scholarly journals Comparison of two automated aerosol typing methods and their application on an EARLINET station

2018 ◽  
Author(s):  
Kalliopi Artemis Voudouri ◽  
Nikolaos Siomos ◽  
Konstantinos Michailidis ◽  
Nikolaos Papagiannopoulos ◽  
Lucia Mona ◽  
...  
Keyword(s):  
Atmospheric Conditions ◽  
Raman Lidar ◽  
Type Definition ◽  
Typing Methods ◽  
Degree Of Confidence ◽  
The One ◽  
Aerosol Types ◽  
Good Agreement ◽  
Aerosol Type

Abstract. In this study we compare two automatic algorithms for the characterization of the aerosol layers derived from a Raman lidar and we test their application over a specific environment in continental Thessaloniki. Both automated aerosol typing methods base their typing on aerosol intensive properties. The methodologies are briefly described and the application on two case studies is presented. The results are checked for their consistency with satellite products and model simulations. Further application of the two classification tools was conducted. The evaluated dataset corresponds to ACTRIS/EARLINET (European Aerosol Research Lidar NETwork) Thessaloniki data acquired during the period 2012–2015. 80 layers out of 116 (percentage of 69 %) were successfully typed by both algorithms and assigned to four major types of aerosols: Dust, Maritime, Polluted Smoke and Clean Continental. The analysis showed that the two algorithms are in a very good agreement, when applied to real atmospheric conditions, with an agreement percentage of 88.8 % for Dust, 93.7 % for Polluted Smoke and 70 % for Clean Continental. The Maritime category was the one with the largest spread. These differences are attributed to differences in defining the aerosol types for the two methods. The overall consistency of the aerosol typing between the two automatic procedures despite the different aerosol type definition, allows their applicability to lidar data for characterization purposes. The joint characterization shows the highest degree of confidence in identifying Dust and Polluted Smoke, and emphasizes the need of further investigation for Maritime and Clean Continental type.

scholarly journals Comparison of two automated aerosol typing methods and their application to an EARLINET station

2019 ◽  
Vol 19 (16) ◽  
pp. 10961-10980 ◽  
Author(s):  
Kalliopi Artemis Voudouri ◽  
Nikolaos Siomos ◽  
Konstantinos Michailidis ◽  
Nikolaos Papagiannopoulos ◽  
Lucia Mona ◽  
...  
Keyword(s):  
Atmospheric Conditions ◽  
Characterization Methods ◽  
Identification Rate ◽  
Automatic Mode ◽  
Lidar Measurements ◽  
Typing Methods ◽  
Threshold Criteria ◽  
Selection Of ◽  
Aerosol Type

Abstract. In this study we apply and compare two algorithms for the automated aerosol-type characterization of the aerosol layers derived from Raman lidar measurements over the EARLINET station of Thessaloniki, Greece. Both automated aerosol-type characterization methods base their typing on lidar-derived aerosol-intensive properties. The methodologies are briefly described and their application to three distinct cases is demonstrated and evaluated. Then the two classification schemes were applied in the automatic mode to a more extensive dataset. The dataset analyzed corresponds to ACTRIS/EARLINET (European Aerosol Research Lidar NETwork) Thessaloniki data acquired during the period 2012–2015. Seventy-one layers out of 110 (percentage of 65 %) were typed by both techniques, and 56 of these 71 layers (percentage of 79 %) were attributed to the same aerosol type. However, as shown, the identification rate of both typing algorithms can be changed regarding the selection of appropriate threshold criteria. Four major types of aerosols are considered in this study: Dust, Maritime, PollutedSmoke and CleanContinental. The analysis showed that the two algorithms, when applied to real atmospheric conditions, provide typing results that are in good agreement regarding the automatic characterization of PollutedSmoke, while there are some differences between the two methods regarding the characterization of Dust and CleanContinental. These disagreements are mainly attributed to differences in the definitions of the aerosol types between the two methods, regarding the intensive properties used and their range.

