launch – NOAA Teacher at Sea Blog

July 12, 2019July 12, 2019

Meg Stewart: What Does the Seafloor Look Like? Hydrography Can Tell Us, July 11, 2019

NOAA Teacher at Sea

Meg Stewart

Aboard NOAA Ship Fairweather

July 8 – 19, 2019

Mission: Cape Newenham Hydrographic Survey

Geographic Area of Cruise: Bering Sea and Bristol Bay, Alaska

Date: July 11, 2019

Weather Data from the Bridge
Latitude: 58° 36.7 N
Longitude: 162° 02.5 W
Wind: 1 knot N
Barometer: 1011.0 mb
Visibility: 10 nautical miles
Temperature: 58° F or 14° C
Weather: Partly cloudy, no precipitation

Red Sky — *“Red sky at night, sailors’ delight. Red sky in morning, sailors take warning.”* This old mariner’s adage did NOT prove to be true when I saw this sunrise viewed from NOAA Ship *Fairweather* at 5:21am yesterday. It turned out to be a perfect delight for a surveying day!

What is NOAA and the Teacher at Sea program?

You may be wondering what, exactly, am I doing going “to sea” with NOAA. First off, NOAA stands for the National Oceanic and Atmospheric Administration and originates back to 1807 with Thomas Jefferson founding the U.S. Coast and Geodetic Survey (as the Survey of the Coast) with a mission to provide nautical charts to the maritime community for safe passage into American ports. Over time, the Weather Bureau was added and then the U.S. Commission of Fish and Fisheries was developed. In 1970, these three agencies were combined under one umbrella organization and named NOAA, an agency that supports accuracy and precision of physical and atmospheric sciences, protection of life and property, and stewardship of natural resources. NOAA is within the Department of Commerce.

Meg on flying bridge — I am standing on the flying bridge of the *Fairweather* where you get a fantastic 360° view.

NOAA’s Teacher at Sea (TAS) program has existed since 1990, sending over 800 teachers on NOAA research cruises. The TAS mission is “to give teachers a clearer insight into our ocean planet, a greater understanding of maritime work and studies, and to increase their level of environmental literacy by fostering an interdisciplinary research experience.” There is usually just one teacher sent per leg of a mission, that way the TAS gets full exposure to the research process and attention from the crew, scientists and staff on the ship. And it is true, everyone onboard has been friendly, helpful, welcoming, and willing to answer any question I might have, like, where is C deck? (That’s where my stateroom is located).

Science and Technology Log

Now that you understand NOAA’s mission, it should not surprise you that I am on a research cruise that is mapping a part of the seafloor that has not had detailed soundings. “Soundings” means the action or process of measuring the depth of the sea or other body of water. See the map below as that is where I am right now, in Bristol Bay. By the way, NOAA nautical charts are available for free at this NOAA site.

Bristol Bay nautical chart — The NOAA nautical chart of Bristol Bay, Cape Newenham and Hagemeister Strait. Note that where there are small numbers in the white and blue sections of the chart (that is all water), you can see the sounding depths to surface shown in fathoms. The red polygon is drawn on by me. We are working in the upper, northwest part of that “poorly mapped” section. Notice that there are essentially no soundings in that region.

When I’ve told friends, family and students that I was chosen to be on a NOAA research vessel that was compiling a detailed map of the sea floor off of Alaska, it was met with great surprise. “The ocean floor hasn’t been mapped before? How could that be?” In fact, more than 80 percent of the ocean bottom has not been mapped using modern, highly precise technologies. But we do have a very coarse ocean floor – or bathymetric – map, created in the early 1950s by Marie Tharp using sounding data collected by the U.S. military and her collaborator Bruce Heezen. Tharp’s early map of the sea floor beautifully revealed the Mid-Atlantic Ridge and added another piece of evidence in support of the theories of continental drift plate tectonics. There’s a terrific Cosmos: A Spacetime Odyssey episode featuring Tharp.

1977 colorized ocean floor map — This is the Tharp and Heezen (1977) colorized ocean floor map. This map is used under the Creative Commons license.

