Brandy Hill: What Lies Beneath the Surface, July 1, 2018

NOAA Teacher at Sea

Brandy Hill

Aboard NOAA ship Thomas Jefferson

June 25, 2018 –  July 6, 2018

 

Mission: Hydrographic Survey- Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 1, 2018

 

Weather Data from the Bridge

Latitude: 29° 10.1’ N

Longitude: 093° 54.5’ W

Visibility: 10+ NM

Sky Condition: 3/8

Wind: 16 kts

Temperature:

Sea Water: 29.4° C

Air: 27° C

 

Science and Technology Log

At this point I have been able to understand more of the sonar technology taking place during the survey aboard the Thomas Jefferson. The ship uses two types of sonar: multibeam and side scan. Both work together transmitting and receiving sound pulses to and from the ocean floor. This provides a multispectral analysis.

Julia Wallace, a physical scientist, works at the sonar acquisition station. This requires a large amount of multitasking as she communicates with the bridge (ship steering deck), watches the safety cameras, and makes sure both sonar devices are working correctly.

Julia Wallace, a physical scientist, works at the sonar acquisition station. This requires a large amount of multitasking as she communicates with the bridge (ship steering deck), watches the safety cameras, and makes sure both sonar devices are working correctly.

Multibeam sonar is located underneath the hull of the ship. Multibeam is used to detect bathymetry (the depth of the ocean floor). Multibeam backscatter (reflected wave energy) gives a reading of the surface intensity. For example, a strong signal would mean a harder surface like rock or pipeline. With multibeam sonar, you can also adjust the sound wave frequency. For example, high frequency (primarily used during this survey in the Gulf of Mexico) is used for shallower waters allowing for higher resolution images. Images from multibeam have a color gradient to allow for clear vision of contours and depth differences. One way surveyors aboard the TJ may use backscatter images is to determine areas where bottom sampling might be applicable.

A NOAA ship using mulitbeam sonar. (Courtesy of NOAA)

A NOAA ship using mulitbeam sonar. (Courtesy of NOAA)

Bathymetry acquired using multibeam echosounder layered over a nautical chart.  Blue and green wave lengths penetrate further in water, so the coloring corresponds to this observation. This poster is from a previous Thomas Jefferson hydrographic survey near Savannah, Georgia. (Prepared by CHST Allison Stone)

Bathymetry acquired using multibeam echosounder layered over a nautical chart.  Blue and green wave lengths penetrate further in water, so the coloring corresponds to this observation. This poster is from a previous Thomas Jefferson hydrographic survey near Savannah, Georgia. (Prepared by CHST Allison Stone)

3D bathymetry imagery from the Okeanos Explorer. (NOAA)

3D bathymetry imagery from the Okeanos Explorer. (NOAA)

A close-up view of multibeam data. The third window down shows multibeam backscatter.

A close-up view of multibeam data. The third window down shows multibeam backscatter.

The side scan sonar is used alongside multibeam to provide black and white scans of images. Like multibeam backscatter, side scan measures the intensity of the sound returning from the sea floor. For example, a side scan return with high intensity could indicate a difference in material like pipeline or a wreck. A low intensity value could mean that the side scan sonar waves have reached a muddy substrate. Julia used the analogy of a tennis ball being bounced against a wall of different materials. For example, the tennis ball hitting a concrete wall would bounce back with higher intensity than one being bounced against a soft wall. Side scan sonar is very effective at detecting features that protrude off the sea floor, and for shallow water surveys, typically can see farther and cover a greater area the sea floor than multibeam echosounders alone.

The side scan sonar sensor is located on a torpedo-shaped “towfish” and pulled behind the boat. When viewing side scan images, surveyors typically look for the acoustic shadow cast by a feature protruding off the sea floor. By measuring the length of the acoustic shadow, hydrographers can determine whether the feature requires additional investigation. For example, the outline of a shipwreck, bicycle, or pipeline. However, it can also detect mammals like dolphins or schools of fish.

Diagram of side scan sonar. (Courtesy of thunder bay 2001, Institute for Exploration, NOAA-OER)

Diagram of side scan sonar. (Courtesy of thunder bay 2001, Institute for Exploration, NOAA-OER)

The Thomas Jefferson sidescan sonar on deck.

The Thomas Jefferson sidescan sonar on deck.

In the early morning, the sidescan sonar picked up the image of an incorrectly charted shipwreck. Height is estimated using the "shadow" of the wreck.

In the early morning, the sidescan sonar picked up the image of an incorrectly charted shipwreck. Height is estimated using the “shadow” of the wreck.

Sidescan sonar imagery layered on a nautical chart. It is important to remember that sidescan data does not account for depth, it is a measure of differences in sea floor substrate.

Sidescan sonar imagery layered on a nautical chart. It is important to remember that sidescan data does not account for depth, it is a measure of differences in sea floor substrate.

Look closely and you can see arc lines in the sidescan imagery. Lt. Anthony Klemm explains that these arcs are from ships dragging anchor and stirring up the sea floor.

Look closely and you can see arc lines in the sidescan imagery. Lt. Anthony Klemm explains that these arcs are from ships dragging anchor and stirring up the sea floor.

While this is happening, surveyors are also towing a MVP or Moving Vessel Profiler to capture information about the water column. This is important because multiple factors in the water column need to be corrected in order for accurate sonar calculations. For example, the speed of sound in salt water is roughly 1500 m/s but may change while the ship is traveling over different parts of the sea floor or passing through a thermocline (steep temperature gradient) or halocline (steep salinity gradient). The MVP is similar to the CTD used on the launch boat (see previous post), but the MVP allows the ship to continue moving at about 10 knots (average survey speed), while the CTD must be cast when the ship is stationary.

Information from the Moving Vessel Profiler. From left to right, the MVP tracks sound speed, temperature, and salinity in relation to depth.

Information from the Moving Vessel Profiler. From left to right, the MVP tracks sound speed, temperature, and salinity in relation to depth.

