Tuesday, May 22, 2012

Erin Hunter's Internship, Spring 2012 - Part 5

Week 3: Water Column Data/End of cruise


Multibeam screen.
After passing Miami and heading northeast to map, we were unable to continue due to tropical storm Alberto. Instead of weathering high seas we headed to MayPort Navy base near Jacksonville, FL to shelter from the storm. An unexpected port call that included a bowling excursion on the base and opportunity to walk on stable land was welcomed by every one. We all made it back to the ship before leaving Monday morning at 10:00 am.

  • In my earlier posts, I have described how how mutlibeam mapping data are acquired. These data still need some processing to be presented in images like I shared with you earlier. There are three main types of information that we can glean from the multibeam sonar mapping data:
  • Seafloor depth (or bathymetry) is calculated by using the time it took for the sound waves to travel from the sonar to the seafloor and back (two way travel time) and an estimate of the sound speed in water.
  • Seafloor backscatter information uses the amount of the acoustic energy that a particular seafloor reflects back towards the sonar. This information allows scientists to differentiate between low reflective seafloors (e.g. mud and sand) and high reflective seafloor (e.g. rocks).
  • There is one more way the multibeam data can be used from the changes seen in the water column. As transmitted sound waves pass through the water columnn on their way to the seafloor, any targets in the water column reflect energy back to the sonar. Possible water column targets may include strong water temperature and salinity changes gradients, schools of fish, marine mammals, gas seeps or planktonic organisms. When there are such objects in the water column, the multibeam computer screen shows a change in image color. One commonly seen color pattern are large stratified diffuse masses that vertically ascend and descend in the water column at night. This could be interpreted as phytoplankton or zooplankton making their evening migration in the water column. To compensate for changes in water temperature and salinity that might alter the multibeam data, regular XBT casts are launched to record a water column profile that allows the computers to adjust the raw data.

We are ending our trip now and have acquired and processed a lot of useful data for the scientific community and general public.

Wednesday evening the NOAA Ship Okeanos Explorer will port in Norfolk, VA and await the next crew. Here are some final ship pictures. I will miss my time at sea. Thank you for following along and sending me your questions. Thank you also to the people who have helped me be part of this, my advisor Dr. Wade Jeffrey, Tracy Ippolito for the website and the crew of NOAA Ship Okeanos Explorer who made my stay on the ship a memorable experience for me.

Okeanos' Remotely Operated Vehicle (ROV) - Little Hercules
The ROV wench aboard Okeanos Explorer
VSAT satellite terminal
Oil rig in the Gulf of Mexico
Okeanos' small boat


Post Author:
Erin Hunter

Friday, May 18, 2012

Erin Hunter's Internship, Spring 2012 - Part 4

Dear Pensacola Beach Elementary School Students,

What great questions, I am so happy you have asked me about all these things. Let's share these with other classrooms and yes I will attach a bunch of pictures from the ROV dives. Here are a few questions for you from your Kindergarten friends...
  • Did you get sea sick? (River says you have medicine!)
  • Is it fun?
  • Do the waves make you fall asleep?
  • Are there a lot of computers?
  • Can you send us more pictures from the sea floor?
  • Is the ship realllllly big?
  • Did you see a clam shell?
  • Do people get time off to go on jet skis?
  • Did you see any pearls?
  • Did you see any sharks?
  • Did you see dolphins?
  • Did you see killer whales?
So let's get started — 
Right now, the seas are rising to about 10 feet and rising so I should probably take some sea sick medicine right away. So far I have not been sick. This big ship was modified with extra features to keep it steady so the mapping could be done accurately. When we turn though-like we are right now, we rock and roll.
It is fun- if I didn't miss my family (River this means you) I would like to do this more. There are always people to talk to and plenty to do. 
Yes the waves make me sleep like a peaceful baby. That is one thing I will really miss.
COMPUTERS!!!!! all over our work spaces and then more in hidden rooms for the multibeam sonar. Computers all day- if you want to work in any science field and many others, learn how to program computers and process data. I think these tools will make work easier.
The ship to me is so big that it took me days to find my way around the six decks. The exercise room is right under the ice cream cooler room so I always feel a little guilty every time I go for ice cream and a movie instead of working out. Also, 43 people can bunk on the ship. We have private bathrooms, a laundry room, two lounges a large mess hall (dining room), many labs and more. I will send some pictures of ship stuff next week.

Benthothuria.
Deep sea crab.
Deep sea ice worms.

I saw a clam shell on the underwater footage. It had pretty little hairs protruding from its valve.
As far as pearls go, well there is a wooden ship wreck that was explored on the last leg. There was a pearl trade at one time from the West Indies, so maybe there are pearls waiting to be found.
I wish we could jet ski but we have to stay on the ship. The crew took a small boat off the ship and went diving in the Keys.
Sharks- well apparently that is the reason we are not supposed to swim.
We have only seen dolphins, flying fish and floating algae called Sargassum.

