R1b albedo

We're back, our first return to Station 1 is complete. Things have changed a lot since our initial visit! The refrozen lead our previous albedo transect crossed didn’t survive the warm conditions and is now fully melted. That meant our original colocated measurements with the ROV team needed to be relocated. Our team was quick to adapt to the changing conditions of the Arctic summer. We worked with the ROV team to establish a new 65-meter transect for measurements on what remained of the floe. With most of the refrozen lead gone, we also created a new representative optics transect to capture the updated surface conditions. These new transects included a diverse range of melt ponds.

Measuring melt pond depth in the remains of the refrozen lead. Photo credit: Matthias JaggiAn unlevel Kipps En route to the next measurement point on the transect. Photo credit: Matthias JaggiUsing the ASD to measure fresh snow along the transect. Photo credit: Matthias Jaggi

We also teamed up with colleagues to collocate snow pit and GEM-2 measurements. This will allow us to link surface and subsurface measurements with our albedo data. At the far end of the transect (where the lead hadn’t completely melted through) we completed additional albedo measurements and CTD profiles. This was of particular interest to capture the unique thin ice conditions and how that changes during the transition to beneath the surface.

Our preliminary results show dramatic change in the two weeks since our first visit with diverging stories between the ponds and dry surface. Our first transect measurements followed a rain-on-snow event and the wet surface reflected less light, resulting in a mean surface albedo of 0.51. On our second visit a fresh snow layer blanketed much of the surface and raised the mean surface broadband albedo to 0.71. The signature of melting was clear in the ponds, which were deeper and darker than our first visit. They often featured thaw holes and false bottoms underneath, and the intricate melt pond lids of our first visit were replaced by delicate shards of platelet ice. 

We were particularly excited by the thin, melting ice in the refrozen lead. The ice was at times fragile and unpredictable, so we changed into survival suits for safety and surveyed along the edge of the lead. The result was a huge range of albedo spectra ranging from the fluffy layers of fresh snow to open water eating at the edges of the ice.  

Despite the shifting conditions, the floe continues to be a valuable site for observing the evolution of sea ice melt. It’s exciting (and a little humbling) to see just how dynamic the system can be, even over a short period.

Revisiting Station 1, Round II: complete. More to come as we continue chasing the melt season change across our floes!