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

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