Meredith Salmon: Deciphering the Data! July 30, 2018

NOAA Teacher at Sea

Meredith Salmon

Aboard NOAA Ship Okeanos Explorer

July 12 – 31, 2018

Mission: Mapping Deep-Water Areas Southeast of Bermuda in Support of the Galway Statement on Atlantic Ocean Cooperation

Date: July 30, 2018

Latitude: 35.27°N

Longitude: 73.24.°W

Air Temperature: 27.5°C

Wind Speed:  18.17 knots

Conditions: Partly Sunny  

Depth: 3742.65 meters

Qimera is a hydrographic processing software that was used during this expedition. This computer program allows scientists to edit and process the survey line data as it was being collected. 

Qimera Survey Area

The survey area 200 nautical miles off the coast of Bermuda projected in Qimera. Warmer colors indicate depths close to 4,000 meters while the cooler colors represent deeper regions up to 5,500 meters.

To successfully edit incoming multibeam data, it was necessary to isolate a specific section of the line and use Qimera’s 3D Editing Tool. The 3D Editing Tool was utilized to remove outliers that skew the data.

Essentially, each colorful point in the diagram below is a sounding from the multibeam sonar. The soundings are return signals that bounce back and reach the receivers on the sonar. When scientists are previewing and editing data, certain points are considered outliers and are rejected. The rejected points are shown as red diamonds in the diagram below. Once the edits are made, they are saved, and the surface is updated.  

3D editor qimera

Examples of a data set being processed by the 3D Editing Tool in Qimera. The red dots are rejected points that will not be included when the data is completely processed.

It is especially important to ensure that we are collecting as much data as possible as we continue to survey this area. In order to accomplish this, factors such as required resolution, sea state, water depth and bottom type are used to determine line plans.  By partially overlapping lines, we ensure there is quality data coverage on the outside beams. More overlap tends to mean denser, high quality coverage which will allow our team to develop accurate maps of the seafloor.

Qimera Survey Area

Side view of a section of the survey area projected in Qimera. The warmer colors indicate depths around 4,000 meters while the cool colors indicate depths closer to 5,500 meters.

Another program that was used to process data was known as Fledermaus. This interactive 4D geospatial processing and analysis tool is used to reproject Qimera projects as well as export the Daily Product that was completed and sent onshore where it is publicly available. We also projected the edited data on Google Earth (see below) and would include this in the Daily Product that was sent to shore as well.

Google Earth view

The survey and transit lines are displayed in blue, while previously mapped areas of the seafloor are shown in green.

 

Personal Log

Now that we have left the survey area, we are transiting back to Norfolk and still collecting and processing data. We are scheduled to arrive early on the 31st and a majority of us will depart that evening. Since we are still collecting return transit data, it is still necessary for processing to occur. Although we’ve been working diligently, we still like to make time for fun. On Friday night, we hosted a Finer Things Club Gathering complete with fancy cheese, crackers, sparkling apple juice, and chocolate! It was great! On Saturday, we played the final cribbage tournament game as well as other board games, and on Sunday we had an ice cream party!

Finer Things Club

The Mapping Team hosts a Finer Things Club Meeting complete with sparkling apple juice, crackers, cheese, and chocolate!

Finer Things

Our fancy spread of gourmet snacks!

final match

Charlie and Mike in the FINALS!

ice cream social

Sundaes on Sunday!

 

View of calm seas

Super calm seas on the way home!

Calm Seas

Calm Seas

 

Did You Know?

One of the first breakthroughs in seafloor mapping using underwater sound projectors was used in World War I.

Resources:

https://oceanexplorer.noaa.gov/explorations/03fire/background/mapping/mapping.html

Eric Koser: The Impact of the Work

NOAA Teacher at Sea
Eric Koser
Aboard Ship Rainier
June 22-July 9
Mission: Lisianski Strait Survey, AK
July 4, 2018: 1000 HRS

Weather Data From the Bridge
Lat: 55°57.7’          Long: 133°55.7’
Skies: Clear
Wind Light and variable
Visibility 10+ miles
Seas: <1 ft
Water temp: 7.2°C
Air Temp: 14.1°C Dry Bulb, 12.5°C Wet Bulb

Pelican Harbor

The harbor at Pelican, Alaska.

