Variability of light transmission through Arctic land-fast sea ice during spring 1Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
20 Jun 2013
2Norut Narvik AS, Narvik, Norway
3Norwegian Polar Institute, Fram Centre, Tromsø, Norway
Received: 17 Sep 2012 – Published in The Cryosphere Discuss.: 12 Oct 2012 Abstract. The amount of solar radiation transmitted through Arctic sea ice is
determined by the thickness and physical properties of snow and sea ice.
Light transmittance is highly variable in space and time since thickness and
physical properties of snow and sea ice are highly heterogeneous on variable
time and length scales. We present field measurements of under-ice irradiance
along transects under undeformed land-fast sea ice at Barrow, Alaska (March,
May, and June 2010). The measurements were performed with a spectral
radiometer mounted on a floating under-ice sled. The objective was to
quantify the spatial variability of light transmittance through snow and sea
ice, and to compare this variability along its seasonal evolution. Along with
optical measurements, snow depth, sea ice thickness, and freeboard were
recorded, and ice cores were analyzed for chlorophyll a and particulate
matter. Our results show that snow cover variability prior to onset of snow
melt causes as much relative spatial variability of light transmittance as
the contrast of ponded and white ice during summer. Both before and after
melt onset, measured transmittances fell in a range from one third to three
times the mean value. In addition, we found a twentyfold increase of light
transmittance as a result of partial snowmelt, showing the seasonal evolution
of transmittance through sea ice far exceeds the spatial variability.
However, prior melt onset, light transmittance was time invariant and
differences in under-ice irradiance were directly related to the spatial
variability of the snow cover.
Revised: 16 May 2013 – Accepted: 17 May 2013 – Published: 20 Jun 2013
Citation: Nicolaus, M., Petrich, C., Hudson, S. R., and Granskog, M. A.: Variability of light transmission through Arctic land-fast sea ice during spring, The Cryosphere, 7, 977-986, doi:10.5194/tc-7-977-2013, 2013.