOAA Teacher at Sea
Denise Harrington
Aboard NOAA Ship Pisces (In Port)
May 04, 2016 – May 17, 2016

Mission: SEAMAP Reef Fish Survey

Geographical Area of Cruise: Gulf of Mexico

Date: Saturday, May 7, 2016

Tenacity helps NOAA manage our seafood supply.

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Tenacity, otherwise known as perseverance or stamina, is a required skill at the National Oceanic and Atmospheric Administration (NOAA). Aboard NOAA Ship Pisces, we are all anxious to head out to collect data about the type and abundance of reef fish along the continental shelf and shelf edge of the Gulf of Mexico.  However, things don’t always go as planned. Much like the animals we study, scientists must rapidly adapt to their changing circumstances. Instead of waiting for a problem to be solved, fisheries biologists of all ages and experience work in the lab, using the newest, most sophisticated technology in the world to meet our demand for seafood.

As I ate dinner tonight in the mess (the area where the crew eats), I stared at the Pisces’ motto on the tablecloth, “patience and tenacity.”

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The Pisces is a “quiet” ship; it uses generators to supply power to an electric motor that turns the ship’s propeller. The ship’s motor (or a mysteriously related part) is not working properly, and without a motor, we will not sail. This change of plans provides other opportunities for me, and you, to learn about many fascinating projects developing in the lab. Sound science begins right here at the Southeast Fisheries Science Center Laboratory in Pascagoula, Mississippi.

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Kevin Rademacher, a fishery biologist in the Reef Fish Unit, meets me at the lab where he works when he isn’t at sea. As he introduces me to other biologists working in the protected species, plankton, and long line units, I begin to appreciate the great biodiversity of species in the Gulf of Mexico. I get a glimpse of the methods biologists use to conduct research in the field, and in the lab.

While it looks like a regular old office building on the outside, the center of the building is filled with labs where fish are taken to be discovered.  Mark Grace, a fisheries biologist in the lab, made one such discovery of a rare species of pocket shark on a survey in the gulf. The only other specimen of a pocket shark was found coast of Peru in 1979. Mark’s discovery raises more questions in my mind than answers.

When I met Mark, he explained that capability of technology to gather data has outpaced our ability to process it. “Twenty years ago, we used a pencil and a clipboard. Think about the 1980s when they started computerizing data points compared to the present time… maybe in the future when scientists look back on the use of computers in science, it will be considered to be as important as Galileo looking at the stars” he said. It’s important because as Mark also explains,  “This correspondence is a good example.  We can send text, website links, images, etc…and now its a matter of digital records that will carry in to the future.”

How do fishery biologists find fish?

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Charlie McVea, a retired NOAA marine biologist, and his trusty assistant Scout, pictured above, learned they may need more sophisticated equipment to locate fish.

Earth has one big connected ocean that covers the many features beneath it. Looking below the surface to the ocean floor, we find a fascinating combination of continental shelves, canyons, reefs, and even tiny bumps that make unique homes for all of the living creatures that live there.  Brandi Noble, one of 30-40 fishery biologists in the lab, uses very complicated sonar (sound) equipment to find “fish hot spots,” the kinds of places fish like to go for food, shelter and safety from predators. Fisheries sonar sends pulses of sound, or pings, into the water.  Fishery biologists are looking for a varied echo sound that indicates they’ve found rocky bottoms, ledges, and reefs that snapper and grouper inhabit.

The sonar can also survey fish in a non-invasive way. Most fish have a swim bladder, or a gas filled chamber, which reflects sonar’s sound waves.  A bigger fish will create a returning echo of greater strength. This way, fisheries biologists can identify and count fish without hurting them.

sonar fish

The circular image shows a three-dimensional map NOAA scientists created from the sonar data they collected about the seafloor and a school of fish.

Ship Pisces uses a scientific methods to survey, determining relative abundance and types of fish in each area. They establish blocks of habitat along the continental shelf to survey and then randomly sample sites that they will survey with video cameras, CTD (measures temperature, salinity, and dissolved oxygen in the water), and fishing. Back in the lab, they spend hours, weeks, and years, analyzing the data they collect at sea. During the 2012 SEAMAP Reef Fish Survey, the most common reef fish caught were 179 red snapper (Lutjanus campechanus), 22 vermillion snapper (Rhomboplites aurorubens), and 10 red porgy (Pagrus pagrus).  Comparing the 2012 data with survey results from 2016 and other years will help policy makers develop fishing regulations to protect the stock of these and other tasty fish.

How do fishery biologists manage all the information they collect during a survey?

Scientists migrate between offices and labs, supporting each other as they identify fish and marine mammals from previous research expeditions.

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Kevin Rademacher, at work in the lab.

Our mission, the SEAMAP Reef Fish Survey has been broken into four parts or legs.  The goal is to survey some of the most popular commercially harvested fish in the Gulf of Mexico.  Kevin Rademacher is the Field Party Chief for Leg 1 and Leg 3 of the survey.

Last week, he showed me collections of frozen fish, beetle infested fish, and fish on video. At one point the telephone rang, it was Andrew Paul Felts, another biologist down the hall. “Is it staying in one spot?” Kevin asks. “I bet it’s Chromis. They hang over a spot all the time.”

We head a couple doors down and enter a dark room.  Behind the blue glow of the screen sits Paul, working in the dark, like the deep water inhabitants of the video he watches. Paul observes the physical characteristics of a fish: size, shape, fins, color.  He also watches its behavior. Does it swim in a school or alone?  Does it stay in one spot or move around a lot?  He looks at its habitat, such as a rocky or sandy bottom, and its range, or place on the map.

