NOAA Teacher at Sea
Onboard NOAA Ship Fairweather
May 17 – May 27, 2010
NOAA ship Fairweather
Mission: Hydrographic survey
Geographical Area of Cruise: SE Alaska,
from Petersburg, AK to Seattle, WA
Dates: Saturday, May 22 and Sunday, May 23
Weather Data from the Bridge
Position: Customhouse Cove Position: Customhouse Cove
Time: 0800 on 5/22 Time: 0800 on 5/23
Latitude: 550 56.01’ N Latitude: 55006.5’N
Longitude: 1310 13.75’ W Longitude: 131013.7’W
Clouds: Mostly Cloudy Clouds: Mostly Cloudy
Visibility: 10 miles Visibility: 10 miles
Winds: 6 knots from the NW Winds: 6 knots from the SE
Waves: Less than one foot Waves: Less than one foot
Dry Bulb Temperature: 12.20C Dry Bulb Temperature: 11.00C
Wet Bulb Temperature: 10.20C Wet Bulb Temperature: 9.80C
Barometric Pressure: 1015.0 mb Barometric Pressure: 1010.0 mb
Tides (in feet): Tides (in feet):
Low @ 0224 of 2.8 Low @ 0335 of 1.5
High @ 0828 of 12.2 High @ 0943 of 12.4
Low @ 1436 of 1.6 Low @ 1537 of 2.0
High @ 2105 of 14.6 High @ 2159 of 15.4
Sunrise: 0424 Sunrise: 0423
Sunset: 2100 Sunset: 2101
Science and Technology Log
On Saturday morning I went out and made observations at a tide gauge in Customhouse Cove. We took measurements over a three hour period every six minutes for a one minute interval. We used a pair of binoculars to read the tide staff, which was about 20 feet away, to the nearest millimeter. The purpose of taking this reading over a period of one minute is because the water is constantly moving both toward the shoreline and away from it. This interval ensures that you can get the most accurate reading as possible.
On Sunday, I again went out on a small launch boat. This time we needed to complete a few more holidays using the multi‐beam sonar, then we went to two small islands, Smeaton and South Twin, to recover the GPS (global positioning systems) base stations.
The GPS base station data is recorded daily, while the survey project is underway. The data is then uploaded during the processing phase and used to correct the precise position of the Fairweather and its launches to within a few centimeters of accuracy. This allows the survey technicians to know the exact horizontal position when all of the data was collected by the multi‐bean sonar. Sunday was the last day that data was collected on this project, and that is why we recovered both of the GPS bases stations.
When the tide gauge was established for measurements, during April of 2010, a three hour period of observations was made, similar to what I did on Saturday morning. In the time since April, observations are to be made each week for at least 1‐2 hours. Due to the remote nature of some of the tide gauge locations this is not always possible. The purpose of the observations of the rising and falling tide is to establish the vertical location of the tide gauge sensor, which is submerged below the surface, in relation to the tide staff. These observations help in correlating the height observed on the tide staff, with benchmarks that were previously installed by the Fairweather crew along the beach.
Maritime activities throughout the world depend on accurate tidal and current information for safe operation. NOAA’s National Ocean Service collects studies and provides access to thousands of historical and real‐time observations as well as predictions of water levels, coastal currents and other data.
Ocean tides move in response to gravitational forces exerted by the moon and sun. Since the moon is much closer to the Earth it is the dominant force that affects Earth’s tides. Whichever side of the Earth is facing the moon experiences a greater gravitational attraction, and the oceans get pulled towards it causing a bulge.
When the highest part or crest of the wave reaches a particular location, high
tide occurs; low tide corresponds to the lowest part of the wave, or its trough. The difference in height between the high tide and the low tide is called the tidal range. Here, in SE Alaska there is almost a 15 feet difference between high and low tide.
