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Chlorophyll Fluorescence and Modeled Irradiance of Evergreen Needles

Submitted by Welch, Jessica on 2020-09-28
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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.

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In situ measurements of needle-level chlorophyll fluorescence and other irradiance products are now available.

Landscape-Scale Estimates of Methane Ebullition from Lakes

Submitted by ORNL DAAC Staff on 2020-07-29
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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.

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Synthetic Aperture Radar (SAR) was used to estimate methane ebullition flux for thousands of lakes in five regions across Alaska.

Carbon Combustion Following Saskatchewan Wildfires

Submitted by ORNL DAAC Staff on 2020-07-28
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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).

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A new Arctic-Boreal Vulnerability Experiment (ABoVE) provides spatial estimates of carbon combustion and uncertainty on a 30 m grid.

Soil Pit Properties from the Arctic-Boreal Vulnerability Experiment

Submitted by ORNL DAAC Staff on 2020-07-20
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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).

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Active layer thickness, soil dielectric profiles, and soil physical properties are key variables for understanding the Arctic permafrost layer.

High Res/Cloud-Free Snow Cover Extent and Depth

Submitted by ORNL DAAC Staff on 2020-07-13
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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).

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One kilometer resolution, cloud-free snow cover extent and snow depth data are available for Alaska from 2001 to 2017.

Spatial Patterns in Methane Fluxes of Arctic Vegetation

Submitted by ORNL DAAC Staff on 2020-07-06
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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.

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A new dataset provides diffusive methane (CH4) fluxes of emergent and upland vegetation at two thermokarst lakes in Alaska.

Surveying the Ecological Effects of Fire on Alaska's Yukon-Kuskokwim Delta

Submitted by ORNL DAAC Staff on 2020-05-18
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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.

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Ecological field data and maps of vegetation cover spanning gradients of fire history in upland tundra are available from the Arctic-Boreal Vulnerability Experiment (ABoVE).

Open Water Masks from AirSWOT Flight Paths over Alaska

Submitted by ORNL DAAC Staff on 2020-02-24
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Example of color-infrared imagery shown alongside the corresponding semi-automated open water classification at Old Crow Flats, Alaska.

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Over 3,000 km2 of open surface water were mapped from AirSWOT flight lines made in Summer 2017 for the Arctic-Boreal Vulnerability Experiment (ABoVE).