How Snow Drives the Seasonal Evolution of Land and Sea Surface Albedos in the Alaskan High Arctic

The Arctic is warming faster than the rest of the planet. Identifying the cause or causes driving this “Arctic Amplification” has been the subject of many research studies over the past 50 years. Is the amplification driven by the surface-albedo feedback, the cloud-radiation feedback, or a combination of processes inside and outside Arctic boundaries? In our work, we are focusing on the surface-albedo feedback, not by performing regional or global model simulations or by examining multi-decadal satellite records, but by directly measuring the reflection of sunlight from the snow surface in the springtime during its melt evolution, when snow reflectivity matters because of increased sunlight. Our approach is to think globally but act locally by measuring a comprehensive set of surface properties and performing local model calculations that the research community can use to inform regional and global models.

Snow cover on Arctic tundra

tundra

A type of ecosystem dominated by lichens, mosses, grasses, and woody plants. Generally located at high latitudes (arctic tundra) and high altitudes (alpine tundra).

Source: NASA earth observatory Source

and sea ice is thin and wind-blown, with the snow deposited on substrates with surface features ("relief") nearly equal to that of the mean snow depth. As the Arctic emerges from winter, the highly reflective snow surface (reflecting 80% of incoming sunlight, for an albedo of 0.8) transforms into a surface that reflects only 20%, sometimes in just a few days. This significant drop in the amount of reflected sunlight, multiplied by the vast area covered by snow, has global climate ramifications. The Snow ALbedo eVOlution campaign (SALVO) allows us to look anew at specific processes driving these albedo changes. We hope to unravel how changes in snow albedo directly affect melt rates through detailed spatial measurements of spectral albedo, snow depth, snow stratigraphy, snow-grain characteristics, and water percolation through the snowpack.

The SALVO project has four objectives: (1) to measure the variability in space and evolution in time of the albedo and snow properties on Arctic tundra and coastal sea ice, with an emphasis on understanding the albedo transition, (2) to provide the research community with an organized data catalog that links the many surface types observed during the spring melt with their albedos and other significant properties, (3) to use this rich data set to drive calculations of atmospheric radiative fluxes,

radiative flux

The measurement of the amount of radiant energy that is released from the Earth's atmosphere across specific wavelengths ranging from solar to thermal infrared.

Source: NASA POWER | Docs Source

atmospheric heating rates, and the surface energy balance, and (4) to put these local measurements into context against data from larger regions through the use of remote sensing

remote sensing

The process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite or aircraft).

Source: USGS Source

data. The 2019-2020 MOSAiC expedition established a similar data set for central Arctic sea ice; the SALVO and MOSAiC campaigns together provide a unique opportunity to better quantify the processes that drive the evolution of albedo in the Arctic.