Shipwreck.
Salt volcanoes.
Squid.
Maybe we will see a whale or something before Norfolk. Really there is just water everywhere and when anything else is spotted like land or the other day some balloons, we get all excited. 
Enjoy the pictures and I will wee you when I return to Pensacola Beach.
Erin Hunter
P.S. We had to change our course to Norfolk, VA because the first tropical storm of the season, Alberto, is in our path. We have been feeling it all day so I am glad we are now heading southwest.
Post Author:
Erin Hunter

Erin Hunter's Internship, Spring 2012 - Part 3

Week 2.5: Seafloor Features


Erin Hunter in the Okeanos Explorer control room.
We have made a long track mapping around the Northwest Florida Escarpment and following it down to the Keys. After reaching southern Florida a couple days ago, heading into the Dry Tortuga shoals for dive operations, we had to turn away due to rough sea conditions near shore for our small boat. The next day we stopped near Key Largo for a dive instead. During our first night in the Atlantic we watched a starlight movie on the fantail. It was great being out on deck at night.

During the Gulf of Mexico part of our trip we have picked up many features on the seafloor that I want to share with you. The multibeam has picked up numerous salt domes, seeps and sediment driven channel formations that look similar to rivers on land and other unusual seafloor characteristics. Some of these, Green Canyon (salt dome city), Mississippi Canyon and Desoto Canyon are all situated around the Mississipi delta and Northwest Florida Escarpment. These canyon areas are characterized by a sloping topography, rather than a sudden and continual drop off as with an escarpment.

Images that have been mapped on the NOAA Okeanos Explorer.
From mutlibeam soundings, water column data and previous remote operated vehicle (ROV) dives, seeps from salt domes found in these canyons can be seen as areas that either rise or remain flat, and where gas escapes the seafloor in a vertical fashion. Often masses of mussels, corals, and tube worms adorn this calcareous limestone bedding where the salt domes have risen. Salt domes have formed from ancient salt deposits originating from evaporated seas. Layers of depositional strata were later formed over the salt beds and under the salt layer gas and oil may reside. When the seafloor strata shifts or weakens the pressure change may allow this gas or oil to leak out of the areas where the salt domes have formed by building pressure. At right are some images that have been mapped on the NOAA Okeanos Explorer. Also their website has the ROV footage and track lines.

Two more features that intrigued me are a very long and winding sediment driven channel formation and two unusual semicircle formations on the West Florida Escarpment. The sediment river, or subterranean channel, originates around the Mississipi Delta southwest of Desoto Canyon and runs southeast for 164 km (or more-entire are not mapped yet). In the lower southern region, approximately 20m high ridge walls span 300m to over 700m across the channel. This entire snakelike formation lies at a seafloor depth of 2,954m. This is deep! The Northwest Florida Escarpment, situated directly to the northeast of the subterranean channel, rises 1,885m above the seafloor and presents a scene of an alien landscape.
The Northwest Florida Escarpment, situated directly to the northeast of the subterranean channel, rises 1,885m above the seafloor and presents a scene of an alien landscape.

Another more mysterious formation was read on the multibeam in the lower region of the escarpment west of the Florida Everglades. For now, since we only have half the picture, it looks like two large semicircles They are large in diameter with the southern formation stretching 8,247m but shallow in height with ridges of about 35m or less. We will have to wait for the next Gulf of Mexico cruise to fill in the blanks on these features.

Well if you are following along, I hope you are enjoying riding along the mapping adventures of the Okeanos Explorer. I will send another entry before we wrap things up in Norfolk next week. Cheers, Erin

Post Author:
Erin Hunter

Monday, May 14, 2012

Erin Hunter's Internship, Spring 2012 - Part 2

Week 2: Multibeam Sonar

A multibeam echosounder is a device used by hydrographic surveyors to determine the depth of water and the basic geomorphology of the seafloor.
The rhythmic pitch from bow to stern, the steady roll from side to side wake me from my mid-shift sleep. It's time for watch. The seas are about four feet and the ship is steady with its anti-roll stabilizers. We are making a 180 degree turn easily and swiftly with the dual shaft rudder system accompanied by two stern thrusters and combination hydrualic bow thrusters. We stay on our mapping line via GPS coordinates while the internal motion unit (IMU) keeps track of the sonar transducers' position under the hull at a rate of a several times per second. Our every move is recorded and used to record the multibeam soundings accurately.

Down the hall and into the control room, the two watchstanders turn over their shift. Computer screens fill the room. The multibeam sonar readings are up on the big screen, and are used to determine the depth of the seafloor. We are cruising 105 km (168 miles) due south of the Pensacola pass. Our water depth is 2,906 m or the equivalent of 29 football fields deep.

View of the control room on the Okeanos.
This multibeam screen shows an underwater sediment river.