For more information on multispectral analysis and sonar, see these resources:

https://oceanexplorer.noaa.gov/explorations/09bermuda/background/multibeam/multibeam.html

https://oceanservice.noaa.gov/education/seafloor-mapping/how_sidescansonar.html

Personal Log

One of my goals in the classroom is to teach students to be comfortable making and learning from mistakes. Making mistakes in math and science is common and welcome because they lead to great discussion and future change. Often, my sixth graders get discouraged or so caught up in failure that they become paralyzed in making further attempts. While aboard the Thomas Jefferson, I have witnessed several aspects not go according to plan. I think these experiences are important to share because they provide real-life examples of professionals coming together, learning from mistakes, and moving forward.

Around 4:00 am, the towfish side scan sonar became entangled with the MVP. This was a horrendous disaster. The crew spent about 16 hours contemplating the issue and collecting data using the multibeam only, which is less than ideal.  One of XO LCDR McGovern’s many roles aboard the ship is to serve as the investigator. She reviewed tapes of the early morning, talked with the crew, and later held a debrief with all involved. When something like this happens, the ship must write a clear incident report to send to shore. There were many questions about why and how this happened as well how to best proceed. In the end, the towfish and MVP were untangled with no damage present to the sensor. Within the same day, both were cast out and back in use.

I find this to be an astounding example of perseverance and teamwork. Despite being disappointed and upset that a critical tool for collecting accurate data was in dire shape, the crew came up with a plan of action and executed. Part of the engineering and scientific processes include evaluation and redesign. Elements of the sea and a center drift of the side scan lead to a documented new plan and refiguring the process so that this is unlikely to happen again.

Lt. Charles Wisotzsky's sketch of the complications with launching both the sidescan sonar (which tends to centerline) and MVP towfish with a current coming from port side.

Lt. Charles Wisotzsky’s sketch of the complications with launching both the sidescan sonar (which tends to centerline) and MVP towfish with a current coming from port side.

This camera image captures the entanglement of the sidescan sonar and MVP.

This camera image captures the entanglement of the sidescan sonar and MVP.

Peaks

+Saw a tuna eat a flying fish

Flying Fish. (www.ocean.si.edu)

Flying Fish. (www.ocean.si.edu)

+There is a large sense of purpose on the ship. Despite complex sleep schedules to enable 24 hour operations with a smaller crew, people are generally happy and working hard.

+ There seems to be an unlimited supply of ice cream in the ice cream freezer. Junior Officer, ENS Garrison Grant introduced me to a new desert- vanilla ice cream, a scoop of crunchy peanut butter, and chocolate syrup. I also found the rainbow sprinkles.

Trevor Hance: Water, Water Everywhere… Time for a Bath(ology), June 17, 2015

NOAA Teacher at Sea
Trevor Hance
Aboard R/V Hugh R. Sharp
June 12 – 24, 2015

Mission: Sea Scallop Survey
Geographical area: New England/Georges Bank
Date: June 17, 2015

Science and Technology Log

We’re now at the half-way point of this journey and things continue to run well, although the weather has picked up a bit.  I mentioned to one of my fellow crew members that the cloud cover and cool weather reminded me of “football and gumbo” and he said, “Yeah… around here, we just call it ‘June’.” Touché, my friend.

“June,” huh…. Hey, this guy got jokes!

I am continually impressed by both the ship’s crew and the science party’s ability to identify work that needs to be done and set a course towards continued, uninterrupted success of the mission.  The depth and breadth of knowledge required to navigate (all puns intended!) extended scientific expeditions requires professional dedication matched with a healthy sense of humor, and it is truly an honor to be invited to participate in this unique opportunity for teachers. I am learning volumes each day and will forever treasure this wonderful adventure.  Thanks again, NOAA!

Remember students, don’t kiss frogs.  Gigantic lobsters?  Well…

Remember students, don’t kiss frogs. Gigantic lobsters? Well…

Science and Math

My instructional path is rooted in constructivist learning theory, and I work diligently to secure resources for my students to have authentic, project-based learning experiences where they determine budgets, necessary tools and physically build things that we use on our campus.

Most recently, my math class designed and built some raised mobile garden beds that will be used by the youngest students on our campus as well as those with unique mobility challenges.  Through these hands-on learning experiences, I expect my students to develop a solid working-level of mathematic and scientific literacy, and I’m proud of the fact that when I present a new concept, my students never ask “When am I going to have to use this in real life?”

My students doing math.  More doing, more learning...

My students doing math. More doing, more learning…

I believe fifth grade students can understand any science concept, and I am seeing additional opportunities to test that idea using what I learn out here, so thought I’d share a few examples of some of the things I’ve learned as they will be presented in my G5 classroom starting this fall.

With a basic understanding of the objective for this survey presented in the last blog, I’ll explore some of the geographic and hydrodynamic concepts associated with this part of the world in this post.  In the next blog, I’ll dive deeper into a specific study of scallops and lobsters, and in the fourth post I’ll talk more about the effects of current marine/fisheries management practices, with particular focus on those relating to closed areas (somewhat akin to the Balcones Preserve behind our campus.)

This is a Sculpin Longhorn, distantly related to BEVO

This is a Sculpin Longhorn, distantly related to BEVO

Georges Bank…water, water everywhere, time for a bath(ology)

We all know that water is central to our survival, and “playing” with water provides a strong anchoring point (am I pushing the puns too far?) for understanding systems relationships as students progress through their educational path.  For the past couple of years, I have been accepted to participate in a “Scientist in Residence” program offered through the University of Texas’ Environmental Science Institute, which pairs local teachers with a graduate level scientist for an entire school year.  In my first year, I was paired with (recently graduated) Dr. Kevin Befus, whose work focuses on hydrology.  Through my work with Kevin (note to students:  I can call him Kevin, you call him Dr. – he’s earned it!), I learned much about water and the importance of “flow,” and when you understand some of the “flow” relating the world’s most productive fishery, Georges Bank, I think you’ll agree with me.

