How did August fly by so fast? Looking back I can’t believe I’ve been out here a month already – everything seems a blur of seismic wiggles and multibeam pings. I’ve been really busy the last few days trying to proliferate images of the ocean. Oh buddy, do I have some cool looking images! I’m so excited to take this data back to Wyoming and show people! Yesterday was our last day of multichannel seismic acquisition (insert sad face) and we are headed towards Dutch today. It will take two and a half or more days to get back to Dutch Harbor, (yes – we are indeed that far away). There is supposedly a storm tailing us so we are making as much good time as possible. I really want to do a blog about all the sounds you hear on a ship and what the food tastes like etc… (the 5 senses blog mentioned in an earlier post) but I think with our proximity to the end of the cruise I should first write about what we did in the beginning.
I flew into Dutch Harbor on the 6th of August aboard a Saab 370. Tiny little plane, but definitely not the smallest I’ve been in (take the vomit-comet out of Laramie sometime – now that can be an adventure!). The plane ride offered some great views of Adak and Atu (Aleutian volcanoes pictured). I was already sick when I got on the plane in Anchorage and by the time I got on the Langseth the sick was in full force. I had some nasty combination of sore throat, flu, and cold. The last place you want to be sick is at sea. Thankfully, I don’t get seasick and my sea legs come along in no time otherwise I would have really been in a poor position. Being sick, I wasn’t able to make it through my first midnight to noon watch (I think I made it to 3 a.m.), but was back to adjusting my schedule the next night. Since being sick, we’ve had some yuck-weather for probably about five or six days total which means 5-meter seas and 40-50-knot winds. What that really means is very little sleep for those who are concerned about falling out of the bunk when the ship rolls around 45 degrees from center.
Back to the beginning. Once we transited to our survey sight seismic operations got underway. The first equipment to be deployed is the eight-kilometer long hydrophone array called a streamer. These sensors are like “ears” that listen for energy (aka signal) traveling from a source through the water and earth and then back through the water. There are 636 channels on the streamer and 12 hydrophones make each group or channel. The next to be deployed is the energy source called a tuned air-gun array. There are four strings holding 36 air-guns that release 6600 cubic inches of compressed air into the water every 50 meters. The bubble pulse from the guns sends waves that travel through the earth/water and come back loaded with information about what they “saw”. All this information is recorded and then we “the beakers” (otherwise known as scientists) process the data to produce images that are like cross-sections of the earth. We gathered hundreds of kilometers of multi-channel seismic data over ten days. One of my goals on this cruise is to better understand the oceanography of the Bering Sea via seismic data. In order to corroborate with the seismic images we are throwing the following overboard: expendable bathy-thermographs (XBTs) that measure a temperature profile through the water column, expendable conductivity-temperature-depth sensors (XCTDs) that measure temperature, depth, and indirectly the salinity of the water column, and casting a CTD with a 12 bottle rosette to bring up water samples. Have I mentioned that the water at the bottom of the Bering is some of the oldest water on the planet due to the manner in which the ocean circulates? It is probably thousands of years old and I have tasted, sampled, and am taking home some of it! Pretty exciting and perhaps a topic for a future blog… All this data will take months/years to process and understand.
In all this mention of shooting and deploying equipment, I should also mention the protected-species observers (PSOs) who observe around the clock to make sure we are not harassing any marine life. Our PSOs are rockstars that brave nasty winds and cold weather on top of a tower for hours on end. They also get some cool photos (see below).
So, that pretty much sums up the data acquisition for the first half of the cruise. I’ve also included a few pictures from Dutch Harbor for your pleasure.