Caroline Singler – Page 2 – NOAA Teacher at Sea Blog

August 20, 2010April 22, 2021

Caroline Singler, August 16-20 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean
Date of Post: 20 August 2010

Out in the Canada Basin — 16-20 August 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy
Mission: Extended Continental Shelf Survey
Geographical area of cruise: Arctic Ocean
Date of Post: 20 August 2010Location and Weather Data from the Bridge
Date: 16 August 2010

Time of Day: 2240 (10:40 p.m. local time); 05:40 UTC
Latitude: 71º 34.5’ N

Longitude: 156º 42.2’ W
Ship Speed: 16.5 knots Heading: 19.2º (NE)
Air Temperature: 8.2ºC/46.7ºF
Barometric Pressure: 1006.3 mb Humidity: 92.6%
Winds: 16.6 knots NE

Wind Chill: 2.5ºC/36.7ºF
Sea Temperature: 6.3ºC Salinity: 30.96 PSU
Water Depth:124.7 m (on continental shelf near Barrow AK)Date: 17 August 2010 Time of Day: 2120 (9:20 p.m. local time); 04:20 UTC
Latitude: 74º 6.1’ N Longitude: 150º 26.4’ W
Ship Speed: 4.2 knots Heading: 14.8º (NNE)
Air Temperature: 1.5ºC/34.7ºF
Barometric Pressure: 1003.7 mb Humidity: 91.5%
Winds: 22.9 knots E

Wind Chill: -5.7ºC /21.7ºF
Sea Temperature: -0.7ºC Salinity: 25.00 PSU
Water Depth:3729.1 mDate: 18 August 2010

Time of Day: 2320 (11:20 p.m. local time); 06:20 UTC
Latitude: 75º 25.1’ N Longitude: 153º 16.9’ W
Ship Speed: 4.7 knots Heading: 311.1º (NW)
Air Temperature: 0.45ºC/32.8ºF
Barometric Pressure: 1010.1 mb Humidity: 95.3%
Winds: 20.7 knots SE

Wind Chill: -5.8ºC /21.5ºF
Sea Temperature: -1.0ºC Salinity: 24.87 PSU
Water Depth:3848.4 mDate: 19 August 2010

Time of Day: 2230 (10:30 p.m. local time); 05:30 UTC
Latitude: 76º 11.8’ N Longitude: 155º 14.3’ W
Ship Speed: 4.4 knots Heading: 83.1º (NE)
Air Temperature: -0.47ºC/31.1ºF
Barometric Pressure: 1013.9 mb Humidity: 100%
Winds: 7 knots SE
Sea Temperature: -0.76ºC

Salinity: 24.7 PSU
Water Depth:~2100 mDate: 20 August 2010

Time of Day: 2200 (10:00 p.m. local time); 05:00 UTC
Latitude: 76º 28.4’ N

Longitude: 149º 5.3’ W
Ship Speed: 4.9 knots Heading: 80.1º (NE)
Air Temperature: -0.23ºC/31.6ºF
Barometric Pressure: 1020.9 mb Humidity: 98.2%
Winds: 5.7 knots WNW Wind Chill: -0.23ºC /31.6ºF
Sea Temperature: -1.2ºC Salinity: 25.99 PSU
Water Depth:3824.4 mScience and Technology Log
I have fallen behind on my writing this week, and I am trying to get back on track. I have a couple of logs in progress, but none are finished yet. So I thought I would give a quick update on where we are and what we are doing.

We started the week with a quick trip to Barrow, Alaska to pick up a crew member and some equipment for Louis. It was a beautiful day. Healycannot dock in Barrow, so we waited a couple of miles offshore while a small boat went in to shore.
We had a great view of the coastline. The air smelled different that close to land; there were lots of birds flying around, and some people evenspotted whales. Late Monday we started our trip back into the Canada Basin and met up with Louisearly Tuesday morning.

We are now fully involved in the two-ship partnership with the Louis. We have been traveling together for four days. Most of the time, Healyleads Louis, though once yesterday the two ships switched positions, and Louis broke ice for Healywhile they made repairs to their seismic equipment. My personal theme for the mission is “If we’re moving, we’re mapping” which means that the multibeam and subbottom profiler are always collecting data. Sometimes in ice we don’t get perfect data, but all data are useful data, and each line we follow unveils a little more information about the Arctic seafloor. Sometimes we cross areas that were mapped on previous trips by Healy or other vessels, filling in gaps in the bathymetry and giving Louis the opportunity to collect deeper subsurface data. My favorite times are when we cross areas that have never been mapped before.Most of the time, we have been out on the abyssal plain of the Canada Basin. The abyssal plain is FLAT – flatter, I am told, than a pool table. Yesterday we crossed the eastern side of a feature called the Northwind Ridge which separates the Canada abyssal plain from the Chukchi plateau and abyssal plain. It was a nice change to see some different depths on the multibeam. Different depths show up as different colors on the screen display – yellows, greens and light blues instead of just the deep blue and purple that represent depths over 3000 meters. As a watch stander, there is more to watch when we are crossing an area changing depths, and we have to make frequent adjustments of the depth limits for the instruments. Sometimes in the lab at night, I look at the display screen and forget that what I see on the bathymetric map is the seafloor, not what is out my window. I look at the camera that shows the water in front of and behind the ship, and I see flat water or ice, but underneath, there are ridges, slopes, and plains. It is incredible that we can use sound to remove the cover of the water and see what lies beneath.

