Caroline Singler, August 31, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy
Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean
Date of Post: 31 August 2010

Back to School – Tuesday 31 August 2010

Midnight in the Arctic Ocean

Midnight in the Arctic Ocean

Location and Weather Data from the Bridge
Date: 31 August 2010 Time of Day: 00:00 (12:00 a.m. local time); 07: UTC
Latitude: 76 º 37.6 ‘ N Longitude: 138 º 31.2 ‘ W
Ship Speed: 8.7 knots Heading: 197 º (SSW)
Air Temperature: 0.19 ºC/ 32.3 ºF
Barometric Pressure: 1009.0 mb
Humidity: 98.8 %
Winds: 6.3 knots W Wind Chill: -5.3 ºC/ 22.4 ºF
Sea Temperature: -0.3 ºC Salinity: 25.32 PSU
Water Depth: 3666.9 m
This is a special message for my new Earth Science students, members of the class of 2014 who are participating in 9th Grade Orientation at Lincoln-Sudbury Regional High School today. I am sorry that I cannot be there with you. I am excited to be your teacher this year – you are important to me, and I look forward to getting to know you when I return. You are in the caring and capable hands of Mrs. Iskandar during my absence. Please be respectful of her and thank her for agreeing to cover my classes for the next week in addition to her normal responsibilities in the Science Department.
As you can see, I am a bit too far north to get there on time. I am currently in the Arctic Ocean on board the U.S. Coast Guard Cutter Healy. The ship icon on the map below shows where I was at midnight on 31 August, which was 3 a.m. in Massachusetts. The red lines on the map show different places that we have been during the last month.
Map of Locations

Map of Locations

We left Dutch Harbor, Alaska (pictured on the right) on Monday 2 August, cruised North through the Bering Sea, and have been in the region of the Arctic known as the Beaufort Sea and the Canada Basin for the last four weeks. I am here participating in an oceanography research expedition as a representative of the NOAA Teacher at Sea program. The research mission is called the Extended Continental Shelf Project. It is an international, multiyear effort between the United States and Canada to map the seafloor and the subsurface in the Arctic Ocean off the coasts of the two countries. Healy (pictured on right) and the Canadian Coast Guard Ship Louis S. St. Laurentare both icebreaker ships designed specifically for scientific expeditions in the polar regions. We made it as far north as 82.5º North and are now moving south again. There is still ice around us now, but not as much as we saw just a few days ago. I have been taking a lot of pictures, and I can’t wait to share them with you. Here are just a few from the last couple of days.

USCGS Cutter Healy

USCGS Cutter Healy

Arctic ocean at night

Arctic ocean at night

Louis at Sunset

Louis at Sunset

A week from now, on Monday, 6 September, we will leave the Healy by helicopter at Barrow, Alaska, the northernmost town in the United States. I expect to be back at school on Friday, 10 September.

Ice

Ice

Breaking Ice

Breaking Ice

Before then, I hope you will take some time to look through my blog and read about some of the things I have seen and done. Then, I would appreciate it if you would send me a short email at this address: caroline.singler@healy.polarscience.net Introduce yourself to me and then either make a comment or ask a question about the Arctic, either based on something you read in my blog or just something you wonder about and would like to know. I will do my best to answer all your questions, and I will give you an extra credit homework grade for your effort.

Enjoy your first week of high school. Don’t get too overwhelmed by the size of the building or the crazy way the class schedule works. You will get used to it in no time. Have fun.

I’m looking forward to hearing from you. I will see you soon.
Miss Singler

Caroline Singler, August 25, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy


Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean

Date of Post: 27 August 2010

Farthest North – 26 August 2010

Farthest North

Farthest North

Location and Weather Data from the Bridge
Date: 25 August 2010 Time of Day: 2300 (11:00 p.m. local time); 06:00 UTC
Latitude: 82º 29’ N Longitude: 138º 50.4’ W
Ship Speed: 4.5 knots Heading: 291º (NW)
Air Temperature: -0.5ºC / 31.1ºF
Barometric Pressure: 1010.7 mb Humidity: 97%
Winds: 9 knots SW
Sea Temperature: -1.2ºC Salinity: 28.2 PSU
Water Depth: 3400 mDate: 26 August 2010 Time of Day: 2230 (10:30 p.m. local time); 0530 UTC
Latitude: 82º 0.5’ N Longitude: 132º 5.5’ W
Ship Speed: 4.3 knots Heading: 163º (SE)
Air Temperature: -1.25ºC / 29.7ºF
Barometric Pressure: 1012.6 mb Humidity: 100%
Winds: 20.4 knots SW Wind Chill: -8.9ºC/15.9ºF
Sea Temperature: -1.35ºC Salinity: 28.47 PSU
Water Depth: 3643 m
We reached our farthest northern location in the early morning hours on Friday 26 August. We stopped a little before midnight local time on 8/25 (07:00 8/26 UTC) for a water sampling event and I captured this map that showed our location at latitude 80º31.85’.
Farthest Northern point on a map

Farthest Northern point on a map

 Here is what the Arctic looks like at 82º31.5’N 139º15’W from the bow of the Healy.