Dolphin splashin’, getting everybody all wet

Dolphin splashin’, getting everybody all wet

Georges Bank is an oval shaped shoal, which is essentially a submerged island that lies about 60 miles off the coast of Cape Cod, and covers nearly 150 square miles.  “The Bank,” or “Georges,” as many people aboard the vessel refer to it, is only recently submerged (i.e. – within the last 100,000 years).  As recently as ten years ago scientists found mastodon tusks on the Bank, and legend holds that in the early 1900s, fishing vessels would stop on an island in Georges Bank (now submerged to about 10m) and play baseball (note:  I have yet to find a bat and ball aboard the Sharp, but hope remains!)

Just like good soil helps support plant life, good water helps support marine life, and the key to the abundant life along Georges Bank lies in the nutrient rich water that is pushed towards the surface as it approaches Georges from the north and south.  On three sides of Georges Bank, the sea floor drops dramatically.  To the north sits the Gulf of Maine, which drops to approximately 1000m deep, and to the east and south, the Atlantic Ocean quickly reaches depths of over 2500m.

NASA photo

NASA photo

Almost all water enters Georges Bank from the north via the Gulf of Maine. The Gulf of Maine is fed via natural river discharges (including those from the Damariscotta and Merrimack Rivers) and the Labrador Currents that hug the coastline south around Nova Scotia before turning west into the Gulf of Maine.  Water also enters the Gulf of Maine through The North Channel on the east side of Maine from the Gulf Stream and that very salty, warm water is important, particularly when it comes to the biology of Georges Bank (as we’ll look at more in the next blog entry.)

Much of the water exiting the Gulf of Maine enters The Great South Channel, which is something like a “river in the ocean” that runs between Cape Cod and Georges Bank.  Deep within the Channel is a “sill,” which is a type of landform barrier, similar to a fence that doesn’t reach up to the surface.  The sill rises quickly from the sea floor and extends across the Great South Channel, effectively blocking the deepest, densest water, resulting in strong, deep, cold currents that are pushed east around the outer edge of Georges Bank before returning towards the United States’ east coast in a clockwise path, resembling “from 11 until 7” on a clock’s face.  Yes students, I do mean an analog clock!

After the deep currents make their way back to southern Massachusetts, they head south on the Longshore Coastal Current, which is like a “jet” of water that sprints southbound right along the eastern United States coastline (note:  those of us from the Gulf Coast frequently hear friends wonder why the Atlantic Ocean is so cold when they visit Florida, and this is partly why!)

At this point, I’m going to take a moment and speak directly to my students:   Just as the water flows into and mixes at Georges Bank from different directions, I’m hopeful that your thoughts are starting to swirl as you recognize the connection to concepts we have studied relating to energy, weather and climate, mixtures and solutions, salinity (and conductivity/resisitivity) and density (and buoyancy) – they are all evident and part of this story! And YES — this WILL be on the test!

b3g - 4 shells

I pulled these four scallops from one of our dredges to show the unique, beautiful patterns we find while sorting

While the deep-water currents that circle around Georges Bank’s edges exist year-round, in the winter there isn’t tremendous difference in the three primary water measurements (“Conductivity, Temperature and Density,” or “CTD”) between the water in The Great South Channel versus that sitting atop Georges Bank.  As you might recognize, in normal conditions, there shouldn’t be much cause for warm or fresh water to be added to the area during the cold winter months, as our part of the world seems to slow down and a goodly amount of water freezes.  In the spring, however, the northern hemisphere warms and ice melts, adding lots of warmer-and-fresh water to the Labrador Current and river discharges I mentioned above, ultimately sending that water south towards Georges Bank.  At this point, things get really interesting…

The new, warmer water is less dense than the deeper water. The warm and cold water ultimately completely decouple and become fully stratified (i.e. – there are two distinct layers of water sitting one on top of the other.)  The stratified layers move in separate currents:  the deeper, colder, more-dense layer continues its clockwise, circular path along the outer edge of the Bank before heading south; and the top, “lighter” layer gets “trapped” in a clockwise “gyre,” which is the formal word for a swirling “racetrack” of a current that sits on the Bank. This gyre goes full-circle atop Georges Bank approximately 2.5 to 3 times per summer season.

Bigelow and Bumpus:  Going with the Flow

The stratified/gyre relationship was confirmed almost 90 years ago by Henry Bigelow (note: those familiar with NOAA will no doubt recognize his name for several reasons, including the fact that a ship in the NOAA fleet is named after him).  Essentially, Bigelow used a type of “weighted-kite-and-floating-buoy” system to observe and confirm the two layers.  Bigelow’s “floating-buoy” was tied to the “weighted-kite” (actually called a drogue) and set at various depths, with each depth tested as an independent variable.  Once set, Bigelow drogued the water, chasing after the floats-and-kites, ultimately confirming that the stratified currents did in fact exist.  When you look at our dry lab here on the Sharp, complete with dozens of computers constantly monitoring hundreds of variables, Bigelow’s paper-and-pencil study aboard a 3-masted schooner is pretty awesome, and makes me feel a little lazy!

Source:  Bigelow, HB (1927): Physical Oceanography of the Gulf of Maine

Source:  Bigelow, HB (1927): Physical Oceanography of the Gulf of Maine

In a different study conducted later in the 1900s that perhaps might evoke romantic images of the sea, physical oceanographer Dean Bumpus performed a study similar to Bigelow’s, but in a slightly different fashion. Over the course of a few years, Bumpus put notes in over 3,000,000 test-tubes and set them adrift from Georges Bank.  The notes provided instructions on how to contact Bumpus if found, and he used the returned notes to determine things like current speed and direction.  While I’m not sure if Bumpus also used this methodology to find true love, the experiment did reinforce the idea of the currents that exist around Georges Bank!

b3i - Bumpus

Yep, it’s pretty cool to hear stories of those old-school scientists getting their names in the history books by just going with the flow.

Gulf Coast Style Kicking It Up North

One other unique hydrologic influence on Georges Bank relates to “meanderings” by the Gulf Stream.  Normally, as the Longshore Coastal Current sprints southbound along the east coast faster than a recent retiree snowbirding to Florida, a little further offshore, the Gulf Stream is heading north, bringing with it warm water.  As the water moves towards Georges Bank, the bank does its thing, acting as a berm (my BMX students might better identify with that term), and pushes that water off towards the east.  The warm water ultimately reaches England, and when mixed with the cool air there, causes the cloudy conditions and fog we frequently associate with life in the U.K.