The Impact of the Work
“We’re a part of history!” This notion, shared by a colleague on a launch yesterday, brings home the importance of the work of this team and NOAA’s Hydrographic Branch. Lisianski Inlet was last surveyed in 1917 by lead line! The charts of the inlet were old and not likely accurate. This week – fresh data has been collected by Ship Rainier and her launches to bring the next century of mapping tools below their shores.

Pelican Harbor in the town of Pelican, Alaska was last surveyed between 1970 and 1989.–until we surveyed it yesterday with Rainier Launch RA-3. Our team drove in and out between each of the docks in the harbor, carefully pinging sound waves off of the floor of the harbor to construct a new digital map of the bottom.

Pelican Guys

Guys on a mission…walking to pickup the HorCon.

Pelican HorCon

This is the Horizontal Control station, or HorCon, setup on the breakwater at Pelican before we took it down.

Part of our task yesterday, in addition to conducting MBES survey from our launch, was to dock in Pelican and retrieve our HorCon (a GPS reference radio setup on land that we have used there all week). As we walked through the very small town carrying two car batteries in backpacks, a pair of antennas, tripods, and other gear back to the launch – surely people were interested in what we were up to. Several people stopped to chat as we made our way from the pier, along the boardwalk, and down to the docks to go back to our launch. People asked who we were – and if we were the NOAA team that was in town. There was much appreciation expressed to NOAA for the work being done in the inlet to update the nautical charts. Here in Pelican, the water is the primary mode of transport. Accurate nautical charts provide security and safety.

 

 

 

Pelican

Here is a bit of history on the city!

Main Street, Pelican, Alaska

Main Street, Pelican, Alaska

 

Pelican

It’s a comfortable place, here in Pelican!

There are no roads to Pelican. A few cars are in town – to pull trailers and move equipment. But the primary mode of land transport is four-wheelers. The ‘main street’ is really a raised boardwalk that runs along the rocky shore – and is the heartbeat of the community.   Folks that live up or down the inlet from the town get there in small launches – there are no roads. A ferry comes to Pelican twice a month and is how cars and trucks come and go here. A seaplane comes through a few times a week—often bringing tourists in and out – and the mail. It’s a beautiful spot centered in a small inlet on the edge of the Pacific Ocean.

 

 

 

 

 

 

Pelican Seaplane

The fastest transportation in many parts of Alaska.

Pelican House

A house up the shoreline from Pelican.

Science and Technology Log

It’s mission accomplished for Lisianski Inlet!

Nautical charts are broken up into sheets. And within each sheet, areas are broken down into smaller polygons for data collection. Each launch (small boat), as well as the ship itself, can bring in multibeam data with the equipment mounted on each hull to complete plotting polygons and eventually complete sheets.

The hydrographic survey team is working away today in the plot room and on “the holodeck” of Ship Rainier (an office area on the top of the ship behind the plot room) processing the data we have collected the past several days. A combination of ship and launch multibeam data in addition to bottom samples and shoreline updates have been collected. Now the work of the scientists continues and becomes data processing.

Holideck

Part of the hydrographic team on the holodeck.

As the data is combined, it is reviewed and refined to make a complete picture of the survey area. Once the team on the ship has completed their work, the data goes to the Pacific Hydrographic Branch of the Office of Coast Survey of NOAA. Here, the PHB team reviews that data again and assures it meets the specifications and standards needed to become finalized for use.

From PHB, the data is passed to two places. One is the NCEI (National Center for Environmental Information) office. They archive all of the raw and processed data including the digital surfaces themselves and the descriptive reports written by the hydrographers here.

The data also goes to the Marine Chart Division, an office of NOAA Coast Survey. Here is where the nautical charts are produced in both ENC and RNC (electronic and paper versions). It is this branch that publishes the data for use by mariners and the general public. Anyone can see the charts at nauticalcharts.noaa.gov (try the “Chart Locator”).

Nautical Chart

Here is a finished chart we are using to navigate today. Notice the two buoys in purple and green on the chart, and the narrow space between them.

Flybridge Approach

This is the view from the flybridge as we approach these same two buoys that are indicated on the chart.

 

Who is on board?

Tyanne

Tyanne Faulkes is a hydrographic scientist with NOAA.

