Monday, March 13, 2017

Prepping for Round Two

We just concluded a 24-hour transit to our new location with a cast from the ship's CTD and a midnight deployment of SWIMS to start surveying the area. During the transit, even though we weren’t actively gathering new data with most of our instruments, we still had plenty to do. As thoroughly as we tested everything before we left, the ocean is a harsh and unpredictable place, and there are always improvements to be made to insure that we make the most of our time out here, whether it’s cleaning an instrument, opening it up to check the circuits, or fixing glitches in our processing programs.  

One of the projects we undertook was stabilizing the ADCP attached to the bottom of the buoy chain. The design of the cage around the ADCP was such that the battery and instrument weren’t being held in place as tightly as they needed to be, threatening the power cable and reliability of the measurements. The new-and-improved design increases the friction between the clamps and the frame, and secures the power cable more tightly to the instrument.

The ADCP (black) and its battery (blue) in the holding cage. It hangs vertically from the buoy chain, which means preparing for strong vertical motions is important for keeping the instrument working. (Photo credit: Rosalind Echols)

Every time we use the big ship-board CTD with the rosette (a set of 24 bottles used to gather water samples from different depths for biological and chemical tests), we have to empty it, reset all the firing pins that close the bottles, and rinse it thoroughly with fresh water. In fact, every time we take an instrument out of the water we perform this fresh water rinse to minimize the corrosive effects of the salt water. One of the primary challenges oceanographers face when trying to make measurements in the ocean is that many of the interesting characteristics of the ocean (it is deep, turbulent, and salty, for example) are really bad for electronics, metals, and so on. Many of the engineering challenges are comparable to launching something into space.

Our biologist, Kate Kouba (from Portland State University) resets firing pins at the top of the CTD rosette after gathering water samples. (Photo credit: Rosalind Echols)

Before we put everything back in the water, we are also looking at the data we’ve already gathered, both to keep an eye out for interesting physics but also to see if there were any bizarre data standouts that might suggest a malfunctioning instrument. Sometimes, weird, unexpected features of the data are interesting phenomena, but they can also mean that a probe isn’t working correctly, so closely monitoring the data as it comes in is an important step in making sure that the data we come home is meaningful.

1 comment:

  1. keep up the good work! Interested in what conditions you find in the next series of measurements.