Since the second half of the 1980s several efforts started to establish the laser induced vegetation fluorescence as remote sensing tool to detect the growth and/or stress status of plants. The most extended European project, the EUREKA project LASFLEUR (1989 - 1994), demonstrated the technical feasibility and the significance of the sensed data. Exciting leaves with strong light pulses anywhere in the UV-A region of the electromagnetic spectrum stimulates a broad fluorescence emission from 400 to 750 nm. This emission is separated in two main components, the 'blue-green' (400 - 600 nm) and the red fluorescence region (680 - 750 nm). The blue-green band is originated by polyphenolic compounds of the cell walls, NADPH of the photosynthetic apparatus and possibly by several other plant pigments, except chlorophyll, which is the only emitter of the fluorescence at two bands in the red and in the NIR respectively. On the basis of the photon flux in these channels and with additional information, derived from e.g. the elastic back scattered signal, the time duration of back scatter and fluorescence signal, environmental light conditions, etc. a large set of vegetation parameters could be determined. During several demonstration campaigns status parameters as e.g. the chlorophyll concentration, photosynthetical activity and canopy structure were investigated. Additionally stress conditions as e.g. drought-, UV-stress and infection with different kinds of fungi were examined as well as the differentiation of plant types as e.g. mono-and dicotyledons. Extrapolating the knowledge of the EUREKA project leads to two different main applications. First with an advanced airborne remote sensing system monitoring of the vegetation status and stress conditions may be possible independently of other remote sensing techniques or the data may be used as input parameter for e.g. passive radiometer images. The second application will be a miniaturized sensor for agricultural machines giving direct access to plant parameter and hence the possibility for individual plant treatment as e.g. determining the growth state, fertilization or weed protection.
The contamination of soil by aromatic mineral hydrocarbons (MHC) (e.g., gasoline, oil, etc.) has become a severe environmental problem because not only men, animals, and plants are threatened but also the water and air. With the unification of Germany a great number of suspected contaminated sites in the new countries were registered. An estimation of the German Federal Ministry of Environment (BMU) counts 180,000 areas contaminated with different pollutants, 55,000 are situated in the former GDR. On military settlements for example more than fifty percent of the chemicals are MHCs. Hence one can get an idea of the importance of soil pollution by hydrocarbons. Other zones contaminated due to carelessness or accidents are civil petrolstations, airports, refineries, pipelines, and traffic disasters. At the present time for most of these areas the contamination is assumed due to recent use. Due to the large extension of the problem an estimation and evaluation of the potential hazard for the environment is difficult and expensive to perform. In the case of an actual endangering the total area must be mapped in detail resulting in increasing costs for the owner. Nevertheless it is necessary to find reliable timesaving areal mapping and monitoring methods. One opportunity presented in this paper is the application of remote sensing by laser induced fluorescence from an airborne platform. It promises to fulfill these requirements in a sufficiently fast manner with very high spatial resolution. The access to the pollutant detection is the specific laser induced fluorescence emitted by the MHC (finger print). The present work shows the requirements for a helicopterborne lidar system for MHC mapping and how the detected signals are to be evaluated and interpreted.
Lidar systems are widely used in remote-sensing measurements relating to the study of atmospheric physics and its application to environmental protection. Large optical depth values give rise to multiplescattering effects that should be corrected for many lidar applications- in atmospheric gaseous constituent concentration measurements using the differential absorption method and for optical communications. On the other hand, these effects can be used to extract information about the scatterer. In both cases, the single-scattering events need to be separated from those caused by multiple scattering. A lidar simulation program is explained. Experimental methods are described that separate the multiple-scattering effects and use it for the determination of cloud microphysical parameters.
Backscatter lidar systems are widely applied for remote measurements relating to atmospheric physics and environmental protection. One application is the observation of the dispersion of aerosol plumes close to the surface. Plumes from smoke stacks, industrial complexes and power stations are included in the problem. To evaluate various dispersion theories, many artificial plumes were observed with backscatter lidars installed in a van.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.