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This paper presents a new code for the analysis of gamma spectra generated by an equipment for continuous measurement of gamma radioactivity in aerosols with paper filter. It is called pGamma and has been developed by the Nuclear Engineering Research Group at the Technical University of Catalonia - Barcelona Tech and by Raditel Serveis i Subministraments Tecnològics, Ltd. The code has been developed to identify the gamma emitters and to determine their activity concentration. It generates alarms depending on the activity of the emitters and elaborates reports. Therefore it includes a library with NORM and artificial emitters of interest. The code is being adapted to the monitors of the Environmental Radiological Surveillance Network of the local Catalan Government in Spain (Generalitat de Catalunya) and is used at three stations of the Network. [ABSTRACT FROM PUBLISHER]

This paper describes an equipment for continuous measurement and identification of gamma radioactivity in aerosols developed by the Nuclear Engineering Research Group (NERG) at the Technical University of Catalonia (UPC) and Raditel Serveis i Subministraments Tecnològics, Ltd. A spectrometric analysis code has been specially designed for it. Spectrum analysis identifies and determines activity concentration of aerosol emitters captured by a fiberglass paper filter. This new equipment is currently operating in three radioactivity monitoring stations of the Environmental Radiological Surveillance Network of the Generalitat of Catalunya (local Catalan government): two near Ascó and Vandellòs Nuclear Power Plants in the province of Tarragona and one in the city of Barcelona. Two more monitors are expected to be deployed at Roses, Girona, Spain, and Puigcerdà, Barcelona, Spain. Measurements and evolution analysis results of emitters identified at these stations were also provided. [ABSTRACT FROM PUBLISHER]

This paper presents design, fabrication, characterization, and cascade assembly of chip-scale aerosol inertial impactors (airborne micro/nanoparticle collector). Microelectromechanical resonant mass balances are integrated within the fabricated chip-scale aerosol impactors for real-time particulate matter (PM) concentration measurement. A microfabrication process including only three-lithography steps has been developed to form the main impactor stage components: mass balance, impactor nozzle, and impaction micro-chamber on a single silicon on insulator (SOI) substrate. This approach enables dramatic miniaturization of the conventional bulky impactors while adding real-time measurement capability. Furthermore, utilization of microfabrication techniques can address some of the existing manufacturing and precision assembly challenges for such devices. Smaller nozzle diameters down to 30 \boldsymbol \mu \textm enabled by micro-lithography minimize the air flow, typically in the few liters per minute range, to milliliters per minute, and consequently the pump capacity and power requirements. Fabricated devices are tested as individual stages as well as cascaded dual-stages. Tests performed in different environments with different particle mass concentrations show an evident correlation between the resonator response and the expected particle concentrations. scanning electron microscopy (SEM) images of the deposited particles for single impactor stages shows particle sizes as small as ~12 nm. For the cascade impactors, the SEM images show particles of ~150 and 41 nm for first and second stage, respectively. This paper demonstrated that segregation of nano-particles was achieved with the proposed dual stage chip-scale aerosol inertial impactor. [ABSTRACT FROM PUBLISHER]

A long-term historical aerosol optical depth (AOD) data set from 1982 to 2011 over China (15–45° N; 75–135° E) with 0.1 spatial resolution has been produced from Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmospheres—Extended level-2B data. The spatial distribution pattern shows that high AOD values are found in central and eastern China over the entire period with AODs larger in summer and spring than in autumn and winter. As the high-quality products from AERONET were absent for this period over mainland China, AOD data obtained using the broadband extinction method from solar radiation stations have been used to verify the quality of the AVHRR AOD data set over China. The intercomparison results show that the interannual variation of AOD has been well captured in the variation curve of the AOD monthly mean and the variation trend is also consistent over the whole period. The correlation coefficient of the monthly mean is mostly larger than 0.55, the agreement index is larger than 0.57, and the relative error is less than 21%. Both AVHRR and visibility data sets show high values in regions with rapid economic development. Using Moderate Resolution Imaging Spectroradiometer AOD data as references, it is found that AVHRR AOD from this paper has better accuracy in general than that from Deep Blue (DB) algorithm over China, especially over eastern and southern China, while DB provides more coverage especially over bright surface such as northwest China. This long-term historic AOD data set can be used together with other AOD data sets to study the climate and environmental changes, especially in the 1980s and 1990s. [ABSTRACT FROM AUTHOR]

In this paper, we propose a two-layer heterogeneous network to realize the remote monitoring and advanced warning for infectious diseases spread by airborne pathogens, whose detection can be considered as a binary detection problem. To intuitively study the detection process, we abstract it as a molecular communication via diffusion (MCvD) model and uncover that one of the key factors to impact the detection performance is inter-symbol interference (ISI), i.e., the viral aerosol from other biological entities. Therefore, overcoming ISI is imperative to ensure reliable detection. In the abstracted MCvD model, the detection performance can be described by the bit error rate (BER) performance. Following this assumption, we propose to optimize the detection interval to minimize the impact of ISI while ensuring the accurate detection of the transmitted information symbol, which is suitable for both the absorbing and passive receivers. For tractability, based on the signal-to-interference difference (SID) and signal-to-interference-and-noise amplitude ratio (SINAR), we design a modified-SINAR (mSINAR) to measure BER performance for the MCvD system with a variable detection interval. Besides, we derive the optimal detection interval in closed-form. Using simulation results, we show that in terms of BER, our proposed mSINAR scheme is superior to the competitive schemes, and performs similarly to the scheme with optimal intervals determined by the exhaustive search. [ABSTRACT FROM AUTHOR]