scholarly journals A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances

2015 ◽  
Vol 15 (18) ◽  
pp. 10597-10618 ◽  
Author(s):  
M. J. M. Penning de Vries ◽  
S. Beirle ◽  
C. Hörmann ◽  
J. W. Kaiser ◽  
P. Stammes ◽  
...  
Keyword(s):  
Classification Algorithm ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Aerosol Composition ◽  
Ångström Exponent ◽  
Aerosol Classification ◽  
Aerosol Index ◽  
Aerosol Types ◽  
Good Agreement ◽  
Aerosol Type

Abstract. Detecting the optical properties of aerosols using passive satellite-borne measurements alone is a difficult task due to the broadband effect of aerosols on the measured spectra and the influences of surface and cloud reflection. We present another approach to determine aerosol type, namely by studying the relationship of aerosol optical depth (AOD) with trace gas abundance, aerosol absorption, and mean aerosol size. Our new Global Aerosol Classification Algorithm, GACA, examines relationships between aerosol properties (AOD and extinction Ångström exponent from the Moderate Resolution Imaging Spectroradiometer (MODIS), UV Aerosol Index from the second Global Ozone Monitoring Experiment, GOME-2) and trace gas column densities (NO2, HCHO, SO2 from GOME-2, and CO from MOPITT, the Measurements of Pollution in the Troposphere instrument) on a monthly mean basis. First, aerosol types are separated based on size (Ångström exponent) and absorption (UV Aerosol Index), then the dominating sources are identified based on mean trace gas columns and their correlation with AOD. In this way, global maps of dominant aerosol type and main source type are constructed for each season and compared with maps of aerosol composition from the global MACC (Monitoring Atmospheric Composition and Climate) model. Although GACA cannot correctly characterize transported or mixed aerosols, GACA and MACC show good agreement regarding the global seasonal cycle, particularly for urban/industrial aerosols. The seasonal cycles of both aerosol type and source are also studied in more detail for selected 5° × 5° regions. Again, good agreement between GACA and MACC is found for all regions, but some systematic differences become apparent: the variability of aerosol composition (yearly and/or seasonal) is often not well captured by MACC, the amount of mineral dust outside of the dust belt appears to be overestimated, and the abundance of secondary organic aerosols is underestimated in comparison with GACA. Whereas the presented study is of exploratory nature, we show that the developed algorithm is well suited to evaluate climate and atmospheric composition models by including aerosol type and source obtained from measurements into the comparison, instead of focusing on a single parameter, e.g., AOD. The approach could be adapted to constrain the mix of aerosol types during the process of a combined data assimilation of aerosol and trace gas observations.

scholarly journals Equivalent Circuit Model for Cu(In,Ga)Se2 Solar Cells Operating at Different Temperatures and Irradiance

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 324 ◽  
Author(s):  
Matteo Bronzoni ◽  
Lorenzo Colace ◽  
Andrea De Iacovo ◽  
Antonino Laudani ◽  
Gabriele Lozito ◽  
...  
Keyword(s):  
Solar Cells ◽  
Equivalent Circuit Model ◽  
Reduced Form ◽  
Large Set ◽  
Atmospheric Conditions ◽  
Accurate Identification ◽  
Pv Systems ◽  
Different Temperatures ◽  
The One

The modeling of photovoltaic cells is an essential step in the analysis of the performances and characterization of PV systems. This paper proposes an experimental study of the dependence of the five parameters of the one-diode model on atmospheric conditions, i.e., irradiance and temperature in the case of thin-film solar cells. The extraction of the five parameters was performed starting from two sets of experimental data obtained from Cu(In,Ga)Se2 solar cells fabricated by the low-temperature pulsed electron deposition technique. A reduced form approach of the one-diode model has been adopted, leading to an accurate identification of the cell. It was possible to elaborate suitable relations describing the behavior of the parameters as functions of the environmental conditions. This allowed accurately predicting the trends of the parameters from a pair of curves, instead of a whole set of measurements. The developed model describing the dependence on irradiance and temperature was validated by means of a large set of experimental measurements on several Cu(In,Ga)Se2 (CIGS) devices built with the same technological process.