As you watch the video below, observe how each fish looks, its habitat, and its behavior.

To learn about fisheries, biologists use the same strategies students at South Prairie Elementary use.   Paul is using his “eagle eyes,” or practiced skills of observation, as he identifies and counts fish on the screen.   All the scientists read, re-read and then “read the book a third time” like a “trying lion” to make sense out of their observations.  Finally, Paul calls Kevin, the “wise owl,” to make sure he isn’t making a mistake when he identifies a questionable fish. paul screen

Using Latin terminology such as “Chromis” or “Homo” allows scientists to use the same names for organisms. This makes it easier for scientists worldwide, who speak different languages, to communicate clearly with each other as they classify the living things they study.

I appreciate how each member of the NOAA staff, on land and at sea, look at each situation as a springboard to more challenging inquiry.  They share with each other and with us what they have learned about the diversity of life in the ocean, and how humans are linked to the ocean.  With the knowledge we gain from their hard work and tenacity, we can make better choices to protect our food supply and support the diversity of life on Earth.

 

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Spined Pygmy Shark Jaw (Squaliolus laticaudus)

Personal Log

Crew members tell me that every day at sea is a Monday.  In port, they are able to spend time with family and their communities.  I have been able to learn a bit about Pascagoula, kayak with locals, and see many new birds like the least tern, swallow tailed kite, eastern bluebird and clapper rail.  Can you guess what I ate for dinner last night?P1050747

 

 

 

 

Nichia Huxtable: Time to Make a Map, May 8, 2016

Posted on by nichiahuxtable2016

NOAA Teacher at Sea

Nichia Huxtable

Aboard NOAA Ship Bell M. Shimada

April 28 – May 9, 2016

Mission: Mapping CINMS
Geographical area of cruise: Channel Islands, California
Date: May 8, 2016
Weather Data from the Bridge:

Science and Technology Log

Seafloor in CINMS

Seafloor in the CINMS

In previous posts, I’ve discussed the ME70 multibeam sonar on board Shimada. You’d think that I’ve told you all there is to know about the wondrous data this piece of equipment provides, but oh, no, dear readers, I’ve merely scraped the surface of that proverbial iceberg. In this post, I will explain how the raw data from the ME70 is used to create important seafloor maps. Heck, I’ll even throw in a shipwreck! Everyone loves shipwrecks.

Nichia Huxtable, Diana Watters, ME70, and EK60; aboard Shimada

Nichia Huxtable, Diana Watters, ME70, and EK60; aboard Shimada

Back to the multibeam. As you may remember, the ME70 uses many beams of sonar to capture a 60 degree image of the water column. It collects A LOT of data, one survey line at a time. Lots of data are good, right? Well, if you want to map the bottom of the ocean, you don’t need ALL the data collected by the ME70, you just need some of it. Take, for example, fish. You don’t want big balls of fish obscuring your view of the seafloor, you just want the seafloor! Leave the schools of fish for Fabio.

Kayla Johnson aboard NOAA Ship Bell M. Shimada

Mapping maven Kayla Johnson

The person you need to make your seafloor map is Kayla Johnson. First, she sends the raw data to a program called MatLab. This nifty software separates the bottom data from all the other stuff in the water column and packages it in something called a .gsf file. Next, this .gsf file goes to this huge processing program called CARIS HIPS, where it is converted into an something called HDCS data.

You’d think that all you’d need to make an accurate seafloor map would be data from the multibeam, but it is actually much more complicated than that (of course you knew that! just look at how long this blog post is). Think about it: while you’re running your survey lines and collecting data, the ocean and, therefore, the ship are MOVING. The ship is heaving, rolling, and pitching, it’s travelling in different directions depending on the survey line, the tides are coming in and out, the temperature and salinity of the water varies, etc. etc. All of these variables affect the data collected by the ME70 and, hence, must be accounted for in the CARIS software. Remember how I said it was HUGE? This is why.

Cross-section of the topography found in the CINMS

Cross-section of the topography found in the CINMS

Everyone still with me? Ok, let’s continue processing this data so that Kayla can make our beautiful map. Next up, she’s going to have to load data into CARIS from the POS. POSMV (POSition of Marine Vehicles) is a software interface used on the ship that collects real-time data on where we are in relation to the water (heave, pitch, and roll).  She’s also going to load into CARIS the local tide information, since the ship will be closer to the seafloor at low tide than at high. Not including tidal change is a good way to get a messed-up map! Once the POSMV and tide files are loaded into CARIS, they are applied to the survey line.

Completed map around San Miguel Island

Completed map around San Miguel Island

Next, Kayla has to compute the TPU (Total Propagated Uncertainty). I could spend the next four paragraphs explaining what it is and how it’s computed, but I really don’t feel like writing it and you probably wouldn’t want to read it. Let’s just say that nothing in life is 100% certain, so the TPU accounts for those little uncertainties.

Since the data was collected using multiple beams at a wide angle, there will be beams returning bad data, especially at the edges of the collection zone. Sometime a bad data point could be a fish, but most often bad data happens when there is an abrupt change in seafloor elevation and the beams can’t find the bottom. So, Kayla will need to manually clean out these bad data points in order to get a clean picture of the seafloor.

These data need a haircut!
These data need a haircut!
Cleaned data
Cleaned data

Almost done! Last, Kayla makes the surface. All the data points are gridded to a certain resolution based on depth (lots of explanation skipped here…you’re welcome), with the end result being a pretty, pretty picture of the bottom of the seafloor. Phew, we made it! These seafloor maps are incredibly important and have numerous applications, including fisheries management, nautical charting, and searching for missing airplanes and shipwrecks (see! I told you there would be a shipwreck!). I’ll be getting into the importance of this mapping cruise to the Channel Islands Marine Sanctuary in my final post, so stay tuned.