Here is what the Arctic looks like at 82º31.5’N 139º15’W from the bow of the Healy.

I took the picture at the beginning of this post myself, at about the same time as the map shows!
Morning Sky With Louis

Morning Sky With Louis

We ended up a little farther north in the early morning as we maneuvered to get back in line withLouis, who rejoined us after some downtime for repairs.

Our official FARTHEST NORTH point was at latitude 82º32’. The original plan called for 85ºN, but the ice is thick and progress is slow, and we have had several delays. Now we are eastward bound, on a line that heads towards but ends before the Queen Elizabeth Islands of Canada. Healyspends a lot of time backing and ramming. There are numerous ridges in the ice formed when ice floes drift with the wind and currents and collide with other flows, and these present big obstacles. First they drive the ship into the ridge, then back up, leaving the impression of the ship’s bow like a snow angel.

Healy Snow Angel

Healy Snow Angel

There is an eerie silence when the ship is backing, and I expected it to be followed by a burst of speed (hence the backing and “ramming”), but the ship just drives forward again over the same track. It can take two or three times to break through a large ridge. Even then, it can be difficult for Louis to proceed with her towed gear even – often the pressure causes ice to drift back into the track before Louis can pass through. On numerous occasions Healy has had to double back to relieve the pressure on Louis by coming around and passing to the side of the ship, trying to give the ice a different way to drift. Sections of Healy’s track line look as if we are doing figure eights around Louis.
Louis in ice

Louis in ice

Since Sunday, we have been at latitudes where the sun does not set. I get off watch at midnight local time, but true midnight is usually an hour or two after that. Here are some views of the sky that I see when I leave the computer lab at night.
Midnight

Midnight 8_23_10

Midnight- 23 August 2010
Midnight 8_24_10

Midnight 8_24_10

Midnight- 24 August 2010
Midnight_8_25_10

Midnight_8_25_10

Midnight- 25 August 2010
Midnight 8_27_10

Midnight 8_27_10

Midnight- 27 August 2010

I can’t always see the sun, but it’s still pretty and peaceful, even when we are banging through ice.

Caroline

Caroline Singler, August 13-15 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGS Healy 

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean north of Alaska in the Canada Basin
Date of Post: 16 August 2010

Follow the Leader – 13 – 15 August 2010

Location and Weather Data from the Bridge
Date: 13 August 2010 Time of Day: 2100 (9:00 p.m.) local time; 04:00 UTC
Latitude: 73º0’N

Longitude: 145º3’W
Ship Speed: 3.9 knots
Heading: 1.8º (north)
Air Temperature: 2.0ºC/35ºF
Barometric Pressure: 1018.9 millibars (mb) Humidity: 100%
Winds: 3-5 Knots SW
Sea Temperature: -0.4ºC Salinity: 25.37 PSU
Water Depth:~3600 m

Ice with Ridges

Ice with Ridges

Date: 14 August 2010

Time of Day: 2105 (9:05 p.m.)
local time; 04:05 UTC
Latitude: 73º36.4’N Longitude: 146º19.21’W
Ship Speed: 4.7 knots Heading: 223º (southwest)
Air Temperature: 2.15ºC/35.88ºF
Barometric Pressure: 1022.3 mb Humidity: 92.1%
Winds: 12.2 knots SE Wind Chill: -3.1ºC/26.5ºF
Sea Temperature: -0.7 ºC Salinity: 24.84 PSU
Water Depth: 3708.6 m
Open Water and Beautiful Sky

Open Water and Beautiful Sky

Date: 15 August 2010
Time of Day: 1500 (3:00 p.m.)
local time; 22:00 UTC
Latitude: 72º56.4’N
Longitude: 150º9.0’W
Ship speed: 11.8 knots
Heading: 220º (southwest)
Air Temperature: 5.6ºC/42.2ºF
Barometric Pressure: 1015.6 mb
Humidity: 98.1%
Winds: 17.7 knots E
Wind Chill: 1.7ºC/35.1ºF
Sea Temperature: 3.9ºC
Salinity: 24.5 PSU
Water Depth:3691.1 mScience and Technology Log

