Arctic

A white spruce tree is instrumented with a hemispherical and field-stop photochemical reflectance index (PRI) sensor and point dendrometer at a northern treeline site along the Dalton Highway, Brooks Range, Alaska. Source: Eitel et al., 2020

Example of Color-infrared imagery shown alongside the corresponding semi-automated open water classification at Old Crow Flats, Alaska.

A perspective of one study plot at the forest-tundra ecotone with mature spruce trees transitioning into short-stature trees and low-stature deciduous shrubs.

Relationship between the quantum yields of fluorescence (Ft) and photosystem II (Fv/Fm) sampled Picea glauca needles in Alaska (A) and Abies grandis needles in Idaho (B). Modeled (A) and observed (B) irradiance is indicated by the coloration of points; grey points in individual sampling period panels show observations from all periods for reference. Plots of sampling periods aligned with the timing of satellite overpasses are outlined in green (A) and blue (B) boxes, respectively.

SAR-based lake ebullition maps. Panel a shows Alaska study regions with SAR footprints outlined in yellow. Subsequent panels show SAR-based CH4 ebullition maps for b) Barrow Peninsula, c) Atqasuk, d) Toolik, e) northern Seward Peninsula, and f) Fairbanks. Study lakes with field-based measurements are outlined (b,c) or boxed (d,e,f) in white. Orange boxes in panel f indicate anthropogenic study lakes.

Spatial estimates of total carbon combustion at 30 m resolution across the 2015 fire perimeters in Saskatchewan (a) and sampled fires (b, c, d). The spatial extents of sampled fires are shown as blue rectangles in (a).

Site sampling plan used for characterizing active layer soils (left). Axes are in meters. At Imnavait Creek, active layer thickness (ALT) was measured on transects intersecting a central soil pit. Soil dielectric properties, in situ moisture and temperature profiles were measured, and soil samples were collected for analyses from the soil pit (right).

Downscaled MERRA-2 snow depth (in meters) data. Images show snow depth for two time periods: spring snow melt for 23-30 April, 2007 (left) and during early snow accumulation for 30 September-7 October, 2007 (right).

The custom-built chamber for measuring in situ trace gas fluxes from soil/vegetation and water surfaces. The chamber (~ 0.5 m3) provides adequate height to enclose emergent grasses and reeds.

Vegetation point-intercept (VPI) any-hit cover metric data were combined with Landsat imagery to develop fractional maps of any-hit cover for four aggregated plant functional types (PFTs);  shrubs bryophytes, lichen, and herbs for the upland tundra area of the Y-K Delta, Alaska. VPI data were collected from plots in areas burned in 1971, 1985, 2005, and 2015.