The lack of medical salt aerosssol concentration detection method and instability powder atomization result in poor aerosol inhalation treatment effects. Considering medical vaporizer specific requirements, physical and chemical characteristics of salt powder commonly used, this paper analyzes salt particle light scattering using T-matrix method based on discrete source, calculated scattering intensity of salt particle with diameter of 0.4 to 6~\mu \textm , develops photoelectric salt aerosol concentration sensor with forward differential scattering light path and weak current signal conditioning circuits. Sensor salt aerosol concentration calibration experiments and performance tests was carried out, and the results show as follows: the maximum residuals of sensor is 0.262 mg/L in calibration experiments and relative error in performance tests was 12.9%, satisfied salt aerosol concentration detection requirements and could provide basis for on line stability control of aerosol concentration in medical salt powder atomization process. [ABSTRACT FROM PUBLISHER]

Recent additive manufacturing technologies, such as 3-D printing and printed electronics, require constant speed motion for consistent material deposition. In this paper, a new path planning algorithm is developed for an \(XY\) -motion stage with an emphasis on aerosol printing. The continuous aerosol stream provided by the printing nozzle requires constant velocity in relative motion of a substrate to evenly deposit inks. During transitioning between print segments, a shutter prevents the aerosol from reaching the substrate, therefore wasting material. The proposed path planning algorithm can control motion of an \(XY\) stage for an arbitrary printing path and desired velocity while minimizing material waste. Linear segments with parabolic blends (LSPBs) trajectory planning is used during printing, and minimum time trajectory (MTT) planning is used during printer transition. Simulation results show that combining LSPB with MTT can minimize the printing time while following the desired path. [ABSTRACT FROM AUTHOR]

Aerosol effects evaluation on Earth’s radiation budget demands knowledge of its concentration, spatial, and temporal distribution. Therefore, long-term measurements of aerosol properties in different regions of Earth are very important. In this paper, indium nitride (InN)- and indium oxynitride (InNO)-based photodiodes calibration was realized. A pyranometer was used in this paper. Calibrated InN and InNO Schottky photodiodes will be used for aerosol detection. According to the calibration tests, it was found that the most suitable sensors for the continuation of an aerosol statistical study in the atmosphere are those made with the InNO deposited with oxygen 10% and 20%; their correlation coefficient values are almost one. Besides, their measures do not reach the saturation point. In future, we intend to use these devices in a quantitative study of aerosols present in the center of a large city, to get a sense of human interference in the atmosphere composition and its consequences. [ABSTRACT FROM PUBLISHER]

Many aerosol retrieval algorithms based on the remote sensing technology have been developed and applied to produce aerosol optical depth (AOD) products for different satellite sensors. The dark target (DT) and deep blue (DB) algorithms are two main MODIS aerosol retrieval algorithms that are suitable for dark or bright areas. The estimation of land surface reflectance (LSR) is necessary to improve the accuracy of AOD retrievals. Therefore, in this paper, a new procedure to improve LSR estimation using MODIS surface reflectance products is developed. A new high-resolution <1000 m> aerosol retrieval algorithm with a priori LSR database support (HARLS) is proposed. The purpose of this paper is to evaluate the spatial adaptability of different MODIS AOD products produced by the above three algorithms. The Beijing-Tianjin-Hebei (Jing-Jin-Ji) region, which features complex surface structures and serious air pollution, was chosen as the study area, and the different AOD products are validated using aerosol robotic network (AERONET) AOD ground measurements from four stations located in dark and bright areas. Compared with the DT retrievals (\textR\approx 0.88- 0.95) , the C6 DB AOD retrievals yield a stronger correlation (\textR \approx 0.94- 0.97) with AERONET AOD and lower RMSE, MRE and MAE values, resulting in approximately 20%–30% less average overestimation. The C6 DT \&DB AOD results show a retrieval quality (\text{R}\approx 0.93- 0.97) similar to that of DB, with approximately 50%–70% of the collections falling within the expected error (EE). Moreover, DT \&DB is much better than DT, with more than approximately 10%–20% of the collections falling within the EE. However, HARLS achieves a high correlation (\textR\approx 0.93- 0.96) with the AERONET AODs, with low RMSE (\approx 0.118- 0.128) and MAE (\approx 0.09- 0.12) and small offsets (\text{intercept}\approx 0.00- 0.04) . HARLS retrievals exhibited 7%–8% less uncertainty than the C6 DB retrievals, 37%–38% less uncertainty than the C6 DT\&$ DB retrievals, and 39%–44% less uncertainty than the C5 and C6 DT retrievals. HARLS achieves greater accuracy and reliability in AOD retrieval, and it is less biased (\text{RMB} \approx 0.90- 1.10) and better overall than the routine MODIS aerosol products over the Jing-Jin-Ji region. [ABSTRACT FROM PUBLISHER]

