Description
Increase of temperatures and loss of sea ice has have dramatically changed the Arctic’s physical system. One of the key factors driving the loss of sea-ice is the ice-albedo feedback resulting in more solar energy accumulated into the surface ocean. Colored dissolved organic matter (CDOM) is a key factor affecting the vertical entrapment of heat and light availability for primary production in the Arctic Ocean. We propose to carry out an extensive study to understand the composition and sources of CDOM and its role in the fate of solar energy in the Nordic Seas and European Arctic, and how it contributes to the solar heating of the upper ocean and contributes to sea-ice melt, penetration of harmful ultraviolet (UV) light and light availability (UV and PAR) for primary production. By combining forces from groups with complementing experience and expertise and provided the access to the Arctic, and state-of-the-art instrumentation we are set to meet this challenging task. This project brings together Polish and Norwegian experts in their respective fields and initiates a new network of researchers and commences collaboration in Norwegian and Polish polar research.
Summary of project results
Measurement of inherent and apparent optical properties of Arctic Ocean was conducted mainly in Western Arctic and Canada Basins. Increase of temperatures and loss of sea ice has have dramatically changed the Arctic’s physical system. One of the key factors driving the loss of sea-ice is the ice-albedo feedback resulting in more solar energy accumulated into the surface ocean. Coloured Dissolved Organic Matter (CDOM) is a key factor affecting the vertical entrapment of heat and light availability for primary production in the Arctic Ocean. To assess the effect of CDOM on optical properties of Nordic Sea waters an extensive field work has been undertaken in Nordic Seas and Fram Strait main gateways of water exchange between Atlantic and Arctic Oceans. Optical measurements were conducted between 2013 - 2016 during three AREX cruises organized by IOPAN and three Fram Strait cruises organized by NPI. Additionally intensive field work related to sea ice processes has been conducted during NPI N-ICE2015 expedition and with collaboration with AWI on TRANSIZZ cruises on board of German ice breaker Polarstern. Results achieved and published in 11 scientific papers demonstrated that, CDOM contribution to total light absorption in European sector of Arctic Ocean and Nordic Sea in visible light has varied between 41-50% and is significantly smaller than in Western Arctic and Siberian Shelf. Although smaller, effect of presence of CDOM on heat deposition on surface waters is significant. CDOM alone contributed to 30% heat deposition in Nordic Seas surface waters compared to clearest oceanic waters. It has been also demonstrated that summer phytoplankton blooms under the ice and in open waters were most significant drivers of optical properties variability, and had similar effects on heating of surface ocean as CDOM. Field work results proved that primary source of CDOM in Atlantic dominated water masses in Nordic Sea is algal biomass. The CDOM composition in those waters is dominated by fluorescence components typical for marine fulvic acids and protein – like organic compounds. In water masses influenced by Polar Water the contribution of protein-like organic compounds decreases and contribution of terrestrial humic – like material increases. Derived bio-optical relationships between chlorophyll a concentration and particulate absorption and protein - like CDOM fraction will enable better prediction of optical properties of Nordic Seas surface waters.
Summary of bilateral results
This collaboration was initiated without any prior research collaboration between the groups involved. This project succeeded in combining the strengths of the two research groups into a coherent research project that will strengthen the future collaboration between the groups, and thus fuel future joint activities and proposals. The bilateral collaboration clearly provided synergy effects by combining the different strengths in the research groups to provide a fruitful environment for exciting science.