Shark!

Shark!

The unique aspect of this relationship occurs when, from time to time, the Gulf Stream misses the turn and a “slice” of the Gulf Stream breaks away.  When this happen, the split portion spins in a counter clockwise fashion and breaks into Georges Bank, bringing with it warm water — and all the chemistry and biology that comes with it.  More on that later…

Water Summary 

So, in a nutshell, that’s the system.  The coldest water at the headwaters of rivers in Maine and that in the arctic freezes and becomes ice.  Deep water doesn’t have access to the warm sunlight, so it stays colder than the warm, less dense water at the surface that is hoping for the chance to boil over and soar up into the skies as water vapor.  Newton tells us that things like to stay still, but will stay in motion once they get started.  Things like sills and submerged islands get in the way of flowing water (yeah, more Newton here), resulting in mixtures and unique current patterns.

From a biological standpoint, the traditional currents associated with Georges Bank bring the deep, nutrient rich waters to the surface. As that water is pushed to the surface, algae and phytoplankton grow in great numbers.  Phytoplankton attracts zooplankton, fish larvae eat the zooplankton, and eventually, “circle gets a square,” the trophic pyramid is complete, and nature finds its equilibrium.

If only it was that easy, right?

Unfortunately, the frequency of warmer weather over the past century has had an impact on the ecology of Georges Bank.  Scientists have noticed more warm water from the north as ice continues to melt and increased frequency of the Gulf Stream meandering from the south. I’m told that 20 years ago, Red Hake were rare here, but I’ve noticed very few of our dredges where Red Hake weren’t at least the plurality, if not majority, of fish we caught.  As Mr. Dylan says, “the times, they are a changin’.”

Okay.  That’s it!  Congratulations students! You have passed Oceanography: Hydrodynamics Short Course 101 and it is time to move on to Oceanography:  Shellfish Biology 101, which we will cover in the next blog.

My students get scribbled maps like this from me all the time. I didn’t draw this one, but it did make me feel good about my methods!

My students get scribbled maps like this from me all the time. I didn’t draw this one, but it did make me feel good about my methods!

Lagniappe:  Dr. Scott Gallager

My students and friends know that I am continually working to learn new things.  I am surrounded by experts on this cruise and I need to go ahead and admit it:  I feel sorry for these folks because they are trapped and can’t escape the questions I’ll wind up asking them about their incredibly interesting work!

As I mentioned earlier, depth of knowledge is important to success of these missions, but, breadth is equally important.  Addressing challenges and solving problems from different perspectives is essential, and it sure would be nice to have a Boy Scout out here.  Oh wait, we actually have a long time Scout Master among us, Dr. Scott Gallagher.  There, I feel better already…

Scott is a scientist at the Woods Hole Oceanographic Institution (“WHOI”), where his work focuses on biological and physical interactions in oceanography, which can perhaps be a little better explained as “working to understand the physical properties and processes of the ocean that impact biological abundance and populations (aka – distributions).”  In other words, “where are the scallops, how many are there, and why are they there and at that number?”

From a scientific perspective, there are three primary controls to analyze when studying shellfish populations:  the total amount of larvae spawned; the transportation, or “delivery”, of the larvae through the water column to the place where they settle; and, post-settlement predatory relationships (aka – the sea stars, crabs, and humans all out to feast on these delicious creatures)… Seems like an easy-peasy career, right? (I kid. I kid.)

This is a shot of the specimen count in the wet lab

This is a shot of the specimen count in the wet lab

Scott cut his teeth as an undergrad at Cornell, starting off in electrical engineering, and ultimately earning degrees in both pre-med and environmental science (see, I told you he could see things from a variety of perspectives!).  In his environmental science courses, Scott studied the Seneca and Cayuga Lakes, and after graduating from Alfred University/Cornell University, moved on and earned a master’s degree in Marine Biology at the University of Long Island.  Over the next several years, he worked at Woods Hole as a research assistant, first working in bivalve (shellfish) ecology, and quickly moving up through the ranks to research specialist.  After a couple of years at WHOI, the magnitude and awesome wonder of the life in our oceans presented Scott with more questions than answers, and he realized it was time to return to school and obtain his PhD so he could start answering some of the questions swimming around in his head (okay, no more puns, I promise).

In our discussion, Scott described the challenge of decoupling the biological processes of the ocean as a fascinating mystery novel that never ends, and never allows you to put the book down or stop turning the pages to see what comes next.  After only a week out here with these good folks, it is evident that passion and curiosity exists in each of them, and it is really cool to feel their continued excitement about their work.

Our live aquarium

Our live aquarium

Aboard the ship, I’ve been fortunate to spend some time working with Scott in the wet-lab, where he helps conduct a more intensive study of a sample of 5-7 scallops from each dredge, according to survey protocol: taking photos, measuring the scallop size and weight, and recording whether it is male or female.

While the survey work is the mission of this cruise, it was the development and operational support for the HabCam that really got Scott working aboard these cruises, and members of his team are aboard each of the three legs every summer to participate in the survey work and provide technical assistance for the HabCam.  I think of my time driving the HabCam of what it must be like to explore Mars with Curiosity.

In addition to his mission-specific field-work, Scott has set up an onboard live aquarium in one part of the deck, using nothing more than an air hose, fresh sea water, and a tote.  The aquarium is a temporary home for many of the unique species we’ve caught on our dredge.  Most species are only kept long enough for me to nerd-out and take some photos, and it has been very interesting to see the interaction of the animals in the confined habitat that would normally only be seen on the sea floor.

Photoblog:

The pasta-looking stuff on the top of the clam shell are wavedwelk eggs. You can see a black-and-white wavedwelk poking out of the shell just to the right of the clam

The pasta-looking stuff on the top of the clam shell are wavedwelk eggs. You can see a black-and-white wavedwelk poking out of the shell just to the right of the clam

Sea urchins.  We catch many of these.  Zoom in on the one on the right.  Yeah, that’s its mouth.  Life’s at sea is tough!

Sea urchins. We catch many of these. Zoom in on the one on the right. Yeah, that’s its mouth. Life’s at sea is tough!

