by Ensign Kaitlyn Seberger, onboard NOAA Ship Thomas Jefferson
Nautical charts are an important tool in navigating safely in coastal waters, and Coast Survey’s mission is to keep these charts up to date. However, maintaining accurate charts can be a challenge in locations where sandy shoals may shift seasonally and present a danger to navigation. These areas differ from the current nautical charts, and bottom contours change so rapidly that it may seem an impossible task to keep up using the traditional survey methods. Office of Coast Survey and NOAA Ship Thomas Jefferson are seeking a solution to this ongoing problem and may have an answer with satellite-derived bathymetry.
Satellite-derived bathymetry (SDB) begins with using multi-spectral satellite imagery, obtained by satellites such as Landsat and WorldView2, which compares green and blue color bands.
If you look closely at any U.S. coastal nautical chart, you’ll likely find that the areas closest to the shore, shoals, and rocks do not have updated depth measurements. In many areas, safety concerns prohibit the use of NOAA ships or launches to survey the shoalest depths. In many areas, the water is too murky to be mapped with the airborne lidar systems used in clear waters. Now, however, charting those shallow areas is about to get safer, thanks to recent purchases of small, commercial off-the-shelf, unmanned surface vehicles.
by Ensign Diane Perry, onboard NOAA Ship Thomas Jefferson
From 2005 through today, NOAA Ship Thomas Jefferson has been surveying Long Island Sound, one project area at a time. Some of the area was last surveyed between the late 1800s and 1939. For the 2014 field season, Thomas Jefferson was assigned her final Long Island Sound project, 89 square nautical miles of Eastern Long Island Sound, Fisher Island Sound, and Western Block Island Sound. When this project is complete, we will have resurveyed over 95% of Long Island Sound and all of Block Island Sound with modern survey technology that allows for a complete picture of the seafloor and highly accurate soundings.
By Ensign Brittany Anderson, Junior Officer, NOAA Ship Thomas Jefferson
After a quiet winter at home port, the NOAA Ship Thomas Jefferson completed her sea trials this week in preparation for the 2013 field season.
Each year, prior to departing for working grounds, the Thomas Jefferson transits to the Chesapeake Bay to perform tests on the ship’s and launches’ systems and hydrographic survey equipment. Crews conduct numerous tests to check the accuracy and precision of multibeam echosounders, side scan sonar, and the sophisticated suite of programs that process all the data. Additionally, this is an opportunity to ensure the safety of the vessel and her crew by performing numerous safety drills and readdressing safety standards and operating procedures.