During this leg of the trip, we have a visiting scientist from NOAA’s is here on board. Tyanne Faulkes works as a physical scientist for the Pacific Hydrographic Branch of NOAA. She is a part of the team that processes the data from the hydro teams on NOAA Ship Rainier and NOAA Ship Fairweather. Her job is to assure that the data meets NOAA’s specifications–so that they can provide evidence of dangers of navigation and accurate depth information for all mariners.

Tyanne loves to be involved in making maps of the sea floor – and getting to see things others have not seen before! She loves that NOAA provides data for free to scientists around the world. Her job includes not only desk work, but also opportunities to make many mapping trips to understand where the hydro data comes from. Ms Faulkes has a bachelors degree in geography and GIS. It was a paid internship just out of college with NOAA that initially brought her to this work. And – she has a ton of fun with what she does. As a kid, Tyanne loved oceanography. Her GIS education tied well with the internship – and it all came together to take her where she is today!

Tyanne Mountains

When she’s not chasing the bottom of the oceans, Tyanne also loves to climb mountains!

She some advice to students – “Learn how to code!”

“Building Python scripts is a very powerful tool to allow us to automate the data review process. Being able to write the code – or at least understand the basic concepts that put it together – allows one to be much more efficient in your work!”

Understanding the concept of an algorithm that can save one hours of work is a very good asset. “I wish in college someone would have taught me how to do this!” One easy example is a bulk file renaming tool that the launch teams use. After collecting 50 some separate files of data in a day, this tool will take the individual file names and append any number of things to the filenames – all automatically.

Want to get involved? Next week, Tyanne and her team at NOAA’s Western Regional Center at Sand Point in Seattle, WA are hosting an annual camp for middle school and high school students! Students from across the US can apply to come to this camp each summer and have great experiences learning all about oceans and hydrography! Check it out on the web: NOAA Science Camp – Washington Sea Grant.

 

Rita Larson, August 19, 2009

NOAA Teacher at Sea
Rita Larson
Onboard NOAA Ship Rainier
August 10 – 27, 2009 

Sunset over Kachemak Bay

Sunset over Kachemak Bay

Mission: Hydrographic Survey
Geographical Area of the Cruise: Kasitsna Bay, AK
Date: August 19, 2009

Weather Data from the Bridge 
Latitude: 59° 28.339′N Longitude: 151° 33.214′W
Sea Water Temperature: 10°C (50°F)
Air Temperature: Dry Bulb: 11.1°C (52°F) Wet Bulb: 10.0°C (50°F)
Visibility: 5 miles

Science and Technology Log 

A launch from the Rainier

A launch from the Rainier

I would like to give a very brief explanation of how surveying becomes a nautical chart. When all the surveying launches return to the Rainier, a debriefing meeting takes place in the wardroom. All the hydrographersin-charge or “Hicks” give a short discripition of the successes and complications they had during surveying for the day. At least one night processor attends these debriefing meetings to have a good understanding of what to expect as they process this data. Some of the things the night processors are looking for are:  How many CTD (conductivity, temperature, depth) casts were made from each launch? Were there any data problems, such as noisy data or gaps in coverage? Then, the night processors collect the Hypack and Hysweep data from the launches and transfer the surveys to the ship’s computers where they will process it with CARIS. The night processors use the program CARIS to convert the “RAW” information from the launches into processed data. This processed data has correctors such as tide and SVP applied to it. This is completed in the plotting room on board the Rainier. The data is then cleaned and examined for problems.

Polygons regions

Polygons regions

This process produces a smooth image depicting the water depth over the area surveyed for the sheet managers. When this is complete, the sheet manager sets up for the next day’s acquisitions and polygon plans for all of the launches. Then, this information is sent to the Pacific Hydrographic Office to further examine the bathymetric data. After that, cartographers use this information to create nautical charts. The U.S. Coast Guard, U.S. Navy, as well as civilian mariners use nautical charts worldwide. This entire process may takes up to a year to complete.

These are various images of data completed during night processing. (Pictures taken by Nick Mitchell.)

Various images of data completed during night processing. (Pictures by Nick Mitchell.)