Why we need a more detailed bathymetry map than the one created by Tharp and Heezen can be explained by the original mission of the early version of NOAA. Jefferson wanted to build a “…survey to be taken of the coasts of the United States…” in order to provide safe passage of ships to ports within the navigable waters of the U.S. As the Bristol Bay chart above shows, there are still coastal areas that have limited to no data. Without detailed charts, mariners cannot know where the shallower waters are (called shoals), or rock obstructions, shifted underwater sand bars, shipwrecks, or other hindrances that cause safety concerns to the movement of boats.

The hydrographic Survey Team on the NOAA Ship Fairweather use several 30 foot boats, called launches, with a multibeam echosounder attached to the hull (the bottom of the ship). The multibeam echosounder uses sonar and is a device useful for both shallow and deep water. In a nutshell, depth measurements are collected by calculating the time it takes for each of the sound pulses to travel from the echosounder through the sea water to the ocean floor and back again. The distance from the instrument to the seafloor is calculated by multiplying the travel time by the speed of sound through seawater, which is about 1,500 meters/second or 4,921 feet/second. Right before a hydrographic survey is started, the team collects information on the conductivity, temperature and depth of the sea water, as temperature and salinity will modify the density and change the travel time of the sonar pulses. The video below can explain the process further.

This NOAA video explains multibeam sounding and hydrographic operations.

launch with echosounder — A launch on a lift right before going out to survey. The multibeam echosounder is permanently fixed to the bottom of the hull. It’s a square, rigid box that sits flat against the hull in front of the keel.

Ali in a launch — This is Ali Johnson in the cabin of a launch. She is a hydrographic survey technician and is analyzing the multibeam echosounder data as it is being collected. The length of a launch is 32 feet, and all the technology needed for the hydrographic surveys are directly on boats in the cabin. Post-processing, or stitching the completed surveys into one comprehensive product, is done “back in the office” on Ship *Fairweather*.

The software used to collect the soundings is created by the multibeam echosounder manufacturer, so the collection of millions of points on a transect is seamless. Data collection runs are taken over multiple days and several “legs” or extended periods of time when the crew are all out at the same time on the Fairweather. Following collection transects, the data are then post-processed using Caris HIPS and SIPS, which is the software that the Fairweather hydrographers use for data processing.

screen showing bathymetry — A close-up of one of the monitors that shows what the sounding data look like. By looking at these data returns, the hydrographers can tell immediately if something is not right with the equipment. The two windows that show maps colored red to yellow to blue (top right and bottom left) show the bathymetry. The red areas are shallow depths and the blue are deeper depths, relatively speaking. Also notice the window at the bottom right with a triangle and circle within the triangle; that is showing the fan-shape of the echosoundings.

Personal Log

We’ve motored to a new location, Cape Newenham, which is the name of this mission, so we will be here for about a week. When we got underway, the ship got to really rocking and my stomach could not handle it. I had one bad night but I am now fine and ship shape!

Cape Newenham is at latitude 58°N so we are up close to the Arctic Circle (66.5°N). At this time of year, there are about 5 hours of darkness per night here in Alaska, which is really cool. Compare that what we have in New York…

Anchorage v NYC — For July 11, 2019, the number of daylight hours in Anchorage, AK (closest large city to where I am now) is 18 hours and 41 minutes. Times of sunrise and sunset are also given….the sun sets at 11:25pm today! And in NYC, NY (where my school is located), you are getting four fewer daylight hours, or about 15 hours of light. Again, times of sunrise and sunset are shown. Source for both: https://www.timeanddate.com/sun/usa

Launches and Fairweather — Launches waiting to get underway. All boats going out for surveys stay close to the *Fairweather* until everyone is securely in their boat, just in case of MOB (man overboard).

Fairweather anchored — This is where Ship Fairweather is anchored for the next few days, as the survey crews transect the project area. We are on the southern side of Cape Newenham. Again, the terrain is tree-less, though we are now adjacent the mainland of Alaska. I’ve seen so many types of sea birds, but the puffins are the best because they seem to not have figured out how to fly. I hear there are walrus in the area, but I haven’t spotted one as yet.

Did You Know?

