Tag: ocean currents

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 1, 2015

Weather Data from the Bridge:  Partly Cloudy, 26˚C, waves 1-3ft, swells 3-6ft.

Science and Technology Log:

Dr. Wilford (Bill) Schmidt has demonstrated the saying, “Where there is a will, there is a way,” throughout this  entire cruise.  He knew this voyage would put his new free vehicle design to the test and he came prepared to modify this, tweak that, collaborate with the crew, confer with his university team, test, and repeat.  He is an engineer and that is the name of the game.

1.  The first deployment looked great. The vehicle reached 1000m.  The magnetometer and 3-axis accelerometer worked great.  All systems were a go.  A water sampling device was used as a dummy payload.

 

 

Crossing fingers for more success.

2.  The next step was to attach a CTD (a probe that measures Conductivity, Temperature, Depth).  The deployment and retrieval process again went smoothly, this time to 2126m, but there was a problem retrieving the log file from the bottom sphere and one of the anchor burn wires did not burn.

 

Collaboration required with folks on shore and the electronics technicians on this ship.  Tweak this, fix that.

Bill opened the spheres to change the batteries for the satellite transponder.

All systems were a go again.

3.  The crew deployed the free vehicle with the CTD to 4679 m.  It took a little longer to find and retrieve the vehicle.

The data files indicated that the galvanic releases released the anchor prematurely, at about 100 meters from the bottom.  Both spheres worked during the mission.  Data files were retrieved from each.  During inspection water was found in the bottom sphere.  Spalling of the glass (flaking) was seen on the inside.  The leak is assumed to have taken place as the surface under low pressure conditions, otherwise the damage would have been worse.  The electronics were in good shape but the bottom sphere had to be retired.

Oh no!  Is that the end?  Not when you have great minds on board!

This is where engineering in the ocean environment gets tricky.  Bill can’t just head back to the university and make the necessary repairs.  Instead he needs to make use of the very valuable ship time by pinch-hitting.  Bill recalculated the buoyant force on the vehicle with only one sphere.  It might just work!

Tweak this, lighten that, new attachments there. Ready for a float test!

Will the single sphere allow it to ascend from the bottom fast enough for us to deploy and retrieve it during our mission?  That question required further testing.  So the crew planned to lower it into the water a short distance with the winch and allow it to float back up.  The weather would not allow it.  The seas were too rough to allow the ship to stay in one place during the vehicle test without dragging the free vehicle thereby negating the results of the test.

Plan B?  The operations team hatched a plan to tie the free vehicle to buoys on a long rope.  That allowed the vehicle to sink and be recovered easily if it rose too slowly. First a buoyancy test had to be done to make sure the buoys wouldn’t sink with the vehicle.

The vehicle rose in less than 10 minutes so the team was back on track!  With a few extras like flags for better visibility, the vehicle was ready to dive!

4.  The deployment into the trench went smoothly.  The crew had that routine down pat.  After 10 hours it was time for the retrieval.  Everyone gathered at the bridge to try to spot it.

It successfully collected data down to the bottom at 8379m, a possible record for a free vehicle!

The CTD data was processed and looked great during the descent.

Inspection of the data log showed that while the vehicle was ascending from the bottom, something was triggering a mission cancel order – 28 times!  This bug required more testing and mission simulating before another deployment in the trench.  Just after 8pm, Bill announced his equipment was ready to go for a 6 am deployment the next day.

5.  The next day, the retrieval took a bit longer due to choppier sea conditions.

Again the vehicle logs showed “cancel mission” messages during the ascent.  It is confounding Bill and his team back home, because during mission simulations the mission goes to completion without a problem.

In all the voyage has been very constructive for Bill’s engineering team.   They successfully deployed the vehicle to the bottom of the Puerto Rico Trench known to be the deepest part of the Atlantic Ocean.  That is something to celebrate!  They have learned a great deal about what types of modifications they should make to improve the retrieval process.

This was a great first test of the free vehicle design.  The next time out at sea will come soon enough and Bill’s team will be ready!

Personal Log

As the voyage comes to an end and we travel nearer to shore, I am filled with mixed emotions.  I will miss the ocean, the feeling of being a part of an exploration expedition, and these people.  I am also very happy to be going home to my family and my students.  I am looking forward to sharing what I have learned.  I will be looking for partnerships to help get students involved in reseach on our inland sea, Lake Superior.  If you have any suggestions, please leave a comment below!

