The 2025 Canadian Arctic ACE/OSIRIS Validation Campaign team — PhD students Petra Duff, Kevin Joshy, and Darby Bates from the University of Toronto and PEARL Site Manager Pierre Fogal — met at Pearson Airport (YYZ) in the early afternoon of March 4 to catch the first of three flights to get from Toronto to Eureka via Edmonton and Yellowknife, with a scheduled intermediate stop en route from Yellowknife and Eureka in Resolute Bay to refuel. The flight to Yellowknife arrived on time at our destination at 20:52 local time. From the Yellowknife Airport, the team hailed taxis at the taxi rank, with the help of a friendly seatmate, and finally made it to our accommodation where we stayed for two nights, awaiting the flight chartered by Environment and Climate Change Canada (ECCC) to carry produce to Eureka this month (called the 'produce charter'), on March 6.

During the layover day in Yellowknife on March 5th, the team went downtown in the morning and had breakfast at a coffee shop and did some grocery and souvenir shopping before taking a scenic walk back to our accommodation and soaking in the beautiful weather; it was mostly sunny all day and about –20°C. Along the way, we met a local contractor who recommended three local attractions: the Back Bay Cemetery, the Back Bay Ice Falls, and the Snowcastle.

After a home-cooked lunch of hearty miso soup with tofu, mushrooms, vegetables and noodles, we set out on a three-hour adventure and visited all three attractions. Our first stop was Back Bay Cemetery, the first cemetery in Yellowknife. Then, we took "the long-way" to get to our second stop: the Back Bay Ice Falls, and eventually found the Falls thanks to the help of a friendly snow-mobile rider. The Back Bay Ice Falls were well worth the trek. While admiring the beauty of the frozen waterfalls, the rocks, and the lichen, we had fun capturing the moment on camera. Then, we found "the short way" back to the cemetery. Finally, we crossed the frozen Back Bay and walked under a bridge to continue toward our last destination of the day — the Snowcastle. We admired the impressive Snowcastle, which featured an entrance gate flanked by giant chains made out of snow and ice-sculpture gargoyles and had massive snow sculptures on display outside. We had pizza for dinner before packing up and getting some sleep before our flight the next morning.

At about 08:00 on March 6, we went to the airport to catch the produce charter. The plane flew first to Resolute Bay and stopped to refuel, so the team had a chance to stretch their legs and take a photo with the plane before continuing on to Eureka. The plane landed in Eureka at about 17:10 local time, we were greeted by the Eureka Weather Station staff and said hello and goodbye to the outgoing staff. Then, we helped load the produce from the plane into a van and then unload the van into the kitchen at the ECCC Weather Station. It was –28°C (–41°C with windchill), but we stayed warm ferrying food from the loading dock into the storeroom. We thawed out during a spaghetti dinner in the dining hall and got settled in at the Weather Station. Don Lavallée, the Station Program Manager, gave us the safety briefing and a tour of the facilities after dinner. We chose a movie from the curated library of VHS tapes and showed Kevin how to rewind a video cassette.

During this campaign, each student is responsible for maintaining and operating a subset of the instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) and the Zero Altitude PEARL Auxiliary Laboratory (0PAL). At the Ridge Lab, Petra is responsible for the Bruker 125HR, which is a Fourier transform infrared (FTIR) spectrometer, which operates in the mid- and near-infrared ranges, and Kevin is responsible for the two ultraviolet-visible spectrometers, the PEARL Ground-Based Spectrometer (PEARL-GBS) and the University of Toronto Ground-Based Spectrometer (UT-GBS) at the Ridge Lab. At 0PAL, Darby is responsible for the Pandora UV-Visible spectrometer, the Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI), and the Micro-Pulse Lidar (MPL). Pierre is the Site Manager for PEARL operations, in charge of the labs and ensuring the safety and well-being of the team. The ECCC Weather Station staff will launch ozonesondes on Wednesdays and weather balloons twice daily, at 06:15 and at 18:15 local time. Also, they will launch ozonesondes daily for the beginning part of the campaign. These launches started on February 28 and will continue to March 12.

Cheers,
Darby Bates
[on behalf of the 2025 Canadian Arctic ACE/OSIRIS Validation Campaign team]