You probably know that Charles Darwin was the naturalist on board the HMS Beagle which set sail on December 27,1831. Over the nearly five years the Beagle was at sea, Darwin developed his ideas on natural selection and evolution of species. But what you might not know is that the captain of the Beagle, Robert FitzRoy, was an officer in the Royal Navy, a meteorologist and hydrographer. In fact, the primary mission of the Beagle was to survey the coastline of South America and, in particular, the Strait of Magellan, at the southernmost tip. Better, more accurate charts were needed by the British government, to navigate the treacherous, rough waters of the channels. In addition, FitzRoy was a protégé of Francis Beaufort (who developed the Wind Force Scale which is still used to help explain wind speed) and both worked together to create the science of weather forecasting.

Quote of the Day

“In every outthrust headland, in every curving beach, in every grain of sand there is the story of the earth.” – Rachel Carson

August 13, 2018August 16, 2018

Tom Savage: Surveying the Coastline of Point Hope, Alaska, August 12, 2018

NOAA Teacher at Sea

Tom Savage

Aboard NOAA Ship Fairweather

August 6 – 23, 2018

Mission: Arctic Access Hydrographic Survey

Geographic Area of Cruise: Point Hope, northwest Alaska

Date: August 12, 2018

Weather data from the Bridge

Wind speed 8 knots
Visibility: 10 nautical miles
Barometer: 1010.5 mB
Temp: 8.5 C 47 F
Dry bulb 8 Wet bulb 6.5
Cloud Height: 5,000 ft
Type: Alto Stratus
Sea Height 2 feet

Science and Technology

Why is NOAA taking on this challenging task of mapping the ocean floor? As mentioned in an earlier blog, the ocean temperatures worldwide are warming and thus the ice in the polar regions are melting. As the ice melts, it provides mariners with an option to sail north of Canada, avoiding the Panama Canal. The following sequence of maps illustrates a historical perspective of receding ice sheet off the coast of Alaska since August 1857. The red reference point on the map indicates the Point Hope region of Alaska we are mapping.

This data was compiled by NOAA using 10 different sources. For further information as how this data was compiled visit https://oceanservice.noaa.gov/news/mar14/alaska-sea-ice.html.

The light grey indicates 0-30% Open Water – Very Open Drift. The medium grey indicates 30 – 90 % Open drift – Close Pack. The black indicates 90 – 100% very close compact.

Ships that sail this region today rely on their own ships sonar for navigating around nautical hazards and this may not be as reliable especially if the ships sonar is not properly working (it’s also problematic because it only tells you how deep it is at the ship’s current location – a sonar won’t tell you if an uncharted hazard is just in front of the ship). Prior to mapping the ocean floor in any coastal region, it requires a year of planning in identifying the exact corridors to be mapped. Hydrographers plot areas to be mapped using reference polygons overlaid on existing nautical charts. Nautical charts present a wealth of existing information such as ocean depth, measured in fathoms(one fathom is equal to six feet) and other known navigation hazards.

As mariners sail closer to the shorelines, the depth of the ocean becomes increasingly important. Because of this uncertainty in the depth, the Fairweather herself cannot safely navigate safely (or survey) close to shore. In order to capture this data, small boats called “launches” are used. There are a total of four launch boats that are housed on the boat deck of the Fairweather. Each boat can collect data for up to twelve hours with a crew of 2-5. Depending on the complexity of the area, each daily assignment will be adjusted to reasonably reflect what can be accomplished in one day by a single launch. Weather is a huge factor in the team’s ability to safely collect data. Prior to deployment, a mission and safety briefing is presented on the stern of the ship by the Operations Officer. During this time, each boat coxswain generates and reports back to the operations officer their GAR score (safety rating) based on weather, crew skills and mission complexity (GAR stands for Green-Amber-Red … green means low risk, so go ahead, amber means medium risk, proceed with caution; red means high risk, stop what you’re doing). In addition, a mission briefing is discussed outlining the exact area in which data will be collected and identified goals.

