Tag: TEXIX LADS

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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
Date: 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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Leyf Peirce, July 12, 2004

NOAA Teacher at Sea
Leyf Peirce
Onboard NOAA Ship Rainier
July 6 – 15, 2004

Mission: Hydrographic Survey
Geographical Area: Eastern Aleutian Islands, Alaska
Date: July 12, 2004

Time: 18:00
Latitude: N 55°17.29
Longitude: W 160°32.13
Visibility: 2 nm
Wind direction: 115
Wind speed: 12 knots
Sea wave height: 0 – 1 foot
Swell wave height: 1 foot
Sea water temperature: 10.0 °C
Sea level pressure: 1011.0 mb
Air temperature: 12.2 °C
Cloud cover: 8/8

Science and Technology Log

Today we took a field trip to Sand Point, AK, a small fishing town on Popof Island. It also happens to be a base for the TEXIX LADS, Inc. which is a research facility for airborne laser bathymetry. The goal of this research facility is the same as the RAINIER’s: to chart the ocean floor. However, this group gathers data using a laser attached to the bottom of an airplane as opposed to a boat. The advantage of this type of data collection is that coast line depths can be easily taken without the risk of a boat crashing into uncharted rocks. The technology used aboard the plane is similar to the multibeam sonar systems used on the RAINIER, however instead of a multibeam sonar system, a laser is used. This laser has a pulse rate of 990 pulses per second, a depth range of 70 meters dependent on water clarity, a topographic range of 50 meters above sea level and a swath width that can range from 240 meters to 100 meters depending on flight velocity. And, to acquire the data, the plane travels at between 150 and 175 knots!

While this mode of data acquisition is faster than that aboard the RAINIER, it can only accurately acquire data in shallower waters because of light refractions at deeper depths. Therefore, NOAA works in conjunction with this group to survey the ocean bottom in and around Alaska. While the Tenix LADS, Inc. surveys the coast line, and will warn NOAA ships of any bottom features that might protrude in deeper water, the RAINIER charts the deeper waters (between 30 meters and 400 meters). The data will then be collaborated to produce accurate nautical charts.

We also went to the office where the data collected aboard the plane is processed. While I did not get to study the software used, I did notice that the data processing was very similar to that on the RAINIER; both require data processors to go through the data and filter any outlying points before the data can be applied to the nautical charts. The data is also collected according to “mowing the lawn” lines, similar to the RAINIER. However, these lines are along the shore line as well as going about 250 meters onto the coast itself.

Personal Log

Learning about data acquisition aboard a plane was very interesting today! It was also nice to go to land, where we got an excellent coffee at the only café in Sand Point. We also went on a tour of the town, seeing its one school, one restaurant, and one store. The small homes reminded me of those that sprinkle the south-west Swedish coast line— simple homes that beacon stories and the occasional wonderer. I am amazed at the amount of mystery such towns hold while also giving off such a welcoming, cozy feel. The weather today was the opposite, with the first rain we saw bringing larger swells and more fog. I really can’t complain too much, though, for we have been here for almost a week and still hadn’t seen rain until today. It did make for a very interesting small vessel ride to and from the shore!

I spent a lot of time today talking with Sena Norton, the other Teacher At Sea, about lesson plans and ideas for next year. We have both agreed it would be great for our students to establish a line of communication between our classes. In doing this, we can share various projects, such as an on-going weather project that we are planning to start in January—it will be very interesting to gather data in our own regions and then share and compare weather in Oregon and weather in North Carolina. We are also thinking about conducting a lab involving charting, navigation, and depth measurements where we have our classes work together to complete the final navigational chart of a large section. This is such a great opportunity to not only use the data and information gathered aboard the RAINIER, but to also start establishing a connection with another class in another school! I can’t wait to work on these ideas more tomorrow!

Question of the Day:

Given a different type of laser, could accurate data be collected from a plane at depths greater than 30 meters? Would this be a better way to conduct hydrographic research other than using boats?