0 1989, by the American Society of Limnology and Oceanography, Inc. Laboratory measurements of optical beams in young sea ice

• Main Authors: J. S. Schoonmaker, K. J. Voss, G. D. Gilbert
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.584.7484; http://www.aslo.org/lo/toc/vol_34/issue_8/1606.pdf

The optical properties of young sea ice (< 20 cm thick) have been measured in the Naval Ocean Systems Center Ice Optics Lab. Measurements of the upwelling irradiance from the ice surface as a function of distance from the center of the beam spot (r in cm) were performed. The irradiance distributions were transformed to find the modulation transfer function (MTF) and beam spread function (BSF) as a function of ice thickness. The BSF could be approximated by BSF(r, z) = exp (- k,z) exp (- r2/2 ( r2)), with ham =0.404 cm- ’ and (r2) ” = 0.105 z’.~ ’ cm, where z is ice thickness (in cm). Angular radiance above the ice surface, resulting from a laser beam entering the ice from below, was measured as a function of ice thickness for a specific growth condition. The angular field followed a function of L(0, z) = L(0, z)cos”(~), with y1 = 8.1 z-0,71, while the peak value followed a Beer’s law decay of the form L(0, z) = L(0, O)exp(-0.5 14~). Past measurements of the light fields and optics of Arctic sea ice have largely been concerned with irradiance fields in the Mar-ginal Ice Zone, e.g. the natural light irradi-