Vertically resolved profiles of optical properties of aerosols were measured using a multi-wavelength lidar system-RALI,
set up at the scientific research center in Magurele, Bucharest area (44.35 N latitude, 26.03 E longitude) during 2008.
The use of multiple laser wavelengths has enabled us to observe significant variations in backscatter profiles depending
on the particle origins. An air mass backward trajectory analysis, using Hysplit-4, was carried out to track the aerosol
Aerosols can serve as valuable tracers of air motion in the planetary boundary layer (PBL). The height of layers in the
lower troposphere from lidar signal was calculated using the gradient method- minima of the first derivative. The
Richardson number method was used to estimate PBL height from the radio-soundings. We have used pressure,
temperature and dew point profiles as well as the wind direction profiles from NOAA (National Oceanic and
Atmospheric Administration) data base. The results were consistent with the ones obtained from LIDAR.
Daily PM10 concentrations of samples collected at two sites, urban and rural from Romania have been used to estimate
the aerosol direct radiative forcing. Using OPAC (Optical Properties of Aerosols and Cloud) model we determined the
single scattering albedo, the aerosol optical depth and aerosol
up-scatter fraction, aerosol's properties needed to estimate
the magnitude and sign of direct aerosol radiative forcing. The surface albedo was assumed 0.2 for the urban site and
0.06 for the rural site for all wavelengths. For aerosol scale height we used 1km in winter and 2 km in the summer to
calculate the optical depth of the boundary layer. Statistical analysis of the PM10 concentration for both sites show clear
seasonal cycle with maxima in the winter. As a consequence of urban atmospheric pollution the radiative forcing for
urban site appears strongly modified in comparison with rural site.
The properties of aerosol particles are highly variable, both in time and space. This refers to the number density, the microphysical properties (size distribution, refractive index, effective radius), and to the height distribution. In most cases the actual properties are not known. Using lidar data together with models can help improve the knowledge regarding the particulate atmospheric constituents which affect local radiative forcing, the radiation balance of the earth, and thus climate.
This paper presents an attempt to integrate elastic backscatter lidar data in OPAC software package in order to find the most realistic aerosol vertical distribution and their optical and microphysical characteristics. The necessity to reduce the variability of naturally occurring aerosols to typical cases, but without neglecting possible fluctuations, is achieved in OPAC by the use of a dataset of typical internally mixed aerosol components. In addition, any mixtures of the basic components can be used to calculate the overall optical parameters. Experimental or modeled meteorological profiles (temperature, pressure, relative humidity) in complementary to experimental lidar data are used to calculate the solutions of lidar equation that fits, in an iterative manner, to the output of the model. Two type of uncertainties are diminished in this way: first, the modeled profiles of lidar ratio are used in lidar data processing instead of a constant value; second, aerosol height profiles are no longer being assumed in the model, but directly measured. This procedure was applied to synthetic lidar signals in order to test its advantages and limitation.
A lidar measurements campaign took in Magurele Platform, southwestern part of Bucharest, during on June 25th, 26th and 28th of 2007 and was intended for aerosol loading characteristics over the urban area. An event of long-range Saharan dust transport to Eastern Europe (Romania) observed during this time is presented in here.
We have used an elastic backscattering lidar, based on an Nd:YAG laser, at 1064nm sounding wavelength. It can detect in real time aerosols density profiles up to 10 Km high with a spatial resolution of 12 m.
Origin of lidar sampled air masses arriving at various heights over Bucharest have been determined by the analytical back-trajectories from NOAA HYSPLIT model. Saharan dust layers reached the southern part of Romania predominantly by cyclonic circulation due to the strong through observed at all the levels from a cyclonic system located in northwestern part of Africa. Analysis of cloud cover and dust load was estimated by the Dust Regional Atmospheric Modeling (Dream model).
The dust event presented highlights how the synergy of Lidar data together with 3-D back trajectories analysis and model calculations can improve our ability to determine accurately the source of high aerosol loading.
The paper presents preliminary laboratory results in an investigation by laser induce fluorescence of the
environmental effects on the seawater. The aim of the paper was to analyze the fluorescence of the polluted water in the
south area of the Romanian Black Sea coast. The characteristics of the spectral fluorescence of water (intensity, shape,
bands) were analysed in connection with the extraction area and pollutants type. The fluorescence spectra are compared
with those of natural seawater samples measured at different laser excitation wavelengths (266 nm, 355 nm and 532 nm).
Fluorescence spectra of DOM (Dissolved Organic Matter), oil products (OP) and phytoplankton were characterized in
correlation with the band of the water Raman scattering and by their specific fluorescence decay. Seawater physicochemical
parameters and chlorophyll concentration were taking into account in seawater pollution analysis.