Shipwreck in Buzzard's Bay, MA image courtesy of NOAA Ship Thomas Jefferson
Shipwreck in Buzzard’s Bay, MA image courtesy of NOAA Ship Thomas Jefferson
U-boat image courtesy of NOAA Ship Thomas Jefferson
U-boat image courtesy of NOAA Ship Thomas Jefferson

Endnote: A word about XBTs                                                                                                      

Deploying an XBT off Shimada

Deploying an XBT off Shimada

 Before all your data are processed, you need to know how fast the sound waves are travelling through the water. When sound is moving through water, changes in temperature and salinity can bend the wave, altering your data. An XBT is an expendable bathythermograph that is sent overboard every four hours. It transmits temperature and salinity readings throughout its quick trip to the ocean bottom, allowing the computer to make data adjustments, as needed.

 

 

Did You Know?
Hey, you’ve made it to the bottom of this post! If you are interested in seafloor mapping, have I got an institute of higher learning for you. The College of Charleston has a program called BEAMS, which trains future ocean surveyors and includes a course called Bathymetric Mappings. Three of the hip young scientists on board have taken this course and it seems to be pretty amazing. If you love sailing the high seas AND data processing, you might want to check it out.

Emily Whalen: Station 381–Cashes Ledge, May 1, 2015

Posted on by Emily Whalen

NOAA Teacher at Sea
Emily Whalen
Aboard NOAA Ship Henry B. Bigelow
April 27 – May 10, 2015

Mission: Spring Bottom Trawl Survey, Leg IV
Geographical Area of Cruise: Gulf of Maine
Date: May 1, 2015

Weather Data from the Bridge:
Winds:  Light and variable
Seas: 1-2ft
Air Temperature:   6.2○ C
Water Temperature:  5.8○ C

Science and Technology Log:

Earlier today I had planned to write about all of the safety features on board the Bigelow and explain how safe they make me feel while I am on board.  However, that was before our first sampling station turned out to be a monster haul!  For most stations I have done so far, it takes about an hour from the time that the net comes back on board to the time that we are cleaning up the wetlab.  At station 381, it took us one minute shy of three hours! So explaining the EEBD and the EPIRB will have to wait so that I can describe the awesome sampling we did at station 381, Cashes Ledge.

This is a screen that shows the boats track around the Gulf of Maine. The colored lines represent the sea floor as determined by the Olex multibeam. This information will be stored year after year until we have a complete picture of the sea floor in this area!

This is a screen that shows the boats track around the Gulf of Maine. The colored lines represent the sea floor as determined by the Olex multibeam. This information will be stored year after year until we have a complete picture of the sea floor in this area!

Before I get to describing the actual catch, I want to give you an idea of all of the work that has to be done in the acoustics lab and on the bridge long before the net even gets into the water.

The bridge is the highest enclosed deck on the boat, and it is where the officers work to navigate the ship.  To this end, it is full of nautical charts, screens that give information about the ship’s location and speed, the engine, generators, other ships, radios for communication, weather data and other technical equipment.  After arriving at the latitude and longitude of each sampling station, the officer’s attention turns to the screen that displays information from the Olex Realtime Bathymetry Program, which collects data using a ME70 multibeam sonar device attached to bottom of the hull of the ship .

Traditionally, one of the biggest challenges in trawling has been getting the net caught on the bottom of the ocean.  This is often called getting ‘hung’ and it can happen when the net snags on a big rock, sunken debris, or anything else resting on the sea floor.  The consequences can range from losing a few minutes time working the net free, to tearing or even losing the net. The Olex data is extremely useful because it can essentially paint a picture of the sea floor to ensure that the net doesn’t encounter any obstacles.  Upon arrival at a site, the boat will cruise looking for a clear path that is about a mile long and 300 yards wide.  Only after finding a suitable spot will the net go into the water.

Check out this view of the seafloor. On the upper half of the screen, there is a dark blue channel that goes between two brightly colored ridges. That's where we dragged the net and caught all of the fish!

Check out this view of the seafloor. On the upper half of the screen, there is a dark blue channel that goes between two brightly colored ridges. We trawled right between the ridges and caught a lot of really big fish!

The ME70 Multibeam uses sound waves to determine the depth of the ocean at specific points.  It is similar to a simpler, single stream sonar in that it shoots a wave of sound down to the seafloor, waits for it to bounce back up to the ship and then calculates the distance the wave traveled based on the time and the speed of sound through the water, which depends on temperature.  The advantage to using the multibeam is that it shoots out 200 beams of sound at once instead of just one.  This means that with each ‘ping’, or burst of sound energy, we know the depth at many points under the ship instead of just one.  Considering that the multibeam pings at a rate of 2 Hertz to 0.5 Herts, which is once every 0.5 seconds to 2 seconds, that’s a lot of information about the sea floor contour!

This is what the nautical chart for Cashes Ledge looks like. The numbers represent depth in fathoms.  The light blue lines are contour lines.  The places where they are close together represent steep cliffs.  The red line represents the Bigelow’s track. You can see where we trawled as a short jag between the L and the E in the word Ledge

The stations that we sample are randomly selected by a computer program that was written by one of the scientists in the Northeast Fisheries Science Center, who happens to be on board this trip.  Just by chance, station number 381 was on Cashes Ledge, which is an underwater geographical feature that includes jagged cliffs and underwater mountains.  The area has been fished very little because all of the bottom features present many hazards for trawl nets.  In fact, it is currently a protected area, which means the commercial fishing isn’t allowed there.  As a research vessel, we have permission to sample there because we are working to collect data that will provide useful information for stock assessments.