Exciting moments?  Seeing these creatures!

Other great moments include driving the ship and making video fly-bys of the ocean floor with the bathymetry and backscatter data.  Very awesome!  The videos will be coming soon so stay tuned!

Did you know?

Do you remember the flying fish I wondered about a few blogs ago?  I have never seen them before.  At first I thought I was seeing things.  I thought I saw a very large dragonfly dive into the water.  Then I saw more.  – schools of them jumping away from the boat all at once.  In a blink of an eye they were gone.

According to Wikipedia, there are 64 species of flying fish!  They fly out of the water to evade predators.  That’s a pretty cool adaptation!  You can learn more here.

Question of the Day:

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: March 29, 2015

Weather Data from the Bridge:  Partly Cloudy, 26.7˚C, waves 1-3ft, swells 2-4ft.

Science and Technology Log:

We launched and recovered a CTD earlier this week.

A CTD (Conductivity, Temperature and Depth probe) is used to study the characteristics of ocean water masses, as well as to insure data quality and accuracy from XBTs (Expendible Bathythermograph). In a previous blog, I discussed how the XBT is used to measure the temperature of the water to a depth of about 760 meters. That coupled with the conductivity sensors on the vessel are used to calculate salinity and pressure to derive a measure of the velocity of sound through water, an important factor when collecting sonar data.

An XBT can be launched while the vessel is underway without pausing the sonar, but it doesn’t collect data all the way to the bottom of the water column.

A CTD can go all the way to the bottom, depending on the depth of the ocean, the length of the tether cable, and the pressure rating of the frame and equipment making up the CTD.  The titanium frame and equipment making up the CTD currently aboard the Okeanos can be lowered to 6500 meters.   It is very large and requires the vessel to stay put during the entire process since it is tethered to the ship.

Since a CTD collects all three factors involved in the computation of speed of sound in water (salinity, temperature, and depth) and is therefore more accurate than an XBT which only collects temperature, it is used at least annually to provide comparison data for the XBT measurements. This is the reason our scientists used it on this cruise.  Additionally, scientists on board a vessel may want to deploy a CTD more often if water masses are expected to change, or if they are interested in studying other features of the water column such as particulates, gaseous seeps, dissolved oxygen or oxygen reduction potential, or if they want to collect water samples at different depths.

In the above photo the small red arrow is pointing to the water sample tubes, the large blue arrow to the CTD, and the large red arrow to the altimeter which senses when the probe is within 200 meters from the bottom allowing winch operators to slow the descent to avoid damaging equipment.  Scott Allen is the Survey Tech on board.  His job is to maintain and calibrate the CTD.  He helps launch and recover the CTD and then operates the software to collect and process the data.

The CTD software plots the temperature (green), sound velocity (pink), conductivity (yellow), and the salinity (blue) on the x-axes against depth on the y-axis.  You can see locations on the graph where the values for temperature and salinity shift in a significant way with changes in depth.  These shifts can indicate a boundary between different water masses.  The upward spikes in the data are likely caused by some error in the equipment connections.

Let’s conduct an experiment!

Have you ever wondered what would happen to a styrofoam cup if you lowered into the water 2100 meters? The folks here tell me you get some pretty interesting results, so we had to give it a try.

Problem:  Determine the effect of extreme pressure on a styrofoam cups.

Background:  Styrofoam, properly called expanded polystyrene foam, is made by infusing air into polystyrene (a synthetic polymer) using blowing agents. Learn more here.

Hypothesis:  What is your hypothesis?  What do you think will happen to the air pockets if we send the cups to the depths of the ocean?

Procedure:

1.  Decorate your cups, leaving one as a control for comparison after submersion.

2.  Place the cups in a mesh dive bag and attach to a CTD.

3. Lower the CTD to 2100 meters

4.  Raise the CTD and examine the cups.

Analysis:

So how much pressure was exerted on the cups at 2100 meters?  We can use this formula to calculate it:

P = pgh

Pressure in a fluid = (density of water) x (acceleration due to gravity) x (height of the fluid above the object).

If the density of seawater is 1027 kg/cubic meter, the acceleration due to gravity is 9.8 m/s/s and the depth is 2100 meters, what is the pressure?

