Inherent optical properties of dissolved and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer

Abstract. There have been considerable efforts to understand the hydrography of Storfjorden (Svalbard). A recurring winter polynya with large sea ice production makes it an important region dense water formation at scale Arctic Ocean. In addition, this fjord is seasonally influenced by freshwater inputs from melt and surrounding islands Svalbard archipelago, which impacts hydrography. However, understanding factors controlling optical properties waters in are lacking crucial for development more accurate regional bio-optical models. Here, we present results first detailed field survey conducted early summer 2020. Our observations based on spectrometric analysis samples situ vertical profiles absorption attenuation meter, a fluorometer, conductivity, temperature, depth (CTD) sensor. addition expected seasonal contribution phytoplankton, find that optically complex significant coloured dissolved organic matter (CDOM, 33 %–64 % non-water 443 nm) despite relatively low CDOM concentrations nearshore or near seabed non-algal particles (up 61 550 nm). surface waters, spatial variability light was mainly controlled inorganic suspended originating river runoff. distinct subsurface maximum largely driven phytoplankton bloom, stratification resulting melt. Lastly, cold bottom periodically overflows sill mouth can thus reach Fram Strait. It contained elevated levels both matter, likely caused flows nepheloid layer interacting bed.