The Extended Continental Shelf Project is a multi-year effort between the United States and Canada. The two countries share knowledge, resources, and information to allow greater coverage of the region and more cost effective achievement of the mission objectives. For this mission, the USCGC Healy is working in tandem with the Canadian Coast Guard ice breaker Louis S. St. Laurent, called Louis(pronounced “Louie”) for short. Healy is responsible for collecting bathymetric data and shallow subsurface imaging while Louis performs deeper subsurface imaging with her air-gun array. The instrumentation on Louis is towed behind the ship and requires a clear path through the ice; therefore, Healy’s primary responsibility when the ships are in ice is to lead and break ice for Louis. Healy opens a path and Louis follows, typically about one to two miles behind depending on ice and visibility conditions. It was foggy for most of the day on Friday as we led the way north along the first track line. The only way I knew that Louis was behind us was by watching the ship tracking chart and listening to occasional radio chatter between the two boats as the crews communicated about ice conditions. Skies cleared as we moved farther north and deeper into the ice on Saturday. Near midday, the fog lifted and there was Louis, first emerging like a ghostly image out of the fog and then, as we made the turn onto a new transect line, she was in full view. By Sunday afternoon we were heading south in open water, so Healy moved away fromLouis to conduct other business while our ice breaking services were not needed.
USCGS Healy Leading USCGS Lewis

USCGC Healy Leading CCGS Louis

USCGS Louis on Ice

CCGS Louis on Ice

While multibeam sonar allows us to “see the bottom”, subbottom profiling uses a different sound-producing system to see what is under the bottom. Geologists use the subbottom data both from Healy andLouis to estimate sediment thickness and make inferences about sediment types and structures beneath the seafloor. It makes me think of Superman’s x-ray vision! Like multibeam sonar, subbottom profilers are echosounding devices. They are active sonar systems – sound signals are transmitted and received by the instrument.
Healy’s profiler is a “chirp” system mounted inside the bottom of the ship’s hull – so called because it sounds like a bird chirping, a sound that one hears in the background throughout the ship. It releases high frequency pulses of acoustic energy that travel through the water column and (in theory) hit the seafloor and penetrate into subsurface materials to depths of tens of meters. Signals are reflected at the seafloor and at interfaces between different subsurface layers within the seafloor. The reflection of acoustic energy depends on the “acoustic impedance” of the material encountered. Acoustic impedance is related to the density of the material and the velocity of sound in that medium. Different materials have different acoustic impedance and therefore different reflectivity. The concept is similar to that of albedo when one considers the reflection of solar energy from different surfaces. A smooth, light-colored surface like a field of snow reflects a high percentage of incoming solar rays and therefore has a high albedo– hence the glare that hurts your eyes on a sunny day. Dark-colored surfaces reflect much lower percentages of incident light and therefore have low albedo. (They also absorb more energy which is why they get hotter on a sunny day.)
With subbottom profiling, sands typically reflect sound differently than mud, and layers or other structures in the subsurface result in different signal strengths returning to the receivers on the ship. The picture on the right shows an image of the raw chirp data displayed on the computer screen at the watch stander station. It does not show a lot in this state, but after processing the data will provide important information about the subsurface in the Arctic Ocean.
Chirp Display

Chirp Display

Subbottom surveying on Louis is performed with a multi-channel air gun system that is towed behind the ship. Three air guns, powered by air compressors on the ship’s deck, provide the acoustic energy source. A streamer with an array of 16 hydrophones trails behind the air guns; the hydrophones receive the return signals reflected by the seafloor and subsurface sediments. In open water, the air guns are attached to a float and hang about three to five meters below the surface, at a distance of about 100 meters behind the ship. In ice, the air guns are attached to a metal sled (depressor) that hangs below the sea surface (and hence the ice) to a depth of about 10 meters and at a distance of about 10 meters behind the ship. When fired, the air guns simultaneously emit large air bubbles into the water column. As the bubbles collapse, an acoustic pulse is produced that moves through the water. It is similar to what happens in the atmosphere when air rapidly expands and contracts as a lightning bolt passes through, creating the sound we know as thunder. The air guns generate sound at a lower frequency than the chirp system; sound at these lower frequencies penetrates deeper into the subsurface but produces lower resolution than the higher frequency chirp system. Such air gun systems can provide images to depths of several kilometers below the seafloor.

