Journal Entry

Moving Targets

Just as a warning, I like maps. A LOT. When my team mentioned that they were plotting the Automatic Weather Station (AWS) on the moving ice sheet, I thought to myself "That sounds FUN!" Prepare yourself for a land navigation geek out session! Let's see if you agree with me.

Gill AWSThis is the Gill AWS after servicing November 29th, 2017 Photo Credit AMRC.

There are more than 100 Automatic Weather Stations distributed all over the continent of Antarctica. A few of them are on solid ground or rock. Those AWS include Cape Bird, White Island, Marble Point, Minna Bluff, Thurston Island, Evans Knoll, and Bear Peninsula, and they don't experience any movement since they are on solid ground. Most of the Automatic Weather Stations are on ice. The problem with the AWS being placed on ice is that ice moves. That means that most of the AWS are NOT where they were last seen. They don’t have onboard GPS locators so they are moving targets! We better get out a map!

Why is that a problem? AWS need to be serviced, repaired and extended (they get buried in snow) periodically. So, we need to calculate where we expect them to be to provide the pilots with accurate Longitude and Latitude coordinates to find the AWS. Some are relatively stationary and are hardly moving at all, but some of them are in faster moving areas than others. AWS on the Ross Ice Shelf (or any ice shelf) move a lot faster than those AWS on the ice over land. I analyzed the movement of a variety of our AWS, which are listed below. These were calculated by using GPS coordinates every couple of years and averaging the distance per year. 

I’ll use the AWS named 'Gill' as an example. I'll write a journal on how AWS get their names in the near future. Gill, by the way, is named for an Antarctic LC-130 pilot! Gill is about 232 miles (by Twin Otter airplane) from McMurdo Station.

Math or GIllThis shows the math involved in tracking the movement of Gill AWS.

The tables above show the last known positive locations of Gill AWS. So, without getting too far into the weeds with the math… If we figure out how far Gill moved over the periods between getting the last known positive locations and divide each distance by the number of years (or months to be more accurate) we SHOULD get an average yearly distance that the ice sheet has drifted on which Gill sits. But we aren’t done yet because it isn’t traveling in a straight line! Isn't this getting EXCITING? The ice sheet is drifting off to the East at +.0767˚ per year. FUN!

Gill MovementThis shows the movement of the Gill AWS from 1994 to 2017 and the expected location for 2018.

So, where should Gill be if we need to tell a helicopter pilot where to find it?

Ross Ice Shelf This shows the Ross Ice Shelf, and the locations of McMurdo Station and Gill AWS.

Well, it SHOULD be .77km further north and .075˚ east of the last known positive location. Or, more precisely: 79°49’27.24”S, 178°32’10.83"W. Easy right?

Twin OtterThis is a Twin Otter, the type of airplane that would be used to get to Gill. Photo credit Tim Spuck ARCUS.

Here are the drift rates for a few other AWS – Provided to me by Carol Costanza (who provided much of the info for this journal).

Elaine:  Movement 0.31 km/yr 

Gill:  Movement 0.77 km/yr 

Lettau:  Movement 0.35 km/yr 

Marilyn:  Movement 0.58 km/yr 

Schwerdtfeger:  Movement 0.54 km/yr 

Vito:  Movement 0.91 km/yr 

Comments

Thu, 10/11/2018 - 14:20

michelle

Awesome blog Mike! Love the math. This is real stuff that students can wrestle with! Enjoyed.

Tue, 10/30/2018 - 08:08

Alex Baker

Hi this is a student from Dansville middle school. I was wondering how do you know where the weather stations are?

Tue, 10/30/2018 - 10:29

Camden

What is the furthest a GPS has moved ?

Tue, 10/30/2018 - 10:32

Gracie

Hi Im Gracie and I was wondering what does the place look like we’re your living in?

Tue, 10/30/2018 - 10:36

Dylan

Do you think the trip to Antarctica will be fun?

Tue, 10/30/2018 - 10:40

Violet Hacker

Hi this is Violet,a Dansville middle school student . I was wondering do you have to uncover the AWS very often?

Tue, 10/30/2018 - 10:44

Vanessa

Hi this is a student from Dansville. I was wondering since the wheather sations are so tall, how do you service them?

Wed, 10/31/2018 - 07:36

Chloe

This is Chloe Moore from Dansville middle school and we where wondering if you disagree with your groupmates

Wed, 10/31/2018 - 07:42

Brandon Ide

if the AWS gets lost off the antarctic, will it be a major problem? or will it me a minor problem?

Wed, 10/31/2018 - 07:44

Brandon Ide

Sorry that I didn't post this earlier in the message, but I'm a student from Dansville Schools also

Thu, 11/01/2018 - 08:20

Mike Penn

Alex,As I described in the journal, we know where the AWS WERE. Other scientists have plotted the course and movement of the glaciers and Icesheets that the AWS are on, so we have a good idea of how far they have moved. If the AWS has been in existence for a long time we have positive coordinates for where it was at specific times. Given that information, we can figure out the average rate of movement and if it is changing directions (drifting East or West) and how far that drift is.

Thu, 11/01/2018 - 08:23

Mike Penn

Camden, That is a good question. I don't know the answer to that. I know that "GIll" is one of the faster moving AWS. I chose it as an example because it has moved a lot. Others that are on solid rock don't move at all. I'll have to ask my team to find that answer for you.

Thu, 11/01/2018 - 15:53

Mike Penn

Gracie, nearly all of the continent of Antarctica is covered in ice. At the South Pole, the ice is 9300 feet deep! The surface of the ice at South Pole is mostly a smooth ice sheet.

Thu, 11/01/2018 - 16:02

Mike Penn

I'm not sure fun is the word I would use. I will definitely enjoy it very much, but I'd describe it with words like interesting and challenging! Do you think an experience like this would be fun?

Thu, 11/01/2018 - 16:05

Mike Penn

Violet,Yes, they do get buried in snow and ice often. We won't actually unbury the whole tower, usually, we will extend the AWS by adding a piece of the tower to the top and then moving all of the instruments up so that they are well above the surface again.

Thu, 11/01/2018 - 16:14

Mike Penn

Actually, almost all of the automatic weather stations are only about 12 feet tall. There is at least one that is about 100 feet tall. It is called "Tall Tower." That one has to be climbed by people who are certified as "riggers."

Thu, 11/01/2018 - 16:20

Mike Penn

While the AWS are on moving ice sheets and eventually the will break off as icebergs someday. It will take thousands and maybe as many as 100,000years for some of them to move that far. No worries!

Thu, 11/08/2018 - 17:34

Michael Penn

Chloe, I don't expect that I will disagree with my teammates. Both Dave and Lee have been to Antarctica many times each. They are much more qualified and experienced than I am. So I will comfortably defer to their opinions and their decisions. I am definitely the new an inexperienced guy in the group.

Wed, 11/14/2018 - 10:35

Hayden

Do you think you will have to climb one of those towers?

Thu, 11/15/2018 - 18:37

Mike Penn

Hayden, Climbing harnesses are listed among our supplies. As long as we are adequately supplied and the conditions (wind) will allow it...Sure! Heights aren't my favorite thing, but I could climb a tall tower if it needs to be done.

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