Oleg A. Romanovskii

Application of laser-induced fluorescence for remote sensing of vegetation

The possibilities of applying a fluorescent lidar based on the second harmonic of a Nd:YAG laser to study vegetation under natural conditions are analyzed. The dynamics of development has been studied for several species of arboreous plants grown in West Siberia in a five-year measurement cycle. The fluorescent lidar developed has been used for identification of plant species and for investigation of fading caused by an adverse environment. It is shown that the fluorescent signal can be used for remote detection of plant stresses at earlier stages, when there are no visible symptoms. For the first time, the quantitative relations are established between the intensity of red nanosecond fluorescence and the chlorophyll concentration in needles and leaves of the most typical representatives of West Siberian arboreous plants. Fluorescent data were checked using the traditional spectrophotometric method. The spectrophotometric data and lidar measurements were used to calibrate the lidar, and this calibration has allowed the chlorophyll concentration in arboreous plants to be determined from the ratio of signals of laser-induced fluorescence.

Remote sounding of vegetation characteristics by laser-induced fluorescence

Experimental investigations of the fluorescence intensity of plants in red and ultraviolet spectral ranges induced by the laser radiation have been carried out during one year. Dependence of the quantum yield of chlorophyll a fluorescence on plant species has been established and investigated. The largest range of seasonal variations of the fluorescence intensity was observed for the deciduous trees. Seasonal variations of the florescence intensity have the tendency to insignificant variations for the coniferous trees. Application of the fluorescence method to the remote specific categorization of the plant tissue and determination of the chlorophyll content is shown to be promising.

Intercomparison of Ozone Vertical Profile Measurements by Differential Absorption Lidar and IASI/MetOp Satellite in the Upper Troposphere–Lower Stratosphere

This paper introduces the technique of retrieving the profiles of vertical distribution of ozone considering temperature and aerosol correction in DIAL sounding of the atmosphere. The authors determine wavelengths, which are promising for measurements of ozone profiles in the upper troposphere–lower stratosphere. An ozone differential absorption lidar is designed for the measurements. The results of applying the developed technique to the retrieval of the vertical profiles of ozone considering temperature and aerosol correction in the altitude range 6–15 km in DIAL sounding of the atmosphere confirm the prospects of ozone sounding at selected wavelengths of 341 and 299 nm with the proposed lidar. The 2015 ozone profiles retrieved were compared with satellite IASI data and the Kruger model.

Calculation of lidar echo signals during N2O and NO2 sounding alonge tropospheric paths in 3-4 μm range

Possibilities of N2O and NO2 sounding in the 3–4 μm range along tropospheric paths are estimated on the basis of numerical simulation. The results are presented of search for information-bearing wavelengths and calculation of lidar echo signals during differential-absorption gas sounding.

Spectroscopic analysis of multicomponent gas mixtures with wide range carbon monoxide laser

Possibility to apply wide range CO-laser for detection of trace gas pollutions in multicomponent gas mixture is studied both theoretically and experimentally. Parameters of sensitivity and selectivity for multicomponent gas analysis with CO-laser were calculated.

Fluorescence lidar system for remote monitoring of the state of vegetative cover for the purpose of its prediction

The comparative research of the chlorophyll contents for number of wood plants by traditional spectrophotometric and fluorescent laser methods is carried out.The seasonal changes of the chlorophyll sums in the sprint-summer period at coniferous and deciduous wood plants are analyzed. The supervision over changes in the chlorophyll contents in connection with a withering of needles and leafs are carried out. The experimental results are received by spectrophotometric and lidar methods of study of a course of chlorophyll seasonal dynamics and pigment complex destruction of during a withering of needles and leafs of wood plants. The results of the joint analysis have shown identity of results received essentially by various methods.

Using TEA CO2 laser radiation harmonics in helicopterborne lidar for controling leakage of toxic and dangerously explosive gases

The characteristics of a helicopter-borne lidar based on tunable TEA CO2 laser and its third harmonic designed for remote detecting the methane and ammonia leakages from pipe-lines are analyzed numerically. The spectral range near 3 micrometers is shown to be most promising for remote sensing of methane emissions. Parameters of radiation of the tunable pulse-periodic mini-TEA CO2 laser and generators of harmonics to be utilized in the helicopter-borne differential absorption lidar are estimated. Emissions of different gases intensity are analyzed for possible detectability at a distance up to 1 km. The use of the third harmonic of the TEA CO2 laser allows methane emissions from a pipe-line to be detected and measured with mean measurement error from 10 to 15% for methane concentrations varying from the background level to the explosion-hazardous one. The optimal pair and possibilities of the ammonia remote sensing on the base of the first harmonic of TEA CO2 laser was determined as well.

Simulation of the remote atmospheric sounding by OPO lidar system in the near- and mid-IR

We test the technique developed for lidar sounding of trace atmospheric gases, which combines the advantages of differential absorption and differential optical absorption spectroscopy methods. We performed numerical experiments in order to estimate the capability of remote atmospheric sounding using a laser system with optical parametric generation in the spectral regions 1.8–2.5 and 3–4 μm. On the basis of this technique, we have found and selected certain wavelengths informative for the gas analysis and simulated lidar signals, the analysis of which showed a possibility of remote monitoring of HCN and C2H6 at 1-km horizontal paths, CH4, at 5-km horizontal paths in the mid-IR, and CO2 and H2O at 5-km horizontal paths in the near-IR.

Experimental estimation of the efficiency of trace gas sounding in the mid-IR by the OPO lidar system

The results of the development of a mid-IR differential absorption lidar based on the optical parametric oscillator (OPO) are presented. The receiving and transmitting parts of the OPO-lidar are described. The sounding efficiency of trace atmospheric gases in the mid-IR using an OPO lidar system developed is experimentally estimated. Echo signals of the OPO-lidar system in the mid-IR are experimentally detected.

Lidar system for measurement of vertical profiles of ozone in the upper troposphere-stratosphere

A lidar for DIAL measuring the vertical distribution of ozone at the wavelengths 299/341 nm and 308/353 nm is presented. The wavelengths used allow monitoring of vertical stratification of ozone within the upper troposphere - stratosphere. The results of lidar ozone sensing are given in comparison with the IASI/MetOp and MLS/AURA satellites. The results of comparison of the reconstructed profiles of the vertical distribution of ozone with allowance for temperature and aerosol correction confirm the prospects of using the complex of the ozone probing wavelengths of 299/341 nm and 308/353 nm. The results of the comparison show a high accuracy of ozone concentration measurements in the altitude range of 5 to 45 km.