WHOI Subbottom Profiling Diagram

WHOI Subbottom Profiling Diagram

Image source: USGS Woods Hole Science CenterReferences:
USGS Woods Hole Science Centerhttp://woodshole.er.usgs.gov/operations/sfmapping/seismic.htm
NOAA Coastal Services Centerhttp://www.csc.noaa.gov/benthic/mapping/techniques/sensors/subbottom.htm

Personal Log
Saturdays are “Field Days” on Healy. No, we did not all get into boats and take a trip away from the ship or get out onto the ice. Field Day is a fancy way of saying that it is time for cleanup and inspection of common areas and personal berthing areas. All personnel on board are responsible for trash removal and cleaning of staterooms, restrooms and common living and working spaces. Anyone who is not on duty pitches in to clean the Science lounge and labs – vacuuming, sweeping, washing floors and generally putting things in order. The “trash vans” are open twice a week; everyone brings trash and recycling to two large blue bins on the port side of the 02 deck (the same deck as the science staterooms). Coast Guard volunteers work the trash vans. Healy will be at sea for another long mission after this one, so efficient trash removal and storage is critical. Healy personnel are dedicated to recycling and have an award winning recycling program on board – no small feat when it is necessary to haul it all around for months at sea. Think about that when you are tempted to complain about separating recyclables from trash at home or at school.

Since everything was neat and tidy, I decided it was a good time to show you my living space on Healy. Science staterooms are set up for three occupants, but on this trip we have two people per room. I share a room with Sarah Ashworth, a marine mammal observer; she is currently on Louis, so for now I have my own room. The room is more spacious than I expected on a ship, similar in size to a lot of college dorm rooms.

My Rack

My Rack

Space is used very efficiently. There are bunk beds; Sarah has more experience at sea than I, so she has the top bunk or “rack”.

Bunks

Bunks

Each person has a good sized locker for clothes and since there are only two of us, we each have a desk and filing cabinet, so there is plenty of storage space – more than we need for our personal belongings.
Sink and Locker

Sink and Locker

Desk Area

Desk Area

There’s nothing like a room with a view, even if they left the tape on the window the last time they painted the ship.

Sun on Water Through Porthole

Sun on Water Through Porthole

Each room has its own sink, and shares a bathroom with the adjoining room. Okay, they call it a “head” on a ship; don’t ask me why! The bathroom is small, but one does not linger when taking a “sea shower”, and there is always plenty of hot water. In case you ever wondered what a marine toilet looked like, here it is.

Shower

Shower

Marine Toilet

Marine Toilet

We headed towards Barrow on Sunday to pick up a crew member and some supplies for the Louis. There was a steady wind from the east for most of the afternoon, and the boat was rolling a little, but I was more prepared for it this time than I was the first time it happened, but I still stumble when I walk down the hall.

We have had beautiful views of ice, sea, and sky for the last few days.

Ice with cool clouds

Ice with cool clouds

Waves and sky

Waves and sky

Caroline Singler, August 11-12 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Beaufort Sea in the Arctic Ocean
Date of Post: 13 August 2010

Maneuvering in Ice – 7-10 August 2010

Location and Weather Data from Bridge
Date: 11 August 2010

Time of Day: 1015 (10:15 local time); 17:15 UTC
Latitude: 71º 23.2’ N
Longitude: 144º 43.2’ W
Ship Speed: 9.7 knots
Heading: 106.6º (ESE)
Air Temperature: 5.1ºC /41.2ºF
Barometric Pressure: 1010.6 millibars
Humidity: 100%
Winds: 30.6 knots ENE
Wind Chill: -2.2ºC /28.14ºF
Sea Temperature: 4.8ºC
Salinity: 23.70 PSU
Water Depth:2952.9 mDate: 12 August 2010
Time of Day: 1900 (7:00 local time); 02:00 UTC
Latitude: 71º 10.94’ N
Longitude: 144º 40.28’ W
Ship Speed: 11.9 knots
Heading: 265.3º (WSW)
Air Temperature: 6.73ºC /44.12ºF
Barometric Pressure: 1016.7 millibars
Humidity: 97.9%
Winds: 18.8 knots ESE Wind Chill: 3.96ºC /39.12ºF
Sea Temperature: 6.0ºC Salinity: 24.32 PSU
Water Depth:2496.0 mScience and Technology Log
I want to give you a sense of how ice can affect the progress of the ship. It was not something that I could imagine before coming on the Healy. When we first encountered ice, I was captivated by its beauty – it is a wilderness of an entirely different sort than I have ever experienced. I knew the ice would slow our progress, and I knew from talking to the scientists that it could complicate the mapping with the multibeam system. I did not realize all the ways in which it would challenge everyone involved in the mission, for example:

