First field trip
Transitioning from the lab to field work was a learning experience - A first outing to Crook Glacier in the Central Oregon Cascades served as a worthy shakedown for the new instrument for glacier characterization
When I was wrapping up testing and calibrating my new photon-counting LiDAR that I would use to measure the optical properties of glacier ice, one of my mentors at the lab - retired professor Mike Raymer -suggested we should “try it out somewhere” before taking the new instrument up on a glacier. He had a point: I didn’t want to walk up to the glacier, find out something didn’t work, the glacier behaved different or there was a mistake in my theoretical predictions, and come back empty handed. For field work, the pressure was on, it had to work, and the first snow moving in threatened t end the glacier season. But the setup was designed to work specifically with the properties of glacier ice - not snow, or water, or scattering phantoms like the ones used for medical imaging. There was nothing that would work, only glacier ice.
Shakedown, step 1. On a beautiful Monday night, I invited the lab’s graduate students over to my backyard for cider and science. The objective: Measure the distance between the fire pit and the shed using a photon-counting LiDAR that cost more than my car. But I had calculated that it would take light about the same time to make it across the yard, get scattered of the side of the shed, and back to me where the detector was standing, as it would to traverse a couple meters through bubbly glacier ice. Turns out it was about 50ft. We confirmed the measurement that we carried out with a photon-counting LiDAR with a $15 tape measure. But that wasn’t the point really. I had packed everything in hardcases, put it back together in my backyard, taken “data”, and nothing had broken so far.
Shakedown, step 2. Bouncing photons around the backyard is fun, but lacking a few things we would encounter on a real glacier. It wasn’t cold or wet, and we didn’t even know if glacier ice behaved the way we thought it would. So a compromise had to be found. We set out sights on Crook Glacier on Broken Top near Bend, Oregon. It’s a tiny, sad, debris covered glacier surrounded by steep rock faces. Not a prime objective for science, but at least it’s only two miles from the trailhead. Not a lot of wasted time in case something didn’t work.
So me and my helpers for the day hiked up, set everything up in a basically random spot (not that we knew what a “good” spot looked like), and shot some lasers. Even before wiring up the detector, we saw the first pleasant confirmation of what I hoped glaciers around here looked like: Bubbles. In the backscattered green light, there were clearly visible bubbles in the ice. So they didn’t exist only in deep ice in the arctic, but close to the surface even on a small glacier in Oregon.
Round, beautiful bubbles!
As it got dark, I started the photon counter. First I didn’t see anything at all. The only reference measurements to tell me what I could expect were from Greenland. I’ve never been there, but I assume it doesn’t look anything like Oregon. So I moved the detector closer to the laser, cranked up the power, as one would have to if the ice was a lot bubblier and dirtier than it usually is in Greenland, and there was my signal! At the edge of what my setup was capable of measuring, but it was there. I went through the set of tests I had planned on doing, got some nice data, and called it a night. It wouldn’t be the most spectacular data set or something that anybody would even be interested in, but now I know how to set everything up and how to get data. I call that a success.