Personal Log
I still find it surprising when I go out on one of the aft decks and see another ship behind us. I wonder how it would look to someone flying over us – way out in the ocean, no other boats around, but there are two ships following the same course about a mile apart. It takes a lot of coordination for two ships to work together like this. The chief scientists and captains consult frequently about the planned course. When I am on watch, I enjoy listening to the chatter between the bridges of the two ships, sharing information about ice conditions, checking speeds, confirming how well the track cleared by Healy is staying clear for Louis. That is not as easy as it might sound. The ice is drifting, and Healy’s crew must take that into account and determine where the ice might be when Louis reaches it.

I am fascinated not only by the sea and ice but also by the constantly changing Arctic sky. Every day, the sky is a new canvas for interesting cloud formations, sun shining through fog, and the sometimes subtle and sometimes spectacular colors of Arctic sunsets, which for a while (when we were in the southern part of the basin) coincided with the end of my nightly watch stander shift. Now that we are north of 75º, the sun sets between 1 and 2 a.m. local time and rises again around 4 a.m., so it is usually still quite bright when I leave the computer lab. Perhaps one night before we head south, I will stay up all night and get a sense of how dark it really gets between sunset and sunrise – my impression is that it is not fully dark – there always seems to be at least some light coming through the porthole when I wake up during the night. Here are some of my favorite sky-shots from the last week.

Bottom of the Arctic on a map — Bottom Relief of the Arctic on a map

Sometimes when I’m in the Science conference room, I like to look at the map of “Bottom Relief of the Arctic Ocean”. The other night, I noticed a picture in the picture. What do you see?FYI…

I got an email from a colleague (thanks, Mark) who asked me how far from land we were when we saw the polar bear that I photographed on August 9th. The map below shows where we were relative to the coastline of Alaska. We were stopped at the station labeled “001” at the time, which is approximately 172 nautical miles (319 kilometers) north of the town of Gordon, Alaska. (The dotted red line connects the two points.) Gordon is just west of the U.S./Canada border. As of today, that is still the only polar bear that I have seen. There have been at least six sightings from Healy and several more from Louis.

Caroline

August 15, 2010April 22, 2021

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

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

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

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.

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.

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.

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”.

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.

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.

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.

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.

August 11, 2010April 22, 2021

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”.

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.

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.

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 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.

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.

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

August 8, 2010April 22, 2021

Caroline Singler, August 8, 2010

NOAA Teacher at Sea: Caroline Singler
Ship: USCGC Healy

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

Date of Post: 8 August 2010

Polar Bear, Polar Bear! – 9 August 2010

Yes, folks, they are out here. There were a couple of sightings on Sunday 8 August, but I missed them both. However, Monday 9 August 2010 was the day that I saw my first polar bear in the Arctic. The last time I saw a polar bear was in the St. Louis Zoo, and it looked about as unhappy to be in the heat and humidity as I was. This time was a lot different.

I received a page while working in a lab on one of the lower decks. Before I turned off my pager, Bill came running down to get his camera and told me there was a polar bear off the port side of the ship. We could just barely see a spot on the distant horizon, slightly less white than the surrounding ice. I went up to the Bridge to get a better view, and most of the science team was there. I didn’t have to ask where it was; I just followed the line of everyone’s binoculars and cameras. Once I had a sense of what to look for and where to look, it became easier to spot, and it obliged us by moving closer to the ship. We were holding position at the time for a water sampling event, so we got a good long view as the bear ambled along. It was like watching a nature movie. It stopped every once in a while to sniff the air, and it walked along, stepping or jumping across melt ponds on the ice. We watched for at least a half hour before it moved out of site.Here are some of my best shots.

I hope those images help cool you off for a minute or two!
Caroline

August 7, 2010April 22, 2021

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.

Source: NOAA Top Ten Breakthroughs

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:

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.

Sources:
NOAA Ocean Explorer http://oceanexplorer.noaa.gov/technology/technology.html
NOAA 200th Top Tens – The Breakthroughs
http://celebrating200years.noaa.gov/breakthroughs/welcome.html

Personal Log

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.

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!