  • the chief scientist and the rest of the science team have to decide how to alter the ship’s track without sacrificing the mission objectives;
  • the ice analysts use satellite imagery and ice buoy data and try to predict where the ice may be and advise the Chief Scientist and the ship’s crew regarding possible changes in course;
  • the Coast Guard officers and crew who try to keep us as close to our planned course as possible, keeping in constant communication with the Chief Scientist and with the watch standers in the geophysics lab to be sure that we are able to collect good data;
  • the computer specialists have to figure out how to get the best ultibeam data, even when ice clogs the seawater intake that provides data for the sound speed profile and when sound beams transmitted from the surface bounce in all directions and cannot find bottom;
  • geophysics watch standers like me have to watch for tiny clues from the instruments that the ice might be interfering with the transmission of the sound signals and the acquisition of reliable data.

Everything about working in the Arctic is a lesson in patience and flexibility; one must learn to “go with the floe”.

Bow of the USCGS Healy

Bow of the USCGS Healy

View of Ice Breaking from the Bridge

View of Ice Breaking from the Bridge

Since our primary objective is to collect bathymetric data, the locations of transect lines were determined before the mission to best meet the objective. Some lines provide data about previously unmapped areas; others fill in gaps between existing data tracks. We are able to follow the plan when we are in open water, but once we are in the ice, sometimes plans change. This became immediately apparent when I went on watch on the night of 7 August. We were heading north in the Beaufort Sea into thicker ice. There was a flurry of activity in the geophysics computer lab. The scientists were studying the ship’s track and the latest satellite images of the ice. We were on course to encounter some very large floes. I was about to get my first real taste of what an ice breaker does.

An ice breaker is designed differently from other ships. It is double-hulled with extra thick steel at the bow, stern and water line. It has a flat hull with a rounded bow that slopes gradually upward to allow it to ride up over the ice. (I am told that same feature makes it roll considerably in rough seas, though thankfully the Healy’s design is somewhat modified from the earlier Coast Guard ice breakers, so it does not roll as much as it could!) There are numerous mechanical modifications that allow ice breakers to work in an environment that would crush other ships. (See Cool Antarctica for a good summary of the characteristics of ice breakers.) The ship weighs over 11 tons, and the basic principle of ice breaking is to ride up over the ice and allow gravity to do the work, using the ship’s weight to fracture the ice. Healy’s typical cruising speed is 12 knots, with a maximum of 17 knots; depending on ice conditions, Healy’s speed typically decreases to 7 knots, and it is often necessary to go even slower through large floes, particularly if the multibeam is not recording good data. In the thickest ice, the ship uses a technique called “backing and ramming” which is pretty much exactly as it sounds – the ship is driven on the ice, then backed up and driven back onto the ice again. But while Healy is a powerful ship, a large tabular floe of multiyear ice has a lot of inertia, and it takes an incredible force to move it. More often than not, it is a better idea to try to find a way around the large floes instead of breaking through them.

The next few photos show what happens when Healy breaks through ice. Cracks radiate out in all directions as the weight of the ship is forced into the floe. The deep blue color indicates that much of the ice is “multiyear ice” – ice that has lasted through at least one summer melting season.
Close up of USCGS Healy breaking ice

Close up of USCGS Healy breaking ice

The following maps show how one large floe affected our progress in the early morning hours of 8 August 2010. I came on watch at 8:00 p.m. local time (04:00 UTC) on 7 August. We were at the point labeled “0” on the first map, travelling through open water and light ice at a speed of approximately 11.7 knots. We reached point “1” at 11:30 p.m. (07:30 UTC) and were beginning to slow down in the ice. In 3.5 hours, we covered a distance of 38.88 nautical miles (nm), at an average speed of 11.1 knots. At 12:57 a.m. (08:57 UTC), we reached point “2”, 7.89 nm from point 1 – that’s an average speed of about 5.3 knots.
Map

Map

Things got tricky after that. Notice the change in scale on the second map, which shows the ship’s progress over the next 3 hours until point “11” at 4:00 a.m. (12:00 UTC) on the 8th. In that time, we covered 15.48 nm and had to deviate off a straight line course and change direction several times to maneuver around ice. Our average speed continued to be about 5 knots, but there were times during that stretch when the speed was a low as 1 or 2 knots. Relative to the original planned straight line course, the distance covered in that period was 6.7 nm.

Map

Map

Map 3 shows the remaining course we followed for that transect (the right hand track line) – note again the different map scale. We covered the remaining distance along the line between points 11 and 12, about 91 nm, over the next 3 hours. The trackline on the left shows our subsequent course, about a day later.