As the ship holds its course, from under the ships' hull a sound pulse, or ping, is transmitted through the water column to the seafloor. After the ping bounces off the seafloor the receiver, positioned next to the transmitter. The time it takes for the ping to go to the bottom and return, translates to the depth of the seafloor at that position. When a ping takes longer to return from the seafloor, the depth is greater. A multibeam acoustic sensor can cover a large area, or swath. It has several transmitters and receivers called transducers that change electric pulses to acoustic pulses and vice versa. This allows a large area to be mapped on one heading, or line. The E302 multibeam used aboard the NOAA Okeanos Explorer can generate 486 depth sounding per swath at a rate of 10 swaths per second. This seafloor depth information, or bathymetric data, is used to create the maps produced today. All of this data is publicly available on the NOAA website. The Okeanos-google digital atlas is also a good place to look at survey sites.

http://www.ncddc.noaa.gov/website/google_maps/OkeanosExplorer/mapsOkeanos.htm

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

Personal Log for Week 2

All is well. There was a movie night outside on the fantail, or aft deck, and they watched The Grey, about Arctic wolves. We have been eating an array of cookies and cakes. My favorite spot to hang out is on a wooden bench on the bow. It is nice to sit up there, get fresh air and read a good book. We had safety drills again today (it was my shower time), luckily we only had to put on life jackets and not the big survival suits, aka gumby suits.

Post Author:
Erin Hunter

Wednesday, May 9, 2012

Erin Hunter's Internship, Spring 2012 - Part 1

Erin Hunter is a graduate student at the University of West Florida and is currently participating in a 3-week internship on the NOAA Okeanos Explorer research vessel.
 

About Erin Hunter's Internship Experience

The boundary between physical science and biological science from ecosytsem effects to molecular effects has encompassed the large part of my education. After studying at the University of Texas at Austin and receiving a B.S. in Biology:Ecology, evolution and conservation degree with a marine specialty from UT Marine Science Institute in Port Aransas, my studies have continued at the graduate level under Dr. Wade Jeffrey from the University of West Florida, Center for Environmental Diagnostic and Bioremediation department. Currently, research on environmental stressors like ultraviolet radiation and temperature change on microbial communities with analysis at the genetic level defines my thesis work. This includes phylogenetic identification of the bacterioplankton populations under different levels and types of stress. Implications of research in microbial ecology can reach from environmental systemic impacts to human impacts. This internship on the NOAA Okeanos Explorer, using multi-beam sonar mapping to gather bathymetric data, is a new avenue into the physical science of Oceanography and represents a human drive to discover and examine all of Earth's processes.

On the bridge of the NOAA Okeanos Explorer.

Week 1: Background

Recently, a third grade class was asked how much of the world's ocean has been explored. The correct answer was not readily acquired because it was unfathomable to these children, literally living on the Gulf Coast, to imagine that 95% of the oceans are yet to be explored.
To help fill this void, in 2008, the NOAA Okeanos Explorer was commissioned as the only federal vessel dedicated solely to ocean exploration and discovery. This 224 ft vessel, with officers and crew of approximately 27 and up to 19 mission personnel, travels the globe mapping the seafloor with numerous scientific and technological tools.

The bow of the Okeanos.
http://www.moc.noaa.gov/oe/
http://oceanexplorer.noaa.gov/okeanos/

On the Okeanos Explorer, new seafloor characteristics and potential targets for exploration are identified using a high-resolution multibeam sonar with water column capabilities. A permanently housed deep water remote operating vehicle (ROV) allows dives on target sites of interest shortly after mapping. Another feature of the Okeanos is the ability to live stream ROV dives and other communications to scientists, educators and the general public.

http://oceanexplorer.noaa.gov/okeanos/media/exstream/exstream04.html

The 2012 Gulf of Mexico mission has been a successful venture with three legs already completed. Among other exploration, there was a ROV dive on a discovered shipwreck, a dive examining deep water coral habitats and a mapping mission on the DeSoto Canyon south of Pensacola, FL. We are currently mapping two more sites, Green Canyon and the Mississippi Canyon before heading out into the Atlantic to map the Blake Ridge. Check out the mapping, dives and mission logs for photos and complete information.

http://oceanexplorer.noaa.gov/okeanos/explorations/ex1202/welcome.html
http://oceanexplorer.noaa.gov/okeanos/explorations/ex1202/logs/welcome.html

Personal Log for Week 1

Sunset off the bridge of the Okeanos.
We have all been assigned our cabins, room mates and shift times. I am watchstanding on the 8am-noon and 8pm-midnight shifts. In spare time, we eat a lot (the food is very good), watch movies, read, work on projects, go to the exercise room, do laundry or sit out on deck oh and I almost forgot sleep. The seas have been mostly calm at 1-2 feet for several days now. There are supposed to be higher seas by Friday. Learning the computer systems and programs has been my focus but I am happy to say I can make a google ready image from sonar pings from under our ship to imagery. Next log I will explain this process in a little more detail. Good night.

Post Author:
Erin Hunter