SALVOII

The springtime, surface-albedo transition in the Alaskan Arctic and the forcings that determine the duration and nature of that transition are the focus of our Snow ALbedo eVOlution(SALVO II) campaign. The SALVO II team will assess the “whys” and “how longs” of the stages of the spring melt during which albedo values drop from 0.8 to 0.1, the largest and most significant change of the year. Do the steepest measured albedo changes occur during a “water-dominated” period, when water is retained in and under the snow as interstitial water or beneath the snow as ponded water? Were there late winter snowfalls that drove the albedo trajectories on the tundra and sea ice? Answers to these questions will better inform model studies of the arctic surface energy balance and radiative processes in the atmosphere. The near-shore location of the ARM NSA observatory makes this an ideal place to investigate these questions.

Fieldwork for SALVO II will be conducted at the ARM NSA central facility in Utqiagvik, Alaska. A comprehensive “springtime in Alaska” data set will be collected in spring 2022 and 2023, comprised of spectral and broadband albedos, snow and meltwater depths, snow stratigraphy and snow grain-size data, and aerial imagery. In April of each of the two years of the project before the snow begins to melt, we will establish survey lines at four locations: inland tundra, coastal tundra at the NSA C1 site, Elson Lagoon, and offshore on the sea ice of the Chukchi Sea. We will establish a line 200-m long marked every 5-m to facilitate repeated measurements of surface albedo and snow depth at each location. During each site visit, the SALVO II team will dig at least one snow pit to carefully examine the characteristics of the vertical snow layers, including the type and size of snow grains and snow density, and to identify the distribution of liquid water. We will also assess the characteristics of flowing or pooled water at the bottom of the snowpack.

SALVO II is informed by results from our successful 2019 SALVO I melt season campaign and prior work on the melt transition period conducted by Grenfell and Perovich (2004). Complementary to this effort, a rich data set was just collected from the 2019-2020 arctic sea ice MOSAiC expedition (Shupe et al., 2020). SALVO II uses the ARM NSA observatory, thus: meetings a core tenet of theAtmospheric Radiation Measurement (ARM)User Facility Decadal Vision to “provide comprehensive and impactful field measurementsupport scientific advancement of atmospheric process understanding.”

Timeline

Campaign Data Sets