Seasonal effects on the estimation of height of boreal and deciduous forests from interferometric TanDEM-X coherence data

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Volume Title
Conference article in proceedings
Date
2015
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Mcode
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Language
en
Pages
1-8
Series
Earth Resources and Environmental Remote Sensing/GIS Applications VI, SPIE - International Society for Optical Engineering. Proceedings, Volume 9644
Abstract
The aim of this study is to assess the performance of single-pass X-band bistatic SAR interferometric forest height estimation of boreal and temperate deciduous forests under variable seasonal conditions. For this, twelve acquisitions of single-and dual-polarized TanDEM-X coherence images over 118 forest stands were analyzed and compared against LiDAR forest height maps. Strong correlations were found between interferometric coherence magnitude and LiDAR derived forest stand height for pine forests (r2=0.94) and spruce forest (r2=0.87) as well as for deciduous trees (r2=0.94) during leaf-off conditions with temperatures below 0°C. It was found that coherence magnitude based forest height estimation is influenced by leaf-on and leaf-off conditions as well as daily temperature fluctuations, height of ambiguity and effective baseline. These factors alter the correlation and should be taken into account for accurate coherence-based height retrieval. Despite the influence of the mentioned factors, generally a strong relationship in regression analysis between X-band SAR coherence and LiDAR derived forest stand height can be found. Moreover, a simple semi empirical model, derived from Random Volume over Ground model, is presented. The model takes into account all imaging geometry dependent parameters and allows to derive tree height estimate without a priori knowledge. Our results show that X-band SAR interferometry can be used to estimate forest canopy height for boreal and deciduous forests in both summer and winter, but the conditions should be stable.
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Keywords
Forest height, radar interferometry, synthetic aperture radar (SAR), TanDEM-X, vegetation mapping, Xband
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Citation
Olesk , A , Voormansik , K , Tamm , T , Noorma , M & Praks , J 2015 , Seasonal effects on the estimation of height of boreal and deciduous forests from interferometric TanDEM-X coherence data . in U Michel , K Schulz , M Ehlers , K G Nikolakopoulos & D Civco (eds) , Earth Resources and Environmental Remote Sensing/GIS Applications VI : Proceedings of SPIE . , 964406 , SPIE - International Society for Optical Engineering. Proceedings , vol. 9644 , SPIE , pp. 1-8 , Earth Resources and Environmental Remote Sensing/GIS Applications , Toulouse , France , 22/09/2015 . https://doi.org/10.1117/12.2194340