ping – NOAA Teacher at Sea Blog

NOAA Teacher at Sea
Denise Harrington
Aboard NOAA Ship Rainier
April 20 – May 3, 2014

Mission: Hydrographic Survey

Geographical Area of Cruise: North Coast Kodiak Island

Date: April 30, 2014, 11:44 a.m.

Location: 58^o 03.175’ N 127^o 153.27.44’ W

Weather from the Bridge: 6.3^oC (dry bulb), Wind 5 knots @ 250^o, clear, 1-2′ swell.

Our current location and weather can also be seen at NOAA Shiptracker: http://shiptracker.noaa.gov/Home/Map

Science and Technology Log

The last couple of days have been the best ever: beautiful weather, hard work, deep science. We acquired data along the continental shelf and found a cool sea floor canyon and then set benchmarks and tidal gauges.

In hydrography, we gather data in seven steps, by determining: our position on Earth, depth of water, sound speed, tides, attitude (what the boat is doing), imagery and features. Step 1 is to determine where we are.

In this picture you can see a GOES satellite antenna and a GPS antenna that helps us determine our precise location. — In this picture you can see a GOES satellite antenna (square white one) that is used to transmit tide data ashore and a GPS antenna (the small white eggs shaped one) that provides the tide gauge with both position and UTC time. Photo by Barry Jackson

In this picture Brandy Geiger, Senior Survey Technician, uses the GOES from various locations to determine the exact location of the tide gauge. — In this picture Brandy Geiger, Senior Survey Technician, uses GPS to record the positions of the benchmarks we have just set for the tide gauge. Photo by Barry Jackson

tide gauge install 023 — Where we are happens to be the most beautiful place on earth. Photo by Barry Jackson

In Step 2, we determine the depth of the water below us.

Bathymetry is a cool word that means the study of how deep the water is. Think “bath” water and metry “measure.” When your mom tells you to get out of the tub, tell her to wait because you’re doing bathymetry.

As I explained in my first blog, we measure depth by sending out a swath of sound, or “pings,” and count how long it takes for the pings to return to the sonar, which sits beneath the ship or smaller boat.

Yesterday we used the multi-beam sonar to scan the sea floor. Here is a screen shot of the data we collected. It looks like a deep canyon, because it is!

Here is the image of the trench Starla Robinson, a Senior Survey Technician, and I discovered. We decided it should be named Denla Canyon, after us. — Here is the image of the sea floor canyon Starla Robinson, a Senior Survey Technician, and I discovered. We decided it should be named Denla Canyon, after the two scientists who discovered it.

Here I am, gathering pings.

Here I am talking with "the bridge," the team responsible for navigating the ship while surveyors collect data. — While collecting data, I kept in contact with “the bridge,” the team responsible for navigating the ship, by radio to ensure the ship’s safety and maximum, quality data acquisition. Photo by Starla Robinson

Step 3, we take into consideration the tide’s effect on the depth of the water. Tides are one predictable influence on water depth. There are over 38 factors or “constituents” that influence the tides. The gravitational pull of the sun and the moon at various times of the day, the tilt of the earth, the topography, and many other factors cause water to predictably bulge in different places on earth at different times. The Rainier crew works 24 hours a day and 7 days a week, so they must find a way to measure depth throughout the days and month, by taking into account the tide. Arthur Doodson, who was profoundly deaf, invented the Doodson Numbers a system taking into account the factors influencing tide in 1921. Flash forward to the 21st century, our Commanding Officer, Commander Rick Brennan worked with a team of NOAA scientists to develop a software program called TCARI, as an alternate method to do tide adjustments, taking into account 38 factors, even the moon’s wobble. Inventions abound at NOAA.

The Rainier crew worked for 14 hours today to set up a tide gauge station, an in depth study of how the tide affects our survey area. On this map, there is a Red X for each tide gauge we will install. This process only happens at the beginning of the season, and I feel fortunate to have been here–the work we did was….amazing.

