NOAA Teacher at Sea
Aboard NOAA Ship Rainier
September 17 — October 7, 2011
Mission: Hydrographic Survey
Geographical Area: Alaskan Coastline, the Inside Passage
Date: Tuesday, October 4, 2011
Weather Data from the Bridge
Clouds: Overcast 7/8
Visibility: 8 Nautical Miles
Wind: 21 knots
Dry Bulb: 12.0 degrees Celsius
Barometer: 997.0 millibars
Latitude: 55.23 degrees North
Longitude: -133.22 degrees West
Science and Technology Log
I was able to go out on another launch boat Sunday to collect survey data. It was a beautiful day with amazing scenery to make it by far the best office I have ever been too. Despite the fact that the ship is usually “off the grid” in many ways, the location of their work environment, or office, in Alaska is visually stunning no matter where you turn. Keeping your eyes off the cedar trees and focused on the sonar in a launch can be challenging at times! However, when there is a specific job to be done that involves time and money, then the scenery can wait until the job is finished. During Sunday’s launch survey we had to clean up some “Holidays” and acquire some cross line data.
The word “Holiday” might lead to some confusion about what you might think we are doing when you read that word. Holiday =vacation right? In this case it is when there is a gap, or missing information, in the survey data that is acquired. This poses a problem for the survey technicians because this leaves holes in the data that they must use for their final charts. Holidays can be caused by the boat or ship being off the planned line, unexpected shoaling (or where the water gets shallow) so the swath width decreases, or a slope angling away from the transducer so that a return path for the sound wave is not possible. The speed, direction, weather, swells, rocking of the boat, and the launches making wider turns than anticipated. It is easy to see where holidays occur as we are surveying because amidst the rainbow of color there will be a white pixel or square showing that data is missing. When we are finished surveying or “painting” an area, we communicate with the coxswain where we need to go back and survey over the missing data or holidays. If there are holidays or data is missing from the survey, then the survey technicians must explain why the data is missing in their final Descriptive Report. This document covers everything that was done during the project from how the area was chosen to survey, what data was collected, what data wasn’t collected and why. This is where holidays are explained, which could be due to lack of time or safety concerns.
This launch was a little different because we were cleaning up holidays from the Rainiers’ multibeam. Not only do the smaller survey boats collect sea floor surface data, but the Rainier has its own expensive multibeam sonar as well. The ships sonar is called a Kongsberg EM 710 and was made in Norway. Having the Rainier fitted with a multibeam sonar allows the ship to acquire data in deeper water and allows for a wider swath coverage. The lines that are surveyed on the ocean floor are also much longer than those in a launch. This means that instead of taking around 5-10 minutes to acquire a line of data, it can take around 30 minutes or more with the ship. This is great data because again, the ship can cover more area and in deeper water. We also took the ships previous data and ran cross lines over it. The importance of running a cross line over previous survey data helps to confirm or deny that the data acquired is good data. However, there is a catch to running a cross line. To confirm the data they have to use a different system than what was used before, the cross line has to be conducted on a different day, and it has to be during a different tide. All of this is done to know for sure that the data is acquired has as few errors as possible before the projects are finished.
Each day when the scientists go out and survey the ocean floor they acquire tens of gigabytes of information! The big question is what is next after they have acquired it all? When they are on the launch they have a small external hard drive that holds 500 gigabytes to a terabyte of information plugged into their computer. At the end of the day all their information and files are downloaded to this hard drive and placed in a water tight container in case it happens to get dropped. Keeping the newly acquired data safe and secure is of the utmost importance. Losing data and having to re-survey areas due to a human error costs tens of thousands of dollars, so everything must get backed up and saved constantly. This is where I have noticed that computer skills and file management are so important in this area of research.
Once we get off of the boats the data is brought upstairs to what is called the plot room. This is where all the survey technicians computers are set up for them to work on their projects. The technicians that are in charge of downloading all the data and compiling all the files together is called night processing. There are numerous software programs (tides, CTD casts, POS, TPU, Hypack,) and data from these programs that all have to be combined so that the technicians can produce a finished product for the Pacific Hydrographic Branch (part of Hydrographic Surveys Division), who then process the data some more before submitting to Marine Charting Division to make the final chart. The main software program that combines all the different data is called Caris and comes out of Canada. Once all of the data has been merged together it allows the technicians start cleaning up their data and produce a graphic plan for the launches to follow the next day. Every movement on the keyboard or with the mouse is very important with surveying because everything is done digitally. Numerous new files are created each day in a special way so that anyone that reads the name will know which ship it came from, the day, and the year. File management and computer skills are key to keeping the flow of work consistent and correct each day.
We have also had numerous fire drills while on the ship. This is very important so that everyone knows where to go and what to do in case of an emergency. They had me help out with the fire fighters and the hose this time. I learned how to brace the fire fighter so that the force from the hose doesn’t knock them over. I never knew that would be an issue with fire fighting until this drill. I learn so many new things on this ship every day!
Student Questions Answered
Question of the Day