You should get 21 million Pascals (Newtons/square meters) or 21,000 kPa.  If 1 kPa = 0.145 psi, how many pounds of pressure per square inch are exerted on each cup?   About 3000 pounds per square inch.  That’s about the weight of a compact car over each square inch!  For comparison, at sea level the atmospheric pressure is 14.7 psi.

So what happened to our cups under all that pressure?  Check it out!

Conclusion:

Was your hypothesis supported or refuted?  What happened to the air trapped in the styrofoam?

Air extraction is the reason that Dr. Wilford Schmidt uses iron rebar rather than cement to provide the anchor for his free vehicles.  The cement crumbles as the air pockets give way and air is squeezed out.  Cement is not as flexible as the polystyrene.

What other materials might change under pressure?  If you don’t have access to the deep ocean or a CTD, you could always try a pressure cooker – but be safe!

Personal Log:

I am inspired by all the people working on this vessel.  They are so adventurous and have seen so much.  I wondered what inspired them to do what they do.  Here are some of their answers:

Mapping Intern, Kristin Mello:  Took a class in scuba diving and realized she loved it and wanted to learn more.  Her dive instructor encouraged her to do an internship as a research diver and she has been studying the ocean ever since.

Free Vehicle Tech, Zamara Fuentes:  Built a model of a volcano in school became very interested in geology.  Now she studies tsunami impacts on the Caribbean islands.

NOAA Corps Officer, Nick Pawlenko:  Had never really spent much time on boats as a kid, but was inspired by Clive Cussler novels to explore the ocean.

Expedition Coordinator, Meme Lobecker: Her love of the oceans made her want to put her geography skills and interest in data collection to work in the ocean environment.

Engineer, Chris Taylor:  Wanted to put his love of engineering to work for good pay.  “There is never a dull moment,” he says.

Mapping Watch Lead, Melody Ovard:  Just likes being near the ocean.  “It’s a proximity thing.  I am curious about what goes on in it,” she says.

Free Vehicle Scientist, Bill Schmidt:  Loved surfing and was interested to learn what caused the changes in the surfing conditions day-to-day.  Then he read Willard Bascom’s book, Waves and Beaches, and was hooked.

NOAA Corps Officer, Bryan Pestone:  Swimming competitively and lifeguarding on the beach led him to a degree in marine biology.

Mapping Intern, Jossue Millan:  An astrobiology poster caught his eye in his physics class, which peaked his interest in life in extreme environments.  He enjoys the interdisciplinary sciences.

Teacher at Sea, Theresa Paulsen:  I am inspired by the wonder in a kid’s eye or on a proud parent’s face and by the beauty that surrounds us from the depths of the oceans to the expanses of space.  Life is amazing – and far too short to waste, so we have to make the most of it while we can.

What inspires you?  Post a comment and let me know!

Did You Know?

For every 10 meters you go below the surface, pressure increases by one atmosphere (14.7 psi).  Scuba instructors typically don’t recommend diving deeper than 40m to decrease the risk of decompression sickness, known as “the bends,” or equipment failures that could lead to drowning.

Question of the Day:

The deepest successful dive in the Guiness Book of World Records is currently 332.35 meters (1090ft)!  Yikes!  Read about it here.

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: March 19, 2015

Weather Data from the Bridge:  Partly Cloudy, 26.7˚C, waves 1-3ft, swells 2-4ft.

Science and Technology Log:

This morning at breakfast Commanding Officer Mark Wetzler, or CO, explained that we would be deploying instruments today.  The first one was a glider for the Navy. The Slocum electric glider is like a tiny, unmanned submarine built like a non-explosive torpedo with small wings. It has the ability to be remote-controlled for weeks to months at sea operating 24 hours a day even in the worst weather.  They can be programmed to travel back and forth, dive, and rise periodically to communicate data back to the mainland and accept new missions.  These autonomous underwater vehicles (AUVs) can collect many different types of data such as temperature, conductivity, or audio recordings, depending on the sensors attached. Gliders like this one can help detect tsunamis or other changes in the ocean.

Our vessel also records data 24 hours a day but is limited in its duration at sea by the needs of the people and fuel onboard.  Have you wondered how we can stay out at sea for nearly 3 weeks at a time without hitting the grocery store or service station?  I’ll explain more about that in a future blog.

