NOAA Teacher at Sea
Onboard NOAA Ship Fairweather
June 15 – July 1, 2009
Mission: Hydrographic Survey
Geographical area of cruise: Shumagin Islands, Alaska
Date: June 21-22, 2009
Weather Data from the Bridge
Position: Northwest Harbor
Clouds: Mostly Clear
Visibility: 10+ miles
Wind: 13 knots
Waves: less than 1 foot
Temperature: 8.2 dry bulb
Temperature: 7.2 wet bulb
Science and Technology Log
Launches are excellent for collecting data near the shoreline, but the Fairweather is better at open water data collection. The polygons are larger, but the ship must still be traveling at approximately 6 knots for optimum results. The ship also uses the multibeam to sweep the ocean floor, just like the launches. Of course, multiple computer screens are again necessary to monitor data collection on the ship. Also similar to the launches and their CTD’s, the ship uses a device called a Moving Vessel Profile (MVP) that collects information about sound velocity as it is dropped through the water. It is commonly called the “fish” since it is dropped into the water and manipulated to “swim” at different depths for data collection.
A definite advantage of the MVP is that the fish can be deployed while the ship is moving; however, the launch must be stopped to use the CTD. Additionally, the MVP measures sound velocity directly where as the CTD collects data that must be plugged into a formula to calculate the measurement for sound velocity. Data collected from both the launches and the ship must be processed and converted. Much of the data processing involves moving data uploaded from launches into networked folders. At times while I watched data processing, there were too many folders open on multiple computer screens for me to personally keep track of. Also, I noticed certain data sets being converted from one form to another. Sometimes, the data conversion takes a long time so computers must be marked so nobody interrupts the conversion process. Patience, computer literacy, and organization skills are a must for working on data processing!
Another part of working with data collected from the launches and the ship involves cleaning “dirty” data. Even through the best efforts to collect data, pings are sometimes lost or interference occurs. Perhaps the speed of the vessel exceeded 6 knots or maybe there was a section of the water with an unusual density. So, a software program called Caris is used to work with the data on a dual screen computer. The ocean floor that is color coded by depth can be viewed on one screen. Then, the person working with the data selects small segments of the ocean floor to view on the other screen. The plane of the ocean floor and all of the pings are shown in a variety of color scales. Data that is very accurate at a high confidence level can be shown in violet, but the lower the confidence level gets, the further up the spectrum the colors are shown. Many people choose to show different lines of pings in different colors to make it easier to see how many times the same section of the ocean floor was swept.
The person working on the computer can choose to delete certain pings, especially if they were located at the far end of the multibeam. These pings are more likely to be lost or misrepresent the depth. Additionally, a measurement can be taken on the screen with a ruler tool to determine if a group of pings are within specification limits. If they are not, a segment of data can be designated for further investigation. The person working on this must make many decisions, so it is important to be able to infer information from data as you work.
I went sea kayaking a few years ago in Mexico, but sea kayaking in Alaska is by far more dangerous. Even though the kayaks are paddled the same way and I could keep the boat balanced relatively easily, the danger of flipping over and freezing to death in the sea water is a constant thought. The beauty of the islands as I paddled near them was mesmerizing. The Shumagin Islands look like something out of a prehistoric world. I keep expecting to see a dinosaur walking up one of the rocky hillsides. I didn’t see any prehistoric creatures on the kayak, but I did see some puffins, a seal, and a wide variety of other seabirds too far away for identification. Kelp was also floating around in abundance. I should mention that I was sea kayaking from about 8:30 to 11:00pm, but it was still daylight the whole time. It is near the summer solstice, so daylight lasts for about 18 hours or so each day. Right now, the sun is rising at about 6:00am each morning and setting at about 11:30 each night. It is really unusual to be out on a sea kayak in bright daylight in the middle of the night!
Create Your Own NOAA Experiment at Home
You can use simple items from your kitchen to see how cold the water in Alaska feels. You will need some ice water, a thermometer, and a bowl. First, put the ice in the bowl and pour the water over it. Next, place the thermometer in the bowl with the ice water. Wait until the temperature goes down to about 45 degrees Fahrenheit. Now, place your bare hand in the ice water. How does it feel? Try it with a glove on. Do you feel a difference? Remember, your body temperature is about 98 degrees Fahrenheit, so you are putting your hand into water that is about half your body temperature. Can you imagine how it would feel to fall into this water?