Snow Albedo Evolution
1 May 2019 - 30 June 2021
Lead Scientist: Matthew Sturm
Scientists seek to better quantify high-latitude radiative processes through the study of the seasonal evolution of the surfaces (ground and ice) at the North Slope of Alaska (NSA) atmospheric observatory. We will study the evolution of albedo of this snow-covered coastal region from pre-melt through the complete melt of the snow cover. Our focus is on the terrestrial-sea ice linkage. We intend to explore several questions including: As the land warms does that accelerate melt on the sea ice cover? Does the cold sink of the sea ice cover slow snow melt on land? The near-shore location of the ARM NSA observatory makes this an ideal location to investigate these questions.
Three field campaigns are planned and consist of repeated surveys of spectral and wavelength-integrated snow and ice albedo measurements on land (2 locations) and on shore-fast sea (1 location). These will require over-snow travel on both tundra and sea ice to access the three locations. Each of the three years of the project (2019 – 2021), in April, before the snow begins to melt we will establish these snow and albedo survey lines, one inland on the tundra, one at the NSA site, and one off-shore on the sea ice of the Chukchi Sea. At each location, we will establish a line 200 to 500 m long marked every 5-m to facilitate repeat measurements.
In April we will make baseline measurements, then over a 2 to 3 week period in May and June, we will make measurements as the snow melts. A distinguishing feature of this campaign is that the albedo measurements will be paired with detailed measurements of the snow properties themselves. The measurements will provide detailed understanding of the melt evolution that we can extrapolate along the line using satellite remote sensing products.
Our intensive operational period will be late-May to early-June, and will be keyed to when melt begins. Modeling will be used to interpret and to extend the observations. We will use a Discrete Element Model of snow radiative transfer to examine in detail the impact of changing grain size and meltwater in the snow cover on spectral albedo. Additional radiative transfer modeling will be performed using DISORT and will focus on the large-scale partitioning of sunlight by a melting snow cover.