 

The next deployment was a test run of a “free vehicle.”  Dr. Wilford “Bill” Schmidt, and his assistants, Rolf-Martin Vieten and Zamara Fuentes from the University of Puerto Rico, Mayguez (UPRM) are testing the design of vehicles that can be deployed from a vessel like the Okeanos Explorer or a smaller ship.  These vehicles are inexpensive to make, easy to deploy, and do not need to be tethered to the ship.  They can be programmed to dive to the deepest parts of the ocean, or whatever depth desired, in order to take samples or record data.  Once the vehicle has completed data collection or sampling, it releases its anchor and rises the surface where it is retrieved.  Meanwhile the deployment vessel can continue other operations such as mapping.  Time is not wasted on a research vessel!  On this cruise they will use the device to sample the conductivity, temperature and depth of the water column.  This will help them learn more about the interaction between different water masses in the Puerto Rico Trench.

 

Water masses in the trench are of particular interest to Bill, a professor of physical oceanography, because they could hold a key to understanding the flow of different ocean currents.  He explained that water masses form at the surface at a particular temperature and with a certain salinity corresponding to the surface conditions at the time.  Temperature and salinity are conservative properties, meaning they don’t change as the water mass moves.   So as a water mass formed in Antarctica sinks and moves toward the deepest parts of the ocean due to its density, its cold temperature and salinity don’t vary significantly. So temperature and salinity can serve as fingerprints of water masses.  Therefore as he measures these factors through the entire water column in the trench, we would expect to see the values change as we move from the North Atlantic Deep Water to the Antarctic Bottom Water.  The image below shows a generalized representation of the typical flow pattern of large water masses.

Bill’s work is supported by NOAA and the National Science Foundation. The NOAA Office of Exploration and Research recently provided him with an award to produce 5 free vehicles with his university team.  The fact that Bill’s vehicles are able to travel untethered into the hadal zone at a very low cost makes them uniquely valuable to researchers.  Data from the hadal zone is virtually non-existant because only enormous vessels would be able to support winches that could handle the 10,000+ meters of cable that would be required for the tethered vehicles currently used.  Since the average depth of the ocean is only 4000m, there is not a large enough demand to make manufacturing such large winches economically feasible.

Also, Bill’s free vehicles are small and can be deployed on very short notice, allowing them to capture data as major events occur. The vehicles can carry interchangeable payloads that could be used in all scientific disciplines. A biologist could request water or bottom substrate samples to examine life forms in the hadal zone that may not exist elsewhere.  A geologist might also like to sample the bottom substrate or might wish to record seismic activity at the bottom of the trench to better understand plate interactions.  A chemist interested in oceanography could examine the water for trace elements or compounds that were emitted into the air at one point in time, such as chloroflourocarbons (CFCs) that were once used but are now illegal in the US due to their impact on the ozone layer, or tritium (H-3) remnants from nuclear bombs used in WWII. This could provide us with an estimate of how long ago the water mass was at the surface and help us determine the rate of flow into the trench.  The research possibilities are endless.

Initial tests looked good. During our 19 day voyage, Bill’s team and the crew will deploy the vehicle up to 11 more times with up to 6 locations strategically placed in the Puerto Rico Trench.

Personal Log:

Are you interested to know what the accommodations are like aboard the Okeanos?  They are comfortable enough for a work boat.  Take a look for yourself!

 

I love the curtain around my bottom bunk.  It reminds me of the forts my brothers and sisters and I built as kids.  I have slept like a baby ever since arriving.  The rocking of the boat is very calming.

There are a couple of nice spots to relax and chat, and write in my blog.  Here are the library and the lounge.

I am surprised that I really haven’t been seasick. Motion sickness medication really helps. If you really get sick, there is a medical officer on board and sick bay.

I showed you the galley in the last post.  We eat in the Mess Hall.  The Chief Steward puts tennis balls on the bottom of the chairs to avoid scratching the finish on the floor.  Good thinking!

And when I have eaten too much, there is the fitness room!  There is a scale in the fitness room, but when you stand on it, the action of the boat rocking causes the scale to oscillate by 30-40 pounds.  It is a great demonstration of the difference between mass and weight!

The best place to hang out is outside, of course, where you can possibly see a spouting whale or swimming dolphin.  I have seen both on this trip already but I need to be quicker with the camera!  Maybe next time!!

Question of the Day: