Robert Graham
Norwegian Polar Institute, Tromso & Alfred Wegener Institute, Potsdam

The Norwegian Young Sea Ice Campaign & two Arctic winter states


From January – June 2015 the R/V Lance was frozen into an area of thin first year sea ice north of Svalbard in the Arctic Ocean, as a part of the Norwegian Young Sea Ice (N-ICE 2015) project. Detailed meteorological, oceanographic, cryospheric and biological measurements were taken over four separate ice floes during the campaign. I will begin by providing some background to the N-ICE project, a brief overview of the campaign, and some initial results from the different work packages. Photos of polar bears will be included!
As part of my own research we have been comparing the atmospheric winter observations from the N-ICE campaign to those from the 1998 Surface Heat Budget of the Arctic campaign, which took place over a thick multi-year ice floe in Beaufort Sea. Both data sets clearly show that the Arctic atmosphere operates with two distinct winter states: a cold ‘radiatively clear’ state and a warmer ‘opaquely cloudy’ state. We further compare the two Arctic winter data sets to the ERA-I reanalysis and a coupled Arctic regional climate model. ERA-I performs very well and is able to capture the main characteristics of the two states. In contrast, the regional model is not able to simulate the two observed winter states. Finally, we use the full ERA-I record from 1979-2015 to investigate changes in the relative occurrence of the radiatively clear and opaquely cloudy winter states over the Arctic and explore how these are related to the recent warming trends.

Time and place
Tuesday 17 May 2016, 11.15
Room C609, Arrhenius Laboratory, 6th floor