Located at a distance more than 3400Km from Iceland, where the eruption of Eyjafjallajökull volcano occurred,
Romania was under the influence of volcanic ash transported by middle altitude air masses across Europe. Apart from
two clear episodes on April 18 and April 21, 2010 the mix of volcanic ash with Saharan dust was detected by the
multiwavelength Raman lidar in Bucharest. Optical properties of aerosol layers for these particular cases showed an
increase of the linear particle depolarization, as well as a decrease of the Angstrom exponent, compared with the pure
long-range transported volcanic ash. The case of May 5th, 2010 is analyzed from lidar and ground-level data, accounting
for layer dynamics, optical properties and chemical composition. Using high resolution lidar data we could make a clear
distinction between ash and dust layers up to their mixing in the PBL. In order to account for similarities and differences,
the same analysis was done for May 10th and 11th, when several distinct layers were depicted. The signature of ash
(sulfate) was identified by Aerosol Mass Spectrometer at ground-level, on May 5th and May 11th.
EARLINET, the European Aerosol Research Lidar NETwork, established in 2000, is the first coordinated lidar network
for tropospheric aerosol study on the continental scale. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardised data
exchange format. At present, the network includes 27 lidar stations distributed over Europe.
EARLINET performed almost continuous measurements since 15 April 2010 in order to follow the evolution of the
volcanic plume generated from the eruption of the Eyjafjallajökull volcano, providing the 4-dimensional distribution of
the volcanic ash plume over Europe. During the 15-30 April period, volcanic particles were detected over Central Europe
over a wide range of altitudes, from 10 km down to the local planetary boundary layer (PBL). Until 19 April, the
volcanic plume transport toward South Europe was nearly completely blocked by the Alps. After 19 April volcanic
particles were transported to the south and the southeast of Europe. Descending aerosol layers were typically observed
all over Europe and intrusion of particles into the PBL was observed at almost each lidar site that was affected by the
volcanic plume. A second event was observed over Portugal and Spain (6 May) and then over Italy on 9 May 2010. The
volcanic plume was then observed again over Southern Germany on 11 May 2010.
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
plumes.
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.
Coordinated lidar observations of Saharan dust over Europe are performed in the frame of the EARLINET-ASOS
(2006-2011) project, which comprises 25 stations: 16 Raman lidar stations, including 8 multi-wavelength
(3+2 station) Raman lidar stations, are used to retrieve the aerosol microphysical properties. Since
the launch of CALIOP, the two-wavelength lidar on board the CALIPSO satellite (June 2006) our lidar
network has been performing correlative aerosol measurements during CALIPSO overpasses over the
individual stations. In our presentation, we report on the correlative measurements obtained during Saharan
dust intrusions in the period from June 2006 to June 2008. We found that the number of dust events is
generally greatest in late spring, summer and early autumn periods, mainly in southern and south-eastern
Europe. A measurement example is presented that was analyzed to show the potential of a ground based lidar
network to follow a dust event over a specific study area, in correlation with the CALIOP measurements. The
dust transport over the studied area was simulated by the DREAM forecast model. Cross-section analyses of
CALIOP over the study area were used to assess the model performance for describing and forecasting the
vertical and horizontal distribution of the dust field over the Mediterranean. Our preliminary results can be
used to reveal the importance of the synergy between the CALIOP measurement and the dust model, assisted
by ground-based lidars, for clarifying the overall transport of dust over the European continent.
The present knowledge of the aerosol distribution is not sufficient to estimate the aerosol influence on global and
regional environmental conditions and climate. This observational gap can be closed by using advanced laser remote
sensing. EARLINET (European Aerosol Research Lidar Network) is the first aerosol lidar network, established in 2000,
with the main goal to provide a comprehensive, quantitative, and statistically significant database for the aerosol
distribution on a continental scale. EARLINET is a coordinated network of European stations (25 at present) using advanced lidar methods for the vertical profiling of aerosols. The network activity is based on simultaneous scheduled
measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a
standardised data exchange format. Further observations are performed to monitor special events.
EARLINET-ASOS (Advanced Sustainable Observation System) is a five year EC Project started in 2006, based on the
EARLINET infrastructure. The main objectives are: to make EARLINET a world-leading instrument for the observation
of the 4-D aerosol distribution on continental scale; to foster aerosol-related process studies, validation of satellite
sensors, model development and validation, assimilation of aerosol data into operational models; and to build a
comprehensive climatology of the aerosol distribution.