My watch came on duty at noon, at which time the Bigelow was scouting out the bottom and looking for a spot to sample within 1 nautical mile of the latitude and longitude of station 381.  Shortly before 1pm, the CTD dropped and then the net went in the water.  By 1:30, the net was coming back on board the ship, and there was a buzz going around about how big the catch was predicted to be.  As it turns out, the catch was huge!  Once on board, the net empties into the checker, which is usually plenty big enough to hold everything.  This time though, it was overflowing with big, beautiful cod, pollock and haddock.  You can see that one of the deck crew is using a shovel to fill the orange baskets with fish so that they can be taken into the lab and sorted!

You can see the crew working to handling all of the fish we caught at Cashes Ledge. How many different kinds of fish can you see?

You can see the crew working to handling all of the fish we caught at Cashes Ledge. How many different kinds of fish can you see? Photo by fellow volunteer Joe Warren

 

At this point, I was standing at the conveyor belt, grabbing slippery fish as quickly as I could and sorting them into baskets.  Big haddock, little haddock, big cod, little cod, pollock, pollock, pollock.  As fast as I could sort, the fish kept coming!  Every basket in the lab was full and everyone was working at top speed to process fish so that we could empty the baskets and fill them up with more fish!  One of the things that was interesting to notice was the variation within each species.  When you see pictures of fish, or just a few fish at a time, they don’t look that different.  But looking at so many all at once, I really saw how some have brighter colors, or fatter bodies or bigger spots.  But only for a moment, because the fish just kept coming and coming and coming!

Finally, the fish were sorted and I headed to my station, where TK, the cutter that I have been working with, had already started processing some of the huge pollock that we had caught.  I helped him maneuver them up onto the lengthing board so that he could measure them and take samples, and we fell into a fish-measuring groove that lasted for two hours.  Grab a fish, take the length, print a label and put it on an envelope, slip the otolith into the envelope, examine the stomach contents, repeat.

Cod, pollock and haddock in baskets

Cod, pollock and haddock in baskets waiting to get counted and measured. Photo by Watch Chief Adam Poquette.

Some of you have asked about the fish that we have seen and so here is a list of the species that we saw at just this one site:

  • Pollock
  • Haddock
  • Atlantic wolffish
  • Cod
  • Goosefish
  • Herring
  • Mackerel
  • Alewife
  • Acadian redfish
  • Alligator fish
  • White hake
  • Red hake
  • American plaice
  • Little skate
  • American lobster
  • Sea raven
  • Thorny skate
  • Red deepsea crab

 

 

 

 

I think it’s human nature to try to draw conclusions about what we see and do.  If all we knew about the state of our fish populations was based on the data from this one catch, then we might conclude that there are tons of healthy fish stocks in the sea.  However, I know that this is just one small data point in a literal sea of data points and it cannot be considered independently of the others.  Just because this is data that I was able to see, touch and smell doesn’t give it any more validity than other data that I can only see as a point on a map or numbers on a screen.  Eventually, every measurement and sample will be compiled into reports, and it’s that big picture over a long period of time that will really allow give us a better understanding of the state of affairs in the ocean.

Sunset from the deck of the Henry B. Bigelow

Sunset from the deck of the Henry B. Bigelow

Personal Log

Lunges are a bit more challenging on the rocking deck of a ship!

Lunges are a bit more challenging on the rocking deck of a ship!

It seems like time is passing faster and faster on board the Bigelow.  I have been getting up each morning and doing a Hero’s Journey workout up on the flying bridge.  One of my shipmates let me borrow a book that is about all of the people who have died trying to climb Mount Washington.  Today I did laundry, and to quote Olaf, putting on my warm and clean sweatshirt fresh out of the dryer was like a warm hug!  I am getting to know the crew and learning how they all ended up here, working on a NOAA ship.  It’s tough to believe but a week from today, I will be wrapping up and getting ready to go back to school!

Theresa Paulsen: Mission Accomplished, April 2, 2015

Posted on by tpaulsen2015

NOAA Teacher at Sea
Theresa Paulsen
Aboard NOAA Ship Okeanos Explorer
March 16-April 3rd

Mission: Caribbean Exploration (mapping)
Geographical Area of Cruise: Puerto Rico Trench
Date: April 2, 2015

Weather Data from the Bridge: Partly Cloudy, 26 C, Wind speed 12 knots, Wave height 1-2ft, Swells 2-4ft.

Science and Technology Log:

What are the mappers up to?

After we completed our two priority areas of the cruise, the mappers have been using Knudson subbottom sonar to profile the bottom of the trench. Meme Lobecker, the expedition coordinator sends that data directly to the United States Geological Survey (USGS) for processing. They returned some interesting findings.

The subbottom sonar sends a loud “chirp” to the bottom. It penetrates the ocean floor. Different sediment layers reflect the sound differently so the variation and thickness of the layers can be observed. The chirp penetration depth varies with the sediments. Soft sediments can be penetrated more easily. In the picture below, provided by USGS, you can see hard intrusions with layers of sediments filling in spaces between.

image

The intrusions are basement relief, likely uplifting deformation ridges created by the subduction of the North American Plate. The subduction is now oblique, with the North American and Caribbean plates mostly sliding past each other now – sort of like the San Andreas Fault – but there is still some subduction happening. Subbottom Image and caption courtesy of USGS.

How does the bathymetry look?

