title: Observing the forest canopy with a new ultra-violet compact airborne lidar.
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 m(2) 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.
authors.affiliation: Laboratoire de Météorologie Dynamique-IPSL/École Polytechnique, 91128 Palaiseau, France. cuesta@lmd.polytechnique.fr
authors.forename: Juan
authors.initials: J
authors.lastname: Cuesta
authors.forename: Patrick
authors.initials: P
authors.lastname: Chazette
authors.forename: Tristan
authors.initials: T
authors.lastname: Allouis
authors.forename: Pierre H
authors.initials: PH
authors.lastname: Flamant
authors.forename: Sylvie
authors.initials: S
authors.lastname: Durrieu
authors.forename: Joseph
authors.initials: J
authors.lastname: Sanak
authors.forename: Pascal
authors.initials: P
authors.lastname: Genau
authors.forename: Dominique
authors.initials: D
authors.lastname: Guyon
authors.forename: Denis
authors.initials: D
authors.lastname: Loustau
authors.forename: Cyrille
authors.initials: C
authors.lastname: Flamant
mesh_terms: D004867:Equipment Design; D016468:Forestry / Q000295:instrumentation / Q000379:methods*; D005602:France; D007834:Lasers; D008962:Models, Theoretical; D028223:Pinus / Q000502:physiology; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014197:Trees / Q000502:physiology*; D014466:Ultraviolet Rays