Personal Log 

I am so amazed in the way the professionals from NOAA work together and share the responsibilities for the purpose of creating safety for others. By creating these nautical charts, it makes the waters of the world a safer place to be. Everyone on the ship has a meaningful purpose and it is clear to me that they take great pride in what they contribute in the mission of the Rainier. I feel like I belong here after such a short time.

Animals I Saw Today  
A bald eagle in a tree using the large binoculars nicknamed, “big eyes” from the Rainier. I also saw a sea otter.

Nautical chart of the geographical area the Rainier is surveying at this time.

Nautical chart of the area the Rainier is surveying at this time.

Jill Stephens, June 29, 2009

NOAA Teacher at Sea
Jill Stephens
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 29, 2009

Weather Data from the Bridge: 
Position: 55°13.516’N  161°22.812’W
Scattered clouds with 10 miles visibility
Wind: 195° at 14 knots
Pressure at sea level: 1023 mbar
Temperature: Sea; 7.8°C  Dry bulb; 13.3°C; Wet bulb; 11.1°C

Assistant Survey Technician, Todd Walsh, and I release the bottom sample that was collected from the sea floor.

Assistant Survey Technician, Todd Walsh, and I release the bottom sample that was collected from the sea floor.

Science and Technology Log 

Today was another awesome day at sea.  The ship picked up the anchor at 0830 to begin our move to a new anchorage. The plan for the day called for bottom sampling while in transit to the new anchorage. Bottom sampling is used to determine the composition of the sea floor.  The bottom sampler is attached to a winch with the cable run through a boom to move the sampling device over the starboard side of the ship. The bottom sampler has a bucket that is designed to close when it hits the bottom, collect a sample of the material on the seafloor, and then it is brought back to the surface.  The bucket must be secured and locked in place prior to lowering it to the bottom. The operation requires two people manning the device and examining the specimen and another person operating the winch.

The bottom sampler is ready to be deployed to collect a seafloor specimen.

The bottom sampler is ready to be deployed to collect a seafloor specimen.

The bottom sampler is opened once it is back on deck and examined by survey technicians.  The sediment is observed for color and felt to determine texture elements.  Most of the samples examined today were determined to be green sticky mud or volcanic ash and broken shells. This form of sampling provides information about the seafloor that will be of importance to ships that might consider anchoring in the area.  Samples are sometimes collected for more extensive study.

While the people on the fantail are examining the sea floor samples, personnel in the plot room prepare to enter the information into the computer.  The plot room crew enters the GPS location into the computer plus all descriptive data regarding the samples from the sampling crew. If the sampler returns to the surface in the open position, the sample is determined to be unsuccessful and is repeated.

Sitting in with a night processor allowed the opportunity to review data collected during the day and clean out noise that prevents the computer from selecting the best representation of the sea floor.

Sitting in with a night processor allowed the opportunity to review data collected during the day and clean out noise that prevents the computer from selecting the best representation of the sea floor.

Personal Log 

Working the bottom sampler and feeling the sea floor sediment was exciting for me.  I thoroughly enjoy working with soils to determine various characteristics, so this activity was right up my alley.  Although the sampler itself can be managed by one person, it is easier and safer for two people to operate the sampler while a third person operates the winch and boom. My partner and I worked together very efficiently and processed between five and ten samples during one shift.  The shifts were divided into one and a half hour periods. I was lucky enough to get two sampling shifts and one shift in the plot room recording the data.

After dinner, I was able to work with one of the night processors to convert and clean data that was collected on one of the launches during the day.

Animal Sightings

A baby crab and a worm were found in some of our bottom samples.

Findings in the bottom sample

Findings in the bottom sample

Mary Patterson, June 29, 2009

NOAA Teacher at Sea
Mary Patterson
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 29, 2009

Weather Data from the Bridge 
Broken clouds
Wind 6 kts
10 mi visibility
Pressure 1023.9 mb
Dry Bulb Temp 7.8 ˚C, 46˚ f Wet bulb 6.7˚C, 44˚ f
Seas 0-1 ft.
Water temp 7.2˚C

Small “bite” on the propeller

Small “bite” on the propeller

Science and Technology Log 

During one of the launch missions of the day, one boat ran aground on an uncharted rock. Immediately, they radioed in and announced that all were safe and they were attempting to back off the rock. Another launch in the vicinity radioed in that they were available to help if needed. Safety is always a priority! The launch was able to get past the rock safely and came back to the ship to be checked out. After the boat was picked up by the gravity davits, the damages were checked out. A few bites out of the propeller and some scrapes across the keel were the extent of the damages. I discovered that extra parts such as a propeller are often kept on board for emergencies such as this. The crew switched launches and went back out to continue surveying.

