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Observing the Forest Canopy with a New Ultra-Violet Compact Airborne Lidar
Laboratoire de Météorologie Dynamique–IPSL/École Polytechnique, 91128 Palaiseau, France
Laboratoire Atmosphères, Milieux, Observations Spatiales–IPSL/75252 Paris, France
Laboratoire des Sciences du Climat et l’Environnement–IPSL/91191 Saclay, France
UMR TETIS, Cemagref/34196 Montpellier, France
INRA, UR1263 EPHYSE, F-33140 Villenave d’Ornon, France
* Author to whom correspondence should be addressed.
Received: 6 May 2010; in revised form: 1 June 2010 / Accepted: 21 June 2010 / Published: 6 August 2010
Abstract: We have developed a new airborne UV lidar for the forest canopy and deployed it in the Landes forest (France). It is the first one that: (i) operates at 355 nm for emitting energetic pulses of 16 mJ at 20 Hz while fulfilling eye-safety regulations and (ii) is flown onboard an ultra-light airplane for enhanced flight flexibility. Laser footprints at ground level were 2.4 m wide for a flying altitude of 300 m. Three test areas of ~500 × 500 m2 with Maritime pines of different ages were investigated. We used a threshold method adapted for this lidar to accurately extract from its waveforms detailed forest canopy vertical structure: canopy top, tree crown base and undergrowth heights. Good detection sensitivity enabled the observation of ground returns underneath the trees. Statistical and one-to-one comparisons with ground measurements by field foresters indicated a mean absolute accuracy of ~1 m. Sensitivity tests on detection threshold showed the importance of signal to noise ratio and footprint size for a proper detection of the canopy vertical structure. This UV-lidar is intended for future innovative applications of simultaneous observation of forest canopy, laser-induced vegetation fluorescence and atmospheric aerosols.
Keywords: vegetation active remote sensing; laser; canopy lidar; airborne lidar; ultra-violet emission; ultra-light airplane
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Cuesta, J.; Chazette, P.; Allouis, T.; Flamant, P.H.; Durrieu, S.; Sanak, J.; Genau, P.; Guyon, D.; Loustau, D.; Flamant, C. Observing the Forest Canopy with a New Ultra-Violet Compact Airborne Lidar. Sensors 2010, 10, 7386-7403.
Cuesta J, Chazette P, Allouis T, Flamant PH, Durrieu S, Sanak J, Genau P, Guyon D, Loustau D, Flamant C. Observing the Forest Canopy with a New Ultra-Violet Compact Airborne Lidar. Sensors. 2010; 10(8):7386-7403.
Cuesta, Juan; Chazette, Patrick; Allouis, Tristan; Flamant, Pierre H.; Durrieu, Sylvie; Sanak, Joseph; Genau, Pascal; Guyon, Dominique; Loustau, Denis; Flamant, Cyrille. 2010. "Observing the Forest Canopy with a New Ultra-Violet Compact Airborne Lidar." Sensors 10, no. 8: 7386-7403.