Publikationsdatum:
2019-07-17
Beschreibung:
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
Repository-Name:
EPIC Alfred Wegener Institut
Materialart:
Article
,
isiRev
Format:
application/pdf
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