Gravity Davits

Gravity Davits

After all launches return, there is a daily survey meeting where each HIC (Hydrographer in charge) reports what they accomplished that day and any problems they had with weather, computers, hardware, software or boat issues. Many times, this turns into a great discussion and problem-solving opportunity. This is a true community of scientists communicating and sharing ideas. The group tries to understand a problem so that it is not repeated. Especially after today, I can truly understand the importance of the work this ship and its crew does every day. We saw a tug towing a barge and several fishing boats in the area today. I can only imagine what could happen if they were to run aground. The survey work being done in this area is essential for mariners. Other work done aboard the ship today included taking bottom samples from the seafloor as we moved to another anchorage. This task required communication from the bridge to the fantail (back of the boat) and the fantail to the plot room and the plot room to the bridge.  For the first shift, I worked in the plot room.  I used the Hypack software that shows an electronic navigation chart to tell the bridge where we wanted the next sample to take place.

Collecting seafloor samples

Collecting seafloor samples

The bridge navigated to that location and gave the fantail permission to sample the seafloor. The scientists on the fantail operated a claw-like device to collect the seafloor samples. As they lowered the claw, they radioed to the plot room to tell us how far down it was in 25 m increments. When it reached bottom, I marked that spot on the computer. Then, the fantail radioed as the claw came back up to the surface and finally, what was in the sample. The scientists on the fantail used a chart to identify the size and type of particles found. I made notes as to what was found in the sample on the electronic navigation chart. My partner used Caris Notebook to enter the attributes of the seafloor surface. Then, it was my job to show the bridge, via the electronic navigation chart, where the next target was located. Most of the seafloor we sampled was identified as green, sticky, mud. However, one sample held worms and another held some fine gravel and some broken shells. My next shift was down on the fantail, collecting the samples. This was a great time to dig in the mud! My final shift was back in the plot room logging in the samples.

Personal Log 

Collecting seafloor samples

Collecting seafloor samples

I was initiated into the bottom sample crew with a swath of mud smeared on my face. Later, I realized what a great sea mud mask I could have and wished I’d kept a bucket full of that mud! As we completed our transit to our next anchorage, I spent some time on the bridge. As the conning officer called out instructions, the helmsman and the EOT (Engine Order Telegraph) officer repeated the instruction and ended with “Aye.” I asked if they really had to say “Aye” and ENS Reed explained to me that “Aye” is a confirmation that they have understood the direction given. For example, If the direction was engines full ahead, and you did not say “Aye,” it would mean that the engines were already at full ahead.

Another interesting thing I found on the bridge was the words “left” and “right” on plaques attached beside the front windows on the bridge. I thought for sure that these incredibly smart mariners would know their right from their left without a visual reminder. Again, I was told that it has to do with safety and communication. Think about the times you were driving and you told someone to take a right and they went left by accident. On the ship, the order is given to go right and the helmsman looks at the plaque and turns correctly. This is crucial for stressful situations such as a whale crossing your path or narrow passages etc.

Did You Know? 

The EOT (Engine Order telegraph) term dates back to when a pilot wanting to change speed would “ring” the telegraph on the bridge, moving the handle to a different position on the dial. This would ring a bell in the engine room and move their pointer to the position on the dial selected by the bridge. The engineers would move their handle to the same position to signal their acknowledgment of the order, and adjust the engine speed accordingly. This term is still used today even though the bridge can control the engines from their control panel. The same is true of the phrase, “steam ahead.” Even though few modern ships are steam powered, it is a phrase that has come into common usage.

Hydrographer in Charge, Ian Colvert, and me with my “initiation” mud mask!

Hydrographer in Charge, Ian Colvert, and my “initiation” mud mask!

