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...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: T. Taskjelle, S. R. Hudson, M. A. Granskog, B. Hamre
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2017
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Online Access:https://doi.org/10.5194/tc-11-2137-2017
https://doaj.org/article/00cb42e231eb4bacab09fb033aab8c70
Description
Summary: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.