Each Red X is approximately where a tide gauge will be installed. The one we installed today in Diver's Bay is in the north west corner of the sheet map. — Each Red X is approximately where a tide gauge will be installed. The one we installed today in Driver Bay is in the north west corner of the sheet map.

You can see an animation here that shows the combined effect of two sine waves that produce a signal like our tide data. Just imagine what it looks like when you factor in 38 different variables.

The earth goes around the sun in 24 hours and moon goes around the earth in a little more than 12 hours, much like these two gray sine waves. Interestingly, when you add two different waves, you get the wonky blue sine wave, with ups and downs. This combined effect of the sun and the moon (two dots) causes the ups and downs of the tide (blue wave). Graph taken from Russell, D. Acoustics and Vibration Animation, PSU, http://www.acs.psu.edu/drussell/demos/superposition/superposition.html.

Low tide is the best time to see sea stars, mussels and barnacles, but it is also a more hazardous time in the tidal cycle for mariners to travel. Therefore, navigational charts use the mean lower low water level, low tide, for the soundings, or depth measurements on a chart. The black numbers seen on a nautical chart, or soundings, represent depth measurements relative to mean lower low tide. Driver Bay, the area on the chart where we installed the tide gauge today, is the crescent shaped bay at the northwest end of Raspberry Island.

This is a nautical chart used to help mariners navigate safely.

Installing Tide Gauge Stations

Before gathering sonar data, ground and boat crews install a tide gauge to measure changes in water level and to determine the mean lower low water level datum. A tide gauge is a neat device that has air pumped into it, and uses air pressure, to determine how deep the water is. The tide gauge uses a formula of (density of sea water)(gravity)(height) = pressure. The gauge measures pressure, and we apply factors for gravity and sea water. The only missing factor is height, which is what we learn as the gauge collects data. This formula and nuances for particular locations is a fascinating topic for a blog or master’s thesis. Scientists are looking for tidal fluctuations and other location specific variances. Then, by computer they determine the mean lower low tide depth, factoring in the tidal fluctuations.

There are permanent tide gauge stations all over the world. The nearest permanent tide gauge station to our study area is in Kodiak and Seldovia. These permanent gauges take into account many factors that affect tides over a 19 year period of time, not just the gravitational pull of the moon.

The tide gauge stays in place for at least 28 days (one full tidal cycle). During the month, data of the tides is collected and can be compared to the other tide gauges we install.

Installing the Tide Gauges and Benchmarks

Excitement built as the crew prepared for the “Tide Party,” packing suitcases full of gear and readying the launches. Installing Tide Gauges signals the beginning of the season and is one of the few times crew gets paid to go on shore.

Why Bench Mark?

There are three reasons I have figured out after many discussions with patient NOAA crew as to why we put in bench marks.

I installed this benchmark by having a hole drilled in bedrock and affixing the benchmark with concrete if anyone ever returns and needs to know their exact location. — I installed this benchmark in Driver Cove by having a hole drilled in bedrock and affixing the benchmark with concrete if anyone ever returns and needs to know their exact location. Photo by Barry Jackson

The first reason we install benchmarks is to provide a reference framework to ensure both our tide staff and the tide gauge orifice are stable and not moving relative to land. The second reason is if we ever come back here again to gather or compare data to previous years, we will know the elevation of the tidal datum at this location relative to these benchmarks and can easily install a new tide gauge. The third reason is that the earth and ocean floor changes constantly. As scientists, we need to make sure the survey area is “geologically stable.” We acquire several hours of GPS measurements on the primary benchmark to measure both its horizontal and vertical position relative to the earth’s reference frame. Should there ever be an earthquake here, we can come back afterwards and measure that benchmark again and see how much the position of the Earth’s crust has changed. After the last big earthquake in Alaska, benchmarks were found to move in excess of a meter in some locations!

