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LIDAR FLUORESCENT MONITORING IN THE SEA:
REMOTE IMPLEMENTATION OF LASER SPECTROSCOPY
A.M. CHEKALYUK and M.Yu. GORBUNOV*
Moscow State University
Dept, of Physics (*Dept. of Chemistry), Moscow 119899 (Russia)
ABSTRACT:
Oceanographic applications of lidar-fluorosensor are based on remote detection
and spectral analysis of optical response induced by pulsed laser excitation
of near-surface water column. The complete monitoring cycle includes
point-by-point measurements while a lidar carrier moves across the sea area,
data processing, and reconstruction of along-track horizontal distributions of
detected parameters and maps based on these data. There are several important
contributions to the spectra detected: the water Raman scattering band, as
well as fluorescence of organic matter (both "yellow substance" and oil
pollutions) and pigments of phytoplankton. The general approach is estimating
the content and other characteristics of fluorescence substances in water. The
choice of laser parameters and the requirements for detecting system are
discussed. The examples of profiles and maps of horizontal distributions of
chlorophyll and organic matter are presented. Relying on these data, the
advantages and limitations of lidar technique applied to sea investigation and
survey are analyzed. Future applications of lidar technique in oceanography
and its place in the system of monitoring in the sea will strongly depend on
progress in solution of related problems. Recent advances in these fields are
briefly reviewed, possible directions for further development are discussed.
KEY WORDS: Lidar, Sea, Monitoring, Fluorescence, Laser, Spectroscopy
1 - INTRODUCTION
One of the major peculiarities of the sea as an object for study or survey is
the principal difficulties in subdividing the temporal and spatial scales of
phenomena under investigation. The growing understanding of inadequacy of
available methods and instruments in solutions of the problems of vital
importance (e.g. the role of marine bio-geochemical processes in global carbon
cycle, "green-house" effect, increasing environmental load in coastal zones,
etc.) was probably the main cause of fast progress in development of various
techniques for remote sensing of the sea during last two decades. The
presented paper is devoted to the brief review of state of the art, current
possibilities and relevant problems of lidar-fluorosensors applications in
this field.
Oceanographic applications of lidar-fluorosensor systems are based on
remote detection and spectral analysis of optical response induced by pulsed
laser excitation in near-surface water column (see Fig.l). The complete
monitoring cycle includes point-by-point measurements while a lidar carrier
moves across the sea area, data processing, and reconstruction of along-track
horizontal distribution of detected parameters (profiling) and maps (mapping)
based on these data.
