کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4460343 1621324 2008 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Interpretation and topographic compensation of conifer canopy self-shadowing
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات کامپیوتر در علوم زمین
پیش نمایش صفحه اول مقاله
Interpretation and topographic compensation of conifer canopy self-shadowing
چکیده انگلیسی

The self-shadowing of conifer canopies results from the size and arrangement of trees within a stand and is a first-order term controlling radiance from forested terrain at common pixel scales of tens of meters. Although self-shadowing is a useful attribute for forest remote-sensing classification, compensation for the topographic effects of self-shadowing has proven problematic. This study used airborne canopy LiDAR measurements of 80 Pacific Northwest, USA conifer stands ranging in development stage from pre-canopy closure to old-growth in order to model canopy self-shadowing for four solar zenith angles (SZA). The shadow data were compared to physical measurements used to characterize forest stands, and were also used to test and improve terrain compensation models for remotely sensed images of forested terrain. Canopy self-shadowing on flat terrain strongly correlates with the canopy's geometric complexity as measured by the rumple index (canopy surface area/ground surface area) (R2 = 0.94–0.87 depending on SZA), but is less correlated with other stand measurements: 95th percentile canopy height (R2 = 0.68), mean diameter at breast height (dbh) (R2 = 0.65), basal area ha− 1 (R2 = 0.18), and canopy stem count ha− 1 (R2 = 0.18). The results in this paper support interpretation of self-shadowing as a function of canopy complexity, which is an important ecological characteristic in its own right. Modeling of canopy self-shadowing was used to assess the accuracy of the Sun-Canopy-Sensor (SCS) topographic correction, and to develop a new empirical Adaptive Shade Compensation (ASC) topographic compensation model. ASC used measured shadow (as an estimate of canopy complexity) and the SCS term (to describe the illumination geometry) as independent variables in multiple regressions to determine the topographic correction. The ASC model provided more accurate radiance corrections with limited variation in results across the full range of canopy complexities and incidence angles.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Remote Sensing of Environment - Volume 112, Issue 10, 15 October 2008, Pages 3820–3832
نویسندگان
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