Map

Map

It takes a special ship to do what Healy does, and it takes a crew and science team who are capable, flexible, and cooperative to get the job done.

Personal Log

A lot happened in the last few days. If you pay attention to the location information at the beginning of some posts, you will notice that we have traveled north and south, east and west through the Beaufort Sea between the Mackenzie Delta region on the Canadian coast and the Prudhoe Bay area of the Alaska coast. We had the long-awaited rendezvous with Canadian Coast Guard Cutter Louis S. St. Laurent on Tuesday 10 August. Three members of our science team (two marine mammal observers and one ice analyst) went to the Louis and three members of their team joined us on the Healy. It was exciting to watch the helicopter exchange of personnel. I was not prepared for how fast the helicopter moved, and I was not quick enough to capture any close-ups.
Here’s a look at the helicopter approaching the helo pad aft on Healy and flying back to the Louis.

Here’s a look at the helicopter approaching the helo pad aft on Healy and flying back to the Louis.

Here’s a look at the helicopter approaching the helo pad aft on Healy and flying back to the Louis.

Here’s a look at the helicopter approaching the helo pad aft on Louis and flying back to the Healy.

We took some cores of the seafloor on Wednesday and Thursday – more on that exciting change in routine in another post. We were out of the ice for several days, and I missed it, but we are moving north again now, farther north than we have been so far and we have started the cooperative part of the mission, in which Healy will lead and break ice forLouis.

Tomorrow, it seems, is Saturday. It is extremely hard to keep track of the days at sea, especially when there is not much darkness at night. Saturday is cleaning day, so we have to make sure everything is “ship-shape” in our staterooms and the science work areas. Stay tuned for some photos of my room after it’s neat and tidy!

Did you know?

Distance at sea is typically measured in nautical miles. One nautical mile is equal to approximately 1.15 statute miles or 1.85 kilometers. Speeds are measured in knots. One knot is equal to 1 nautical mile per hour or 1.15 miles per hour.

Caroline

Caroline Singler, August 7-9, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean 41 miles north of Alaska
Date: 9 August 2010

Seeing the Bottom — 7 August 2010

It’s taken me several days to write and post this entry. I wanted to learn more about the sonar technology that we are using for the bathymetric mapping, then we lost internet early on the morning of 8 August 2010 while heading north in the Beaufort Sea. This happened at about the same time as we started encountering heavy ice, but I do not believe that the two events were related. I am including location and weather data for several days to give you a sense of where we were and where we are heading as well as the physical changes in our environment.Thankfully, email works even when internet does not – it took my non-IT oriented mind a while to wrap itself around that concept. While I am out of range, my dear sister Rosemary has agreed to post for me as long as I can get emails to her. (Thanks, Ro!) You already have her to thank for the polar bear post. Please keep emailing and/or posting comments. I look forward to reading comments when I come home.
Location and Weather Data from the Bridge
Date: 7 August 2010 Time of Day: 1400 (2:00 p.m.) local time; 22:00 UTC
Latitude: 70º47.6’N Longitude: 142º42.3’W
Ship Speed: 15.1 knots Heading: 111º (southeast)
Air Temperature: 5.1ºC /41.6ºF
Barometric Pressure: 1005.3 millibars
Humidity: 87 .9%
Winds: 27.7 Knots NE
Sea Temperature: 2.3ºC
Salinity: 20.22 PSU (practical salinity units)
Water Depth:1270 .8 mDate: 8 August 2010
Time of Day: 1245 (12:45 local time); 20:45 UTC
Latitude: 72º12.72’N
Longitude: 138º28.7’W
Ship Speed: 7.7 knots
Heading: 36.2º (NE)
Air Temperature: 0.5ºC /32.9ºF
Barometric Pressure: 1012.7 millibars Humidity: 86.3%
Winds: 19.3 Knots NE
Wind Chill: -7.48ºC/18.53ºF
Sea Temperature: -1.2ºC Salinity: 25.5 PSU
Water Depth:2547.8 mDate: 9 August 2010
Time of Day: 1530 (3:30 local time); 22:30 UTC
Latitude: 72º 29.8’N
Longitude: 139º 40.9’W
Ship Speed: 6.3 knots
Heading: 183.5º (SSW)
Air Temperature: -0.03ºC /31.94ºF
Barometric Pressure: 1009.7 millibars Humidity: 92.2%
Winds: 17.7 Knots NE
Wind Chill: -6.02ºC /21.17ºF
Sea Temperature: -1.2ºC Salinity: 25.08 PSU
Water Depth:2969.0 mScience and Technology Log
The primary objectives of the science mission are to map the seafloor and image the underlying sediments. Bathymetry is the measurement of depth of water bodies, derived from the Greek bathos meaning deep and metria meaning measure. Early bathymetric surveys used the “lead-lining” method, in which depths are manually recorded using a weighted line. This method is slow and labor intensive, and it is not practical for depths greater than about 100 feet. (Ironically, I spent the summer of 2009 doing just such a survey of a small lake on Long Island, NY working with two other teachers as DOE-ACTSinterns at Brookhaven National Laboratory.) Modern bathymetric surveys use echo sounding, or SONAR (Sound Navigation and Ranging) to determine depth and shape of the seafloor. These systems make it possible to map large areas in extreme detail, leading NOAA to name the 20th Century advancements in hydrographic surveying techniques to its list of Top Ten Breakthroughs during the agency’s first 200 years.SONAR uses sound signals to locate objects beneath the sea surface. Passive systems use receivers such as hydrophones to detect signals transmitted by other sources, such as animals or submarines. Active systems transmit and receive signals. A transmitter mounted on the ship’s hull emits a signal. The signal travels through the water column and bounces off an object in its path. It returns as an echo to a transmitter on the ship that measures the strength of the return signal. The time between transmission and reception is used to determine range, where range equals (speed of sound in seawater) times (travel time divided by 2). When the object that reflects the signal is the seafloor, the range is the water depth.