An ocean pout.  They crush sand dollars and eat them for breakfast.

An ocean pout.  They crush sand dollars and eat them for breakfast.

The smaller birds were enjoying that fish until the big dog bombed them and stole it away. Katie said it was cleptoparasitism; Fancy Nancy would approve.

The smaller birds were enjoying that fish until the big dog bombed them and stole it away. Katie said it was cleptoparasitism; Fancy Nancy would approve. 

Barnacles growing atop this scallop.  I think this was one of the designs tossed around for NASA’s recent “UFO” launch

Barnacles growing atop this scallop.  I think this was one of the designs tossed around for NASA’s recent “UFO” launch

It’s remarkable watching these guys zig-and-zag through rough seas, their wings not ever touching the water, but sometimes too close to it to see light peeking through from the other side

It’s remarkable watching these guys zig-and-zag through rough seas, their wings not ever touching the water, but sometimes too close to it to see light peeking through from the other side

I kept looking for a button to push and see if it would sing “Feliz Navidad”

I kept looking for a button to push and see if it would sing “Feliz Navidad”

Stars on the water

Stars on the water

Don't be a skater-hater

Don’t be a skater-hater

Dredge playlist:  Metallica, Dierks Bentley, Spoon, The National

Special thanks to Dr. Gallager for his help with this one.

Okay, that’s it, class dismissed…

Mr. Hance

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

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

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!

Theresa Paulsen: Preparing to Explore the Ocean Floor, March 9, 2015

NOAA Teacher at Sea
Theresa Paulsen
Preparing to Board NOAA Ship Okeanos Explorer
March 16 – April 3, 2015

Mission:  Caribbean Exploration (Mapping)
Geographical Area of Cruise:  Caribbean Trenches and Seamounts
Date: March 9, 2015

Personal Log

If you could have any super power imaginable, what would it be?  Growing up, my son asked me this question numerous times as we walked our dog.  While he pondered the advantages of flight, invisibility, or spontaneous combustion, my answer was always the same.  I want Aquaman’s powers (but a better looking outfit).  I want to swim underwater without the need for dive gear, seahorses, or gillyweed, to see what few others have seen.  I want to communicate with whales and dolphins to find out what their large brains can teach us about our planet.  While I may not be able to attain superhero status, I can join some real-world adventurers on an amazing vessel equipped to conduct research that will help realize my dream of seeing the unseen depths of the ocean.

Hello, from Northern Wisconsin!  My name is Theresa Paulsen.  I am a high school science teacher in Ashland, WI.  I have been teaching for 17 years while living along the south shore of Lake Superior with my husband and our two children.

My husband, Bryan

My husband, Bryan

Our children, Ben and Laura, paddling the sea caves in the Apostle Islands, N.L.

Our children, Ben and Laura, paddling the sea caves in the Apostle Islands, N.L.

The pristine lake and the rich forests around the region provide the resources that sustain our local communities.  As we work to promote local stewardship in the classroom, we must recognize that the health and welfare of the resources we treasure are connected to the greater global environment which is heavily influenced by the processes that occur in our oceans. The geological processes occurring near our research zone are fascinating.  The North American plate slides passed the Caribbean plate creating the Puerto Rico trench, the deepest part of the Atlantic Ocean.

Bathymetry of the northeast corner of the Caribbean plate. Image courtesy of USGS.

Maps generated by the vessel’s state-of-the-art multibeam sonar on our mission will help geologists learn more about the tectonic activity and potential seismic hazards in the area. (Let’s hope the only rumblings I feel are those caused by the typical mild sea-sickness!)  The maps will also be used by marine biologists and resource managers to investigate and assess unique habitat zones.  Learn more the mission goals here.

My students and I have been checking in on the vessels live video feed periodically as the ship sails from Rhode Island to Puerto Rico, mapping along the way.  I will join the crew in Puerto Rico on the 14th to begin training before the vessel sets sail for the second leg of the mission on the 16th.  Throughout our journey, scientists will use the maps we generate to determine areas that require further investigation with the vessel’s remotely operated vehicle (ROV) on the third leg of the mission.

NOAA Ship Okeanos Explorer with camera sled, Seirios, deployed and below that, IFE’s Little Hercules—a science-class ROV. Credit: Randy Canfield and NOAA.

My goal is to learn as much as I can on this expedition!  There is no better way to motivate students to become life-long learners and scientific thinkers than to show them how exciting real research can be.   Through the NOAA Teacher at Sea program, my students and I will have the rare opportunity to learn first-hand about the science and technology oceanographers use to study fascinating places in the ocean.   I will return to the classroom in April, equipped with lesson ideas and answers to questions about ocean research and careers! Thank you for following me on my journey.  Please post questions or comments.  I will do my best to address them in future posts (although communication aboard the vessel can be tenuous, I am told).  Here is my first question for you:

Emina Mesanovic, Acoustic Lab: Let’s Make Some Maps, July 28, 2014

NOAA Teacher at Sea

Emina Mesanovic

Aboard the NOAA Ship Pisces

July 20 – August 2, 2014

 Mission: Southeast Fishery- Independent Survey

Geographic area of the cruise: Atlantic Ocean, off the coast of North Carolina and South Carolina

Date: July 28, 2014

Weather Information from the Bridge

Air Temperature: 27.5 C

Relative Humidity: 86%

Wind Speed: 15.03 knots

 Science and Technology Log

There is a lot of work that goes into allowing the fishery team to be able to set traps every day. The acoustics lab/ night shift is responsible for creating the maps of the seafloor that will be used the following day. The team consists of David Berrane a NOAA fisheries biologist, Erik Ebert a NOAA research technician, Dawn Glasgow from the South Carolina Department of Natural Resources and a Ph.D student at the University of South Carolina, as well as Mary a college student studying Geology at the College of Charleston and Chrissy a masters student at the University of South Carolina. This team is amazing! Starting at around 5:00 pm the day before they stay up all night mapping the ocean floor.

