We caught a mooring.....and a fish!

Some rough weather at the start of the cruise slowed us down a bit, but over the last week our crew has been busy recovering moorings. So far we have picked up 3 of the source moorings and the vertical receiver array mooring.

We've had some exciting moments during these recoveries! On Monday, we discovered that the mooring wire had become entangled with fishing line and our mooring had caught a rather large fish! The pictures (taken by the Able Sea Chicks good friend Mr. Lloyd Green) show the fish coming out of the water and on deck, just before it was cut off the line and fell back into the water. You should be grateful that these pictures can't convey smell! This tuna had been dead a long time and had quite a strong aroma.

There was quite a lot of line wrapped up in the mooring. The third picture shows three of our science crew (Meghan, Matt, and Jim) cleaning up the tangled wire.

Roomba's seagoing sister

Seagliders are underwater robots made by the company iRobot, the same company that makes the Roomba (you know, that vacuum cleaner that zooms around your house all by itself while you aren’t home)! Well, the company may be the same, but these gliders are not out there cleaning up the Pacific Garbage patch or anything. (That would be cool, though wouldn’t it?!) Instead of cleaning, these gliders are actually out there taking oceanographic measurements. They dive down to about 1000 meters and then back up to the surface, measuring temperature and salinity along the way. Gliders dive for about 8 hours at a time. When they come to the surface they stick their tail up in the air (the tail is an antenna) to communicate with a satellite. They get their latitude and longitude position from GPS and then they send back the temperature and salinity data that they collected during the dive. While they are at the surface the Seaglider pilots can also tell them where to go on the next dive.

The University of Hawaii put out four Seagliders in November and now Lora is here to pick them all up and bring them back to Hawaii. We have just one more to pick up, Seaglider 513. We are tracking it while we are out here at sea, so we know exactly where it is. When we take a break from recovering moorings, we will go out and grab it! You can follow it too, if you’d like. Check out the glider web page at: http://hahana.soest.hawaii.edu/seagliders/history513.html

Overview

We were eager to start recovering our moorings, but the sea is pretty choppy today, so we are going to wait until tomorrow. While we’re waiting, we thought we’d give you a little refresher as to what we are doing out here so that you know what to expect in the coming weeks.

As you may recall, last year we deployed six acoustic sources and a Distributed Vertical Line Array (DVLA) in the Philippine Sea. The map shows the locations of the 6 sources and the DVLA. Right now we are at he location of Source 5. The DVLA consists of approximately 5km of wire with 150 hydrophones (underwater microphones) attached to it. Each of the six source moorings also has a smaller array with four hydrophones on it. All of the moorings are anchored to the bottom and held vertical by a subsurface buoy. The basic idea is to transmit sound back and forth between the different sources to map out the temperature and currents of the ocean in between the moorings. Check out our earlier post “An ocean acoustic tomography experiment” for more info.

The sources have been out here transmitting and collecting data for almost a year now, so we are going to go pick up the moorings one by one and start downloading the data. We are also going to be making some of the same types of measurements we made during our last cruise. For example, we plan to make more maps of the ocean floor between our moorings (see our post Sounding Out the Ocean’s Depths) and we will be doing some more CTDs (see our post Good Morning CTD). In addition we have a couple other exciting side projects that are going on during this cruise as well. We will be recovering a couple acoustic seagliders, which are underwater robots that have been listening to the sources and measuring temperature and salinity in the upper ocean. We'll also be sampling some mud from the bottom of the ocean!

Back, by popular demand

The able sea chicks are back! Remember all those moorings we deployed last year? Well, the time has come for us to head back out into the Philippine Sea to recover them and download all the data that has been collected over the past year.

We are experiencing a little deja vu as we sail out of the harbor in Kaohsiung, Taiwan on the R/V Roger Revelle, but a lot has happened since we set out on our deployment cruise a year ago.

Able Sea Chick Kathleen finished up her sabbatical at the Scripps Institution of Oceanography in San Diego and is back teaching at George Mason University. Lucky for us, she could take a few weeks off and join us for another oceanographic expedition.

Able Sea Chick Lora finished up her postdoc at Scripps, and has started a research position at the University of Hawaii (Aloha!). She was out on the Revelle here in the Philippine Sea last November to deploy acoustic Seagliders, which have been swimming around the moorings making measurements since that time. We will be recovering two of these gliders during this cruise and will tell you all about them in later posts.

Welcome aboard for another cruise, and feel free to spy on us on the ship's webcam.