This project is part of a larger NSF initiative called the Study of the Northern Alaska Coastal System (SNACS). Most regional observation networks indicate that dramatic changes have occurred across the Arctic in recent decades, but comparatively little work has been done to assess atmospheric and oceanic responses to the dramatic observed terrestrial changes. Both increases in surface air temperature and a shift in arctic air circulation patterns are likely to contribute to changes in ice distribution.
This project is examining how biological and physical processes interact to control carbon uptake, storage and release in Arctic tundra ecosystems and how the self-organizing nature of these interactions varies across multiple spatial and temporal scales. Approximately 25% of the world’s soil organic carbon reservoir is stored at high northern latitudes in permafrost and seasonally-thawed soils in the Arctic, a region that is currently undergoing unprecedented warming and drying, as well as dramatic changes in human land use.
In the process of urbanization, land formerly occupied by crops, grasslands or forest becomes permanently paved for buildings, parking lots and transportation. While urban areas have generally a lower photosynthetic capacity than the surrounding rural environments, intensively irrigated and fertilized lawns and trees often counterbalance the decline in net primary productivity (NPP) due to the replacement of vegetated surface with constructed materials.
For decades scientists have sought to develop regionally applicable estimators of crop yield using models formulated from remote sensing data. With a few exceptions, most broad scale models, based on remote sensing, have used the Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) to derive retrospective, empirical relationships between NDVI and yield. However, while retrospective analyses provide insight into past performance, they do little to satisfy the need for near real time yield information.
Until recently, the Advanced Very High Resolution Radiometer (AVHRR) was the only broad scale, globally applicable satellite that provided direct spectral data suited for continual monitoring of vegetation. As such, many studies have successfully used AVHRR normalized difference vegetation index (NDVI) to infer photosynthetic monitor growing season phenology and estimate vegetation. On 18 December, 1999 the first Moderate Resolution Imaging Spectroradiometer (MODIS) was launched on the Terra platform of the Earth Observing System (EOS).
The geography and dynamics of water across this pan-Arctic region are important elements of the larger Earth System especially given growing evidence of the vulnerability of the Arctic climate and terrestrial biosphere to global change. The scope of this multidisciplinary project is develop online, near-real time capabilities for rapid assessment and monitoring pan- Arctic water budgets and river discharge to the Arctic Ocean.
The lack of available water constrains hydrologic and ecological processes for two-thirds of the Earth’s land surface. We are working with colleagues at the NASA Jet Propulsion Laboratory to develop new satellite microwave remote sensing algorithms for detecting and monitoring land-atmosphere water and energy exchange over North America.
Flathead Lake, located in northwest Montana, is one of the 300 largest natural freshwater lakes in the world, covering an area of 480 km2 with a maximum depth of 113 m. The Lake is oligotrophic, yet experienced an increase in eutrophication from 1977 to 2001, and two lakewide blooms of macroalgae in 1984 and 1994 that represented anomalous declines in water quality likely due to increasing nutrient inputs from anthropogenic sources.
The Western Arctic Linkage Experiment (WALE) was initiated to investigate the role of northern terrestrial ecosystems in the larger Arctic system response to global change through model and satellite remote sensing analyses of regional carbon, water and energy cycles (McGuire et al. overview paper below). The NTSG portion of this investigation focused on assessing annual variability and regional trends in vegetation productivity for the WALE domain of Alaska and NW Canada, and the primary mechanisms driving observed changes over the 19-year (1982 - 2000) study period.