Filters: Tags: B1-High Resolution Land Cover Imaging (X)
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Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
P2-Changes in Plant and Animal Species Due to Climate Change
SPARC: New Cloud, Snow, and Cloud Shadow Detection Scheme for Historical 1-km AVHHR Data over Canada
The identification of clear-sky and cloudy pixels is a key step in the processing of satellite observations. This is equally important for surface and cloud-atmosphere applications. In this paper, the Separation of Pixels Using Aggregated Rating over Canada (SPARC) algorithm is presented, a new method of pixel identification for image data from the Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA satellites. The SPARC algorithm separates image pixels into clear-sky and cloudy categories based on a specially designed rating scheme. A mask depicting snow/ice and cloud shadows is also generated. The SPARC algorithm has been designed to work year-round (day and night) over the temperate and polar regions...
1.?Mixed-wood boreal forests are often considered to undergo directional succession from shade-intolerant to shade-tolerant species. It is thus expected that overstorey gaps should lead to the recruitment of shade-tolerant conifers into the canopy in all stand development stages and that the recruitment of shade-intolerant hardwoods would be minimal except in the largest gaps. 2.?We analysed short-term gap dynamics over a large 6-km2 spatial area of mixed-wood boreal forest across a gradient of stands in different developmental stages with different times of origin since fire (expressed as stand ?age?) that were affected differentially by the last spruce budworm (SBW) outbreak. Structural measurements of the canopy...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
P3b-Future Vulnerability to Land use Change
Trends in the growing season Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time-series were analyzed for the time period from 2000 to 2010 to understand landscape-level patterns of vegetation change in ecosystems of interior Alaska. The analysis compared data-sets for Alaska vegetation cover types, wetland cover classes, wildfire boundaries since the 1940s, permafrost type, and elevation to identify the most likely combination of factors driving regional changes in habitat quality and ecosystem productivity. Approximately 48% of all ecosystem areas in interior Alaska were detected with significant (p < 0.05) positive or negative MODIS growing season EVI trends from 2000 to...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
M1-Ecosystems
Tracking landscape-scale water status in high-latitude boreal systems is indispensible to understanding the fate of stored and sequestered carbon in a climate change scenario. Spaceborne synthetic aperture radar (SAR) imagery provides critical information for water and moisture status in Alaskan boreal environments at the landscape scale. When combined with results from optical sensor analyses, a complementary picture of vegetation, biomass, and water status emerges. Whereas L-band SAR showed better inherent capacity to map water status, C-band had much more temporal coverage in this study. Analysis through the use of L- and C-band SARs combined with Landsat Enhanced Thematic Mapper Plus (ETM+) enables landscape...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
R1-Vulnerability Forest Species and Communities to Climate Change
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
B3-Hydrological Datasets
Categories: Publication;
Types: Citation;
Tags: A1: Best mangement practices,
B1-High Resolution Land Cover Imaging,
landscape scale conservtion
Snow accumulation and melt are dynamic features of the cryosphere indicative of a changing climate. Spring melt and refreeze timing are of particular importance due to the influence on subsequent hydrological and ecological processes, including peak runoff and green-up. To investigate the spatial and temporal variability of melt timing across a sub-arctic region (the Yukon River Basin (YRB), Alaska/Canada) dominated by snow and lacking substantial ground instrumentation, passive microwave remote sensing was utilized to provide daily brightness temperatures (T b ) regardless of clouds and darkness. Algorithms to derive the timing of melt onset and the end of melt-refreeze, a critical transition period where the snowpack...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
M2-Standardized Stream and Lake Information
An interferogram reflecting the motion of Black Rapids Glacier, Alaska, U.S.A., was obtained from two European Remote-sensing Satellite (ERS-1) synthetic-aperture radar (SAR) images, acquired on 22 and 25 January 1992. We investigate whether the interferometric data are quantitatively consistent with terrestrial velocity measurements along three transverse profiles. These terrestrial data are from different years (1987, 1990, 1996) and cover different periods (6-28 April, 23 May-7 July and a whole year) than the SAR interferogram. Terrestrial ice velocity at the date of the SAR imagery is obtained via seasonal and annual corrections that are calculated from other terrestrial velocity measurements available at higher...
Mean stand height is an important parameter for forest volume and biomass estimation in support of monitoring and management activities. Information on mean stand height is typically obtained through the manual interpretation of aerial photography, often supplemented by the collection of field calibration data. In remote areas where forest management practices may not be spatially exhaustive or where it is difficult to acquire aerial photography, alternate approaches for estimating stand height are required. One approach is to use very high spatial resolution (VHSR) satellite imagery (pixels sided less than 1m) as a surrogate for air photos. In this research we demonstrate an approach for modelling mean stand height...
Increasing amounts and types of timely and accurate data are required for monitoring to ensure compliance with natural resource regulatory requirements. This study developed a cost-effective method to partially fulfill these data requirements using super large scale aerial photography (Scale: greater than 1:2,000). Two synchronized, metric, Rolleiflex 70mm (2.76in) cameras mounted 12m (40ft) apart on a rigid platform and carried at 5.6 km/hr (3 knots) by a helicopter collected this high resolution, 3D imagery from Alaska and Washington. The overlapping photo pairs provided 3D views of natural resource objects as fine as twigs. The 12m (40ft) inter-camera distance improved ground visibility between tree crowns of...
Trends in the growing season Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time-series were analyzed for the time period from 2000 to 2010 to understand landscape-level patterns of vegetation change in ecosystems of interior Alaska. The analysis compared data-sets for Alaska vegetation cover types, wetland cover classes, wildfire boundaries since the 1940s, permafrost type, and elevation to identify the most likely combination of factors driving regional changes in habitat quality and ecosystem productivity. Approximately 48% of all ecosystem areas in interior Alaska were detected with significant (p < 0.05) positive or negative MODIS growing season EVI trends from 2000 to...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
M1-Ecosystems
Global products of leaf area index (LAI) usually show large uncertainties in sparsely vegetated areas because the understory contribution is not negligible in reflectance modeling for the case of low to intermediate canopy cover. Therefore, many efforts have been made to include understory properties in LAI estimation algorithms. Compared with the conventional data bank method, estimation of forest understory properties from satellite data is superior in studies at a global or continental scale over long periods. However, implementation of the current remote sensing method based on multi-angular observations is complicated. As an alternative, a simple method to retrieve understory NDVI (NDVIu) for sparse boreal...
Categories: Publication;
Types: Citation;
Tags: B1-High Resolution Land Cover Imaging,
M1-Ecosystems
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