Mary Patterson, June 24, 2009

NOAA Teacher at Sea
Mary Patterson
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 24, 2009

Sunset in the Pavlof Islands

Sunset in the Pavlof Islands

Weather Data from the Bridge 
Overcast
Wind Light
6 mi visibility
Pressure 1009.1 mb
Dry Bulb Temp 6.7˚ C Wet bulb 6.7˚ C
Seas 0-1 ft.
Water temp 6.1˚ C 42˚ F

Science and Technology Log 

Once the data has been collected by the survey boats, it needs to be processed into meaningful information. The data from the boats is called raw data and it is saved onto a thumb drive. The assistant survey tech takes the thumb drive and loads the data into the computers on the ship. From here, the raw data is imported into a software program called CARIS Hips and Sips. CARIS is the primary hydrographic data processing software. It is used to:

  • Merge all sensor data into a common reference frame
  • Apply various correctors to sounding data
  • Edit sounding data in both time and spatial domain
  • Create gridded surfaces (BASE. CUBE)
  • Review side scan data and select contacts
  • Prepare data deliverables for the hydrographic branches 
Flying through the surface in 3D

Flying through the surface in 3D

The night processors apply correctors for variables that can affect the data such as tides, sound velocity, true heave and TPE (total propagated error). Then they can generate a surface of the sea floor. Finally, they must look for flyers; data points that are inconsistent with the statistical model. This is where the technology is so cool! The software enables you to view the surface in 3D. Using your mouse, you can literally fly over and under your surface. The night processors add their comments to the acquisition log and create a tiff file to show the sheet managers the coverage for the day. A detailed report about the area surveyed (DR) is written and submitted. The Descriptive Report (DR) is the written record of the survey work completed in an area. It accompanies and complements the digital data. Our survey area will not be completed during this leg of the trip. After some import time in Seward, AK for the Fourth of July, the Rainier will return to the Pavlof Islands to continue their survey. After data acquisition is complete and data has been reviewed aboard the ship to ensure it meets requirements, it is signed off by the Captain, the Chief Survey Tech, the Sheet Manager, and the FOO (Field Operations Officer).  When the sheets are completed, they are sent to the Pacific Hydrological Branch in Seattle, WA.

Screen shot 2013-04-30 at 8.42.55 PMThere, they will complete quality control analysis of the data and either accept or reject the survey sheet. They look for any data that is inconsistent with the required Specification and Deliverables. If the data does not meet specification, the area will likely need to be surveyed again. When the data is accepted by the branch they will further process the data to highlight important features and then send the survey sheet to the cartographers at the Marine Charting Division (MCD). The cartographers use the data submitted to place additional soundings and navigation hazards onto the US Navigation charts. A navigational hazard is generally defined as anything 1 meter shoaler than surrounding depths in water less than 20 meters deep. Currently, it may take years for a survey to be charted and reach the mariner. Critical corrections (such as DToNs -Danger to Navigation) or high priority areas can be updated more quickly.

Practicing my launch driving skills

Practicing my launch driving skills

Personal Log 

I’ve noticed that marine measurements are not consistent in their use of one system. Some measurements are in meters, some in feet, some in fathoms and some in ancient mariner terms such as shots. Since we “speak only metric,” in my class, I asked why mariners don’t stick to just one system of units.  The explanation I received makes sense. Navigation of the seas is a world-wide occurrence. Crews aboard vessels are often multi-national. Using a system that is accepted world-wide makes sense.

One of Rainier’s launches

One of Rainier’s launches

Each day I go out on the launch, I feel more a part of the team. I can comfortably cast and log data on the launch computers. I am starting to understand more about running the sonar. Each day, I get to practice my boat driving skills. Thanks especially to coxswain Foye, I have even completed a starboard side pick up for a man overboard drill! As always, safety is a key component. We practice drills on board as well as on the launches. On the launches, we do radio and iridium phone check-ins periodically. You can keep track of where we are by using Shiptracker.

Word of the Day Shot: 90 feet of chain; used to describe how much anchor chain to let out.

Mary Patterson, June 17-19, 2009

NOAA Teacher at Sea
Mary Patterson
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 17-19, 2009

Weather Data from the Bridge 
Overcast
Wind 15 kts
8 mi visibility
Pressure 999.5 mb
Dry Bulb Temp 6.7 C Wet bulb 5.6 C
Seas 0-1 ft.
Water temp 6.7C, 44 F

Here I am getting ready to cast the CTD.

Here I am getting ready to cast the CTD.