Safety Briefing by LT Manda – photo by Tom Savage

Deploying a launch boat – photo by Tom Savage

The sonar equipment that transmits from the launch boats is called EM2040 multi beam sonar. A multi beam sonar is a device that transmits sound waves to determine the depth of the ocean. It is bolted to the hull that runs parallel to the boat, yet emits sound perpendicular to the orientation of the sonar. In the beginning of the season, hydrographers perform a patch test where they measure the offsets from the sonar to the boat’s GPS antenna, as well as calculating any angular misalignments in pitch, roll or yaw. These measurements are then entered in to software that automatically corrects for these offsets.

deploying CTD — TAS Tom Savage deploying the conductivity, temperature and density probe ~ photo by Megan Shapiro

The first measurement to collect is the ocean’s conductivity, temperature and depth. From this information, the scientists can determine the depths in which the density of the water changes. This data is used to calculate and correct for the change in speed of sound in a given water column and thus provide clean data. The boats travel in pre-defined set lines within a defined polygon showing the identified corridor to be collected. Just like mowing a lawn, the boat will travel back and forth traveling along these lines. The pilot of the boat called the Coxswain, uses a computer aided mapping in which they can see these set lines in real time while the boat moves. This is an extremely valuable piece of information while driving the boat especially when the seas are rough.

The coxswain will navigate the boat to the position where data collection will begin inside a defined polygon. Since the multibeam echosounder transmits sound waves to travel through a deep column of water, the area covered by the beam is wide and takes longer to collect. In such stretches of water, the boat is crawling forward to get the desired amount of pings from the bottom needed to produce quality hydrographic data. The reverse is true when the boat is traveling in shallow water. The beam is very narrow, and the boat is able to move at a relatively fast pace. The boat is constantly rolling and pitching as it travels along the area.

As the boat is moving and collecting data, the hydrographer checks the course and quality of the data in real time. The depth and soundings comes back in different colors indicating depth. There is at least four different software programs all talking to one another at the same time. If at any point one component stops working, the boat is stopped and the problem is corrected. The technology driving this collection effort is truly state of the art and it all has to operate correctly, not an easy feat. Every day is different and provides different challenges making this line of work interesting. Troubleshooting problems and the ability to work as a team is crucial for mission success!

Personal Log

I have found the work on the Fairweather to be extremely interesting. The crew onboard has been exceptional in offering their insights and knowledge regarding everything from ship operations to their responsibilities. Today’s blog marks my first week aboard and everyday something new and different is occurring. I look forward in developing new lesson plans and activities for my elementary outreach program. Prior to arriving, I was expecting the weather to be mostly overcast and rainy most of the time. However, this has not been the case. Clear blue skies has prevailed most days; in fact I have seen more sun while on the Fairweather than back home in Hendersonville in the entire month of July! For my earth science students, can you make a hypothesis as to why clear skies has prevailed here? Hint, what are the five lifting mechanisms that generate instability in the atmosphere and which one(s) are dominant in this region of Alaska?

Question of the day. Can you calculate the relative humidity based on the dry and wet bulb readings above? Data table below…… Answer in the next blog

Until next time, happy sailing !

Tom

July 17, 2018

David Tourtellot: The Speed of Sound, July 15, 2018

NOAA Teacher at Sea

David Tourtellot

Aboard NOAA Ship Thomas Jefferson

July 9-26, 2018

Mission: Hydrographic Survey – Approaches to Houston

Geographic Area of Cruise: Gulf of Mexico

Date: July 15^th, 2018

Weather Data from the Bridge

Latitude: 28° 49.4115’N

Longitude: 93° 37.4893’W

Visibility: 10+ Nautical Miles

Sky Condition: 4/8

Wind: Direction: 240°, Speed: 7 knots

Temperature:

Seawater: 31.7°C

Air: Dry bulb:31.5°C Wet bulb: 27.5°C

Science and Technology Log

NOAA Ship Thomas Jefferson is well underway in its mission of surveying the seafloor. The primary tool that the ship (as well as its 2 Hydrographic Survey Launches) is using to accomplish this task is sonar. Sonar was originally an acronym for SOund Navigation And Ranging. If you are familiar with echolocation – the system that some animals (such as bats and dolphins) use to navigate their surroundings – then you already have a basic understanding of how sonar works. The sonar transmits a short sound (called a ping) that will travel down, away from the ship, until it hits the seafloor. At this point, it will reflect off of the sea floor, and echo back up to the ship, where it is detected by the sonar’s receiver. The crew aboard are then able to calculate the depth of the water.