The aerosol-assisted atmospheric-pressure planar dielectric-barrier-discharge-type plasma deposition (AA-APPD) system can polymerize monomers and immobilize biomolecules simultaneously. In this paper, we used this technology to deposit biocomposite thin films of polyethylene (PE) along with lysozyme (Lyz) under different aerosol solution temperatures and at different coating positions in the discharge region. In addition, we compared the deposition efficacy of two kinds of Lyz solution using deionized (DI)-water and phosphate-buffered saline (PBS) as solvents, respectively. The results show that deposition rate of thin films increases with increasing solution temperature at most coating positions. In addition, coatings from Lyz-PBS perform higher deposition rates, but with weaker Lyz viability as compared with that of Lyz DI-water. Finally, we also verified that this DBD-type AA-APPD system can not only successfully deposit Lyz in PE thin film, but also maintain Lyz viability after plasma process under different solution temperatures and positions. [ABSTRACT FROM AUTHOR]

This paper presents low-loss 3-D transmission lines and vertical interconnects fabricated by aerosol jet printing (AJP) which is an additive manufacturing technology. AJP stacks up multiple layers with minimum feature size as small as 20 \mu \textm in the $xy$ -direction and 0.7 \mu \textm in the z-direction. It also solves the problem of fabricating vias to realize the vertical transition by 3-D printing. The loss of the stripline is measured to be 0.53 dB/mm at 40 GHz. The vertical transition achieves a broadband bandwidth from 0.1 to 40 GHz. The results of this paper demonstrate the feasibility of utilizing 3-D printing for low-cost multilayer system-on-package RF/millimeter-wave front-ends. [ABSTRACT FROM PUBLISHER]

The quality and accuracy of remote sensing instruments continue to increase, allowing geoscientists to perform various quantitative retrieval applications to observe the geophysical variables of land, atmosphere, ocean, etc. The explosive growth of time-series remote sensing (RS) data over large-scales poses great challenges on managing, processing, and interpreting RS ‘‘Big Data.’’ To explore these time-series RS data efficiently, in this paper, we design and implement a high-performance framework to address the time-consuming time-series quantitative retrieval issue on a graphics processing unit cluster, taking the aerosol optical depth (AOD) retrieval from satellite images as a study case. The presented framework exploits the multilevel parallelism for time-series quantitative RS retrieval to promote efficiency. At the coarse-grained level of parallelism, the AOD time-series retrieval is represented as multidirected acyclic graph workflows and scheduled based on a list-based heuristic algorithm, heterogeneous earliest finish time, taking the idle slot and priorities of retrieval jobs into account. At the fine-grained level, the parallel strategies for the major remote sensing image processing algorithms divided into three categories, i.e., the point or pixel-based operations, the local operations, and the global or irregular operations have been summarized. The parallel framework was implemented with message passing interface and compute unified device architecture, and experimental results with the AOD retrieval case verify the effectiveness of the presented framework. [ABSTRACT FROM AUTHOR]

In this paper, we focus on airborne hyperspectral imaging methodology to characterize particulate matter (PM) near industrial emission sources. Two short-term intensive campaigns were carried out in the vicinity of a refinery in the south of France, in September 2015 and February 2016. Different protocols of in situ PM measurements were performed, at stack measurements (flow rate and offline chemical analysis) and online measurement at the refinery border (size distribution, concentration, and chemistry of aerosols). A multitemporal methodology to retrieve aerosol type, to map the aerosol concentration, and to quantify mass flow rate from airborne hyperspectral data is described in this paper. This method applied to the refinery detected plume from the main stack yields a black carbon to sulfate ratio of 10/90 in mass inside the plume, with an average size distribution smaller than 100 nm. These results are in a good agreement with the online analysis of aerosols at the refinery border. The resulting quantitative map with a metric spatial resolution leads to an estimated flow rate of about 1 g/s and is in a good agreement with in situ stack measurements and modeling. [ABSTRACT FROM AUTHOR]

In the autumn and winter, aerosol is the important atmospheric pollutant over the Beijing–Tianjin–Hebei region. For monitoring aerosol in the autumn and winter, the lack of vegetation and the aging of MODIS sensor are two problems that needed to be solved. In this paper, after analyzing the characteristics of aerosol radiance in the red and shortwave infrared ($2.12~\mu \text{m}$) bands of MODIS, we develop a new algorithm for terrestrial aerosol with the assumption that the reflectance ratio between the red and $2.12~\mu \text{m}$ bands is invariant. With MODIS data over the Beijing–Tianjin–Hebei region from September 2016 to February 2017, the algorithm is applied to aerosol retrieval. The retrieved aerosol optical depth images show that our algorithm can retrieve aerosol over sparse vegetation, and the validation with the AERONET/PHOTONS Beijing site shows that the correlation is greater than 0.9% and 77% of the retrievals fall within the expected error. An error analysis shows that a 2% error in the proportion of the soot component can lead to 15% retrieval error, and over more than 60% of the surface area, the error from the changes in the ratio between the red and $2.12~\mu \text{m}$ bands can lead to retrieved errors less than 0.1. [ABSTRACT FROM AUTHOR]