The open-path technique is a widely use method for air pollution monitoring, being capable of detecting trace gases
down to ppb concentrations. Using this technique, the DOAS system can measure simultaneously several types of
atmospheric molecular compounds having UV absorption spectra, by averaging on a long optical path (hundreds of
meters).
In this paper, two kinds of comparative measurements by DOAS and in situ detectors (using the point monitoring
technique), in high polluted areas from Bucharest and the surroundings, are presented and analyzed. Only point
monitoring is a standardized technique and therefore by comparing the two methods, several strengths and weaknesses of
the open path technique will be evidentiated. This study is intended to mark out main environmental conditions (e.g.
atmospheric fluctuations, topography) responsible for important differences that appear between experimental data
acquired with the two techniques.
The European Aerosol Research Lidar Network (EARLINET) was established in 2000 to derive a comprehensive, quantitative, and statistically significant data base for the aerosol distribution on the European scale.
At present, EARLINET consists of 25 stations: 16 Raman lidar stations, including 8 multi-wavelength Raman lidar stations which are used to retrieve aerosol microphysical properties.
EARLINET performs a rigorous quality assurance program for instruments and evaluation algorithms. All stations measure simultaneously on a predefined schedule at three dates per week to obtain unbiased data for climatological studies.
Since June 2006 the first backscatter lidar is operational aboard the CALIPSO satellite. EARLINET represents an excellent tool to validate CALIPSO lidar data on a continental scale. Aerosol extinction and lidar ratio measurements provided by the network will be particularly important for that validation.
The measurement strategy of EARLINET is as follows: Measurements are performed at all stations within 80 km from the overpasses and additionally at the lidar station which is closest to the actually overpassed site. If a multi-wavelength Raman lidar station is overpassed then also the next closest 3+2 station performs a measurement.
Altogether we performed more than 1000 correlative observations for CALIPSO between June 2006 and June 2007.
Direct intercomparisons between CALIPSO profiles and attenuated backscatter profiles obtained by EARLINET lidars look very promising.
Two measurement examples are used to discuss the potential of multi-wavelength Raman lidar observations for the validation and optimization of the CALIOP Scene Classification Algorithm.
Correlative observations with multi-wavelength Raman lidars provide also the data base for a harmonization of the CALIPSO aerosol data and the data collected in future ESA lidar-in-space missions.
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.
EARLINET-ASOS (European Aerosol Research Lidar Network - Advanced Sustainable Observation System) is a 5-year EC Project started in 2006. Based on the EARLINET infrastructure, it will provide appropriate tools to improve the quality and availability of the continuous observations. The EARLINET multi-year continental scale data set is an excellent instrument to assess the impact of aerosols on the European and global environment and to support future satellite missions. The project is addressed in optimizing instruments and algorithms existing within EARLINET-ASOS, exchanging expertise, with the main goal to build a database with high quality aerosol data. In particular, the optimization of the algorithms for the retrieval of the aerosol optical and microphysical properties is a crucial activity. The main objective is to provide all partners with the possibility to use a common processing chain for the evaluation of their data, from raw signals to final products. Raw signals may come from different types of systems, and final products are profiles of optical properties, like backscatter and extinction, and, if the instrument properties permit, of microphysical properties. This will have a strong impact on the scientific community because data with homogeneous well characterized quality will be made available in nearly real time.
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.
EARLINET, the European Aerosol Research Lidar Network, is the first aerosol lidar network, established in 2000, with the main goal to provide a comprehensive, quantitative, and statistically significant data base for the aerosol distribution on a continental scale. At present, 23 stations distributed over Europe are part of the network. The EARLINET-ASOS (Advanced Sustainable Observation System) EC Project, starting on the EARLINET infrastructure, will contribute to the improvement of continuing observations and methodological developments that are urgently needed to provide the multi-year continental scale data set necessary to assess the impact of aerosols on the European and global environment and to support future satellite missions. The main objective of EARLINET-ASOS 5-year project, started on 1 March 2006, is to improve the EARLINET infrastructure resulting in a better spatial and temporal coverage of the observations, continuous quality control for the complete observation system, and fast availability of standardized data products. This will be reached by defining and using common standards for instruments, operation procedures, observation schemes, data processing including advanced retrieval algorithms, and dissemination of data. The expected outcome is the most comprehensive data source for the 4-D spatio-temporal distribution of aerosols on a continental scale.
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.
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.
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.
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.
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.
KEYWORDS: LIDAR, Signal detection, Statistical analysis, Detection and tracking algorithms, Radon, Interference (communication), Signal attenuation, Optoelectronics, Signal to noise ratio, Target 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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.