To make the necessary calculations, there are 3 variables at play: the time that it takes for the ping to travel; the distance that the ping travels; and the velocity, or the speed, at which the ping moves through the water. If we know two of those variables, it is easy to calculate the third.

When using sonar to determine the depth of the water, distance is the unknown variable – that’s what we’re ultimately trying to figure out. To do so, we need to know the other two variables. Time is an easy variable for the sonar to measure. The sonar has a transmitter, which generates the ping, and a receiver, which hears it. These two components communicate with one another to give us an accurate measure of time. The third variable, velocity, is a bit trickier.

In saltwater, sound travels approximately 1500 meters per second. However, that rate can vary slightly based on water conditions such as temperature and salinity (how salty the water is). In order for sonar to get as accurate a reading as possible, it needs to calculate the precise speed of sound for the particular water it is in at the moment. The sonar is able to do that by using a component called a sound velocity sensor, known colloquially as a singaround.

Sonar 1 Singaround — The sonar on the hull of one of the Hydrographic Survey Launches. The orange rectangles are the projector (or, the transmitter) and the receiver, and the component in the green circle is the singaround

A singaround looks like a bar with a nub on each end. One nub is a projector, and the other is a reflector. The projector broadcasts a ping that travels parallel to the hull of the ship, bounces off of the reflector, and returns to the projector. We use that information to calculate velocity. The calculation uses the same 3 variables as above (time, distance, and velocity), but this time, distance isn’t the unknown variable anymore – we know exactly how far the ping has traveled, because we know how far the projector and reflector are from one another. The singaround electronically measures how long it takes for the ping to travel, and since we now know two of the variables (distance and time) we can calculate the third (velocity) for our particular water conditions at the face of the sonar.

Sound travels roughly 4 times faster in water than it does in air (this is because water is denser than air). To ensure that the sonar gets an accurate reading, it is important that air bubbles don’t get in the way. The boat’s hull (bottom) has a triangular metal plate directly in front of the sonar, which routes air bubbles around to the side of the sonar.

Sonar 2 — The hull of one of the Hydrographic Survey Launches.

Personal Log

Each day, the ship’s CO (Commanding Officer) publishes a POD, or Plan Of the Day. This is full of important information – it tells us what the ship will be doing; if/when we will deploy the launch boats, and who will be on them; what time meals will be; and the expected weather conditions. Below is an example from Friday, July 13^th.

On Friday, I had the opportunity to go out on one of the Hydrographic Survey Launches. Because of their smaller size, the launch boats are great for surveying difficult to maneuver areas. For instance, we spent most of the day surveying an area near an oil rig, and were able to get much closer than the Thomas Jefferson could.

Mike Below Deck — Survey Tech Mike Hewlett collecting and analyzing survey data aboard a launch boat

Oil Rig and Boat — An oil rig and a supply vessel

I’ve been very impressed by how multi-talented everyone on the ship seems to be. In addition to analyzing data, the ship’s survey techs can also be found handling lines as the survey boats are launched and recovered, and do a lot of troubleshooting of the hardware and software they’re using. The coxswains (people who drive small boats) double as engineers, fixing issues on the launch vessels when away from the ship. I’m surrounded by some very gifted people!

Fixing the AC — Coxswain Francine Grains and Survey Tech Brennan Walters fixing the air conditioner on one of the launch boats that had stopped working unexpectedly. They had it up and running in no time

Did you know?: As president, Thomas Jefferson ordered the first survey of the coastline of the United States. Because of this, NOAA Ship Thomas Jefferson is named for him.

Latest Highlight: While surveying, we spotted a water spout in the distance. A water spout is a tornado that forms over water. Luckily, we were a safe distance away. It was an amazing sight to see!

