NSF COLDEX field team makes big moves to start 2025
Hello again from US National Science Foundation COLDEX. We hope the start of 2025 is going well for you. For our two field teams down in Antarctica, the first few weeks of the year have been busy.
In today’s newsletter, we’ll give you the latest and greatest on what both the I-187 shallow ice coring and I-186 ground geophysics teams have been up to. The I-187 update comes to us from Jeff Severinghaus, science team co-leader for the I-187 team and Professor Emeritus of Scripps Institution of Oceanography at the University of California San Diego, who took over from T.J. Fudge in late December. The I-186 update was written by Bridget Hall, science team member and Master’s student at the University of Minnesota, and features images by various members of the I-186 team.
Without further ado, here is Jeff Severinghaus’ update from our Allan Hills-based team:
“There has been a lot of new progress at Allan Hills in the past 3 weeks. The Blue Ice Drill (or BID for short) successfully reached bedrock and recovered dark greenish ice very near the bed, indicating old ice (although we won’t know the actual age of the ice until it is measured in labs in the US).
This particular borehole is only about 30 meters uphill from last year’s borehole, which found 6 million year old ice and even some gas-free ice immediately below the 6 million year old ice. This season, we unfortunately did not find any 6 million year old ice nor gas-free ice. But laboratory analyses in the next few months may turn up surprises.
Dark green ice from the deepest sample recovered by the Blue Ice Drill this season (total depth 192.06 meters).
Image by Jeff Severinghaus.
We then moved our focus to the 3-inch diameter Eclipse Drill, at a location known as the “Cul de Sac.” This enigmatic low spot seems to be a place where “ice goes to die” due to strong warm katabatic winds rushing downslope, causing sublimation of the ice, and leaving lots of rocks and possibly very old ice.
On Friday, we finished drilling a repeat hole with the Eclipse Drill (just 1.5 meters away from last year’s hole) to test whether last year’s bedrock encounter with the Eclipse Drill was a repeatable event, or just a random rock. We found that the new data was quite repeatable, confirming that we did indeed hit bedrock last year (and not just random small pieces of rock)
At the same time, two hand-augered holes were drilled nearby, also in the Cul de Sac, reaching 26 meters depth. These 3-inch diameter short-cores are valuable for testing whether the deep Eclipse core ages are congruent with the short cores
The Axion inflatable tent provided by the US Ice Drilling Program actually worked fairly well towards the end of our stay, due to the addition of wind shields (an Arctic Oven tent and a plastic-and-bamboo wind screen erected immediately upwind of the Axion).”
And that’s it for the Allan Hills team! As of this writing, the majority of our I-187 team has left the Allan Hills and is currently either in McMurdo Station or transiting back to the United States. As for the cores they collected during this season? They are currently awaiting pickup by the annual McMurdo Station resupply ships, and soon will begin their long journey across oceans and land to the National Science Foundation Ice Core Facility in Denver, Colorado. Once there, they will be sequenced, organized, archived, and made available for any scientist interested in studying them.
Some of the ice cores the I-187 team collected in the Allan Hills this season in transit to McMurdo Station.
Image by Abby Hudak.
Now, for the I-186 update:
“Since the last update, we made our way to South Pole Station where we celebrated Christmas with a lovely Christmas Eve dinner and a gift exchange on Christmas day. Without polling the entire team, I think the favorite gifts were the stickers that Megan had made and the beautiful ceramic mug that Knut brought down.
A week later and our team flew out to meet the Heavy Science Traverse – a crew that drove out all the way from McMurdo through South Pole to our site with lots of the gear needed for our work.
Over the past couple weeks, teams have taken trips out of camp to set up various scientific instruments. Here are a couple introductions to some of the science:
John - We have two radars with larger antenna arrays and greater transmit power to see deep into the ice. The smaller radar operates from 600-900 MHz (40 cm wavelength) and images the stratigraphy through just over 2000 meters of ice. The larger radar operates from 140-190 MHz (182 cm wavelength) and images the stratigraphy in the ice all the way to the bed about 3000 m below the surface. This larger radar has six large antennas (16 ft wide) which will be used to produce a 3D image of the ice bottom during post-field data processing. We have collected about 150 km of survey data. The larger antenna has been challenging to deploy at this location due to the big sastrugi and quite a bit of our time has been spent making adaptations to the structure of the antenna so that it does not break apart!
Image by John Paden.
Image by John Paden.
John-Morgan - Distributed acoustic sensing (DAS) is a technique by which we use fiber optic cables to sense seismic activity or vibrations in the snow or ice. These vibrations or seismic waves tell us something about firn or ice structure, ice flow, or other ice/snow properties. Here, we deployed a fiber optic cable in an “L” shape across the snow surface with each segment being 1 km in length. The “L” shape will help us locate seismic or other acoustic events and the 1 km length will help us better understand how the snow or ice properties vary at these scales. Thus far, we have collected 3 days of data that include days with different weather conditions. We hope to constrain snow and firn structure at the meter scale and observe how these change over the course of this experiment.
Other systems in use are the magnetotelluric system, seismic nodes, and the pRES which will be explained in another update!
Each day has multiple groups taking snowmobiles out to science sites to set up systems, do maintenance, take them down, or, in the case of the radars, drag them along a grid.
On a few of the days, three of us (Bridget, Ellen, and Kirah) have had day trips out of camp on the Twin Otter. These trips get us to various locations between South Pole Station and our field camp where we set up pRES (phase-sensitive radar echo sounding). It has been a balmy -14C (7F) at these sites compared to the -25C to -35C (-13F to -31F) at camp!
The Twin Otter in a Sun Dog. Image by Bridget Hall.
A pRES set up next to the plane. Image by Bridget Hall.
With just under a week to go, it’s now crunch time to make sure that everything gets done, so I better stop writing and get ready for a flight day!”
And that’s it for this update. We’ll be back next week for our next NSF COLDEX 2024-2025 field season update. While this field season is winding down, we are looking forward to sharing all of the great lessons and discoveries our team has made and will continue to make as they come back to the US and dive into the data and samples they’ve collected. Stay tuned!
As a reminder, we’re posting images, videos, and more on our newly created Instagram and LinkedIn accounts, so follow us there if you haven’t done so already.
NSF COLDEX thanks the United States Antarctic Program for logistical support, with coordination and support from NSF Office of Polar Programs, NSF Antarctic Infrastructure and Logistics Program, the NSF Ice Drilling Program, the NSF Ice Core Facility, and the Antarctic Support Contractor.
