data processing – Page 2 – NOAA Teacher at Sea Blog

June 24, 2009April 5, 2021

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

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

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.

There, 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.

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.

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.

June 19, 2009April 5, 2021

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 6.7^◦C, 44^◦ F

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 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.

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.

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.

June 16, 2009April 5, 2021

Mary Patterson, June 16, 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 16, 2009

Weather Data from the Bridge
Overcast
Wind 19 kts
4-6 ft seas, 9-11 ft swells
10 nautical mile visibility
Sea Temp 6.1◦ C
Sea level air pressure 1001.0 mb
Dry Bulb 8.9 Wet Bulb 8.3

Science and Technology Log

The day was spent in 17 hours of transit to our survey location. During the day the seas turned heavy with 4-6 foot seas and 9-11 foot swells. Even some of the crew and seaman had to hold onto the walls as they walked. The ship definitely rocked and rolled! This was a great test of the trans-derm scop patch to prevent sea-sickness. I was so surprised that it worked so well.

ET John Skinner checked my computer to be sure it was virus free and then set up access to the ship’s email and internet. The ship receives internet through a satellite signal. All ship personnel have to take a computer security test in order to login to the ship’s network.

The Rainier sails through 10-foot swells!

After completing my computer safety module, John took me and fellow Teacher at Sea, Jill Stephens, on a quick tour of the launch boats and described the technology installed on them. Each 29 foot launch boat is worth more than a million dollars with all the equipment aboard. John showed us the sound velocity meter, the high and low frequency multibeam echosounder transducers to send and receive the signal, and the computers that collect and store the data. (I’ll explain more about how these work in my next journal). Each boat also has GPS (Global Positioning System), Iridium satellite phone, AIS ship identification (Automatic Identification System that broadcasts in the VHF frequency), marine RADAR, VHF marine radio, fathometer, compass, life raft, fire extinguishers and fire suppression systems.

Here we see the low-frequency multibeam sonar on the left and the high-frequency multibeam sonar on the right.

Personal Log

After dinner, the first POD (Plan of the Day) was posted. This is produced by the FOO (Field Operations Officer). I excitedly found my name on Launch # 5. Our mission tomorrow will be to find a safe anchorage for the ship on the south side of Ukolnoi Island. We will be surveying ocean floor that has not ever been charted before. It’s amazing how easy it is to fall into the ship’s routine here. Breakfast is at 7:00 am, lunch at 12 noon and dinner at 1700 (5:00PM). After dinner, I visit the Bridge and see the many instruments used to guide the ship safely. My favorite piece of equipment is the Clearview screen, or “rain spinner”. It has two pieces of glass that spin and keep the windshield clear of rain.

The Clearview screen, also called a “rain spinner”

I learn that all the weather data is taken here on the bridge and then submitted to NOAA for their meteorological database. Next, I visit the chart room where the survey techs process the data collected by the launches. Tonight, they are anxiously planning the areas to survey tomorrow. The people on the ship are so very interesting and friendly. It’s great to hear their stories of how they came to the ship and how much they enjoy the work they do.

Did You Know?

Sergio Taguba, our Steward, has been on the Rainier the longest of anybody? He’s been here for 36 years!

August 21, 2005March 18, 2021

James Miller, August 21, 2005

NOAA Teacher at Sea
James Miller
Onboard NOAA Ship Rainier
August 13 – 27, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific, Alaska
Date: August 21, 2005

Location: Anchored Northeast side of Mitrofinia Island
Weather: Sun and clouds, low 60’s
Wind: 5-10kts
Seas: Calm
Itinerary: Working around Mitrofinia Island

Science and Technology Log

To ensure completion of some of the longer lines located further out in the open ocean, the ship spent the day running surveying lines. The RAINIER is also fitted with sonar transducers and is used when the lines are 8 miles or longer. I was assigned to work in the plotting room with the surveyors cleaning up data that was collected the previous day.

Many processing steps must be performed on the bottom contour data before it makes it onto a chart. On the ship, the surveyor performs a basic “cleaning” of the data with powerful computers, and very sophisticated software. The surveyors pull up the bottom contour data on the screen and analyze it for stray signals. It is very cool software because they look at the bottom in 3-D and from any angle. At first it doesn’t look like much but a chaotic grouping of lines; however, after the surveyor selects areas and stray signals to cut out, the bottom contour emerges. The surveyor definitely develops an eye for understanding these 3-D images, but it didn’t take long before I was performing some of the basic cleaning tasks. I also downloaded some of the images onto a disk to be used in a PowerPoint presentation.

I had an interesting conversation with one of the surveyors whose background is geology. He said that this entire area is a geologists dream. He described how much of the area was probably form by Mt. Veniaminof volcano, which is visible in the distance and is still active. The thing is immense and stands above all the other surrounding mountains. Additionally, he has also seen clear evidence of structures formed by seismic activity.

Personal Log

It was actually nice to have a day off from the launches. I had time to do some laundry and get caught up with some e-mails. I’m definitely used to the daily routine and I’ve finally learned all the crew and officers names and responsibilities.

We’re scheduled to leave the area in the afternoon tomorrow because of very poor weather forecasts. Winds to 40kts seem to make the captain a bit nervous, so we’re going to run for cover in Chignik Bay on the peninsula about 80 miles or so northeast of the Mitrofania Island. Since it might be my last opportunity to fish, after dinner I went out to the fantail to try for halibut. I was determined and planned to put in some serious time. After about a half hour I hooked and landed a 25 pounder, and then ten minutes later lost a 15 pounder. Then within another 20 minutes I caught one about the same size as the first. By this time many of the crew started fishing. I saw LT Evans wrestling with a fish on the other side of the boat. It was apparent he had something big, so I put my rod down to watch as he slowly reeled it up. About 20 minutes later this hulk of a halibut appeared, it was huge. It took two harpoons, and me and another guy to haul the fish up onto the boat. We didn’t have a scale but it was estimated at over 100 pounds. It also took all night for LT Evans to clean it and bag it.