Blog from the RV Polarstern: MOSAiC trace gas fluxes update 4.4

By Byron Blomquist

Our big development this week is that we finally have a DMS (dimethyl sulfide) chamber flux system to deploy. This photo shows the two equipment boxes required for the CO2/CH4/DMS system and the new 'floating' chamber funnel, deployed at the first-year ice coring site in the Central Observatory. So far the fluxes we have seen seem quite small, even for DMS. Biological activity in and on the sea ice is patchy at our site - definitely less than in the marginal ice zone we passed through during the transit in a few weeks ago. It may still early for the big bloom at our location.

Flux and trace gas sampling from the bow of the ship has not been possible for the past 10 days due to persistent easterly winds blowing from the stern of the ship. Not much hope for a change in winds over the next few days either. Fortunately, measurements at the Met City site, inducing CO2/CH4 fluxes, have been going smoothly. The Leeds SODAR is also operational at Met City as of yesterday.

We're learning a lot about the older 2nd year ice that makes up the 'fortress' area of our original floe. Much of it is still intact, and the melt is revealing a very dirty surface with significant silt layers. People have found stones up to 2-3 cm in diameter, some with attached macro-algae, and even a frozen starfish. It's apparent the 'fortress' flow originated as heavily ridged shore-fast ice, probably somewhere along the Siberian coast. As such it's an interesting case study, but is not representative of the 'new' Arctic sea ice environment. Fortunately, a large section of first-year ice remains intact and attached to the older floe, and this has become the focus of several intensive observational activities.

This Friday brings an 'intensive' 24-hr measurement cycle for the Ocean, Eco and Ice teams which will require assistance from all hands. It will be a busy weekend again.