In the last two days, I have been really enjoying the incredible details in the bathymetry data the multibeam sonar has gathered. We mapped over 15,000 square miles on our voyage! Using computer software we can now look at the ocean floor beneath us. I tried my hand at using Fledermaus software to make fly-over movies of the area we surveyed (or should I say swim-over movies). Check them out:

I also examined some of the backscatter data. In backscatter images soft surfaces are darker, meaning the signal return is weaker, and the hard surfaces are whiter due to stronger returns. One of the interns, Chelsea Wegner, studied the bathymetry and backscatter data for possible habitats for corals. She looked for steep slopes in the bathymetry and hard surfaces with the backscatter, since corals prefer those conditions.

Intern poster project

Intern Poster Project by Chelsea Wegner

Chelsea Wegner Poster (pdf)

On the next leg, the robotic vehicle on the ship will be used to examine some of the areas we were with high-definition cameras. You can watch the live stream here. You can also see some of the images and footage from past explorations here.
This is a short video from the 2012 expedition to the Gulf of Mexico to tempt you into tuning in for more.

Personal Log:

The people on this vessel have been blessed with adventurous spirits and exciting careers. Throughout the cruise, I heard about and then came to fully understand the difficulty of being away from family when they need us.

I would like to dedicate this last blog to my father, Tom Wichman. He passed away this morning at 80 years of age after battling more than his share of medical issues.  As I rode the ship in today I felt him beside me. Together we watched the pelicans and the boobies fly by. I am very glad I was able to take him on a “virtual” adventure to the Caribbean. He loved the pictures and the blog. I thank the NOAA Teacher at Sea program for helping me make him proud one last time.

My parents

My Parents, Tom and Kate Wichman

“To know how to wonder is the first step of the mind toward discovery” – L. Pasteur. These words decorate my classroom wall but are epitomized by the work that the NOAA Okeanos Explorer and the Office of Exploration and Research (OER) do each day.

Thank you to the Meme, the CO, XO, the science team, and the entire crew aboard the Okeanos for teaching me as much as you did and for helping me get home when I needed to be with family. I wish you all the best as you continue to explore our vast oceans! My students and I will be watching and learning from you!

I would also like to thank all of the people who followed this blog. Your support and interest proves that you too are curious by nature. Life is much more interesting if you hold on to that sense of wonder, isn’t it?

Answers to My Previous Questions of the Day Polls:

1.  Bathymetry is the study of ocean depths and submarine topography.

2. The deepest zone in the ocean is called the hadal zone, after Hades the Greek God of the underworld.

3.  It takes the vessel 19 hours and 10 minutes to make enough water for 46 people each using 50 gallons per day if each of the two distillers makes 1 gallon per minute.

4.  NOAA line offices include:

  • National Environmental Satellite, Data, and Information Service
  • National Marine Fisheries Service
  • National Ocean Service
  • National Weather Service
  • Office of Marine & Aviation Operations
  • Office of Oceanic and Atmospheric Research

5. The pressure on the a diver at 332.35m is 485 pounds per square inch!

6.  The deepest part of the Puerto Rico Trench is known as the Milwaukee Deep.

Thank you for participating!  I hope you learned something new!

Lauren Wilmoth: “Wreckish looking rock?” October 15, 2014

Posted on by laurenwilmoth

NOAA Teacher at Sea
Lauren Wilmoth
Aboard NOAA Ship Rainier
October 4 – 17, 2014

Mission: Hydrographic Survey
Geographical area of cruise: Kodiak Island, Alaska
Date: Wednesday, October 15th, 2014

Weather Data from the Bridge
Air Temperature: 4.4 °C
Wind Speed: 5 knots
Latitude: 57°56.9′ N
Longitude: 153°05.8′ W

Science and Technology Log

Thank you all for the comments you all have made.  It helps me decide what direction to go in for my next post.  One question asked, “How long does it take to map a certain area of sea floor?”  That answer, as I responded, is that it depends on a number of factors including, but not limited to, how deep the water is and how flat the floor is in that area.

To make things easier, the crew uses an Excel spreadsheet with mathematical equations already built-in to determine the approximate amount of time it will take to complete an area.  That answer is a bit abstract though.  I wanted an answer that I could wrap my head around.  The area that we are currently surveying is approximately 25 sq nautical miles, and it will take an estimated 10 days to complete the surveying of this area not including a couple of days for setting up tidal stations.  To put this in perspective, Jefferson City, TN is approximately 4.077 sq nautical miles.  So the area we are currently surveying is more than 6 times bigger than Jefferson City!  We can do a little math to determine it would take about 2 days to survey an area the size of Jefferson City, TN assuming the features are similar to those of the area we are currently surveying.

Try to do the math yourself!  Were you able to figure out how I got 2 or 3 days?

Since we’re talking numbers, Rainier surveyed an area one half the size of Puerto Rico in 2012 and 2013!  We can also look at linear miles.  Linear miles is the distance they traveled while surveying.  It takes into account  all of the lines the ship has completed.  In 2012 and 2013, Rainier surveyed the same amount of linear nautical miles that it would take to go from Newport, Oregon to the South Pole Station and back!

Area we are currently surveying.

Area we are currently surveying (outlined in red) with some depth data we have collected.

Casting a CTD (Conductivity, Temperature, and Depth) gauge.

Casting a CTD (Conductivity, Temperature, and Depth) gauge.

Monday, I went on a launch to collect sonar data.  This is my first time to collect sonar data since I started this journey.  Before we could get started, we had to cast a CTD (Conductivity, Temperature and Depth) instrument.  Sound travels a different velocities in water depending on the salinity, temperature, and pressure (depth), so this instrument is slowly cast down from the boat and measures all of these aspects on its way to the ocean floor.  Sound travels faster when there is higher salinity, temperature, and pressure.  These factors can vary greatly from place to place and season to season.