scholarly journals A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances

2015 ◽  
Vol 15 (9) ◽  
pp. 13551-13605
Author(s):  
M. J. M. Penning de Vries ◽  
S. Beirle ◽  
C. Hörmann ◽  
J. W. Kaiser ◽  
P. Stammes ◽  
...  
Keyword(s):  
Classification Algorithm ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Aerosol Composition ◽  
Ångström Exponent ◽  
Aerosol Classification ◽  
Aerosol Index ◽  
Aerosol Types ◽  
Good Agreement ◽  
Aerosol Type

Abstract. Detecting the optical properties of aerosols using passive satellite-borne measurements alone is a difficult task due to the broad-band effect of aerosols on the measured spectra and the influences of surface and cloud reflection. We present another approach to determine aerosol type, namely by studying the relationship of aerosol optical depth (AOD) with trace gas abundance, aerosol absorption, and mean aerosol size. Our new Global Aerosol Classification Algorithm, GACA, examines relationships between aerosol properties (AOD and extinction Ångström exponent from the Moderate Resolution Imaging Spectroradiometer (MODIS), UV Aerosol Index from the second Global Ozone Monitoring Experiment, GOME-2) and trace gas column densities (NO2, HCHO, SO2 from GOME-2, and CO from MOPITT, the Measurements of Pollution in the Troposphere instrument) on a monthly mean basis. First, aerosol types are separated based on size (Ångström exponent) and absorption (UV Aerosol Index), then the dominating sources are identified based on mean trace gas columns and their correlation with AOD. In this way, global maps of dominant aerosol type and main source type are constructed for each season and compared with maps of aerosol composition from the global MACC (Monitoring Atmospheric Composition and Climate) model. Although GACA cannot correctly characterize transported or mixed aerosols, GACA and MACC show good agreement regarding the global seasonal cycle, particularly for urban/industrial aerosols. The seasonal cycles of both aerosol type and source are also studied in more detail for selected 5° × 5° regions. Again, good agreement between GACA and MACC is found for all regions, but some systematic differences become apparent: the variability of aerosol composition (yearly and/or seasonal) is often not well captured by MACC, the amount of mineral dust outside of the dust belt appears to be overestimated, and the abundance of secondary organic aerosols is underestimated in comparison with GACA. Whereas the presented study is of exploratory nature, we show that the developed algorithm is well suited to evaluate climate and atmospheric composition models by including aerosol type and source obtained from measurements into the comparison, instead of focusing on a single parameter, e.g. AOD. The approach could be adapted to constrain the mix of aerosol types during the process of a combined data assimilation of aerosol and trace gas observations.

scholarly journals Airborne high spectral resolution lidar observation of pollution aerosol during EUCAARI-LONGREX

2013 ◽  
Vol 13 (5) ◽  
pp. 2435-2444 ◽  
Author(s):  
S. Groß ◽  
M. Esselborn ◽  
F. Abicht ◽  
M. Wirth ◽  
A. Fix ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Data Set ◽  
Lidar Ratio ◽  
Linear Depolarization Ratio ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
Lidar Observations ◽  
Aerosol Type

Abstract. Airborne high spectral resolution lidar observations over Europe during the EUCAARI-LONGREX field experiment in May 2008 are analysed with respect to the optical properties of continental pollution aerosol. Continental pollution aerosol is characterized by its depolarisation and lidar ratio. Over all, the measurements of the lidar ratio and the particle linear depolarization ratio of pollution aerosols provide a narrow range of values. Therefore, this data set allows for a distinct characterization of the aerosol type "pollution aerosol" and thus is valuable both to distinguish continental pollution aerosol from other aerosol types and to determine mixtures with other types of aerosols.