There are single beam and multibeam sonar systems. Single beam systems measure along a single line beneath the ship and produce a line of depths. Multibeam systems send signals out along a line perpendicular to the ship and generate a “swath” of data for the area beneath the ship. The advantage of this system is that it creates a map that shows depth and shape of the seafloor. The diagram below shows a schematic comparison of three bottom survey methods.

Chart of three survey methods

Chart of three survey methods

Me on watch

Me on watch

Healy is equipped with a hull-mounted multibeam sonar system. It runs continuously whenever Healy is at sea, collecting bathymetric data to add to our knowledge of the seafloor at high latitudes. I serve as one of the watch standers in the geophysics lab each night from 8 p.m. to 12 a.m. We keep an eye on several computer monitors that display the data from the different geophysics tools and others that display water quality and geographic position data. The photo on the right shows me with my watch partner, USGS scientist Peter Triezenberg sitting at the watch station.
There are many variables that can influence the quality of the multibeam data. The speed of sound in water is influenced by many different variables, including temperature and salinity. Therefore, seawater samples are collected from the ship’s seawater intake system to generate a thermosalinograph (TSG) profile to keep the speed of sound accurately calibrated. Additionally, expendable probes (XBTs) are launched twice a day to update the sound speed profiles. Other instruments monitor the attitude (pitch, roll and heave) of the ship and feed that data to the multibeam system. Finally, the ship keeps extremely precise track of time of day and geographical position so that the data can be used for accurate bathymetric mapping of the seafloor. My job as a watch stander is basically to be sure that everything is running properly, and to notify one of the specialists if something is not right.
Multibeam monitors:
Multibeam Monitors

Multibeam Monitors

TSG display:

The end result is a detailed map of the seafloor in which different colors represent different depths. The picture below shows an image of the raw multibeam data superimposed on a seafloor map which we can see on the ship’s Map Server display. The red line shows the ship’s track, and the new multibeam data extends perpendicular to that line. Other data on the map are from transects mapped on earlier Healy cruises and other sources.

Map Server Display

Map Server Display

Personal Log

Breaking ice

Breaking ice

We experienced a range of sea and ice conditions over the last several days as we traveled east of Barrow Alaska and headed north into the Beaufort Sea. Our earliest ice encounters were a gentle preview of what was to come – mostly bumps and scrapes with small pieces as we headed eastward parallel to the Alaska coastline. By midday on Saturday, we began to cross larger floes, and at times the ship was really rocking. One science team member said it feels like riding the subway, that’s a pretty good analogy. Sitting in the Mess on the main deck of the ship – which is about one floor above water line – I hear the grinding of ice on steel and it feels like I’m sitting in a big tin can that’s being crushed in a trash compactor. Fortunately, the ship is tougher than the ice. At times we move so much that everything in the room shakes. Because we are on a ship, everything is bolted down, but I still look up to be sure there is no danger of anything falling on my head. Some team members from California say the sensation reminds them of an earthquake.

