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?