The advanced Himawari imager (AHI) aboard the Himawari-8 geostationary satellite provides high-frequency observations with broad coverage, multiple spectral channels, and high spatial resolution. In this paper, AHI data were used to develop an algorithm for joint retrieval of aerosol optical depth (AOD) over land and land surface bidirectional reflectance. Instead of performing surface reflectance estimation before calculating AOD, the AOD and surface bidirectional reflectance were retrieved simultaneously using an optimal estimation method. The algorithm uses an atmospheric radiative transfer model coupled with a surface bidirectional reflectance factor (BRF) model. Based on the assumption that the surface bidirectional reflective properties are invariant during a short time period (i.e., a day), multiple temporal AHI observations were combined to calculate the AOD and surface BRF. The algorithm was tested over East Asia for year 2016, and the AOD retrieval results were validated against the aerosol robotic network (AERONET) sites observation and compared with the Moderate Resolution Imaging Spectroradiometer Collection 6.0 AOD product. The validation of the retrieved AOD with AERONET measurements using 14 713 colocation points in 2016 over East Asia shows a high correlation coefficient: $R = 0.88$ , root-mean-square error = 0.17, and approximately 69.9% AOD retrieval results within the expected error of $\pm 0.2\cdot {\mathrm {AOD}}_{\mathrm {AERONET}}\pm 0.05$. A brief comparison between our retrieval and AOD product provided by Japan Meteorological Agency is also presented. The comparison and validation demonstrates that the algorithm has the ability to estimate AOD with considerable accuracy over land. [ABSTRACT FROM AUTHOR]

In this paper, an application of aerosol jet 3-D printing with conductive and nonconductive inks for the realization of millimeter (mm)-wave circuits well above 30 GHz is presented and investigated. The Optomec 5X aerosol jet 3-D printing system is used together with polyimide (PI) and silver inks to fully-additive manufacture various microstrip circuits. A section of microstrip transmission line with a transition to a via-less conductor-backed coplanar waveguide was designed together with a T-junction and a branch-line coupler. These circuits were designed to operate within the Ka and V frequency bands. The measured thickness of the PI dielectric substrate is $20.7 \pm 1.35~\mu \text{m}$ , while the silver traces are $2.6 \pm 1.35 ~\mu \text{m}$. A section of the transmission line with the developed transitions was measured up to the W-band, exhibiting a total loss of 0.65 dB/mm at 100 GHz. The T-junction power divider yielded a total loss at its center frequency of 34 GHz of 0.55 dB. The 3-dB branch-line coupler yielded a loss at its center frequency at 42 GHz of 1.1 dB. The experimental results demonstrate the application of this approach for fast and high-resolution mm-wave circuit fabrication. [ABSTRACT FROM AUTHOR]

We describe our effort to use normalized water-leaving radiance at the short blue band 410 nm, nLw(410), derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership to improve the VIIRS ocean color products over coastal and inland waters, in particular, over the regions contaminated by strongly absorbing aerosols. The current standard atmospheric correction algorithm has significant issues when dealing with cases of strongly absorbing aerosols, e.g., dust, smoke, and air pollution from nearby cities. For such cases, satellite-derived normalized water-leaving radiance spectra nLw($\lambda $) are usually biased low and may be negative, particularly for the short blue bands, e.g., for the VIIRS nLw(410). In addition, for extremely turbid waters and waters dominated by colored dissolved organic matter (CDOM) that is strongly absorbing at the short blue band, slightly negative nLw(410) data are also sometimes observed. Obviously, cases with nLw(410) < 0 are unphysical and incorrect. However, VIIRS-derived nLw(410) < 0 do provide useful information to further improve satellite-derived ocean color products in such cases. In this paper, we develop a technique to improve VIIRS ocean color products in cases with strongly absorbing aerosols, CDOM-dominated and extremely turbid waters using VIIRS-derived nLw(410) information. Specifically, for cases with nLw(410) < 0, atmospheric correction can be carried out again to ensure that nLw(410) $\ge 0$ [e.g., assuming nLw(410) = 0], thereby removing unphysical retrievals for VIIRS-derived nLw($ \lambda $) spectra. Using this technique, VIIRS-derived nLw($ \lambda $) spectra are now all ≥ 0, showing considerable improvements for VIIRS ocean color products, particularly for biological and biogeochemical products [e.g., chlorophyll-a concentration and diffuse attenuation coefficient at 490 nm $K_{d}$ (490)] which are derived using VIIRS nLw($\lambda $) spectra. Several detailed examples from VIIRS measurements over various coastal and inland waters are provided and discussed. The new technique has been implemented in the Multi-Sensor Level-1 to Level-2 (MSL12) ocean color data processing system, which has been used for the routine production of VIIRS global ocean color products. [ABSTRACT FROM AUTHOR]

There has been considerable interest in nonthermal atmospheric pressure discharges due to their widely used industrial applications. A repetitively pulsed (RP) discharge ignited in microchannels between two nonequally broad planar electrodes is studied in this paper. The discharge current attains several 10^\mathrm -5 A orders of magnitude, and the ion concentration produced in interelectrode space by RP discharge is estimated to be about 10^17/\textm^3 . The duration of each time of RP discharge is several 10^\mathrm -8 s and the repetition frequency exceeds a few tenths of kilohertz. The repetition frequency of RP discharge depends on the $RC$ product, applied voltage, and the environmental humidity. The experiments of charging aerosol particles by RP discharges have shown that for particles with diameters of 34.8 and 103 nm, the charging efficiency can attain 14.8% and 35%, respectively. [ABSTRACT FROM AUTHOR]