Science and Technology Log 

While the weather holds, we head out on the launches to survey areas that are not charted or were last charted probably back in the time of Captain Cook. After the boats are lowered using gravity davits, 4 boats head out to survey. Upon reaching the survey area, the first thing that gets done is a casting. This consists of lowering the CTD (Conductivity, Temperature and Depth) unit into the water at the surface for 2 minutes for calibration. Then it’s lowered to the sea floor (taking measurements as it goes) and brought back up to the surface with a winch and a pulley system. The sensor unit is cabled to the computer and the data is downloaded. This is a vital step in interpreting the sonar data. Since saltwater conducts electricity differently based on the salt concentration, using the CTD gives the hydrographer information about sound velocity at different depths.

Velocity of sound is most affected by temperature, which is also measure by the CTD.  Next, the hydrographer decides whether to use the high or low frequency transmitter depending on the depth. The hydrographer uses a lower frequency for deeper water.  Casting is often done again after lunch since temperatures can change, especially at the surface. Alaska is known for the confluence of fresh and salt water at the surface due to melting glaciers and fresh water runoff. The MVP (moving vessel profile), is another device used for sound velocity. It looks like a torpedo and it’s towed behind the boat allowing for continuous casting.

The shape of a plane has more points than a boat so is a good way to use points to line up a survey transect.

The shape of a plane has more points than a boat so is a good way to use points to line up a survey transect.

The plane you see on the picture is used instead of a boat because of the position of the GPS sensor relative to the shape. The coxswain can make the plane pivot on a point as they line up on a line to survey. On the survey, the map is broken down into polygons. Each sheet manager gets a sheet with their polygons to survey. Surveying consists of the coxswain driving the boat as they watch the computer screen. As they drive, the screen shows in real-time a swath of color indicating the swath of the beams. After surveying, the boats return to the ship and are hoisted back up onto the davits. All survey techs meet in the wardroom to discuss what happened on their survey. The Captain and FOO (Field Operation Officer) ask questions about what was surveyed and any problems they had with any equipment. This is a true community of scientists who share data and knowledge.

Worksheet with polygons completed

Worksheet with polygons completed

Personal Log 

We load the launches at 8:00 am and complete surveys until noon.  We break for lunch and unpack the ice chest packed by the cooks for us. It’s always a surprise to see what we have! Then we continue surveying until about 4:00 pm when we return back to the ship. I have had the opportunity to cast the CTD unit into the water, drive the launch and collect the data on the computers. The coxswains make driving the boat following the lines on the computer look so easy! Especially in rough seas, the coxswains do an amazing job of helping the survey techs collect data. Again, good communication is a key! I’ve also seen how the techs have to problem- solve on a daily basis.

One day we got into the launch and the engine wouldn’t start and the coxswain had to troubleshoot the problem. Another day, several boats had problems with their CTD units and they had to repeat trials several times. When you are 12 miles away from the nearest help, it’s crucial to have good problem-solving skills. After dinner, there’s time to finish writing journals, do laundry, fish off the fantail, watch a movie, play guitar hero or exercise in the gym area. Then, it’s time for bed and the day will start over again. If you are not on a survey launch, you work in the night processing lab compiling the data collected by the survey techs during the day’s launch. This includes applying various filters to clean up the “noise” or fuzziness from the sonar. The coolest part is seeing the data in three dimensions. After the data is cleaned up, the sheet managers write up a descriptive report that gets sent to Pacific Hydrographic Branch. This ship is a great example of a system: there are many separate parts that when combined with other parts, complete a task. 

Pavolf and Pavlof’s Sister are active volcanoes.

Pavolf and Pavlof’s Sister are active volcanoes.

Each night at 10 pm, fellow Teacher at Sea –Jill Stephens and I go to the bridge and collect weather data that is transmitted directly to NOAA. Although the days have started off hazy and grey, by evening we often see sunshine that lasts until 11:00 pm. This part of Alaska is breathtaking! I love watching the volcanoes, Pavlov and Pavlov’s sister, in different types of light.

Animals Seen 

Whales, Puffins, and Sea gulls.

New Word of the Day 

Cavitation: The sudden formation and collapse of low-pressure bubbles in liquids by means of mechanical forces, such as those resulting from rotation of a marine propeller.