The night shift working together

The night shift collecting data

Every night Zeb Schobernd lets the night shift know which boxes they will work on. These boxes are created in the offseason by the research scientists, they base their selection on information from fishermen, the proximity to already mapped areas, weather and previous experiences. The first step in creating a bathymetric map is to create a line plan, which lets the ship know which area will be covered. The average line takes about half an hour to complete but they can take up to several hours. The ship drives along these lines all night long while the team uses the information that is gathered to create their maps.

So how do they get this information? The ship uses sonar to collect data on the water column and the ocean floor. The Pisces has a 26 multi-beams sonar system, which allows the research team to create a better picture, compared to using single beam sonar. The beams width is about 3 times the depth of water column. This means that depending on how deep the water is in any given location, it will determine how many lines need to be run to cover the area.

Multibeam sonar

Multi-beam sonar (picture from NOAA)

The picture below is one of the computer screens that the scientists look at throughout the night. It provides the sonar information that will then be used to map the floor. Sonar works by putting a known amount of sound into the water and measuring the intensity of the return. A rock bottom will yield a stronger return while a sand bottom will absorb the sound and yield a less intense return. In the image red means that there is a more intense return while blue and yellow signifies a less intense return. You will notice in the center screen there is a strong red return at the top of the beam this is because the ship is sending out the sound and it takes about four meters until you start recording information from the sea floor.

SIMRAD70 (multi-beam sonar)

SIMRAD (multi-beam sonar)

Finally before the maps can be created the team has to launch an XBT (expendable bathy thermograph) two times per box or every four hours. The XBT measures the temperature and conductivity of the water, this is important because sound travels at different rates in cold versus warm water. This information is then used when the scientists calculate the sound velocity, which is used to estimate the absorption coefficient of sound traveling through the water column.

 

Once the data is collected the team begins the editing process. First they have to remove random erroneous soundings in order to get an accurate map; they fondly call this process dot killing (this basically means getting rid of outliers). They do this by drawing a box around the points of data they want to remove and deleting the point. Next they apply tide data to account for the deviations in the tides, this information is obtained from NOAA and is based on the predicted tides for the area. Finally they apply the sound absorption coefficient.

Editing the data (killing dots)

Editing the data (killing dots)

The final product is put into GIS (Geographic Information Systems), which the chief scientists will use to determine where the traps should be set the following morning. On the map below blue indicates the deepest areas while red shows the shallowest. The scientists want to place the traps in areas where there is a large change in depths because this is usually where you will find hard bottoms and good fish habitats.

Finished map (red shallow, blue deep)

Finished map

Personal Log

I have spent the past three nights in the Acoustics/Computer Lab with the night shift mapping the ocean floor. While the ship sails along the plotted course, I have had the opportunity to see the sunrise and sunset on the Pisces as well as a lightning storm from the top deck.

images

Lighting on the ocean (picture from sciencedaily)

On Thursday night a little after midnight after launching the XBT we see decided to go onto the top deck of the Pisces to get a better look at the lighting storm in the distance. Even at night it was still humid and hot and as we climbed up to the top deck it was dark all around us until suddenly there would be a flash of color in the clouds and you could see everything, until it went dark again. We tried to take a picture but the lightening was just too fast for our cameras. This is the closest picture I could find to what it was like that night except the water was not calm.

 

SPOTLIGHT ON SCIENCE

Name: Erik Ebert                  Title: Research Technician

Erik editing data collected on Sunday July 26th.

Erik editing data collected on Sunday July 26th.

Education: Cape Fear Tech (Wilmington, NC)

How long have you worked for NOAA/NOS: 6th field season, 5th year

Job Summary: I work on ecosystem assessments throughout the Gulf of Mexico South Atlantic & Caribbean

– Team oriented production of ocean floor maps

– System setup & keeping the acoustic systems operating correctly

How long have you participated in this survey: Since 2010

What do you like about your job: That the data we collect, and the maps we create can be used again for different studies. The types of data we collect includes bathymetric data, information on the water column, & fish that populate the water column.

How many days are you at sea: 60 days (April-November)

What do you do when you are not on the boat: Process & produce fish density maps from the data collected during the cruises. I also work for National Ocean Services (provide data to policy & decision makers to the state of the ecosystem)

Most challenging about research on a ship: Being away from home is the biggest challenge.

What would be your ideal research cruise: My ideal research cruise would be a cruise similar to what we just completed in Flower Garden Banks in the Gulf of Mexico. It was a 3-year assessment of the reef ecosystem using ROV, Diving and Acoustics to study how the ecosystem changed over time.

Favorite fish: Trigger Fish “cool swimming behavior”

More information about See Floor Mapping   http://www.noaa.gov/features/monitoring_1008/seafloormapping.html

COOL CATCH

Crab with three sea anemones attached to its shell

Crab with three sea anemones attached to its shell

Denise Harrington: The Best Day Ever, April 30, 2014

NOAA Teacher at Sea
Denise Harrington
Aboard NOAA Ship Rainier
April 20 – May 3, 2014

Mission: Hydrographic Survey

Geographical Area of Cruise: North Coast Kodiak Island

Date:  April 30, 2014, 11:44 a.m.

Location: 58 03.175’ N  127o 153.27.44’ W

Weather from the Bridge: 6.3C (dry bulb), Wind 5 knots @ 250o, clear, 1-2′ swell.

Our current location and weather can also be seen at NOAA Shiptracker: http://shiptracker.noaa.gov/Home/Map

Science and Technology Log

The last couple of days have been the best ever: beautiful weather, hard work, deep science. We acquired data along the continental shelf and found a cool sea floor canyon and then set benchmarks and tidal gauges.

In hydrography, we gather data in seven steps, by determining: our position on Earth, depth of water, sound speed, tides, attitude (what the boat is doing), imagery and features.  Step 1 is to determine where we are.

In this picture you can see a GOES satellite antenna and a GPS antenna that helps us determine our precise location.

In this picture you can see a GOES satellite antenna (square white one) that is used to transmit tide data ashore and a GPS antenna (the small white eggs shaped one) that provides the tide gauge with both position and UTC time. Photo by Barry Jackson

In this picture  Brandy Geiger, Senior Survey Technician, uses the GOES from various locations to determine the exact location of the tide gauge.