Teacher on Land Polishing Her Benchmark Photo by Brandy Geiger — Teacher on Land
Polishing Her Benchmark
Photo by Brandy Geiger

Installing the Benchmark

Today, our beach party broke into two groups. We located stable places, at about 200 foot intervals along the coastline. We drilled 5 holes on land and filled them with concrete. A benchmark is a permanent marker you may have seen at landmarks such as a mountain peak or jetty that will remain in place for 100 years or more. We stamped the benchmark by hand with a hammer and letter stamps with our station identification. If we chose a good stable spot, the benchmark should remain in the same location as it is now.

Tide Gauge

As one group sets up benchmarks, another group installed the tide gauge.

Here, Chief Jim Jacobson, Lead Survey Technician, sets up a staff, or meter stick, I used to measure the change in water depth and others used for leveling. Photo by Barry Jackson

To install the tide gauge, you must have at least three approved divers who install the sensor in deep water so that it is always covered by water. Because there were only two crew on board trained to dive, Lieutenant Bart Buesseler, who is a dive master, was called in to assist the team. The dive team secured a sensor below the water. The sensor measures the water depth with an air pressure valve for at least 28 days. During this time there is a pump on shore that keeps the tube to the orifice pressurized and a pressure sensor in the gauge that records the pressure. The pressure is equal to the number of feet of sea water vertically above the gauge’s orifice. An on-board data logger records this data and will transmit the data to shore through a satellite antenna.

Divers install the tide gauge, and spent most of the day in the cold Alaska waters. Good thing they were wearing dive suits! Photo by Barry Jackson

Leveling Run

After the gauge and benchmarks are in place, a group does a leveling run to measure the benchmark’s height relative to the staff or meter stick. One person reads the height difference between 5 different benchmarks and the gauge. Then they go back and measure the height difference a second time to “close” the deal. They will do the same measurements again at the end of the survey in the fall to make sure the survey area has not changed geographically more than ½ a millimeter in height! Putting the bubble in the middle of the circle and holding it steady, leveling, was a highlight of my day.

Observation

Finally, a person–me– watches the staff (big meter stick above the sensor) and takes measurements of the water level with their eyes every six minutes for three hours. Meanwhile, the sensor, secured at the orifice to the ocean floor by divers, is also measuring the water level by pressure. The difference between these two numbers is used to determine how far below the water’s surface the orifice has been installed and to relate that distance to the benchmarks we have just leveled to. If the numbers are consistent, then we know we have reliable measurements. I won’t find out if they match until tomorrow, but hope they do. If they don’t match, I’ll have to go back to Driver Bay and try again.

As we finished up the observations, we had a very exciting sunset exit from Raspberry Island. I was sad to leave such a beautiful place, but glad to have the memories.

Last minute update: word just came back from my supervisor, Ensign J.C. Clark, that my tidal data matches the gauge’s tidal data, which he says is “proof of my awesomeness.” Anyone who can swim with a car battery in tow is pretty awesome in my book too.

The data Starla Robinson and I collected is represented by the red line and the data the gauge collected is represented by the blue line. The exact measurements we collected are on the table.

Spotlight on a Scientist

Lieutenant Bart Buesseler came to us straight from his family home in the Netherlands, and before that from his research vessel, Bay Hydro II. The main reason our CO asked him to leave his crew in Chesapeake Bay, Maryland, and join us on the Rainier is because he is a dive master, capable of installing our sensors under water, and gifted at training junior officers.

Lieutenant Beusseler knows he needs to be particularly nice to Floyd Pounds, an amazing cook from the south who cooks food from every corner of our ocean planet. — Lieutenant Beusseler knows he needs to be particularly nice to the amazing chefs aboard Rainier, including Floyd Pounds, who cooks food from every corner of our ocean planet with a hint of a southern accent.

