Kathy Virdin, July 25, 2004

NOAA Teacher at Sea
Kathy Virdin
Onboard NOAA Ship Rainier

July 20 – 28, 2004

Mission: Hydrographic Survey
Geographical Area:
Eastern Aleutian Islands, Alaska
July 25, 2004

Latitude:55degrees 17.215 N.
Longitude: 160 degrees 32.231 W.
Visibility:1 nautical mile
Wind direction:140 degrees
Wind speed: 10 kts.
Sea wave height: 0-1 ft.
Swell wave height: 2-3 ft.
Sea water temperature:10 degrees C.
Sea level pressure: 997.4 mb.
Cloud cover:Cloudy, light rain

Science and Technology Log

Today we had a visitor from Tenix Lads, Inc. named Mark Sinclair who does LiDAR depth readings for NOAA. LiDAR means light detection and ranging. It is done from a small aircraft, flying at an altitude of 1800-2200 ft. They over fly an area with two laser beams that measure the surface of the water and the depth of the water. They get the difference in these heights, with geometric corrections for tides and other factors, to give them the ocean floor depths. They are able to take an incredible 324 million soundings in an hour! Their information is used for nautical charting, coastal zone management, coastal engineering, oil and gas development, military applications and research and development. They will identify depths, buoys, beacons, lighthouses, kelp areas on digital display (via computers) and on spreadsheets. The benefits of the LiDAR technology is that it is very cost effective, has amazing speed, and greater safety. They do 200% coverage of an area by measuring lines and then taking new lines in between the first lines. They run a swath beam that is 192 meters, which is larger than the ones that the RAINIER does. Each beam of pulsar light is 15 meters with 4 meters in between.

They are finding changes that need to be made on maps that date back to the 1940s. NOAA contracts with this company to do soundings for them and NOAA picks small segments of these areas to do spot checks with the ship to compare accuracy. So far, they have been extremely accurate. At this point in time, they are not comfortable with the greater depth measurements that the RAINIER does, but expect that to change in the future. Various crew members that I’ve spoken with foresee this becoming the depth measurement instrument of the future. Eventually, all depth readings may be done from satellites, which could become very accurate, as well as safe. Right now, NOAA will continue to use both methods.

Personal Log

I spent the day working on the computer, listening to the LiDAR presentation and reading the information about this new system. It’s very interesting to predict how useful this will become in the next 10-20 years. I’d love to see some of my students flying the airplanes that will send back this newer technology. Right now, the RAINIER is anchored while launches go out to do shallow survey each day. It’s fascinating to watch them lower the launches and bring them back onto the boat. They use hydraulic winches that raise and lower the boats. Everyone has to be very careful at this point, wearing hard hats, because it’s a time when equipment failure could bring a dangerous situation. Generally three or four people go out on each day’s launch. They have several more days of launches scheduled, then they must go to the Kodiak Coast Guard base to refuel.

Virdin 7-25-04 screenshot

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