Date: Sun, 17 Feb 2002 23:52:46 +0000 To: karen@icess.ucsb.edu From: "Sirovic, Ana" Subject: Message 09 February 17 2002, 19:45 65 deg 50.72 S lat 69 deg 02.34 W long (shelf somewhere off W Antarctic Peninsula) Air surface temperature: 1.6 degrees C Sea Surface Temperature (SST): 1.7 degrees C Wind speed: 23 knots, 065 degrees Air pressure: 997.2 mBar Hi again! It's been a busy several days down here! Since Friday we have recovered 5 of our instruments and deployed 4 in their place. We have been working from 4am to midnight, taking random naps when an opportunity for a nap arose. But now it's time to take it a bit easier again as we have >24h transit to the next mooring location, and there it will be the WHOI group doing the work. So, let me finally tell you more about our moorings. You have already seen a picture, so it's about time you knew what it was all about! Our instruments (acoustic recording packages, or ARPs as we call them) consist of 2 pressure cases, a hardhat with flotation balls (glass vacuum spheres), and a couple of weights suspended on wires. One pressure case contains the acoustic release system, similar to the one I already described for the WHOI moorings, and a battery pack. The other case contains the data logging unit: a processor and 2 hard disks, 18GB each, and another battery pack. This case is conected to a hydrophone, which is suspended several meters off the bottom, with 2 floats to keep it up. The hydrophone records low frequency noise (upto 250 Hz, with a bottom roll-off at about 5 Hz) which is continuously recorded onto the hard disks. The procedure we follow when recovering the instruments is the following: when we get over the deployment location we ping on the instrument, find out that it's there and send a release signal. A flow of current is then started and it corrodes the wires that the weights are suspended on. It takes about half an hour to burn the wire which releases the weight. After the release the ARP begins to rise to the surface at the rate of approx 40 m/s. Given that all of our 5 instruments were in approximately 3000 m of water, that gave us plenty of time to prepare another instrument for deployment and deploy it during the rising of the first instrument. This way we have minimum amount of time that no data is being collected, and it also saves some shiptime. Final preparations for instrument deployment consist of testing that the wire burning system works, testing the hydrophone, and starting the final 'mission' - giving the processor a command to record for the next 400 days. This is actually longer than we anticipate the instrument to be at the bottom, but you never know... In any case, once all that is done, the ARP is hauled across the deck to the winch, it is lifted over the side, the hydrophone and the flotation balls are dropped over the side and the main body of the instrument is released. And we watch it sink to the bottom, hoping to see it again in less than 400 days. Usually by this time the ARP coming off the bottom is pretty close to the surface so while one person ranges on the instrument, the rest of us go to the bridge to look for it on the surface. Once the ARP is spotted and the ship approaches it, we throw grappling hooks from the main deck and try to get them hooked to some of the lines on the ARP. (If we're good at this, we don't knock the hardhats off our heads while throwing the hook, as I have succeeded in doing! By the way: hardhats have to be worn any time there are 'overhead operations' i.e. when the winches or A-frames are moving things around.) After the ARP is hooked in, we have to get a few taglines around it, hook it to the winch, try not to have it bang on the ship too much, and bring it onboard. Our group has another projects in the Bering Sea, using the same instrumetns. Some of those ARPs came back to our service yard and while they were sitting there all covered with barnacles they were spotted by some people insterested in benthic invertebrates. So they asked us to collect samples for them in the future. As the only 'real biologist' in our group, I took over this task and have dutifully been collecting organisms that we bring up with the ARPs. Given how most of them are quite deep (definitely much deeper than the ARPs from the Bering Sea were), the life on them hasn't been very abundant. I've collected little tube worms on all of them, but that was about it. Except for the second to last instrument, which gaves us a treat! Stuck on the polypro-line near the hydrophone was a ball of eggs. I am not quite sure what animal's they are, but I thought they were really cool and worthy of my picture of the day. As I was taking them off I was surprised to find out that they were really hard, and I managed to peel them off without disturbing the ball shape that they were in on the line. I will be very interested to find out what these guys would have grown up to be had we not so cruelly taken them out of the ocean! So, after I remove all the organisms and put them in some ethanol, we start inspecting the ARP further, checking if it is still recording, turn the recording off, take out the hard disks. If everything seems to be in working order we switch out the batteries, put new hard disks in and get them ready for redeployment. It seems that so far, we've had most problems with the hydrophones, but the problems are kind of difficult to work out because the conditions on the deck are quite different from those at 3000 m depth of a cold ocean. As all this is done, another long and painful process begins: data dumping. We want to copy the data from the SCSI drives that are in the instruments to IDE drives (which is the disk flavor you have in your computer, "disk drive vulgaris"), and eventually make double copies onto tapes, just in case. It takes about 12h do dump (and check) the data from one instrument. That probably doesn't sound too bad when you remember that this is a year's worth of recordings, but when you're the person who, every 25-30 min, has to plug in a few numbers and do some checking of the process, it gets to be a bit tedious. But, I'm happy to report that I have only 2 more instruments to go (more or less)! Anyway, we are now done with the recoveries. We have 3 more deployments of our instruments that will be spread out through the next couple of weeks. WHOI deployments (also 3 instruments, scheduled to be done in the next 2 days) will give me time to finish the data dumping, before we start chasing whales. I bet you'd like to know all about that, but you'll have to wait a few days, just like we have to wait, too. So until later time... keep warm! While I enjoy Antarctic summer snow, inbetween data dumps. Ana