In this picture Brandy Geiger, Senior Survey Technician, uses GPS to record the positions of the benchmarks we have just set for the tide gauge. Photo by Barry Jackson

tide gauge install 023

Where we are happens to be the most beautiful place on earth. Photo by Barry Jackson

 

In Step 2, we determine the depth of the water below us.

Bathymetry is a cool word that means the study of how deep the water is.  Think “bath” water and metry “measure.”  When your mom tells you to get out of the tub, tell her to wait because you’re doing bathymetry.

As I explained in my first blog, we measure depth by sending out a swath of sound, or “pings,” and count how long it takes for the pings to return to the sonar, which sits beneath the ship or smaller boat.

Yesterday we used the multi-beam sonar to scan the sea floor.  Here is a screen shot of the data we collected.  It looks like a deep canyon, because it is!

Here is the image of the trench Starla Robinson, a Senior Survey Technician, and I discovered.  We decided it should be named Denla Canyon, after us.

Here is the image of the sea floor canyon Starla Robinson, a Senior Survey Technician, and I discovered. We decided it should be named Denla Canyon, after the two scientists who discovered it.

Here I am, gathering pings.

Here I am talking with "the bridge,"  the team responsible for navigating the ship while surveyors collect data.

While collecting data, I kept in contact with “the bridge,” the team responsible for navigating the ship, by radio to ensure the ship’s safety and maximum, quality data acquisition.     Photo by Starla Robinson

 

Step 3, we take into consideration the tide’s effect on the depth of the water.  Tides are one predictable influence on water depth. There are over 38 factors or “constituents” that influence the tides.  The gravitational pull of the sun and the moon at various times of the day, the tilt of the earth, the topography, and many other factors cause water to predictably bulge in different places on earth at different times. The Rainier crew works 24 hours a day and 7 days a week, so they must find a way to measure depth throughout the days and month, by taking into account the tide. Arthur Doodson, who was profoundly deaf, invented the Doodson Numbers a system taking into account the factors influencing tide in 1921. Flash forward to the 21st century, our Commanding Officer, Commander Rick Brennan worked with a team of NOAA scientists to develop a software program called TCARI, as an alternate method to do tide adjustments, taking into account 38 factors, even the moon’s wobble. Inventions abound at NOAA.

The Rainier crew worked for 14 hours today to set up a tide gauge station, an in depth study of how the tide affects our survey area.  On this map, there is a Red X for each tide gauge we will install.  This process only happens at the beginning of the season, and I feel fortunate to have been here–the work we did was….amazing.

 

Each Red X is approximately where a tide gauge will be installed.  The one we installed today in Diver's Bay is in the north west corner of the sheet map.

Each Red X is approximately where a tide gauge will be installed. The one we installed today in Driver Bay is in the north west corner of the sheet map.

You can see an animation here that shows the combined effect of two sine waves that produce a signal like our tide data.  Just imagine what it looks like when you factor in 38 different variables.

The earth goes around the sun in 24 hours and moon goes around the earth in a little more than 12 hours, much like these two gray sine waves. Interestingly, when you add two different waves, you get the wonky blue sine wave, with ups and downs. This combined effect of the sun and the moon (two dots) causes the ups and downs of the tide (blue wave). Graph taken from Russell, D. Acoustics and Vibration Animation, PSU, http://www.acs.psu.edu/drussell/demos/superposition/superposition.html.

 

Low tide is the best time to see sea stars, mussels and barnacles, but it is also a more hazardous time in the tidal cycle for mariners to travel. Therefore, navigational charts use the mean lower low water level, low tide, for the soundings, or depth measurements on a chart.  The black numbers seen on a nautical chart, or soundings, represent depth measurements relative to mean lower low tide. Driver Bay, the area on the chart where we installed the tide gauge today, is the crescent shaped bay at the northwest end of Raspberry Island.

This is a nautical chart used to help mariners navigate safely.

This is a nautical chart used to help mariners navigate safely.

Installing Tide Gauge Stations

Before gathering sonar data, ground and boat crews install a tide gauge to measure changes in water level and to determine the mean lower low water level datum. A tide gauge is a neat device that has air pumped into it, and uses air pressure, to determine how deep the water is.   The tide gauge uses a formula of (density of sea water)(gravity)(height) = pressure.  The gauge measures pressure, and we apply factors for gravity and sea water.  The only missing factor is height, which is what we learn as the gauge collects data.  This formula and nuances for particular locations is a fascinating topic for a blog or master’s thesis.  Scientists are looking for tidal fluctuations and other location specific variances. Then, by computer they determine the mean lower low tide depth, factoring in the tidal fluctuations.

There are permanent tide gauge stations all over the world.  The nearest permanent tide gauge station to our study area is in Kodiak and Seldovia.  These permanent gauges take into account many factors that affect tides over a 19 year period of time, not just the gravitational pull of the moon.

The tide gauge stays in place for at least 28 days (one full tidal cycle).  During the month, data of the tides is collected and can be compared to the other tide gauges we install.

Installing the Tide Gauges and Benchmarks

Excitement built as the crew prepared for the “Tide Party,” packing suitcases full of gear and readying the launches.  Installing Tide Gauges signals the beginning of the season and is one of the few times crew gets paid to go on shore.

 

Why Bench Mark?

There are three reasons I have figured out after many discussions with patient NOAA crew as to why we put in bench marks.

 

I installed this benchmark by having a hole drilled in bedrock and affixing the benchmark with concrete if anyone ever returns and needs to know their exact location.

I installed this benchmark in Driver Cove by having a hole drilled in bedrock and affixing the benchmark with concrete if anyone ever returns and needs to know their exact location. Photo by Barry Jackson

The first reason we install benchmarks is to provide a reference framework to ensure both our tide staff and the tide gauge orifice are stable and not moving relative to land.  The second reason is if we ever come back here again to gather or compare data to previous years, we will know the elevation of the tidal datum at this location relative to these benchmarks and can easily install a new tide gauge.  The third reason is that the earth and ocean floor changes constantly.  As scientists, we need to make sure the survey area is “geologically stable.”  We acquire several hours of GPS measurements on the primary benchmark to measure both its horizontal and vertical position relative to the earth’s  reference frame.  Should there ever be an earthquake here, we can come back afterwards and measure that benchmark again and see how much the position of the Earth’s crust has changed.  After the last big earthquake in Alaska, benchmarks were found to move in excess of a meter in some locations!

