Bio‐optical Properties of Arctic Drift Ice and Surface Waters North of Svalbard from Winter to Spring

We have quantified absorption by CDOM, alpha(CDOM)(lambda), particulate matter, alpha(p)(lambda), algal pigments, alpha(ph)(lambda), and detrital material, alpha(NAP)(lambda), coincident with chlorophyll a in sea ice and surface waters in winter and spring 2015 in the Arctic Ocean north of Svalbard. The alpha(DOM)(lambda) was low in contrast to other regions of the Arctic Ocean, while alpha(p)(lambda) has the largest contribution to absorption variability in sea ice and surface waters. alpha(p)(443) was 1.4-2.8 times and 1.3-1.8 times higher than alpha(CDOM)(443) in surface water and sea ice, respectively. alpha(ph)(lambda) contributed 90% and 81% to alpha(p)(lambda), in open leads and under-ice waters column, and much less (53%-74%) in sea ice, respectively. Both alpha(CDOM)(lambda) and alpha(p)(lambda) followed closely the vertical distribution of chlorophyll a in sea ice and the water column. We observed a tenfold increase of the chlorophyll a concentration and nearly twofold increase in absorption at 443 nm in sea ice from winter to spring. The alpha(CDOM)(lambda) dominated the absorption budget in the UV both in sea ice and surface waters. In the visible range, absorption was dominated by alpha(ph)(lambda), which contributed more than 50% and alpha(CDOM)(lambda), which contributed 43% to total absorption in water column. Detrital absorption contributed significantly (33%) only in surface ice layer. Algae dynamics explained more than 90% variability in alpha(p)(lambda) and alpha(ph)(lambda) in water column, but less than 70% in the sea ice. This study presents detailed absorption budget that is relevant for modeling of radiative transfer and primary production.