Hans Edner

Preliminary experiment on the remote sensing of historical buildings by fluorescence lidar

Stone surface monitoring of historical buildings is of interest in the planning of restoration work, both for assessing biodeteriogen growth and for detecting the spectroscopic features of the surface itself. Laser-induced fluorescence (LIF) analysis yields strong signals in the near IR region due to algal depositions while signals through the visible region are useful for the characterization of the stone materials. This paper reports on the first experiments carried out in the framework of a joint project of LTH and IROE-CNR aimed at the fluorescence imaging of historical buildings. We have used a fiber-optical fluorosensor for performing point measurements, and a mobile fluorescence imaging lidar system for remote measurements at a typical distance of 60 m.

Atmospheric NH3 monitoring by long-path UV absorption spectroscopy

Differential optical absorption spectroscopy has been applied in atmospheric ammonia monitoring. The absorption of gaseous ammonia in the UV region between 190 nm and 230 nm has been examined and compared with spectra of interfering species and atmospheric transmission. A wavelength region around 210 nm was utilized in measurements of atmosphric ammonia over a 265 m path in a rural area with a detection limit of 1 ig/m

Possibility of hard-target lidar detection of a biogenic volatile organic compound, alpha-pinene gas, over forest areas

The absorption spectrum of alpha-pinene gas, a biogenic volatile organic compound, was directly measured with a pulsed mid-infrared laser. The maximum absorption wavelength was found to be ~3.42 mum, and an absorption cross section of 4.8 x 10(-23) m(2) molec(-1) was obtained. A simple theoretical calculation with the measured spectral data showed that several hundreds of parts in 10(12) (ppt) of alpha-pinene gas in forest-mountain areas over a range of ~10 km were detectable by a long-path-averaged hard-target absorption lidar. Requirements for system development were also discussed.

Lidar measurements of atmospheric mercury

Mercury is the only atmospheric pollutant that is present in the atmosphere in atomic form. Range-resolved Hg mapping can be performed using the differential absorption lidar (dial) technique employing the 254 nm Hg resonance line. We have used the lidar technique both for mapping of industrial plumes and for background concentration measurements. Our studies also include mercury of geophysical origin. A field test has been performed in Icelandic geothermal fields. We have also attempted studies of Hg emission from lake surfaces.

Lidar remote sensing of the Parma Cathedral and Baptistery

Fluorescence lidar is a well known instrument that is mainly employed for the remote sensing of the Earths surface. In recent years, IROE, in collaboration with other Italian and foreign institutions, carried out the first experiments on remote sensing of historical buildings using fluorescence lidar. The main part of these experiments deals with the remote monitoring of biodeteriogens and the lithological characteristics of the building materials. This paper describes the results of the field experiment carried out at the Parma Cathedral and Baptistery in September 2000. Two systems, the tripled Nd:YAG lidar of the Lund Institute of Technology and the XeCl lidar of the CNR-IROE, operated for one week, in order to test the possible applications of both fluorescence point measurement and fluorescence thematic imaging in the remote non-destructive monitoring of buildings. Apart from confirming the possibility of detecting biodeteriogens, for the first time in our knowledge the processing of the fluorescence data made possible the detection of restorations and the distinction between pigments having the same color.

SALE experiment: ship monitoring of the volcanic emission and water quality in the southern Tyrrhenian Sea

The SALE experiment was carried out in September 1994 in waters of the Southern Tyrrhenian Sea and in Sicilian coastal waters. The aim of the experiments was the test of lidar potential in the simultaneous measurement of atmospheric and marine parameters in this particular environment. A DIAL and fluorescence lidar were successfully employed for the monitoring of volcanic emissions and marine parameters, respectively. the paper describes and discusses the main results of this experiment.

Combination of lidar and plume velocity measurements for remote monitoring of industrial emissions

We describe a new method for gas flux measurements using a combination of differential absorption lidar (DIAL) and wind videography. The wind speed was measured by an imaging method, which calculates the horizontal displacement of the plume with cross correlation techniques. High spatial and temporal resolution is achieved with histogram equalization and window filtering techniques. Simultaneous measurements of the distance, the direction of the plume and the integrated concentration were provided through the lidar measurements. Alternative methods to measure the wind speed at different heights have been used to validate precision and accuracy of the new method for different geometrical combinations. An example of SO2 flux measurements from a paper pulp mill is presented.

Multipath differential optical absorption spectroscopy system for urban pollution monitoring

A fully computer-controlled differential optical absorption spectroscopy (DOAS) system for atmospheric air pollution monitoring is described. A receiving optical telescope can, via a large planar mirror controlled by stepping motors, sequentially tune in to light beams from a number of distant lamp light sources to cover the area. The light is directly coupled into a rapid scanning spectrometer from the computer-controlled secondary mirror in the Newtonian Telescope. The beam-finding servo system and automatic gain control allows long unattended measurements. Using an astronomical code, celestial sources can also be searched and tracked. By computer fitting to stored laboratory spectra the path-averaged concentration of a number of important pollutants such as NO2, SO2, and O3 can be evaluated. A measurement of NH3 and NO close to the UV-limit is also demonstrated. Evaluated data are stored together with meteorological data and other system parameters.