Imagine how it might be different in the summertime versus the winter.  In the summertime, the snow will be melting from the mountains and glaciers causing a increase in the amount of freshwater.  Freshwater is less dense than saltwater, so it mainly stays on top.  Also, that glacial runoff is often much colder than the water lower in the water column.  Knowing all of this, where do you think sound will travel faster in the summertime?  In the top layer of water or a lower layer of water?  Now you understand why it is so important to cast a CTD to make sure that our sonar data is accurate.  To learn more about how sound travels in water, click here.

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I’m driving the boat.

After casting our CTD, we spent the day running the sonar up and down and up and down the areas that needed to be surveyed.  Again, this is a little like mowing the lawn.  At one point, I was on bow watch.  On bow watch, you sit at the front of the boat and look out for hazards.  Since this area hasn’t been surveyed since before 1939, it is possible that there could be hazards that are not charted.  Also, I worked down in the cabin of the boat with the data acquisition/sonar tuning. Some important things to do below deck including communicating the plan of attack with the coxswain (boat driver), activating the sonar, and adjusting the sonar for the correct depth.  I helped adjust the range of the sonar which basically tells the sonar how long to listen.  If you are in deeper water, you want the sonar to listen longer, because it takes more time for the ping to come back.  I also adjusted the power which controls how loud the sound ping is.  Again, if you are surveying a deeper area, you might want your ping to be a little louder.

Eli working the sonar equipment.

Eli working the sonar equipment.

Tuesday, I helped Survey Tech Christie Rieser and Physical Scientist Fernando Ortiz with night processing.  When the launches come back after acquiring sonar data, someone has to make all that data make sense and apply it to the charts, so we can determine what needs to be completed the following day.  Making sense of the data is what night processing is all about.  First, we converted the raw data into a form that the program for charting (CARIS) can understand.  The computer does the converting, but we have to tell it to do so.  Then, we apply all of the correctors that I spoke about in a previous blog in the following order: POS/MV (Position and Orientation Systems for Marine Vessels) corrector, Tides corrector, and CTD (Conductivity, Temperature, and Depth) corrector.  POS/MV corrects for the rocking of the boat.  For the tides corrector, we use predicted tides for now, and once all the data is collected from our tidal stations, we will add that in as well.  Finally, the CTD corrects for the change in sound velocity due to differences in the water as I discussed above.

After applying all of the correctors, we have the computer use an algorithm (basically a complicated formula) to determine, based on the data, where the sea floor is.  Basically, when you are collecting sonar data there is always going to be some noise (random data that is meaningless) due to reflection, refraction, kelp, fish, and even the sound from the boat.  The algorithm is usually able to recognize this noise and doesn’t include it when calculating the location of the seafloor.  The last step is manually cleaning the data.  This is where you hide the noise, so you can get a better view of the ocean floor.  Also, when you are cleaning, you are double checking the algorithm in a way, because some things that are easy for a human to distinguish as noise may have thrown off the algorithm a bit, so you can manually correct for that. Cleaning the data took the longest amount of time.  It took a couple of hours.  While processing the data, we did notice a possible ship wreck, but the data we have isn’t detailed enough to say whether it’s a shipwreck or a rock.  Senior Tech Jackson noted in the acquisition log that it was “A wreckish looking rock or a rockish looking wreck.”  We are going to have the launches go over that area several more times today to get a more clear picture of is going on at that spot.

H12662_DN195_2804 This is an example of noisy data. In this case, the noise was so great that the algorithm thought the seafloor went down 100 extra meters. Manually cleaning the data can adjust for this so our end product is accurate. The actual seafloor in this case is the relatively straight line at about 100 meters depth.

This is an example of noisy data. In this case, the noise was so great that the algorithm thought the seafloor went down 100 extra meters. Manually cleaning the data can adjust for this so our end product is accurate. The actual seafloor in this case is the relatively straight line at about 100 meters depth.

Personal Log 

Monday was the most spectacular day for wildlife viewing!  First, I saw a bald eagle.  Then, I saw more sea otters.  The most amazing experience of my trip so far happened next.  Orcas were swimming all around us.  They breached (came up for air) less than 6 feet from the boat.  They were so beautiful!  I got some good pictures, too!  As if that wasn’t good enough, we also saw another type of whale from far away.  I could see the blow (spray) from the whale and a dorsal fin, but I am not sure if it is was a Humpback Whale or a Fin Whale.  Too cool!

Bald Eagle Sighting!

Bald Eagle Sighting!

Sea otter

Sea otter

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Orca!

Very close orca!

Very close orca!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Did You Know? 

Killer whales are technically dolphins, because they are more closely related to other dolphins than they are to whales.

Lauren Wilmoth: Shore Party, October 12, 2014

Posted on by laurenwilmoth

NOAA Teacher at Sea
Lauren Wilmoth
Aboard NOAA Ship Rainier
October 4 – 17, 2014

Mission: Hydrographic Survey
Geographical area of cruise: Kodiak Island, Alaska
Date: Sunday, October 12, 2014

Weather Data from the Bridge
Air Temperature: 1.92 °C
Wind Speed: 13 knots
Latitude: 58°00.411′ N
Longitude: 153°10.035′ W

Science and Technology Log

The top part of a tidal station. In the plastic box is a computer and the pressure gauge.

The top part of a tidal station. In the plastic box is a computer and the pressure gauge.