LIDAR systems have demonstrated their ability to map aerosol variations throughout the atmospheric column and therefore they have has become a central technology in current strategies for tropospheric aerosol research. Its use is complicated, however, by the fact that the lidar signal contains a convolution of two basic optical properties of the aerosol particles: the backscatter coefficient and the extinction coefficient. A quantitative retrieval of either property requires knowledge of their relationship along the laser path which is referred as lidar ratio. If the lidar ratio can not be measured by high spectral resolution lidar, or Raman lidar, then either an assumed value of LRa must be used in the lidar retrieval, leading to very large uncertainties in light extinction, or models can be used for determination of LRa profile.
Our research refers to the development of an iterative hybrid regularization technique for elastic backscatter lidar data processing and retrieval of the aerosols optical parameters using the atmospheric model, Mie model and Fernald-Klett, but also Ackermann algorithm for lidar ratio calculation based on relative humidity profile. This study focuses on a numerical investigation about the lidar ratio of tropospheric aerosols characterizing Romanian atmosphere. The model can be also used for other type of atmosphere in order to improve the derivation of aerosols optical parameters from elastic backscatter lidar data when no other information than meteorological data are available.
Recently, the Romanian lidar group implemented a routine monitoring scheme over Bucharest for the observation of aerosol optical properties in the troposphere. The measurements are provided twice per week at specific times (at 9:00 UT and 13:00 UT) for at least 2 hours per observation time. The purpose is to establish a quantitative comprehensive database of both horizontal and vertical distribution of aerosol over Bucharest and surrounding industrial areas, using a Nd:YAG laser based lidar system, operating at 1064 and 532 nm wavelengths, which provides in real time aerosol profiles up to 10 Km high, with a 6 m spatial resolution. In this paper, a statistical analysis obtained from several months of regular measurements is presented, ordinary and special events being outlined. For further analysis, the integration in atmospheric transport models of aerosol's spatial and temporal distribution derived from lidar measurements and complementary meteorological data was pursued. The novelty of this technique consists in using the OpenGIS technology (Open Geographical Information Systems), which permits the visualization and complex analysis of pollution in natural environment: numerical model of terrain, vegetation, meteorological and atmospheric characteristics. Lidar data are integrated as location type, direction and sense, as from the view-point of their temporal distribution. The position information is processed through an azimuthal projection GIS data server, considering the radial distribution of data centered to the coordinate point of installation location. Several codes were modified in order to obtain forecast aerosols trajectories and to evidence the impact on nearby regions.
The synergistic use of multi-temporal and multi-spectral remote sensing data offers the possibility of monitoring of environment quality in the vicinity of nuclear power plants (NPP). Advanced digital processing techniques applied to several LANDSAT, MODIS and ASTER data are used to assess the extent and magnitude of radiation and non-radiation effects on the water, near field soil, vegetation and air for NPP Cernavoda , Romania . Cernavoda Unit 1 power plant, using CANDU technology, having 706.5 MW power, is successfully in operation since 1996. Cernavoda Unit 2 which is currently under construction will be operational in 2007. Thermal discharge from nuclear reactor cooling is dissipated as waste heat in Danube-Black -Sea Canal and Danube river. Water temperature distributions captured in thermal IR imagery are correlated with meteorological parameters. Additional information regarding flooding events and earthquake risks is considered . During the winter, the thermal plume is localized to an area within a few km of the power plant, and the temperature difference between the plume and non-plume areas is about 1.5 oC. During the summer and fall, there is a larger thermal plume extending 5-6 km far along Danube Black Sea Canal, and the temperature change is about 1.0 oC. Variation of surface water temperature in the thermal plume is analyzed. The strong seasonal difference in the thermal plume is related to vertical mixing of the water column in winter and to stratification in summer. Hydrodynamic simulation leads to better understanding of the mechanisms by which waste heat from NPP Cernavoda is dissipated in the environment.
The aim of this project is the measurement of urban pollution in the Magurele platform (near Bucharest city where the pollutant sources are known) using LIDAR system operating at 532 and 1064 nm wavelengths. The application is based on the remote detection of aerosols in the atmosphere using a Smoke Analyzer by sending a short light pulse and receiving the radiation scattered in backward direction that provides backscattering signal as a function of distance.
The observable backscattered signal is generated by air density fluctuations (Rayleigh scattering) and by small aerosol particles always present in the atmosphere. The presence of aerosol particles gives rise to an increase of the backscattered signal and thus the aerosol flow can be detected on the background surrounding clean atmosphere.
In these applications, it is important the response time to be as shorter as possible, and the sensitivity to be very high, in correlation with an eventual alert when the pollutants exceeds a risk threshold. Therefore processing the lidar data constitutes an important factor in obtaining air quality information.
