Free Willie!!!

How do you dig out a 40-foot diameter fence buried six feet deep in snow on an ice shelf? It sounds like the beginning of a (really) bad joke. This question vexed a number of people besides ourselves, including National Science Foundation (NSF) representatives, McMurdo station managers, Fleet Operations personnel and others. As the weeks started to slide by, I was somewhat increasingly concerned that I was going to get to know my shovel very, VERY well when we suddenly got an email saying that there was "a plan" to free the shield and instrument and this plan would begin the Sunday following Thanksgiving. But before this plan could take place, we needed to dig out all the wiring that was running between the shield and the datalogger. So, we began the arduous task of trenching down to the cabling to free it from the snow.

Looking down the beginning of the trench we dug to remove the cable

Halfway along the trench.

It took approximately 2 hours to dig the entire cable out. It was also somewhat surprising how quickly the snow had compacted and solidified over the short amount of time it had accumulated, making the digging more difficult the deeper we went. By the time we got to the shield, we had to dig down at least four feet to free the cable. Once the cable was free, the first part of "the plan" was put into action.

"The Plan", Part 1 - Bring a bulldozer

To answer your next question, yes, there are bulldozers in Antarctica! Normally they are kept busy doing other things like helping maintain the roads and the airfield landing strips. The stations managers were able to work in some time to free a bulldozer up for an evening to plow out the area around the outside of the outer shield. Before that could be done though, we needed to remove the guy wires that were holding the shield in place (and were also buried in the snow). This required finding each support post and digging down about 12-16 inches to undo the clips that attached the guy wires to the posts.

Mark digging down along the one of the poles.

Digging about a foot down got us to the eye hook that the guy wires were attached to. Removing the nut and washers freed up the guy wires so the bulldozer wouldn't snag them and tear the shield apart.

Once all the guy wires were unclipped, the bulldozer got to work.

The big dig commenced

More plowing

 At that point, our services were no longer needed so we left for the night. The next day, we came back to this:

The outer shield is finally visible

 Before Part 2 could commence, we needed to remove all the sections of shield. This required digging all the way down the backside of each support post, removing a few vertical slats and then unscrewing the horizontal support beams from each post.

Dismantling the outer shield begins

Once the outer shield sections had been removed, they brought in an excavator to do the next batch of digging.

"The Plan", Part 2 - Bring an Excavator, my new favorite shovel 

Before digging out the next portion of snow to the inner shield, the support posts had to be removed. The excavator operator was extremely skilled and gently pulled each post out, swinging them out and away from the shield so we could collect them. He then began digging in towards the inner shield. Once he cleared the snow away from it, we had to stop and dismantle that shield as well.

Dismantling the inner shield

Once the inner shield was removed, we had to mark off where the final Alter shield was buried so the excavator operator could dig that out. This was accomplished using shovels as markers.

Mark places shovels as markers for where the Alter shield is buried

Once the Alter shield was uncovered, we began to dismantle it as the excavator operator cleared away the remaining snow.

Dismantling the Alter shield

Finally, the precipitation gauge at the center was revealed.

The precipitation gauge and its "snowdo"

After we removed the gauge, the final step was to dig out the tower stand so we could reuse it.

The last of the big dig

We had discussed several ideas of how to proceed forward once the shield and gauge had been dug out. One idea was to reinstall the sensor and hope that it wouldn't get buried again but we quickly decided against that as we didn't want to have to tell them next year the shield had gotten buried again (they might not be so sympathetic towards us next time if we asked for help digging it out again ....). Another idea was to move the shield and gauge to Phoenix since Phoenix had received less snow last year than Willie, but the end result was likely to be the same (it would just happen later in the season). The last idea was to raise the shield considerably higher above the snow (so that the base of the shield was at least six feet off the ground), but we didn't have the materials to make that happen. In the end, we decided to modify the site and remove the DFIR shield altogether for the upcoming winter. We reinstalled the gauge but this time, we decided not to put any type of shield around the gauge. Why would we decide to put an unshielded gauge out when I've repeatedly said you need a shield around the gauge? To show people just how badly gauges collect (or don't collect) the snow when you don't shield them. We had spoken to some other scientists earlier in the season and found out that there are a few very old precipitation gauges used by other projects. They were curious what the difference in accumulation would be between their sensors and ours, and this should allow us to answer that question.

The new unshielded gauge

We also opted to make one additional change at the site. The shorter double Alter-shielded gauge that was installed at the same height as the DFIR was also getting close to being buried. Close enough that we either needed to remove it or raise it.

This shield used to be as tall as me

We opted to raise the shield and gauge (which required some new on-the-fly engineering since we hadn't planned to raise any of the gauges or shields) and make one additional modification. We removed the outer shield so that the gauge was effectively a single Alter-shielded gauge.

The single Alter-shielded gauge in the foreground with the double Alter-shielded gauge in the background -- one of the Antarctic Weather Stations can be seen between the two in the distance

Once those modifications were done, Willie was ready to go for the next winter season!

The full Willie site ready for the 2018/19 winter season

And with that, the only things left to do were to begin the preparations for the trip back north and home. But one question remained ... would Antarctica allow us to leave on our scheduled date or would the weather have other plans?