During his few years of service, LTJG Buesseler adventured through the Panama Canal, along both coasts of North America, and has done everything from repairing gear to navigating the largest and smallest of NOAA vessels through very narrow straits. He loves the variety: “if I get tired of one task, I rotate on to another to keep engaged and keep my mind sharp.” He explains that on a ship, each person is trained to do most tasks. For example, he says, “during our fast rescue boat training today, Cal led several rotations. But what if he is gone? Everyone needs to be ready to help in a rescue.” Bart says at NOAA people educate each other, regardless of their assignments, “cultivating information” among themselves. Everyone is skilled at everything aboard Rainier.
In the end, he says that all the things the crew does are with an end goal of making a chart. His motto? Do what you love to do and that is what he’s doing.

Personal Log

Today was a special day for me for many reasons. It is majestic here: the stark Alaskan peninsula white against the changing color of the sky, Raspberry Island with its brown, golden, crimson and forest green vegetation, waterfalls and rocky outcroppings. I’m seeing whales, Puffins, Harlequin Ducks and got up close with the biggest red fox ever. Most importantly, I felt useful and simultaneously centered myself by doing tide observations, leveling and hiking. I almost dove through the surf to make it “home” to the ship just in time for a hot shower. Lieutenant Buesseler’s reference to “cultivating information” rings very true to me. In writing these blogs, there is virtually nothing I came up with independently. All that I have written is a product of the patient instruction of Rainier crew, especially Commander Brennan. Each day I feel more like I am a member of the NOAA crew here in Alaska.

NOAA Teacher at Sea
Susan Kaiser
Aboard NOAA Ship Nancy Foster
July 25 – August 4, 2012

Mission: Florida Keys National Marine Sanctuary Coral Reef Condition, Assessment, Coral Reef Mapping and Fisheries Acoustics Characteristics
Geographical area of cruise: Florida Keys National Marine Sanctuary
Date: Friday, July 29, 2012

Weather Data from the Bridge
Latitude: 24 deg 36 min N
Longitude: 83 deg 20 min W
Wind Speed: 5.8 kts
Surface Water Temperature: 29.5 C
Air Temperature: 29.5 C
Relative Humidity: 67.0%

Science and Technology Log

Marine Scientist, Danielle Morley, ready for the signal to dive and retrieve a VR2.

Science is messy! Extracting DNA, observing animals in their native habitat or dissecting are just a few examples. On board NOAA Ship Nancy Foster it may even be stinky but only for a little while. That is because the divers are retrieving the Vemco Receivers also called VR2s for short. These devices have been sitting on the ocean floor quietly collecting data on several kinds of grouper and snapper fish. Now it is time to download the VR2s recorded information and give them new batteries before placing them at a new site. So, why are they stinky? Even though the VR2s are enclosed inside another pipe, sea organisms have begun to grow on the top of the VR2. They form a crust that is stinky but can be scraped away with a knife. Any object left in the ocean will soon be colonized by sea creatures such as oysters, algae, and sponges to name a few. These organisms will grow and completely cover the area if they are undisturbed. This crust smells like old seaweed drying on an ocean beach.

Clean VR2 ready to download data and replace batteries.

Really, it isn’t too bad and after a while you don’t notice it so much. Besides this is the only way scientists can get the numbers out of the VR2. These numbers tell scientists which fish have been swimming by and how often. Some of the VR2s have collected over 21,000 data points but most have fewer. This information alone helps scientists understand which areas of the ocean floor each species of grouper and snapper prefer as their home or habitat. These data points can even paint a picture of how these fish use the habitat space over the period of an entire year.

Have you been wondering what the VR2s are listening for? You may be surprised to learn it is a signal called a ping from a tracking device that was surgically implanted while the fish is still underwater! The ping is unique for each individual fish. The surgeries were completed when the study began in 2008. First, the fish are caught in live traps. If the trap is in deep water (>80ft) divers descend to perform the surgery on the ocean floor. The fish’s eyes are covered and it is turned upside down. Then a small incision is made in their abdomen and the tag is inserted below the skin. Stitches that dissolve over time are used to close the incision. Once the fish has recovered a bit it is released. An external tag is also clipped into the dorsal fin so other people will know the fish is part of a scientific study. Fish caught in the upper part of the water column may be brought up to the surface slowly and kept in a holding tank while the surgery performed on the boat. Scientists have noted the fish are less stressed by being caught, handled and tagged using this method. This is a factor for collecting enough data to gain a real understanding of these fishes behavior.