Late Saturday morning, we crossed out of ice and back into open water. As we approached the last pieces of ice before open water, I saw waves hitting the distant edges of the ice; it looked like waves breaking on the shore. At first, I did not grasp the significance of this observation – I thought it was pretty and snapped some pictures and marveled at how we could be in thick ice and then suddenly in open water.

Waves on ice

Waves on ice

In the next hour, I realized that these were the largest waves we had encountered so far on the trip, and while they looked pretty, they also made the ship roll considerably more than it had before. Over the next few hours, I began to sense the movement more than I had in a few days. By dinner time, I had difficulty walking straight across the mess deck, and I was becoming a little apprehensive. I took a motion sickness pill as a preventative measure, and I took a nap because it was far more pleasant to lie in my rack and be rocked by the ship’s motion than to try to remain vertical. We eventually moved into calmer waters, and soon after that, we were back in heavy ice, which I somehow do not find as unpleasant as the waves. Since then, our movement has been slow and steady along our transects through the ice, with an emphasis on slow.

We don’t get much darkness up here in the Arctic, but we do occasionally get treated to some great sunrises and sunsets, if one is awake to catch them. Here are some photos of the sunset on Saturday 7 August 2010. The first was taken about an hour before sunset from the port side of the ship. I was as captivated by the horsetail clouds as I was by the color of the sky. The second was taken just at sunset, right before my camera battery died!

Sunset

Sunset

Sunset from the port side

Sunset from the port side

Caroline Singler, August 6, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean

Date of Post: 2 September 2010

 

Ice, Ice, Baby!

Watching my first ice

Watching my first ice

I’ve had that song in my head since we left Dutch Harbor – well actually that’s the only line I know, and we encountered our first sea ice early this morning, Friday 6 August 2010.

We knew it was coming eventually, and a look at a satellite overlay on the ship tracker during last night’s watch revealed that we were getting close to the ice. The white areas to the south of the ship are clouds, but you can see broken white patches north of the ship’s track that are sea ice.

Ice Map

Ice Map

My watch ended at midnight, and we estimated that we’d be in the ice around 4:00 a.m., so I set my alarm for that time. At first I forgot why my alarm was going off, but then I heard a new sound, something I had been told to expect, and I realized it must be the sound of the ship’s hull scraping against the ice. I looked out the porthole to see patches of ice passing by, so I put on some warmer clothes and headed out on deck and then up to the bridge for my first look at sea ice. I’ll have plenty of opportunities to talk more about ice and the work of an ice breaker over the next couple of weeks, but for now, I want to share with you what I saw. I think you’ll understand why I feel so blessed to have the opportunity to be here.
Enjoy!
Caroline

These were my first views from the fore deck. Notice the sky:

View from Fore Deck - 6AM

View from Fore Deck – 6AM

Morning Sky and first ice

Morning Sky and first ice

The bridge provides some of the best views in the house. The fact that the sun chose to make an appearance through the clouds and early morning mist only added to the beauty.

Sun and ice

Sun and ice

Sun Breaking through the sky

Sun Breaking through the sky

Morning sun over ice

Morning sun over ice

 

ice from the bridge

View of ice from the bridge

Throughout the day, the ice came and went. At times, we rammed into large floes with such force that the entire ship rocked and groaned. Other times, the water was almost ice free.
Small iceberg

Small iceberg

Me on the deck

Me on the deck

Here I am in the Arctic Ocean, and I cannot imagine a better way to spend the summer!

Caroline Singler, August 4, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean

Date of Post: 2 September 2010

Crossing the Arctic Circle

Arctic Circle Crossing Screen View

Arctic Circle Crossing Screen View

On 4 August 2010 at 2017 local time (5 August 2010 04:17 UTC), I crossed the Arctic Circle as a passenger on the USCGC Healy. One of the advantages of being on watch was that I was staring at a computer screen and could photodocument the moment – well, I missed it slightly as I adjusted the camera, but I came close! The map below shows the ship’s position at the time of our crossing. (I can’t figure out how to make it larger, so look for the little red dot!)

Map

Map of ship crossing into the Arctic Circle

The skies have cleared considerably over the last couple of hours. Here are a couple of photos taken from outside the lab, which is located near the stern of the ship.
Looking fore and to port:
View of Arctic sky

View of Arctic sky

Looking aft:

View of Arctic sky

View of Arctic sky

Several people have told me about the recent aurora activity. Unfortunately, between fog and increasing number of daylight hours, we cannot see the displays.
CarolineNew terms
Polar Bear – one who has previously crossed the Arctic Circle at sea and has been initiated.
Blue Nose –one who is making his/her first crossing of the Arctic Circle or has previously crossed and has not been initiated.