Time and frequency domain channel models are proposed for nanonetworks utilizing the terahertz band (0.1–10 THz) for wireless communication. Nanonetworks are formed by tiny nanodevices which consist of nanoscale (molecular scale) components. Channel models capturing the unique peculiarities of the THz band are needed for designing proper physical layer techniques and for accurate performance analysis. Existing channel models have included the free space path loss and the molecular absorption loss, which is significant in the THz band. This paper theoretically analyzes scattering including multiple scattering referring to a sequence of scattering events from small particles, such as aerosols. Both the frequency and the impulse responses are derived. It is shown that the small particle scattering can result into significant additional loss that needs to be taken into account with the loss depending on the density and size distribution of the particles. It is shown that multiple scattering leads to a long tail in the impulse response. As most of the physical layer proposals for nanonetworks are based on the on-off keying, the channel response to pulse waveforms is specifically considered. [ABSTRACT FROM PUBLISHER]

The quantification of aerosol and cloud radiative properties, optical depth (OD), and phase function is of high importance to quantify the human impact on climate. Several approaches now exist based on both active (lidar) and passive (spectroradiometers) sensors. However, passive space observations over land are hindered by the important contribution of the surface to the total reflectance. Retrievals of OD from backscatter lidars do not face this issue but are usually based on the use of an a priori value of the so-called lidar ratio, which may lead to a significant uncertainty. The objective of this paper is to analyze a possible path for the space borne backscatter lidar onboard the Cloud Aerosol Lidar Pathfinder Observations satellite to overcome those issues. We will discuss the space-borne retrievals of ODs based on the land surface returns, either in combination with the Moderate Resolution Imaging Spectroradiometer or as a stand-alone lidar method. Analyses will be presented for a few cases on different surface types. The different error sources are discussed and further solutions to reduce them are explored. We show that the surface types have different polarization and multispectral properties, which can open new research areas based on space lidars. Using such an approach, we show that a retrieval technique based on the use of lidar land surface returns can be used to directly retrieve OD of aerosols and semitransparent cloud. [ABSTRACT FROM AUTHOR]

Over the past few years, regional air pollution has frequently occurred in Mid-Eastern China, especially in Beijing. As the primary pollutant in urban air, atmospheric particulate matter (PM) not only leads to the decrease of atmospheric visibility, but also increases the mortality and morbidity of respiratory system diseases. By analyzing aerosol volume size distribution data downloaded from the AERONET official website, we find that the size distribution of aerosol in Beijing appears a bimodal log-normal structures and parameters of fine mode in AERONET data are mainly contributed by PM $_{\text{2.5}}$. In this paper, a physically based model is developed to estimate the concentration of PM $_{\text{2.5}}$ , in which, fine mode aerosol optical depth (AOD) at 440, 550, and 675 nm, Effective Radius of the Fine particles, ground-based fine particulate matter (PM $_{\text{2.5}}$ ) data, relative humidity, and boundary layer height data from 2015 to 2016 are used. Those from 2015 are used for calculating integrated extinction efficiencies (〈Qext〉) based on the model, and those from 2016 are used for PM $_{\text{2.5}}$ validation. Result shows that R 2 of retrieved PM $_{\text{2.5}}$ against ground-based PM $_{\text{2.5}}$ can reach to 0.70 and RMSE is 33.67 μg/m3 at Beijing site at 440 nm. This study concludes that this method has the potential to retrieve PM $_{\text{2.5}}$ by using AERONET AOD in Beijing, which is independent of ground-based PM $_{\text{2.5}}$ measurement. [ABSTRACT FROM AUTHOR]

The formation of bubbles from breaking waves has a significant effect on air–sea gas transfer and aerosol production. Detailed data in situ about the bubble populations are required to understand these processes. However, these data are difficult to acquire because bubble populations are complex, spatially inhomogeneous, and short lived. This paper describes the design and development of a novel high-resolution underwater optical instrument for imaging oceanic bubbles at the sea. The instrument was successfully deployed in 2013 as part of the HiWINGS campaign in the North Atlantic Ocean. It contains a high-resolution machine vision camera, strobe flash unit to create a light sheet, and single board computer to control system operation. The instrument is shown to successfully detect bubbles of radii in the range 20–10 000 μm. [ABSTRACT FROM PUBLISHER]

Aerosol deposition (AD) method is technique for forming high density ceramic films on substrate material surface at room temperature. The yttrium oxide films formed by the AD method (AD-Y2O3 films) have been developed as plasma resistance coating used for the plasma etching equipment. In recent years, plasma eroded particles from chamber components of the etching devices are regarded as a serious issue that they reduce the semiconductor device yield rate. AD-Y2O3 films which have excellent plasma resistance can reduce the eroded particles in the plasma etching equipment and greatly have contributed to manufacturing high integrated semiconductor devices. In this paper, the plasma erosion behavior of AD-Y2O3 films were investigated compared with sintered Al2O3, sintered Y2O3 and thermal splayed Y2O3 in order to clarify the reason why AD Y2O3 films were superior as plasma resistance material. The plasma etching rates of AD-Y2O3 films were not significantly different from other samples. It was assumed that the etching rates were dependent on the chemical stability to fluorine plasma of material. On the other hand, the surface roughness difference before and after plasma exposure of AD-Y2O3 films were much smaller than other samples. It was assumed that the surface roughness difference is dependent on the crystalline size of material. The structure of AD-Y2O3 films, which had high density and nano-crystalline structure, were eroded homogeneously and smoothly. It suggests AD-Y2O3 films do not generate large eroded particles and are superior to reduce the eroded particles in the etching devices. [ABSTRACT FROM AUTHOR]

