3 research outputs found
Modelling radiative transfer through ponded first-year Arctic sea ice with a plane-parallel model
Under-ice irradiance measurements were done on ponded first-year pack ice
along three transects during the ICE12 expedition north of Svalbard. Bulk
transmittances (400–900 nm) were found to be on average 0.15–0.20
under bare ice, and 0.39–0.46 under ponded ice. Radiative transfer modelling
was done with a plane-parallel model. While simulated transmittances deviate
significantly from measured transmittances close to the edge of ponds,
spatially averaged bulk transmittances agree well. That is, transect-average
bulk transmittances, calculated using typical simulated transmittances for
ponded and bare ice weighted by the fractional coverage of the two surface
types, are in good agreement with the measured values. Radiative heating rates
calculated from model output indicates that about 20 % of the incident
solar energy is absorbed in bare ice, and 50 % in ponded ice (35 % in
pond itself, 15 % in the underlying ice). This large difference is due to
the highly scattering surface scattering layer (SSL) increasing the albedo of
the bare ice
The underwater ligth climate in Kongsfjorden and its ecological implications
Due to its Arctic location at 79°N, Kongsfjorden in Svalbard experiences strong seasonality in light climate, changing from polar night to midnight sun. Sea ice conditions and the optical properties of seawater further modify the amount and the spectral composition of solar radiation penetrating into the water column, thus defining the underwater light climate in Kongsfjorden. Light represents one of the
major shaping factors for the entire marine ecosystem. A number of studies focusing on implications of the underwater light for marine organisms have beenconducted in Kongsfjorden, generating diverse datasets on seawater optical properties, scattered over time and space. This review synthesizes the fragmentary information available from the literature as well as presenting some unpublished data,
and discusses the underwater light climate and its main controlling factors in Kongsfjorden. Furthermore, we provide a short synopsis about the relevance of light for different components of an Arctic marine ecosystem, exemplified by studies carried out in Kongsfjorden. Due to its year-round accessibility and its high-Arctic location, Kongsfjorden has become a prime fjord for studying how the strong seasonal
changes in light availability, ranging from polar night to midnight sun, affect marine life with respect to primary production, behavioural aspects and synchronization of growth and reproduction