This papers presents first results obtained in Romania by direct lidar measurements in the area of Bucharest and the original software developed by the Environmental group in INOE for lidar data processing and PBL height identification.
The LIDAR virtual system represents an interactive software instrument able to optimize the configuration process of a LIDAR installation, but also to represent a virtual environment for modeling studies of the (for) atmospherical processes. With a virtual LIDAR is chooses an optimal configuration before the LIDAR installaiton construction, which is very important if (it takes) the high costs of a functional LIDAR installation are taken into account.
The paper describes the analytic model used to characterize the emission, propagation and reception processes, and a description concerning the system components programming and the graphic interface realization of a LIDAR virtual system.
In this paper we study the predictability of the ideal four-level laser for different pump modulation frequencies. Time series obtained from the well-known two ODE system are processed using the Grassberger-Procaccia algorithm in order to estimate the correlation dimension and the errror-doubling time (computed via the Kolmogorov entropy). Results evidence windows of low predictability, which can be associated with chaotic behavior. The attractor dimension, approximated by the correlation dimension, varies between 1.61 and 2.56 for different pump modulation frequencies. However, these values were obtained in a somehow indefinite or indeterminate way. Supported by the large discrepancies in the results reported when chaotic dynamics is analyzed in other areas of physics (e.g. atmospheric physics), the rather vague character of the criteria used when setting some parameters on which the above-mentioned quantities crucially depend is emphasized.
Urban area is a mosaic of complex, interacting ecosystems, rich natural resources and socio-economic activity. Dramatic changes in urban's land cover are due to natural and anthropogenic causes. A scientific management system for protection, conservation and restoration must be based on reliable information on bio-geophysical and geomorphologic, dynamics processes, and climatic change effects. Synergetic use of quasi-simultaneously acquired multi-sensor data may therefore allow for a better approach of change detection and environmental impact classification and assessment in urban area. It is difficult to quantify the environmental impacts of human and industrial activities in urban areas. There are often many different indicators than can conflict with each other, frequently important observations are lacking, and potentially valuable information may non-quantitative in nature. Fuzzy set theory offers a modern methodology for dealing with these problems and provides useful approach to difficult classification problems for satellite remote sensing data. This paper describes how fuzzy logic can be applied to analysis of environmental impacts for urban land cover. Based on classified Landsat TM, SPOT images and SAR ERS-1 for Bucharest area, Romania, it was performed a land cover classification and subsequent environmental impact analysis.
Elastic backscattering LIDAR represents one of the most promising tools for attaining remotely information about the distribution of aerosols and particulates in the atmosphere, which could lead to a better understanding of climate processes. In this paper we shall examine the uncertainties associated with such measurements and try to determine which of the LIDAR parameters need to be optimized in order to minimize the measurement errors. An optimization method of the operative characteristic associated with the LIDAR signal validation is also proposed.
Change is intrinsic to ecosystems, but is also the essence of instability and the outgrowth of situations that lack sustainability. It must also be recognized that change can be associated with either restoration or degradation. Compressed multiband image data provides increased flexibility and practicality for systematic change detection on a regional basis. Combining such capability with conceptual extensions of spatial pattern analysis represents a methodology for systematically monitoring spatial structure of spectral change across landscapes in order to profile characteristic broad scale regimes of change and to indicate trends in those regimes. Sustainability and ecosystem health are watchwords of contemporary ecosystem management. To solve urgent needs in application of remote sensing data, environmental change must be detected based on monitoring spatial and temporal regimes across landscapes. Environmental landscape level indices are used to examine land cover transitions. Based on classified TM images for North-Western Black Sea, Constantza urban area, Romania, conditional probability matrices of land cover transition are compared to measures of landscape structure. Based on proper algorithms for structural composition modeling were defined landscape elements being estimated the probabilistic behavior of pixels. This approach suggests a means of linking the probabilistic behavior of the fine scale dynamics to the pattern observed at larger spatial scales.
Proc. SPIE. 5227, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies
KEYWORDS: Target detection, Signal to noise ratio, Radon, Statistical analysis, Detection and tracking algorithms, LIDAR, Signal attenuation, Interference (communication), Optoelectronics, Signal detection
In this paper we build a statistical model for the LIDAR signal validation (estimation, selection, statistical validation of the Mie backscattered optical field from pollutants at medium and long range distances). The LIDAR backscattered optical signal is realized via the operative characteristic. Defining Qo as the false alarm probability and Qd the detection probability, the operative characteristic is a curve in the plane defined by the indecision zone of the LIDAR signal validation. The aim of this paper is to propose some optimization methods of the operative characteristic associated with the LIDAR signal validation.