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382 results on '"Grigorov I"'

22. Lidar monitoring and in situ sampling of particulate matter in lowest atmospheric layers over urban area

Author

Nedkov, I., Stoyanov, D., Cherkezova-Zheleva, Z., Groudeva, V., Ilieva, R., Angelova, B., Iliev, M., Kolarov, G., Grigorov, I., and Ghelev, C.

Subjects
In situ sampling, LIDAR monitoring, Particulate matter (PM)
Abstract

The present study is related to elucidating the remote sensing monitoring and capabilities for profiling to particulate matter (PM) mass concentration control in the lowest atmospheric layers. The PM was studied at a distance of 5.5 km from the LIDAR station. The experiments were conducted in May and October 2020 in the South-Eastern part of the Bulgarian capital Sofia during a COVID-19 lockdown. The LIDAR measurement data was compared during the experiments with in situ sampling by mobile devices located just below the spot of the LIDAR beam: (i) Absorber collects particles higher thеn 3 µm; (ii) PM Microcollector type SDS 011; and (iii) Andersen Cascade Impactor for exploring PM size distribution and microbiota. The results obtained show that remote sensing can be very effective when quantitative evaluation has been combined with in situ sampling for PM qualitative assessment.

Published
2021

48. Lidar Observation of Aerosol and Temperature Stratification over Urban Area During the Formation of a Stable Atmospheric PBL

Author

Kolev, I, Parvanov, O, Kaprielov, B, Mitev, V, Simeonov, V, and Grigorov, I

Subjects
Environment Pollution
Abstract

In recent years, the processes in the atmospheric planetary boundary layer (PBL) over urban areas were intensely investigated, due to ecological problems related to the air, soil, and water pollution. New pollution sources in new residential districts, when in contradiction to the microclimate and topography requirements of that region, create a number of considerable hazards and problems. The present study is a continuation of our preceding investigations and aims at revealing the aerosol structure and stratification during the transition after sunset as measured by two lidars. Such observation of the nocturnal, stable PBL formation over an urban area in Bulgaria has not been reported before. The lidars' high time and spatial resolutions allow the changes of the internal structure of the PBL's part located above the surface layer to be observed.

Published
1992

49. A Comparison Between Raman Lidar and Conventional Contact Measurements of Atmospheric Temperature

Author

Mitev, V. M, Simeonov, V. B, and Grigorov, I. V

Subjects
Environment Pollution
Abstract

Described here are the results of comparison between lidar and conventional contact measurements of the vertical temperature profile of the atmosphere. The lidar measurements are based on the method of temperature dependence of pure rotational Raman scattering of nitrogen and oxygen molecules. The presented results show that, as a whole, the motion of the lidar and conventional profiles coincide in the confidence intervals. Still there are districts in which the differences lay out of the confidence intervals. In analysis and estimation of the coincidence and the distinction in moving the profiles, we must take into account the differences between the methods for measuring the temperature profiles by lidar and contact methods, i.e. the next additional factors. The tied balloon meter gives the momentary values of the temperature in particular points of the profile, as these momentary values are the results of consequent, but not simultaneous measurements. In the case of free flying balloon, the time of measuring the lower several hundred meters is little because of high vertical velocity (about 300 m/min). This leads to an indefinite increase of the measuring error. The complete space coincidence between the lidar's and conventional profiles isn't possible. The contribution of the factors mentioned above about the error of comparison could increase because of nonstable layers in the planetary boundary layer of the atmosphere as well as by the influence of the mountains and the city situated nearby.

Published
1992

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