scholarly journals Aerosol climatology: on the discrimination of aerosol types over four AERONET sites

2007 ◽  
Vol 7 (3) ◽  
pp. 6357-6411 ◽  
Author(s):  
D. G. Kaskaoutis ◽  
H. D. Kambezidis ◽  
N. Hatzianastassiou ◽  
P. G. Kosmopoulos ◽  
K. V. S. Badarinath
Keyword(s):  
Forest Fires ◽  
Atmospheric Conditions ◽  
Large Variability ◽  
Mean Values ◽  
Angstrom Exponent ◽  
Ångström Exponent ◽  
Seasonal Basis ◽  
Aerosol Types ◽  
Ångstrom Exponent

Abstract. Aerosols have a significant regional and global effect on climate, which is about equal in magnitude but opposite in sign to that of greenhouse gases. Nevertheless, the aerosol climatic effect changes strongly with space and time because of the large variability of aerosol physical and optical properties, which is due to the variety of their sources, which are natural, and anthropogenic, and their dependence on the prevailing meteorological and atmospheric conditions. Characterization of aerosol properties is of major importance for the assessment of their role for climate. In the present study, 3-year AErosol RObotic NETwork (AERONET) data from ground-based sunphotometer measurements are used to establish climatologies of aerosol optical depth (AOD) and Ångström exponent α in several key locations of the world, characteristic of different atmospheric environments. Using daily mean values of AOD at 500 nm (AOD500) and Ångström exponent at the pair of wavelengths 440 and 870 nm (α 440–870), a discrimination of the different aerosol types occurring in each location is achieved. For this discrimination, appropriate thresholds for AOD500 and α 440–870 are applied. The discrimination of aerosol types in each location is made on an annual and seasonal basis. It is shown that a single aerosol type in a given location can exist only under specific conditions (e.g. intense forest fires or dust outbreaks), while the presence of well-mixed aerosols is the accustomed situation. Background clean aerosol conditions (AOD500<0.06) are mostly found over remote oceanic surfaces occurring on average in ~56.7% of total cases, while this situation is quite rare over land (occurrence of 3.8–13.7%). Our analysis indicates that these percentages change significantly from season to season. The spectral dependence of AOD exhibits large differences between the examined locations, while it exhibits a strong annual cycle.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

scholarly journals Characterization of Tiled Architecture for C-Band 1-Bit Beam-Steering Transmitarray

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1259
Author(s):  
Dmitry Kozlov ◽  
Irina Munina ◽  
Pavel Turalchuk ◽  
Vitalii Kirillov ◽  
Alexey Shitvov ◽  
...  
Keyword(s):  
Communication Systems ◽  
Beam Steering ◽  
Unit Cell ◽  
Electromagnetic Simulations ◽  
Fifth Generation ◽  
Full Wave ◽  
Array Architecture ◽  
Modulation Pattern ◽  
Good Agreement

A new implementation of a beam-steering transmitarray is proposed based on the tiled array architecture. Each pixel of the transmitarray is manufactured as a standalone unit which can be hard-wired for specific transmission characteristics. A set of complementary units, providing reciprocal phase-shifts, can be assembled in a prescribed spatial phase-modulation pattern to perform beam steering and beam forming in a broad spatial range. A compact circuit model of the tiled unit cell is proposed and characterized with full-wave electromagnetic simulations. Waveguide measurements of a prototype unit cell have been carried out. A design example of a tiled 10 × 10-element 1-bit beam-steering transmitarray is presented and its performance benchmarked against the conventional single-panel, i.e., unibody, counterpart. Prototypes of the tiled and single-panel C-band transmitarrays have been fabricated and tested, demonstrating their close performance, good agreement with simulations and a weak effect of fabrication tolerances. The proposed transmitarray antenna configuration has great potential for fifth-generation (5G) communication systems.

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