In a previous post, I discussed how the multibeam sonar data has to be corrected for tides, but where does the tide data come from?  Yesterday, I learned first hand where this data comes from.  Rainier‘s crew sets up temporary tidal stations that monitor the tides continuously for at least 30 days.  If we were working somewhere where there were permanent tidal station, we could just use the data from the permanent stations.  For example, the Atlantic coast has many more permanent tidal stations than the places in Alaska where Rainier works.  Since we are in a more remote area, these gauges must be installed before sonar data is collected in an area.

We are returning to an area where the majority of the hydrographic data was collected several weeks ago, so I didn’t get to see a full tidal station install, but I did go with the shore party to determine whether or not the tidal station was still in working condition.

A tidal station consists of several parts: 1) an underwater orifice 2) tube running nitrogen gas to the orifice 3) a nitrogen tank 4) a tidal gauge (pressure sensor and computer to record data) 5) solar panel 6) a satellite antennae.

Let me explain how these things work.  Nitrogen is bubbled into the orifice through the tubing.  The pressure gauge that is located on land in a weatherproof box with a laptop computer is recording how much pressure is required to push those bubbles out of the orifice.  Basically, if the water is deep (high tide) there will be greater water pressure, so it will require more pressure to push bubbles out of the orifice.  Using this pressure measurement, we can determine the level of the tide.  Additionally, the solar panel powers the whole setup, and the satellite antennae transmits the data to the ship.  For more information on the particulars of tidal stations click here

Tidal station set-up. Drawing courtesy of Katrina Poremba.

Tidal station set-up. Drawing courtesy of Katrina Poremba.

Rainier is in good hands.

Rainier is in good hands.

The tidal station in Terror Bay did need some repairs.  The orifice was still in place which is very good news, because reinstalling the orifice would have required divers.  However, the tidal gauge needed to be replaced.  Some of the equipment was submerged at one point and a bear pooped on the solar panel.  No joke!

After the tidal gauge was installed, we had to confirm that the orifice hadn’t shifted.  To do this, we take manual readings of the tide using a staff that the crew set-up during installation of the tidal station.  To take manual (staff) observations, you just measure and record the water level every 6 minutes.   If the manual (staff) observations match the readings we are getting from the tidal gauge, then the orifice is likely in the correct spot.

Just to be sure that the staff didn’t shift, we also use a level to compare the location of the staff to the location of 5 known tidal benchmarks that were set when the station was being set up as well.  As you can see, accounting for the tides is a complex process with multiple checks and double checks in place.  These checks may seem a bit much, but a lot of shifting and movement can occur in these areas.  Plus, these checks are the best way to ensure our data is accurate.

Micki and Adam setting up the staff, so they can make sure it hasn't moved.

ENS Micki and LTJG Adam setting up the staff, so the surveyor can make sure it hasn’t moved.

Mussels and barnacles on a rock in Terror Bay.

Mussels and barnacles on a rock in Terror Bay.

Leveling to ensure staff and tidal benchmarks haven't moved.

Leveling to ensure staff and tidal benchmarks haven’t moved.

 

 

 

 

 

 

 

 

Today, I went to shore again to a different area called Driver Bay.  This time we were taking down the equipment from a tidal gauge, because Rainier is quickly approaching the end of her 2014 season.  Driver Bay is a beautiful location, but the weather wasn’t quite as pretty as the location.  It snowed on our way in!  Junior Officer Micki Ream who has been doing this for a few years said this was the first time she’d experienced snow while going on a tidal launch.  Because of the wave action, this is a very dynamic area which means it changes a lot.

In fact, the staff that had been originally used to manually measure tides was completely gone, so we just needed to take down the tidal gauges, satellite antenna, solar panels, and orifice tubing.  The orifice itself was to be removed later by a dive team, because it is under water.  After completing the tidal gauge breakdown, we hopped back on the boat for a very bumpy ride back to Rainier.  I got a little water in my boots when I was hopping back aboard the smaller boat, but it wasn’t as cold as I had expected.  Fortunately, the boat has washers and driers.  It looks like tonight will be laundry night.

Raspberry Bay

Driver Bay

Personal Log 

The food here is great!  Last night we had spaghetti and meatballs, and they were phenomenal.  Every morning I get eggs cooked to order.  On top of that, there is dessert for every lunch and dinner!  Don’t judge me if I come back 10 lbs. heavier.  Another cool perk is that we get to see movies that are still in the theaters!  They order two movies a night that we can choose from.  Lastly, I haven’t gotten seasick.  Our transit from Seward to Kodiak was wavy, but I don’t think it was as bad as we were expecting.  The motion sickness medicines did the trick, because I didn’t feel sick at all.

Did You Know? 

NOAA (National Oceanic and Atmospheric Administration) contains several different branches including the National Weather Service which is responsible for forecasting weather and issuing weather alerts.

Animal Spotting

There are sea otters everywhere!

Sea otter (Enhydra lutris) sighting.

Sea otter (Enhydra lutris) sighting.

 

Lauren Wilmoth: Safety First, October 8, 2014

Posted on by laurenwilmoth

NOAA Teacher at Sea
Lauren Wilmoth
Aboard NOAA Ship Rainier
October 4 – 17, 2014

Mission: Hydrographic Survey
Geographical area of cruise: Kodiak Island, Alaska
Date: Wednesday, October 8, 2014

Weather Data from the Bridge
Air Temperature: 3.82 °C
Wind Speed: 6.1 knots
Latitude: 60°07.098′ N
Longitude: 149°25.711′ W

Science and Technology Log

Junior Officer Micki Ream diving in Thumb's Cove. Photo courtesy of Junior Officer Katrina Poremba.

