An examination of the distribution of snow on sea-ice

Snow on sea-ice is an integral, yet pearly understood, component of the oce an-sea-ice-atmosphere interface. Snow exerts a significant control on both shortwave and conductive fluxes due to its high albedo and low thermal cond uctivity. Parameters pertaining to snow distribution and/or thickness are h ard to model and/or to measure using geospatial techniques. In terms of Arc tic hydrology, we consider three aspects of snow important to understanding processes operating within the ocean-sea-ice-atmosphere interface: i) the average magnitude of snow thickness on sea-ice; ii) the spatial distributio n of snow as a function of location and ice type; and ill) the seasonal evo lution of both magnitude and distribution. In this paper we focus on the se cond aspect; distribution. The distribution patterns of snow over first-yea r (FYI), multiyear (MYI) and nibble (RI) sea-ice were evaluated at 15 sites , sampled during two years of field research in the Canadian Arctic. A geos tatistical technique known as the variogram was used to model the statistic al pattern of the snow distribution. The significance of different snow dis tribution patterns was then evaluated using a radiative transfer model unde r various snow and ice type distributions. Results of this study indicate that the variogram provided a good estimate of the type and change of spatial dependence of snow depths over various ty pes of sea-ice. Over FYI, the regular smooth ice topography produced a peri odicity in the snow drifts which was best estimated using a wave (hole-effe ct) theoretical variogram in combination with a Gaussian model. The more un even ice topographies characteristic of MYI and RI produced a more irregula r snow drift pattern. The most appropriate models were a combination of the spherical and Gaussian variogram models (MYI sites) or a single Gaussian m odel (RI sites). The nugget values of the variograms increased as the sea-i ce topography became more irregular (smooth FYI to large uplifted ice piece s in RI). This was attributed to the presence of snow drifts in the MYI and RI sires that were less than the sampling interval. Geometric anisotropy w as present in all 15 sires, indicating a directional trend in the spatial c ontinuity of the snow distribution patterns which we attribute to the preva iling wind direction during depositional storm events. The ramifications of the snow distribution as a function of ice type were illustrated by the tr ansmission of photosynthetically active radiation (PAR) through the three i ce types. As the ice topography becomes more irregular; the areally average d transmission of PAR decreases, thereby illustrating the non-linear nature of the relationship between PAR extinction and snow thickness. The finding s of this case study suggest that by knowing the type of sea-ice we can mak e predictions about the statistical pattern of the associated snow distribu tion. More importantly, the main finding suggests that this snow distributi on pattern will dominate the areally averaged transmission of PAR across th e ocean-sea-ice-atmosphere interface.