Analysis of long-term variations of aerosol optical thickness (AOT) is essential to understand the climate change and earth radiation budget. A simplified method was developed in this study to derive the AOT using more than thirty-year surface visibility and aerosol vertical distribution from LiDAR climatology of vertical aerosol structure for space-based LiDAR simulation studies data. Moderate resolution imaging spectroradiometer (MODIS) TERRA and AQUA daily measurements were used to evaluate the performance of the inferred AOT. Results show that the correlations of monthly AOT between MODIS measurements and inferred data are higher than 0.59 and the annual AOT values have stronger correlations (r > 0.82) than monthly data. The inferred AOT can capture the general spatial distribution similar to satellite images with long-term scale. The correlation of seasonal variation between two datasets is also higher than 0.77. The root mean squared error of inferred AOT relative to MODIS AOT is about 0.22 and 0.11 for monthly and yearly data, respectively. Analysis using singular value decomposition shows that the inferred AOT is consistent with MODIS measurements during 2002–2014 spatially and temporally. The average annual AOT in over 200 stations in China between 1980 and 2014 shows generally upward trends. Results from this paper can be used for further analysis of the aerosol effects on climate change in a regional scale. [ABSTRACT FROM PUBLISHER]

Foreground segmentation of moving objects in adverse atmospheric conditions such as fog, rain, low light, and dust is a challenging task in computer vision. The advantages of thermal infrared imaging at night time under adverse atmospheric conditions have been demonstrated, which are due to the long wavelength. However, the existing state-of-the-art object detection techniques have not been useful in such scenarios. In this paper, we propose an improved background model that utilizes both thermal pixel intensity features and spatial video salient features. The proposed spatial video salient features are represented as an Akin-based per-pixel Boolean string over a local region block, and depend on the effect of neighboring pixels on a center pixel. The result of this Boolean procedure is referred to as the- Akin-Based Local Whitening Boolean Pattern (ALWBP), which differentiates foreground and background region accurately, even against a cluttered background. The background model is controlled via 1) the automatic adaptation of parameters such as the decision threshold $\text{R}_{\mathrm {T}}$ and, learning parameter L, and 2) the updating of background samples $\text{B}_{\mathrm {sample\_{}int}}$ and,- $\text{B}_{\mathrm {sample\_{}ALWBP}}$ to minimize 1) the effect of the background dynamics of outdoor scenes and 2) the temperature polarity changes during the maiden appearance of a moving object in thermal frame sequences. The performance of this model is evaluated using nine existing standard segmentation performance metrics on our newly created-Tripura University Video Dataset at Night Time (TU-VDN) and on the publicly available CDnet-2014 dataset. Our newly created weather-degraded video dataset, namely, TU-VDN, consists of sixty video sequences that represent four atmospheric conditions, namely, low light, dust, rain, and fog. The results of a performance comparison with 14 state-of-the-art detection techniques also demonstrate the high accuracy of the proposed technique. [ABSTRACT FROM AUTHOR]

This paper reports on integration of microelectromechanical systems (MEMS) balance chips with aerosol inertial impactors for real-time monitoring of airborne particulate matter. Cascade inertial impactors have been extensively used for sampling and size separation of micro to nano-size airborne particles since they were first used in 1945. To introduce the real-time measurement capability to such tools, herein, MEMS resonator chips are employed as their impaction substrates. Dual-plate thermal-piezoresistive resonators (TPRs), that are shown to operate as promising mass balances, are integrated within a two-stage custom made aerosol impactor capable of size segregating particles down to a few tens of nanometers. Unlike cantilever-based microbalances or resonators operating in their bulk mode, TPRs provide uniform mass sensitivity over a big portion of their surface area. Upon deposition of airborne particles on the resonant sensors, the mass loading on each sensor and as a result the mass concentrations of size-segregated particles is measured in real-time. The air quality of different environments, including a class 10,000 cleanroom, was analyzed and monitored via the real-time impactor over a four day period. Comparison of the results with those of an optical particle counter demonstrates a clear correlation between the system response and the expected particle counts. Compared to existing optical particle counters, the proposed system offers the added advantage of detecting sub-100nm particles. [ABSTRACT FROM PUBLISHER]

Unlike instantaneous albedo, daily albedo of land surfaces is currently not routinely generated from satellite data, although it is a key input parameter for calculating daily shortwave radiation budget. This paper presents a novel approach to directly retrieve daily mean values of land surface broadband blue-sky albedo from Visible Infrared Imaging Radiometer Suite clear-sky data of apparent reflectance, with the assumption that the atmospheric conditions of the satellite overpass time can represent their daily values. Training data were simulated by atmospheric radiative transfer models, with surface spectra and bidirectional reflectance distribution function data as inputs for four aerosol types and a range of aerosol loadings. Sensitivity analysis was conducted to study the effects of cloud coverage, aerosol, and surface types on retrieval accuracy. Two years of measurements at six Surface Radiation Budget Network and eight Greenland Climate Network stations were used for algorithm validation. Daily albedo of snow-free surfaces can be retrieved with very high accuracy. By excluding far off-nadir observations of snow surfaces, the overall accuracy of retrieving daily albedo has a bias of 0.003 and a root-mean-square error of 0.055. [ABSTRACT FROM AUTHOR]