Junior Officer Micki Ream diving in Thumb’s Cove. Photo courtesy of Junior Officer Katrina Poremba.

The launch that I participated in on Tuesday was awesome!  We went to an area called Thumb’s Cove.  I thought the divers must be crazy, because of how cold it was.  When they returned to the boat from their dive, they said the water was much warmer than the air.  The water temperature was around 10.5°C or 51°F while the air temperature was hovering right above freezing.  One diver, Katrina, took an underwater camera with her.  They saw jellyfish, sea urchins, and sea stars.

The ride to and from the cove was quite bouncy, but I enjoyed being part of this mini-adventure!  Later that day, we did what is called DC (Damage Control) familiarization.  Basically, we practiced what do in case of an emergency.  We were given a pipe with holes in it and told to patch it with various objects like wooden wedges.  We also practiced using a pump to pump water off of the ship if she were taking on water.  Safety drills are also routine around here.  It’s nice to know that everyone expects the best, but prepares for the worse.  I feel very safe aboard Rainier.

Seastar from Katrina Poremba from the dive at Thumb's Cove.

Sea star and anemones taken by diver Katrina Poremba at Thumb’s Cove.

This source diagram from Kodiak Island shows when the latest data was collected in for an area. We will be working near the red x.

This source diagram from Kodiak Island shows when the latest data was collected in for an area. We will be working near the red x.

Today, I got a chance to meet with the CO (Commanding Officer), and he explained the navigational charts to me.  Before the ship leaves the port, there must be a navigation plan which shows not only the path the ship will take, but also the estimated time of arrival to various points along the way.  This plan is located on the computer, but also, it must be drawn on a paper chart for backup.

This illustrates again how redundancy, as I discussed in my last blog post, is a very important part of safety on a ship.  Every ship must have up-to-date paper charts on board.  These charts get updated with the information collected from the hydrographic surveys.  The ocean covers more than 70% of our planet which is why Rainier‘s mission of mapping the ocean is so important.  There are many areas in Alaska where the only data on the depth of the water was collected before sonar technology was used.  In fact, some places the data on the charts comes from Captain Cook in the 1700s!  If you look at the chart below the water depth is measured in fathoms.  A fathom is 6 feet deep.  Places that are less than 1 fathom deep have a 05 where the subscript indicates how deep the water is in feet.

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One of the nautical charts that will help Rainier navigate back to its home port in Newport, Oregon. Notice the ocean depth marked in fathoms.

CO (Commanding Officer) and me after discussing nautical charts.

CO (Commanding Officer) and me after discussing nautical charts.

Today, I also spoke with the AFOO (Acting Field Operations Officer), Adam, about some work that he had been doing on Rainier‘s sister ship NOAA Fairweather.  One project they are working on is connecting hydrographic data to fish distribution and abundance mapping.  Basically, they want to find out if it is possible to use sonar data to predict what types of fish and how many you will find in a particular location

They believe this will work, because the sonar produces a back scatter signature that can give you an idea of the sea floor composition (i.e. what it is made of).  For instance, they could tell you if the sea floor is rocky, silty, or sandy using just sonar, as opposed to, manually taking a bottom sample.  If this hydrographic data is integrated with the data collected by other NOAA ships that use trawl nets to survey the fish in an area, this would allow NOAA to manage fisheries more efficiently.  For example, if you have map that tells you that an area is likely to have fish fry (young fish) of a vulnerable species, then NOAA might consider making this a protected area.

Personal Log

Artwork from the SeaLife Center created by high school students to illustrate how much trash ends up on our beaches.

Artwork from the SeaLife Center created by high school students to illustrate how much trash ends up on our beaches.

On Tuesday, I had a little extra time in the afternoon, so I decided to ride my bike down to the Alaska SeaLife Center which is a must-see if you ever find yourself in Seward.  There were Harbor Seals (Phoca vitulina), Stellar Sea Lions (Eumetopias jubatus), Puffins (Genus Fratercula), Pacific Salmon (Genus Oncorhynchus) and much more.  I really appreciated that the SeaLife Center focused on both conservation and on organisms that live in this area.  A local high school even had their art students make an exhibit out of trash found on the beach to highlight the major environmental issue of trash that finds its way to the ocean.

Can you think a project we could do that would highlight a main environmental concern in Eastern Tennessee?  I also thought is was really interesting to see the Puffins dive into the water.  The SeaLife Center exhibit explained about how Puffin bones are more dense than non-sea birds.  These higher density bones are an adaptation that helps them dive deeper.

Puffin at the Alaska SeaLife Center

Puffin at the Alaska SeaLife Center

I officially moved into the ship today.  Prior to that, I was staying at a hotel while they were finishing up repairs.  We are expected to get underway on Friday afternoon.  I am staying in the princess suite!  It is nice and cozy.  I have all of the essentials.  I have a desk, bunk beds, 2 closets, and one bathroom (head).

Rainier, my home for the next week and a half, in Seward Alaska

Rainier, my home for the next week and a half, in Seward, Alaska

My berthing area (where I sleep) nicknamed "The Princess Suite."

My berthing area (where I sleep) nicknamed “The Princess Suite.”

 

Did You Know? 

Junior Officers get homework assignments just like you.  At the navigation briefing today, the CO (Commanding Officer) told the Junior Officers what that they needed to review several documents before going through the inside passage (a particularly tricky area to navigate).  He is expecting them to lead different parts of the next navigation briefing, but he isn’t going to tell them which part they are leading until right before. Therefore, it is important that they know it all!  It’s a little like a pop quiz and presentation in one.

Word of the Day

Bathymetry – the study of the “beds” or “floors” of bodies of water.