GOVERNMENT

SDSC Iceberg Researcher Joins Antarctic Expedition

 

Returning to Antarctica eight months after a previous expedition, a research team led by Ken Smith, senior scientist with the Monterey Bay Aquarium Research Institute (MBARI), continues to study biogeochemical cycles around icebergs. This third expedition, underway until April 15, is providing scientists the opportunity to study the pelagic ecosystem both near and further away from icebergs during prime growing conditions. Together, the scientists will target three to four tabular icebergs during their 40-day mission in the Northwestern Weddell Sea.

On board the research vessel ice breaker Nathaniel B. Palmer is John Helly, director of the Laboratory for Environmental and Earth Sciences with the San Diego Supercomputer Center at the University of California, San Diego. Now on his third research cruise to the region, Helly is responsible for measuring the physical geometry of icebergs using oceanographic and meteorology instruments, computer systems, laser ranger, and an inclinometer.

Posted below are random logbook entries from Helly, giving readers a glimpse into the daily life aboard a research vessel navigating though often severe conditions. Entries will be made whenever possible, due to limited email and Internet service. Visit the MBARI website to view additional entries from other crew members, research updates and to track the ship’s voyage.

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LOGBOOK: JOHN HELLY

 

Iceberg III: Iceberg Hunting in the Weddell Sea

11 March 2009: NBP0902

Latitude -062 16.8061
Longitude -051 35.8667
Air Temp. 1.8C
Wind Chill -11.4C
Sea Surface Temp. 0.087C

 

We are on station at iceberg C18A after leaving Punta Arenas last Friday, 6 March, at 1000 hrs on the RVIB Nathaniel B. Palmer.  The passage across the Drake was a bit tense since there was a big low waiting for us.  It passed to the south just enough to leave us alone and we continued over in the direction of Clarence Island with the intention of spending a few days in the lee there to do some instrument and procedure testing.  When we arrived there, two days ago, the winds, from a different low, were 35-45 knots and too much for the testing that we wanted to do.    So we moved on to find the nearest target iceberg I've been watching with remote sensing data, C18A.

We've got a new ROV (remotely operated vehicle), four airplanes, two of which are bigger and more powerful than our last cruise, and some additional Lagrangian sediment traps (LST).  The LSTs are designed to be deployed upstream of an iceberg where they are commanded to submerge and drift along below an iceberg to collect any debris that is falling from the melting ice as it cruises below it.

I've been working to develop the surface mapping techniques and analysis software that  I started on the June 2008 cruise and am very happy with the progress on that.  It is coming together very nicely and I now have the help of a 3rd year graduate student in physical oceanography from Scripps.  We are developing some new methods of looking at the very fine-scale structure of the circulation around the icebergs from the acoustic doppler current profiler (ADCP) that is mounted on the hull of the ship.   All of the data that we are accumulating from the various sensors is being ingested into the digital library framework (DLF) software that I've been working on for quite a few years and that is also working very smoothly.

The hours have been pretty long since I'm in that initial phase of excitement, anxiety and anticipation about finding the first iceberg since that's part of my responsibility.  Before yesterday, I had been up for almost 48 hours with only a couple of hours sleep.  I didn't realize how much stage-fright I was experiencing until we found this beautiful iceberg, C18A, that I'd been tracking courtesy of data from our colleagues at BYU.  It was kind of deja vu all over again like the experience I had with A52 in 2005.  At that time, the first time I ever did this, we were driving to the location where I predicted it to be and got there and there was nothing there.   Turned out to be because the iceberg was moving at 2.5 knots and was about 25 nautical miles from where the last image suggested it would be.  We did find it and it was huge.  

This time we got within 24 nautical miles of where I expected to find C18A and, with the radar on 48 miles range, we didn't see anything like C18A.  I experienced the same kind of 'Oh ****' but also had the benefit of understanding the limits of shipboard radars better.  So we kept on heading to the expected location and within 40 minutes we had found this very substantial iceberg and proceeded to circumnavigate it in 0.25 nm visibility; fog and snow.  It's 32 kilometers (~17 nm) by 6 km (~3).  We went all around the iceberg using only the radar for about 7 hours and have a nice digitized perimeter but we never saw the iceberg during all that time.  This morning it is bright and clear and lovely.   After getting done with that 48 hours, I crashed all day from 0700 to dinner at 1730 and felt fantastic when I woke up.  Now we can seriously get to work after breakfast.