The presence of charges on droplets and aerosol particles can increase collisions among these objects, which would ultimately have effects on precipitation and cloud over. The traditional experiments on the effects of growth of charged droplet have deficiency in that the charge of droplet was not accurately controlled. In this paper, better control of equivalent charge on a single droplet was realized by changing the voltage applied on the stainless steel needle whose tip was used as the condensation nuclei of the droplet. The breakdown voltage at the tip of the stainless steel needle (radius 1 \mu \textm ) was 2000 V at the humidity of 98 ± 2% and temperature of 3 ± 1°C. Voltage of less than 700 V could not lead to corona discharge, which further guarantees the accurate control the charge of droplet. Increasing equivalent charge of the droplet not only increased the growth rate of the droplet, but also increased the eventual size of the droplet. The electric field of 1.9 \times 10^7 V/m at the edge of the droplet was found to be the threshold for the growth of charged droplet under this experimental condition. The calculation of collision rate coefficient between the charged droplet and aerosol particles suggests that the contribution of electric force to the growth of droplet was at least three orders of magnitude higher than that of thermophoretic and diffusophoretic forces when the charge of the droplet was greater than 1.43 \times 10^5e . [ABSTRACT FROM AUTHOR]

In this paper, we propose studying the disease spread mechanism in the atmosphere as an engineering problem. Aerosol transmission is the most significant mode among the viral transmission mechanisms that do not include physical contact, where airflows carry virus-laden droplets over long distances. Throughout this work, we study the transport of these droplets as a molecular communication problem, where one has no control over the transmission source, but a robust receiver can be designed using bio-sensors. To this end, we present a complete system model and derive an end-to-end mathematical model for the transmission channel under certain constraints and boundary conditions. We derive the system response for both continuous sources such as breathing and jet or impulsive sources such as coughing and sneezing. In addition to transmitter and channel, we assumed a receiver architecture composed of air sampler and Silicon Nanowire field-effect transistor. Then, we formulate a detection problem to maximize the likelihood decision rule and minimize the corresponding missed detection probability. Finally, we present several numerical results to observe the impact of parameters that affect the performance and justify the feasibility of the proposed setup in related applications. [ABSTRACT FROM AUTHOR]

Interventional magnetic resonance imaging (MRI) could allow for diagnosis and immediate treatment of ischemic stroke; however, such endovascular catheter-based procedures under MRI guidance are inherently difficult. One major challenge is tracking the tip of the catheter, as standard fabrication methods for building inductively coupled coil markers are rigid and bulky. Here, we report a new approach that uses aerosol jet deposition to three-dimensional (3-D) print an inductively coupled RF coil marker on a polymer catheter. Our approach enables lightweight conforming markers on polymer catheters and these low-profile markers allow the catheter to be more safely navigated in small caliber vessels. Prototype markers with an inductor with the geometry of a double helix are incorporated on catheters for in vitro studies, and we show that these markers exhibit good signal amplification. We report temperature measurements and, finally, demonstrate feasibility in a preliminary in vivo experiment. We provide material properties and electromagnetic simulation performance analysis. This paper presents fully aerosol jet-deposited and functional wireless resonant markers on polymer catheters for use in 3T clinical scanners. [ABSTRACT FROM AUTHOR]

The vertical structure of wind is a key factor in modulating air quality, from which the determination of boundary layer height (BLH) remains a major challenge. In this paper, we developed an improved threshold method to determine the BLH from radar wind profiler (RWP) measurements. The normalized signal-to-noise ratio (SNR) profiles were used instead of the original SNR profiles to avoid instrumental inconsistencies. Additionally, a peak filter was designed to indicate the BLH based on the maximum SNR by taking into account the multiple peaks in the SNR profile. This algorithm was then applied to the RWP measurements taken in the summer (June–July–August) of 2018 in Beijing to obtain the BLHs. Validation analyses suggested that the BLH retrievals from RWP exhibited high consistency with those from radiosondes, with an average correlation coefficient of 0.69 (0.66) and a root mean squared error of 0.39 (0.41) in the daytime (nighttime). Additionally, the major features of summertime BLHs in Beijing were examined. In particular, a distinct diurnal variation in BLH was observed with a peak (1630 ± 510 m) occurring at 0600 universal time coordinated (UTC) and a minimum (587 ± 343 m) at 2300 UTC. Therefore, the algorithm presented here has great potential to be applied to other regions to obtain reliable BLHs. The findings obtained here highlight the importance of vertical wind structure in air quality studies. [ABSTRACT FROM AUTHOR]

The retrieval of cloud optical properties for aerosol contaminated water cloud is challenging because of the complexity of physical processes in such situations. Conventionally, cloud optical data products are typically derived, ignoring the aerosol impacts on radiative transfer in the retrieval process. This is potentially a significant source of error. In this paper, the eXtensible Bremen Aerosol Retrieval (XBAER) algorithm has been optimized for the retrieval of aerosol/cloud properties for the aerosol contaminated cloud (ACC) scenarios. This version of XBAER delivers cloud optical thickness (COT) and cloud effective radius (CER) for ACCs and simultaneously retrieves aerosol optical thickness (AOT). The surface parameterization and aerosol types used in the standard XBAER algorithm have been adapted in this retrieval to account for the ACC conditions. Aerosol types in XBAER for the retrieval of ACC scenarios have been parameterized to comprise weak and strong absorptions. The comparisons of COT, CER, and AOT retrieved using this adapted XBAER algorithm and two new NASA algorithms show good agreements, especially for biomass burning aerosol. The correlation coefficients are >0.9 for AOT, ~0.8 for CER, and ~0.7 for COT. There is also a good agreement for dust plume contaminated cloud scene. The XBAER derived AOT values for dust aerosols are systematically smaller than the NASA retrieval, but both products have the same spatial distribution patterns. The comparison of COT retrieved using the adapted XBAER algorithm and that retrieved from ground-based microwave radiometer (MWR) measurements shows much better agreement for ACC conditions with high AOT. [ABSTRACT FROM AUTHOR]