Teacher on Land Polishing Her Benchmark Photo by Brandy Geiger

Teacher on Land
Polishing Her Benchmark
Photo by Brandy Geiger

Installing the Benchmark

Today, our beach party broke into two groups.  We located stable places, at about 200 foot intervals along the coastline.  We drilled 5 holes on land and filled them with concrete.  A benchmark is a permanent marker you may have seen at landmarks such as a mountain peak or jetty that will remain in place for 100 years or more.  We stamped the benchmark by hand with a hammer and letter stamps with our station identification.   If we chose a good stable spot, the benchmark should remain in the same location as it is now.

Tide Gauge

As one group sets up benchmarks, another group installed the tide gauge.

 

Here, Chief Jim Jacobson, Lead Survey Technician, sets up a staff, or meter stick, I used to measure the change in water depth and others used for leveling.

Here, Chief Jim Jacobson, Lead Survey Technician, sets up a staff, or meter stick, I used to measure the change in water depth and others used for leveling.  Photo by Barry Jackson

To install the tide gauge, you must have at least three approved divers who install the sensor in deep water so that it is always covered by water.  Because there were only two crew on board trained to dive, Lieutenant Bart Buesseler, who is a dive master, was called in to assist the team.   The dive team secured a sensor below the water.  The sensor measures the water depth with an air pressure valve for at least 28 days.  During this time there is a pump on shore that keeps the tube to the orifice pressurized and a pressure sensor in the gauge that records the pressure. The pressure is equal to the number of feet of sea water vertically above the gauge’s orifice. An on-board data logger records this data and will transmit the data to shore through a satellite antenna.

Divers install the tide gauge, and spent most of the day in the cold Alaska waters.  Good thing they were wearing dive suits!  Photo by Barry Jackson

Divers install the tide gauge, and spent most of the day in the cold Alaska waters. Good thing they were wearing dive suits! Photo by Barry Jackson

Leveling Run

After the gauge and benchmarks are in place, a group does a leveling run to measure the benchmark’s height relative to the staff or meter stick.  One person reads the height difference between 5 different benchmarks and the gauge. Then they go back and measure the height difference a second time to “close” the deal.  They will do the same measurements again at the end of the survey in the fall to make sure the survey area has not changed geographically more than ½ a millimeter in height!  Putting the bubble in the middle of the circle and holding it steady, leveling, was a highlight of my day.

Observation

Finally, a person–me– watches the staff (big meter stick above the sensor) and takes measurements of the water level with their eyes every six minutes for three hours.  Meanwhile, the sensor, secured at the orifice to the ocean floor by divers, is also measuring the water level by pressure. The difference between these two numbers is used to determine how far below the water’s surface the orifice has been installed and to relate that distance to the benchmarks we have just leveled to.  If the numbers are consistent, then we know we have reliable measurements.  I won’t find out if they match until tomorrow, but hope they do.  If they don’t match, I’ll have to go back to Driver Bay and try again.

As we finished up the observations, we had a very exciting sunset exit from Raspberry Island.  I was sad to leave such a beautiful place, but glad to have the memories.

Last minute update: word just came back from my supervisor, Ensign J.C. Clark, that my tidal data matches the gauge’s tidal data, which he says is “proof of my awesomeness.” Anyone who can swim with a car battery in tow is pretty awesome in my book too.

The data Starla Robinson and I collected is represented by the red line and the data the gauge collected is represented by the blue line.  The exact measurements we collected are on the table.

The data Starla Robinson and I collected is represented by the red line and the data the gauge collected is represented by the blue line. The exact measurements we collected are on the table.

Spotlight on a Scientist

Lieutenant Bart Buesseler came to us straight from his family home in the Netherlands, and before that from his research vessel, Bay Hydro II.  The main reason our CO asked him to leave his crew in Chesapeake Bay, Maryland, and join us on the Rainier is because he is a dive master, capable of installing our sensors under water, and gifted at training junior officers.

 

Lieutenant Beusseler knows he needs to be particularly nice to  Floyd Pounds, an amazing cook from the south who cooks food from every corner of our ocean planet.

Lieutenant Beusseler knows he needs to be particularly nice to the amazing chefs aboard Rainier, including Floyd Pounds, who cooks food from every corner of our ocean planet with a hint of a southern accent.

During his few years of service, LTJG Buesseler adventured through the Panama Canal, along both coasts of North America, and has done everything from repairing gear to navigating the largest and smallest of NOAA vessels through very narrow straits.  He loves the variety: “if I get tired of one task, I rotate on to another to keep engaged and keep my mind sharp.”  He explains that on a ship, each person is trained to do most tasks.  For example, he says, “during our fast rescue boat training today, Cal led several rotations. But what if he is gone? Everyone needs to be ready to help in a rescue.”  Bart says at NOAA people educate each other, regardless of their assignments, “cultivating information” among themselves. Everyone is skilled at everything aboard Rainier.
In the end, he says that all the things the crew does are with an end goal of making a chart.   His motto? Do what you love to do and that is what he’s doing.

Personal Log

Today was a special day for me for many reasons.  It is majestic here: the stark Alaskan peninsula white against the changing color of the sky, Raspberry Island with its brown, golden, crimson and forest green vegetation, waterfalls and rocky outcroppings.  I’m seeing whales, Puffins, Harlequin Ducks and got up close with the biggest red fox ever.  Most importantly, I felt useful and simultaneously centered myself by doing tide observations, leveling and hiking.  I almost dove through the surf to make it “home” to the ship just in time for a hot shower. Lieutenant Buesseler’s reference to “cultivating information” rings very true to me.  In writing these blogs, there is virtually nothing I came up with independently.  All that I have written is a product of the patient instruction of Rainier crew, especially Commander Brennan. Each day I feel more like I am a member of the NOAA crew here in Alaska.