Marco Bazzani

Fluorescence lidar in vegetation remote sensing: system features and multiplatform operation

Fluorescence lidar is a good tool for the vegetation status control, giving information about stresses even in an early, pre-visual stage. In particular, laboratory and field experiments have pointed out the usefulness of a high spectral resolution system for the analysis of vegetation, allowing more correct and detailed information to be obtained. For this purpose, a high resolution fluorescence lidar has recently been developed at the Research Institute on Electromagnetic Waves, giving good results in field operation on various environmental targets and allowing successful performances from different platforms, including aircraft. Remarkable advances in the monitoring and protection of forests and crops can be achieved by means of a proper airborne lidar system.<<ETX>>

Fluorescence lidar remote sensing of vegetation

Fluorescence lidar is an interesting tool for the control of vegetation status, monitoring stresses also at an early, previsual stage. However, a complete physiological interpretation of the fluorescence spectra and their variations related to the plant stresses is still missing. A research project dealing with both instrument development and data interpretation has been carried out at our institutes in the framework of the national programs IPRA and RAISA (technology for agriculture) and of the EUREKA/LASFLEUR (EU380) project. Laboratory experiments dealt with the interpretation of the physiological significance of blue-green and red vegetation fluorescence and with the analysis of the influence of stresses on the spectral behavior. The experiments were carried out both in spectroscopy laboratory, in greenhouses under controlled conditions (i.e., photosynthetic photon flux density, net photosynthesis, and different stresses) and, finally, in the field from ground based and flying platforms using the fluorescence lidar FLIDAR3.

Remote sensing of marine environment with the high spectral resolution fluorosensor FLIDAR3

The FLIDAR, built at IROE-CNR in Florence, was the first of a new generation of sensors operating with high spectral resolution both as fluorescence lidar and passive spectrometer. This research includes the sensor development and the study of a suitable data processing for an extensive monitoring of the marine environment. As a result, both the laboratory and field experiments allowed the monitoring of: (1) water column temperature, by the water-Raman spectral shape; (2) oil pollution (oil class identification and thickness), by both the oil fluorescence spectral features and the water-Raman signal intensity; (3) phytoplankton and phytobenthos (identification and stress), by their fluorescence spectral signatures and their spectral behavior; (4) mucillagine, its observation has been carried out directly in the field, addressing a method for its detection. Finally, the FLIDAR has been operating since 1991 from different platforms, such as ship, helicopter, and airplane.

High-resolution lidar fluorescence spectra for the characterization of phytoplankton

The Laser Induced Fluorescence (LIF) technique has been widely employed for the study and the monitoring of the phytoplanktonic population in the marine environment. Herein a method for the characterization of different phytoplanktonic species by means of a high spectral resolution lidar fluorosensor is presented. The method is based on the detection of the changes in the peak position of the fluorescence of the chlorophyll a that is contained in all phytoplanktonic species. These changes are probably due to the proteic compounds that are present together with the chlorophyll in the thylakoid membranes within the chloroplasts and that vary with the phytoplanktonic species. The main advantage is that this method does not require the presence of characteristic fluorescence features of other light harvesting pigments, such as carotenoids or phycobilines, so that it can be used also with species where only chlorophyll fluorescence is present. Moreover, the light harvesting pigments usually show a weak fluorescence because of the strong resonant coupling between them.

Fluorescence responses of Mediterranean sea grass Posidonia oceanica: Summer 1997 ATOM-LIFT campaign

Aquatic vegetation studies were carried out from Tuesday July 15th, 1997 to Tuesday July 22, 1997 in a sea-side aquarium- laboratory in the city of Livorno on the Tyrrhenian Sea. The investigations involved an important sea grass species Posidonia oceanica that is the main higher aquatic vegetation found in the Mediterranean Sea. Fluorescence measurements were acquired on the aquatic plants treated with different levels of Mercury and Cadmium heavy metal contamination. The measurements included steady state fluorescence and fluorescence induction kinetics, pigment extraction, and photosynthetic gas exchange rates. Fluorescence instrumentation used for the studies included the high spectral resolution fluorescence lidar System (FLIDAR

Remote sensing of Posidonia oceanica by laser induced fluorescence

CPY), the NASA/USDA Fluorescence Imaging System (FIS), and Perkin Elmer Spectrofluorometer. Fluorescence responses showed a significant variations within the leaf as a function location from the base. Heavy metal treatments resulted in distinguishable differences in fluorescence responses.

Lidar measurement of light attenuation in water

Laser induced fluorescence (LIF) is becoming an effective tool for the remote assessment of vegetation. A new field can be the application of this technique to the monitoring of Posidonia beds in coastal waters. This paper describes the measurements carried out during a field campaign in the Tyrrhenian Sea. LIF spectra of Posidonia oceanica were remotely detected with a fluorescence lidar, while a complete spectroscopic analysis and pigment extraction on Posidonia samples were performed in the ship laboratory.

Remote sensing of coastal waters: the IROE activity in the PRISMA project

The total attenuation coefficient is a significant parameter of the water column being strictly related to the light penetration depth and to the quantity of suspended and dissolved substances. This parameter is measured in situ by optical instruments while its remote measurement can be achieved by lidars. The lidar measurement of the total attenuation coefficient is based on the Raman scattering due to the OH stretching of water molecule. This paper discusses the analytical base of the measurement.

Fluorescence responses and photosynthetic rates of sunlit and shaded leaves of Italian alpine forest species: Summer 1997 ATOM-LIFT campaign

The PRISMA is a research project, sponsored by the Italian Ministry for University and Scientific Research, devoted to the study of the Adriatic Sea. Within this project, the general goal of the IROE has been the development of a measurement procedure for the detection of marine fronts which integrates the NOAA-AVHRR imagery and the fluorescence lidar data. The paper reports the activity performed during the different measurement campaigns and discusses the results obtained during the first winter campaign carried out in February 1997. A good agreement was found between the front position as detected on the AVHRR thermal images and the position detected by the fluorescence lidar on the base of the change in chlorophyll and DOM concentration as well as in the change of the water Raman signal.

Airborne fluorosensors, the design of high spectral resolution systems

Terrestrial vegetation studies were carried out in the Italian Northeastern Alps in Val Visdende. The measurement site was 15 Kilometers Northeast of the town of St. Stefano di Calore (Belluno), Italy. Measurements were acquired on a wooded site at the Italian Department of Forestry Station on species native to the Italian Alps. The species included spruce (Picea abies) and alder (Alnus incana) trees. Characterization was also made of the fluorescence responses of several under-story species such as Dactylorhiza fuchsii of the Orchidaceae family, Caltha palustris and Ranunculus ficaria of the Ranuncolcee family, and Trifolium pratense and Trifolium repens of the Leguminosae family. Terrestrial vegetation monitoring was conducted with the Italian FLIDAR remote sensing instrument mounted in a mobile van, the NASA/USDA Fluorescence Imaging System (FIS), and the Spectron SE-590 for optical properties. Photosynthetic CO2 gas exchange rates we made with LI-COR 6400 infrared gas analyzer. Pigments from the samples were extracted and analyzed with a Perkin Elmer Lamda 7 Spectrometer to determine pigment concentrations. Fluorescence responses were collected from vegetation samples grown under different ambient light regimes of sun-lit versus shaded. The vegetation showed different fluorescence characteristics. A fluorescence algorithm, (F740/F680)/F550, and rate of photosynthesis showed a strong linear relationship.