Most coastal areas, experience two high tides and two low tides every lunar day. Almost everyone is familiar with the concept of a 24‐hour solar day. A lunar day is the time it takes for a specific site on the Earth to rotate from an exact point under the moon to the same point under the moon the next day.
On Saturday afternoon, we went back to the tide gauge to take elevation levels of five benchmarks on the beach. The purpose of these measurements is to establish a vertical height of the tide gauge with five existing benchmarks. When the gauge was started in April 2010, the same measurements were made. We verified that the opening and closing measurements were within an acceptable range. After taking height measurements, I helped take out one of the prototype tide gauges since the data was not needed anymore. The regular gauge was later removed on Sunday.
I was able to help out with these height measurements by holding a rod on top of the benchmarks, while another member of the crew looked through a scope and read the levels off of the rod. We also documented the entire site by taking photographs.
The weather on Saturday was probably the best I have had in SE Alaska so far. It was sunny and in the low 60’s. I learned a few days ago, that when you are out at sea and it is sunny you need sunscreen and a baseball hat in order to not get sunburn. As I told you, on Saturday morning I was dropped off by a small boat to observe the level of the tide. Nothing too exciting, but the weather made it just fine. Since we were very close to the ship, I was able to come back on and have “hot” lunch rather than sandwiches and stuff. In the afternoon, we went back to the same tide gauge and I helped out with elevation studies is the easiest way to say it. This was better than the morning for me.
In the morning one other guy and I were literally dropped off on a barely exposed rock just offshore from the tide gauge. When we started there was water between the two of us, but we knew the tide was dropping so we were fine. However, we were sort of stranded there until the small boat picked us up for lunch. We had to take levels of the water every six minutes. Sounds boring but it went by rather quickly. As the tide dropped small tidal pools were exposed and I was able to explore. There was tons of sea life. It reminded me of Point Loma near San Diego, where I vacationed once. While we were there, of course there were bald eagles and even a few seals.
In the afternoon we actually went onto the beach and I got to explore a little. First time on land since Ketchikan; which we are still very close to. I was in my full on geologist mode, breaking and smacking rocks to see what they looked like on the inside. I saw some cool stuff, possibly some small flakes of gold, garnet crystals, and maybe some silver flakes. The captain (CO) also came along with us, which was pretty cool.
Dinner was good. Baked potato bar, some interesting tofu dish (most people ate prime rib, very rare, uncle Jerry style), salad, and coconut lemon cake for dessert. I am getting spoiled from all this good food. I watched another amazing sunset from Customhouse Cove on Saturday (that makes 3 from the same anchor spot).
Sunday, the weather was not as nice as Saturday; at least it did not rain. However I really did enjoy the day. The crew that I was with was great. We all got along very well. I was able to get onto land three times and explore and climb around on the rocks. Also we saw two humpback whales, a bunch of seals, more Dall’s porpoises, and yes more bald eagles.
Being able to go onshore was really special for me. I was not sure this was something I would be able to do. From here we will start making our course to Seattle. We were just told that we WILL be going through the “inside passage” which is supposed to be absolutely spectacular. I can’t wait.
For now the project is almost complete. There is only a small amount of data and bottom samples that need to be collected. I am enjoying my time onboard the Fairweather. Everyone has been very nice. I have developed a routine. I get up at 0640, breakfast begins at 0700, there is a safety meeting on the bow of the ship at 0800, then if you are on a launch you leave and come back in the late afternoon. Dinner is served at 1700, then after dinner we have a debriefing meeting to discuss the day’s work and any problems that may have been encountered.
As I said I have a little routine. Even the breakfast steward (cook) knows me by now. I come into the mess hall (dining area) and ask for my usual. Three scrambled eggs with scallions and cheese. I also have one piece of toast, three strips of bacon, some hash browns and fresh fruit, some coffee and orange juice. Not too bad. If you are doing survey work from the ship there is hot lunch at 1200, otherwise on the launches it is a bag/picnic style lunch. Yes I know I am getting spoiled with all of this good food.