July 10, 2018

Victoria Obenchain: Launching Boats, July 9, 2018

Teacher at Sea Blog

Victoria Obenchain

Aboard NOAA Ship Fairweather

June 25 – July 6, 2018

Mission: Arctic Access Hydrographic Survey

Geographic Area of Cruise: Northwest, Alaska

Date: July 9, 2018

Science and Technology Log

My last few days at sea were rather exciting. Wednesday, I got to attend some medical training necessary at sea in the morning, and then in the afternoon we practiced safety drills. The whole crew ran through what to do in the case of three different ship emergencies: Fire, Abandon Ship and Man Overboard. These drills were pretty life-like, they had a fog machine which they use to simulate smoke for the fire drill. Once the alarm was triggered people gather in their assigned areas; roll was taken, firemen and women suited up and headed to the location where smoke was detected, and from there teams are sent out to assess damage or spreading of the fire, while medical personnel stood prepared for any assistance needed. The abandon ship drill required all men and women on board to acquire their life preserver and full immersion suit, and head to their lifeboat loading locations. Roll is then taken and an appointed recorder jots down the last location of the ship. Once this is done, men and women would have deployed the life rafts and boarded (luckily we did not have to). And for the man overboard drill they threw their beloved mannequin Oscar overboard in a life vest and had everyone aboard practice getting in their look out positions. Once Oscar was spotted, they turned the ship around, deployed an emergency boat and had a rescue swimmer retrieve him.

Fast Rescue Boat — Deployed emergency boat for rescue of the beloved mannequin, Oscar.

These drills are necessary so that everyone on board knows what to do in these situations. While no one hopes these emergencies will happen, knowing what to do is incredibly important for everyone’s safety.

Thursday was maybe my favorite day on board. Due to the fact that there are a handful of new personnel on board, practice launching and recovering the survey launch boats was necessary. There are 4 launch boats on top of NOAA Ship Fairweather, each equipped with their own sonar equipment. These boats sit in cradles and can be lowered and raised from the sea using davits (recall the video from the “Safety First blog a few days ago). These four boats can be deployed in an area to allow for faster mapping of a region and to allow for shallower areas to be mapped, which the NOAA Ship Fairweather may not be able to access. Since this is a big operation, and one which is done frequently, practice is needed so everyone can do this safely and efficiently.

Launch boat on a davit

Davit lowering a launch boat

Ali Johnson inside one of the launch boats

With the aid of Ali Johnson as my line coach, I got to help launch and recover two of the survey launch boats from the davits on the top of the ship into the Bering Sea. This is an important job for all personnel to learn, as it is a key part of most survey missions. Learning line handling helps to make sure the survey launches are securely held close to the ship to prevent damage and to safely allow people on and off the launch boats as they are placed in the sea. From learning how to handle the bow and aft lines, to releasing and attaching the davit hooks, and throwing lines from the launches to the ship (which I do poorly with my left hand), all is done in a specific manner. While the practice was done for the new staff on board, it was fun to be involved for the day and I got to see the beauty of the NOAA Ship Fairweather from the Bering Sea.

And I truly enjoyed being on the small launch boats. I then understood what many of the officers mentioned when they told me they enjoyed the small boat work. It’s just fun!

Me on a launch boat, taken by AB Colin Hogan

NOAA Ship Fairweather from a launch

My trip ended in Nome, Alaska, which was in and of itself an experience. Students, you will see pictures later. I am extremely thankful for the crew on board NOAA Ship Fairweather, they are a wonderful mix of passionate, fun professionals. I learned so much!

Personal Log

Being a Teacher at Sea is a strange, yet wonderful experience. Being a teacher, I normally spend the vast majority of my day at work being in charge of my classroom and beautiful students; leading lesson and activities, checking-in with those who need extra help and setting up/tearing down labs all day, as well as hopefully getting some papers graded. However during this experience, I was the student, learning from others about their expertise, experience and passions, as well as their challenges; being in charge of nothing. And given that I had no prior knowledge of hydrography, other than its definition, I was increasingly impressed with the level of knowledge and enthusiasm those on board had for this type of work. It drove my interest and desire to learn all I could from the crew. In fact, I often thought those on board were older than they were, as they are wiser beyond their years in many area of science, technology, maritime studies, NOAA Ship Fairweather specifics and Alaskan wildlife.

