Field Work

I am back in Christchurch. I left on a C-130 flight operated by the New Zealand Air Force this morning. Clearly, I have fallen behind my posts. I am going to play a little catch up with a couple posts sharing events from the past week and then a final post to close out the season. A few weeks ago I wrote a post on our field work at Tall Tower and labeled it "Part 1". A friend reminded me that I never followed up with that post and overall I have not written much about the field work from this field season. In this post I'll go through two trips in a 10 day period of the field season.

As an opener, it is fitting for me to provide a quick summary and purpose of the work in Antarctica. I am here as part of a project funded by the Office of Polar Programs of the National Science Foundation with a focus on measuring precipitation in Antarctica. This is the second of three fields seasons and this year the concentration is on the maintenance and repairs of the Antarctic Precipitation Systems (APSs). While something as simple as measuring precipitation (snowfall) seems basic it is actually very difficult to do in Antarctica. This is even more true when it is attempted to be done remotely and with the requirements to be run on batteries during the long polar night. The instrument at the focus of the measurements is a weighing bucket precipitation gauge. The gauge collects the snow and has a sensitive scale that weighs the collected snow providing a liquid water equivalent measurement. The gauge by itself can have a difficult time collecting the snow if it is unshielded and there is any level of wind. We have installed a wind shield around the precipitation gauge that is designed to slow the horizontal motion of the precipitating snow so that it is able to be collected in the bucket. In addition to this instrument configuration, we also have instruments to measure particles in the air, wind speed, temperature, measurement of the height of the snow surface, an instrument for particle size and velocity, and a webcam. All of this data is collected by a datalogger and we are able to communicate to the datalogger through an internet connection to McMurdo and then radio communications from McMurdo to the APS sites. This comms configuration allows us to monitor and analyze the observations year-round from Colorado.

Friday, November 23, 2018

This trip was our return trip to Tall Tower. Because of the great weather during our first visit, the amount of work that needed to be completed was somewhat limited. We had removed the datalogger and the instrument to measure particle size and speed and they were re-configured in the lab in McMurdo. We re-installed the two pieces of equipment and verified that things were running correctly. Some other small repairs were done to the instruments and precipitation wind shield. Lastly, at the end of a field visit, I take a series of photos, to capture the status and condition of the instruments, and a series of measurements of the height of the instruments to the surface. This final survey was completed and we were ready to fly onto the next APS site.

The next site to visit is the Lorne APS site. This site is approximately 50 miles to the southeast of McMurdo Station. Typically, the transportation to get to this site is by helicopter. However, we had sufficient time in our day that it was an easy stop on the return flight from Tall Tower. I should add that the conditions at both Tall Tower and Lorne were not as nice as they were on the initial visit to Tall Tower. The winds were around 18-20 knots and the temperature was about 16F. Those are far from horrible conditions but not the beautiful conditions that we've had so many other times during this field season. At Lorne we did similar maintenance and repairs to the site as we had done previously at Lorne and Phoenix APS sites.

One unique part of the visit to Lorne was the removal of a power system (solar panels, batteries, cases) for an instrument that had been installed at Lorne seven years ago. As I described previously, the sites on the Ross Ice Shelf generally have snow accumulation of approximately 1-2 feet per year. That means that over the past seven years the power system for this instrument has been progressively getting buried. We we were at the site a year ago and there was only about 12" above the surface. It was agreed that we would remove this power system on this field visit and return it back to McMurdo. Most all of that work was done by the two field engineers with UNAVCO and the two Twin Otter pilots. They spent about three hours digging a hole down about seven feet to remove the large power system.

Frequently, whenever it is available, we are asked by various support and logistics coordinators for us to bring people from town with us into the field. Officially the trips are referred to as "morale trips" to boost the experience and morale of workers that do not get to leave McMurdo. More frequently they are referred to as "boondogglers" as they get to experience and see a part of Antarctica that they are supporting in their work in town, but they rarely get to see directly. On this trip we had two boondogglers. They were told that they would need to be able to shovel snow. The two boondogglers started to help with the digging out of the power system at Lorne and then Scott and I each used one of them to help us with the work we were doing on the APS instruments. This day in the field will likely be one of the highlights of their season in Antarctica and fun photos are often a part of the trip.

Wednesday, November 28, 2018

When we left the Lorne APS site on the previous visit we had hoped that we had completed all of the necessary work on the APS system, but we were not entirely certain. After getting back to the lab in McMurdo it was realized that a few of the instruments were not working as expected. Fortunately, a return trip to Lorne was also needed to install a GPS receiver, which is being provided by UNAVCO. We once again traveled by Twin Otter as there was Twin Otter availability and the helicopters were still busy catching up from the late start to the season. We also took two more boondogglers with us. When we got to the APS site we were hoping that a quick fix was going to solve the problem with the  three instruments. The expected quick fix was not the problem. Within about 15 minutes we were able to identify a wiring issue and that fixed two of the instruments. The third instrument was more difficult. We ended up spending over an hour troubleshooting the instrument, which measures particle size and speed, to diagnose the problem. Such an in-depth level of analysis is best avoided when doing work in the field, especially on this day with 20 mph winds. In the end, it was determined that the instrument was not communicating with the datalogger and it was pulled to be further investigated in the lab. We would later determine that instrument could not be fixed during this field season and will be returned to Colorado.

We were able to get back to McMurdo in time for a late lunch. That also meant there was more time to get some work done during the day. Earlier in the season we had completed all of the work at the Phoenix APS site except for the re-installation of the webcam and tightening of guy cables. These are two fairly easy tasks to complete so we took a fat-tire truck, required for driving on the snow roads, and drove the 45 minutes to Phoenix Airfield, the location of the Phoenix APS. For local trips we do not have to go through the boondoggler system. I knew of a dining assistant (DA) who had the day off so she came along with us for the quick visit. The work at Phoenix APS took the expected 15 minutes and then on the return back to McMurdo we also stopped at the Willie Field APS site for some quick tests. Overall, it was a busy day of running around and seeing three of the four APS sites.