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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Alaska Ecological Conservation II: Using NASA Earth Observations to Identify Recent Changes in Vegetation Phenology and Its Impacts on Caribou Calving and Migration

Caribou are known for their long-distance migrations from wintering grounds to specified calving zones. Notably, the Western Arctic Herd (WAH) is the largest caribou herd in Northwestern Alaska that exhibits this behavior. These calving zones are highly predictable, and research suggests that calving and the availability of high-quality vegetation are correlated. We partnered with the U.S. National Park Service in Northwestern Alaska to use Terra and Aqua Moderate Resolution Imaging Spectroradiometer(MODIS)and Harmonized Landsat and Sentinel-2 (HLS) imagery to derive Normalized Difference Vegetated Index (NDVI) values and assess vegetation phenology in calving zones from 2000 –2024. Our partners seek to understand if observed changes in caribou migration patterns and calving events correlate with shifts in the availability of nutrient-rich vegetation. Our results showed spatial variations of highly vegetated zones and annual shifts in the timing and length of growing seasons. While limitations existed in the MODIS and HLS datasets, we demonstrated feasibility using National Aeronautics and Space Administration (NASA)Earth observations for NDVI analysis over the study region. Using location data, our results may further research into caribou calving behaviors.

NDVI↗
NASA NTRS2024

Alaska Ecological Conservation: Using NASA Earth Observations to Identify Recent Changes in River Ice Phenology and Its Impacts on Caribou Migration

Each fall, caribou (Rangifer tarandus) in the Western Arctic Herd migrate hundreds of kilometers across northwestern Alaska to acquire seasonal resources and reach wintering grounds. Various rivers intersect migration paths, and caribou can only cross over open water or high-ice extents but are unable to cross rivers in stages of partial freezing. Recent temperature increases in Alaska can alter the timing and duration of ice formation periods, impeding migratory patterns. The Massachusetts NASA DEVELOP team partnered with the National Park Service in Alaska to detect river ice onset dates and formation periods using Landsat 8 Operational Land Imager and Landsat 9 Operational Land Imager-2, Sentinel-1 C-band Synthetic Aperture Radar and Sentinel-2A/B MultiSpectral Instrument imagery in Google Earth Engine. This feasibility analysis measured ice coverage using the Normalized Difference Infrared Index, Relative Difference River Ice, and Vertical-Vertical/Vertical-Horizontal backscatter values based on the spectral and surface characteristics of rivers. The team produced annual freezing timelines, time series plots, and maps at three river stretches to analyze river ice phenology changes. Radar imagery assessed ice coverage more accurately, while optical imagery better identified ice onset dates. Meanwhile indices were unable to robustly establish ice formation thresholds across the study period. These study results can help the National Park Service to better evaluate spatiotemporal migratory shifts and contextualize recent regional caribou declines.

river phenology↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xBN NEON Caribou Creek - Poker Flats Watershed (BONA)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xBN NEON Caribou Creek - Poker Flats Watershed (BONA). This is the FLUXNET version of the carbon flux data for the site US-xBN NEON Caribou Creek - Poker Flats Watershed (BONA) produced by applying the standard ONEFlux (1F) software.

Network), NEON (National Ecological Observatory↗
NASA NTRS1972

Application of ERTS-1 imagery to the study of caribou movements and winter dispersal in relation to prevailing snowcover

The author has identified the following significant results. Habitat differentiation was determined feasible using output from MSS band 6 because of apparent high correlations between surface moisture and habitat type on the test area. Progressive early snow distribution was readily determined from MSS outputs, particularly bands 4 and 5. Approximately thirty thousand caribou migrated into the test area during the reporting period, and aerial reconnaissance data on distribution were obtained for selected areas within several days of satellite overflight.

Lent, P. C.↗
NASA NTRS1974

Application of ERTS-1 imagery to the study of caribou movements and winter dispersal in relation to prevailing snowcover

The author has identified the following significant results. A multiband classification scheme was applied to ERTS-1 MSS digital tape data in a portion of the Yukon Flats area. Primary analytic objectives of mapping the extent of recent wildfire burns and mature forest were realized illustrating application to moose and caribou biology. Additionally, the analysis indicated the presence of new lakes as well as disappearance of lakes present in 1956. Because this is an important waterfowl production area, similar analyses may have significant application potential to waterfowl biology for rapid updating of habitat information. Further field confirmation of this finding is required.

Lent, P. C.↗
NASA NTRS2018

Assessment of the Barren Ground Caribou Die-off During Winter 2015-2016 Using Passive Microwave Observations

In summer 2016, more than 50 Arctic Barren Ground caribous were found dead on Prince Charles Island (Nunavut, Canada), a species recently classified as threatened. Neither predator nor sign of diseases was observed and reported. The main hypothesis is that caribous were not able to access food due to a very dense snow surface, created by a strong storm system in spring. Using satellite microwave data, a significant increase in brightness temperature polarization ratio at 19 and 37 GHz was observed in spring 2016 (60% higher than previous two winter seasons). Based on microwave radiative transfer simulations, such anomaly can be explained with a very dense snow surface. This is consistent with the succession of storms and strong winds highlighted in ERA‐Interim over Prince Charles Island in spring 2016. Using several sources of data, this study shows that changes in snow conditions explain the caribou die‐off due to restricted foraging.

Dolant, C.↗
NASA NTRS1973

Application of ERTS-1 imagery to the study of caribou movements and winter dispersal in relation to prevailing snowcover

The author has identified the following significant results. Step-wise discriminate analysis has demonstrated the feasibility of feature identification using linear discriminate functions of ERTS-1 MSS band densities and their ratios. The analysis indicated that features such as small streams can be detected even when they are in dark mountain shadow. The potential utility of this and similar analytic techniques appears considerable, and the limits it can be applied to analysis of ERTS-1 imagery are not yet fully known.

Lent, P. C.↗