NOAA offers teachers the opportunities to take part in different research done by their ships throughout the research season as a Teacher at Sea. The 3 main types of cruises offered to teachers include (taken from the NOAA Teacher at Sea website):

Fisheries research cruises perform biological and physical surveys to ensure sustainable fisheries and healthy marine habitats.
Oceanographic research cruises perform physical science studies to increase our understanding of the world’s oceans and climate.
Hydrographic survey cruises scan the coastal sea floor to locate submerged obstructions and navigational hazards for the creation and update of the nation’s nautical charts.

I was excited to be placed on a Hydrographic Survey boat, as this is an area in my curriculum I can develop with my students, and one which I think they are going to enjoy learning about!

While I was sad to leave, and half way through had a “I wish I would have known about this type of work when I was first looking at jobs” moment (which I realize was not the goal of this fellowship or of my schools for sending me), I am super excited to both teach my students about this important work and also be a representative of this awesome opportunity for teachers. I will wear my NOAA Teacher at Sea swag with pride!

July 2, 2018July 3, 2018

Heather O’Connell: Surveying Tracy Arm, June 20, 2018

NOAA Teacher at Sea

Heather O’Connell

NOAA Ship Rainier

June 7 – 22, 2018

Mission: Hydrographic Survey

Geographic Area of Cruise: Seattle, Washington to Sitka, Alaska

Date: 6/20/18

Weather Data from the Bridge

Latitude and Longitude: 57°52.9’ N, 133 °38.7’ W, Sky Condition: Broken, Visibility: 10+ nautical miles, Wind Speed: Light Variable, Sea Level Pressure: 1013.5 millibars, Sea Water Temperature: 3.9°C, Air Temperature: Dry bulb: 17.8°C, Wet bulb: 14°C

Science and Technology Log

After the morning meeting of hearing everyone’s risk assessment before getting on the launches, I was part of the four person crew on launch RA-6. Our task for the day was to clean up the data, or collect data in places within the Tracy Arm polygon that weren’t already surveyed. We had to fill in the gaps in L and M polygons on the East point. The entire area of Tracy Arm needed to be surveyed because there are several cruise ships that are coming into this area now that Sawyer Glacier is receding and the area has not been surveyed since the late nineties. Navigation charts must be updated to ensure that the safety of the people that are visiting the area.

Once on the launch, the bright orange POS MV, or Positioning Orientation System Marine Vessel, must be powered to start the survey process. The new acquisition log was created as an excel spreadsheet to record the different casts along with the latitude and longitude, the maximum depth and the sound speed of the water at about approximately one meter. With all of the valuable data recorded, it is important to have a consistent system for managing all of the data so that it can be accessed and managed efficiently.

The EM-2040 Konsberg Sonar S.I.S., Seafloor Information System, program was powered on next. The EM processing unit, which is connected to the multi-beam sonar, has three lines of information when properly communicating with sonar. The right hand monitor in the launch displays the information from the sonar. Creating the file name is another crucial way of ensuring that the data can be managed properly. It is from this computer that you can manually adjust the angle of the beam swath with the sound pings.

Once the computers were started and communicating with each other, we completed a C.T.D. cast to obtain the sound speed profile of the water. There is also a device that measures this right on the multibeam sonar, but it is important that two devices have a similar sound speed profile to ensure data accuracy. If there is a large discrepancy between the two values, then another cast must be taken. Initially, the measuring sound speed profile at the interface was 1437.2 and the C.T.D. sound speed was 1437.8. The final algorithm that determines the depth of the water will take this information into account. Since we were somewhat close to a waterfall, the fresh water input most likely affected the sound profile of the water.

After viewing the data acquired in the sheet, or the assigned area of Tracy Arm to survey, Greg found areas where there were holes. He put a target on the map on the monitor on the left hand side computer. This HYSWEEP interface for multibeam and side scan sonar (which is a subset of HYPAC which is the multibeam software) screen shows a chart of the area with depths in fathoms and any rocks or shoals that would impede driving ability along with a red boat image of the vessel. This display is what the coxswain driving above also sees so that he or she is aware of what direction to travel. Once logging data, this screen also displays the beam so that you can ensure that all necessary data is being acquired. Previous surveys are depicted in a more subdued color so that you can see that the missing data is being collected. From the monitor, the survey technician must control the view of the map to be sure that it includes the targeted area, along with the path of the boat so that future obstructions can be avoided.