Scientists at the Florida Fish and Wildlife Conservation Commission (FWC) are able to conduct this study with support from a National Oceanic and Atmospheric Administration (NOAA) grant. They have also worked with other agencies on this research including the Florida Keys National Marine Sanctuary (FKNMS) the area where the VR2s are positioned. Since 2008 they have learned a great deal to better understand how grouper and snapper use habitat. Both fish are good for eating and are found on the menu in many restaurants around the world. They are commercially harvested and fished by recreational fishermen like you and me. Fishing is a big industry in all coastal locations and especially in Florida. In fact, commercial fishing alone accounts for between 5-8% of total income or jobs in the local economy of the Florida Keys. Knowledge gained from this study will help FWC and FKNMS guide decisions about fishing and recreation in the FKNMS and be aware of negative impacts to these fish populations in the future. Stinky air is small sacrifice to help preserve populations of groupers and snappers.

Jeff Renchen describes the features of the ROV.

Mrs. Kaiser wearing the virtual reality glasses. Photo by Jeff Renchen

You can see that exploring marine habitats takes time, trained people and resources. Luckily a device has been developed to help scientists explore the ocean floor in an efficient and safe way. This little gem is called a Remotely Operated Vehicle or ROV. It is a cool science tool operated with a joy-stick controller. The ROV can dive and maneuver at the same time it sends images back to the operator who is using a computer or wearing virtual reality glasses. Yes, I said virtual reality glasses! The operator can see what the ROV can “see” in the depths of the ocean. I had the opportunity see the ROV in the lab and then ride with the ROV team as they tested the equipment and built their skills manipulating this tool in dive situations. The beauty of the ROV is that it can dive deeper than is allowed for a human diver (>130 feet) and it can stay down for a longer period of time without stopping to adjust to depth changes like a human. If a dive site has a potential risk due to its location or other factors, the ROV can be sent down instead. Scientists can make decisions based on the ROV images to make a plan for a safe live dive and save time and resources. Science is messy, sometimes, but it is cool too!

Personal Log

The weather has been simply amazing with calm crystal clear seas and very smooth sailing. Still, spending the day in the sun saps your energy. However, that feeling doesn’t last too long after a nice shower and a trip to the mess to enjoy a delicious meal prepared in the galley. There Chief Steward Lito Llena and 2^nd Cook Randy Covington work their magic to cook some terrific meals including a BBQ dinner one evening on the upper deck. They have thought of everything, especially dessert! I will be paying for it later by running extra laps when I get back home but it will be worth it.

Mrs. Kaiser's stateroom on the NOAA Ship Nancy Foster. — Mrs. Kaiser’s stateroom on the NOAA Ship Nancy Foster.

My stateroom is a cozy spot with everything one would need and nothing more. A sink is in the room but showers and toilets are down the hall a few doors. One item that is missing is a window. It is so very dark when the lights are off you can’t see your hand in front of your face. It is easy to over sleep! Surprisingly noise has been minimal since the rooms are very well insulated. I share this space with three female scientists but we each have a curtain to turn our bunks into a tiny private space. I enjoy climbing up in my top bunk, closing my little curtain and reading my book Seabiscuit, An American Legend before being rocked to sleep by the ship.

NOAA Ship Nancy Foster officers and crew have been wonderful hosts on this cruise. All have patiently answered my questions and helped me find my way around to do what I need to do. I am curious about their life at sea and the opportunities it affords them to see new places, meet new people and engage in new experiences too. I hope to learn more about their careers as mariners before this voyage ends. The ship truly is a welcome place to call home for these two weeks.

Tag: ping

Denise Harrington: The Best Day Ever, April 30, 2014

Susan Kaiser: Ready, Set, SCIENCE!! July 29, 2012