Since we were avoiding icebergs in the initial part of the clean up, we were going at about two knots. This slow pace allows for an increase in returns, nodes and soundings that increase the data density. Shallow waters take much longer to survey due to the smaller swath width. It is important to have accurate, high resolution data for shorelines since this is the area where many vessels will be traveling. When a sonar pings, every swath, or fan-shaped area of soundings, returns five hundred soundings. Five hundred soundings times a rate of seven pings per second means there are thirty five hundred soundings per second total. This data density enhances the resolution of the maps that will be generated once the data has been processed.

Since there are sometimes safety hazards when surveying there are several different approaches that can be used to ensure the entire area is surveyed in a safe manner. Half stepping included going back over previous coverage far enough away from the hazard. Scalloping is another method which involves turning right before the rock or obstruction. This sends the beam swath near the rock without putting the vessel in danger. Some areas that were too close to icebergs could not be surveyed since it was not safe. But, this hydrographic survey was able to acquire data closer to the Sawyer Glacier than ever before. Being a part of this data collection was gratifying on many levels!

Personal Log

Seeing a white mountain goat amongst some of the most beautiful geological features that I have ever laid eyes on was another benefit of being out on the launch for the day. When a grizzly bear cub ran by a waterfall I continued to appreciate a day on the launch. Seals perched on icebergs were always a fun sight to see. And, the endless pieces of ice drifting by in the sea during our surveying never ceased to amaze me.

Seals on an Ice Berg — Seals on an Iceberg

After a day of surveying, kayaking to a waterfall in William’s Cove and exploring proved to be another fun adventure.

OLYMPUS DIGITAL CAMERA — Waterfall in William’s Cove

Growing Muscle like Growing Character

The other day as I ran on the treadmill, I had a realization. While looking at the lifting weights, I realized that in order to build muscle, one must tear old muscles and rebuild new strands of protein. When these new fibers build on top of each other, muscles grow. I realized that new officers go through a similar process of developing skills and character. Junior officers come in with a two year responsibility where they learn an incredible amount. They are constantly put into new and challenging learning experiences where they tear their muscles. As they acclimate to these experiences, they build character, or muscle. The cycle repeats with subsequent occurrences.

Junior Officer ENS Airlie Pickett has a small triangle tattooed on her inner left bicep. When I asked her the significance of it, she said that the only way that you can truly understand something is to observe how it changes. In math, integrals and derivatives explain this change.

As I appreciated her tattoo, I considered that she must learn quite a lot about herself as a junior officer constantly learning new things. I’ve appreciated the opportunity to experience and observe myself in an unfamiliar surrounding on Rainier. It’s humbling to not understand the nautical terms, endless acronyms of surveying and NOAA Corps structure of life. I appreciated that all hands on Rainier made me feel welcomed, and were patient with explaining new concepts to me. I am grateful for the opportunity to experience the Inside Passage while learning about hydrographic surveying. Living on a ship, learning about navigation and meeting all of the hard working people on Rainier has been an unique experience. Overall, this has been an incredible opportunity. Mahalo nui loa! (Thank you very much). A hui hou Rainier! (Until we meet again)!

Did You Know?

Barometers measure atmospheric pressure in millimeters of mercury or atmospheres. An atmosphere is the amount of air wrapped around the Earth and one atmosphere, atm, is the amount of pressure at sea level at fifteen degrees Celsius. As altitude increases, the amount of pressure decreases since the density of the air decreases and less pressure is exerted. A decrease in altitude increases the amount of pressure exerted and the density of the air increases.

Changes in pressure can signify weather patterns. A drop in barometric pressure means a low pressure system is coming in and there is not enough force to blow away the weather. Weather indicative of this includes windy, cloudy and/or rainy weather. An increase in barometric pressure means a high pressure system is coming in and cool, dry air pushes out the weather resulting in clear skies.

https://www.nationalgeographic.org/encyclopedia/barometer/