We made use of a combination of three models that describe plasma equilibrium, cluster kinetics, and aerosol dynamics in order to investigate solid carbonaceous dust formation in a dc gas discharge where the carbon source is provided by a graphite cathode sputtering. This enabled us to determine the time evolution of some of the particle characteristics, e.g., total density, mean diameter, and average charge, as a function of the sputtering yield. We showed that for a few minutes of discharge duration, the particle density reaches 10^7 – 10^8 cm ^-3 , the particle mean diameter is approximately 40 nm and the particle size distributions are bimodal for all the investigated conditions. We also showed that the variation of the sputtering yield affects in a quite unexpected way the interplay between the phenomena involved in the aerosol dynamics. Basically, larger sputtering yields result in larger density and coagulation rate on one hand, and in a limited nucleation and surface sticking kinetics on the other hand. [ABSTRACT FROM PUBLISHER]

Application specific printed electronic circuits (ASPECs) are the corresponding term with application-specified ICs for printed electronics. The same as any new technology, printed electronics is suffering from some restrictions in design and process technology aspects. An important stage in the ASPEC design is the final wiring of the organic thin-film transistor arrays or gate arrays to customize it to implement any specific target application that fits in their structure. In this paper, we evaluate two additive manufacturing technologies: aerosol jet using Optomec M3D and electrohydrodynamic printer using superfine inkjet. Both techniques are based on direct-writing of the pattern corresponding to any individual circuit being fabricated (digital printing) enabled by the mask-free noncontact deposition of materials. Finally, these structures will be compared with the corresponding photolithography mask technology. Some parameterized test vehicles, with different instantiations for the variation of line widths and separations, have been designed to be wired using the target technologies. These test vehicles have been fabricated at the Centre for Process Innovation by a five masks lithography and subtractive patterning technology. Results show that both direct printing technologies are feasible for the fabrication of the gate-array customization, thus allowing individual personalization of every circuit what can produce added value functionalities at low cost such as the equivalent effect of having an ROM memory which final contents could be customized at home by using low-cost digital printing technologies. Further interactions between transistor bulk and wiring technologies can improve the obtained performance in order to end up in an industrialized process. [ABSTRACT FROM PUBLISHER]

The atmospheric correction approach currently being used operationally by NASA [termed as NASA standard atmospheric correction (NSAC) approach] to process ocean color data relies on traditional “black pixel” approach, with additional modifications to account for nonnegligible water-leaving radiance in the near-infrared (NIR) bands. The NSAC approach underestimates remote-sensing reflectance ($R_{\mathrm {rs}}$ , sr−1) in blue wavelengths in the presence of absorbing aerosols. Addressing this issue requires realistic absorbing-aerosol model and knowledge of the vertical distribution of aerosols, which are currently difficult to achieve. An alternative atmospheric correction approach has been evaluated in this paper for Moderate Resolution Imaging Spectroradiometer (MODIS) data. The approach is based on a previously developed spectra-matching optimization [POLYnomial-based approach established for the atmospheric correction of MERIS data (POLYMER)], where polynomial functions are used to express atmospheric contribution to the measured radiance and where a bio-optical model is used to estimate the water contribution. Evaluation against in situ data measured over the regions frequently affected by absorbing aerosols indicates that, compared with the NSAC approach, the POLYMER approach improves the $R_{\mathrm {rs}}$ retrievals in blue wavelengths while having a slightly worse performance in other wavelengths. Evaluation using NSAC-retrieved $R_{\mathrm {rs}}$ in adjacent days free of absorbing aerosols suggests that the POLYMER approach could improve the spectral shape and increase valid spatial coverage. When applied to time-series MODIS data, the POLYMER approach could generate more temporary coherent daily and monthly $R_{\mathrm {rs}}$ patterns than the NSAC approach. These results suggest that the POLYMER approach could be an alternative approach to partly correct for absorbing aerosols in the absence of explicit information on the aerosol type and the vertical distribution. [ABSTRACT FROM AUTHOR]

This study aims at validating the cloud mask produced by the land surface reflectance code (LaSRC) for Landsat 8 data. To detect clouds in optical satellite imagery, LaSRC uses quality assurance (QA) layers, which are produced during the atmospheric correction process. The QA layers include a “cloud mask,” which is based on the estimation of a residual metric showing the quality of aerosol inversion, and “high aerosol,” which shows the impact of aerosols on the derived surface reflectance. Validation is performed using the “L8 Biome” cloud validation dataset, which is produced by the US Geological Survey, and consists of 96 Landsat 8 scenes distributed globally over 12 different biomes. We show that the LaSRC cloud detection algorithm reliably identifies thick clouds with commission and omission errors less than 4%. Large cloud overdetection errors occur for thin clouds, which is due to the subjectivity of defining and extracting thin clouds in the reference dataset. We conclude this paper with recommendations on using the LaSRC QA layers, and give suggestions on reducing subjectivity, when generating cloud validation datasets. [ABSTRACT FROM AUTHOR]

Under sunlight illumination, the shape of the atmospheric oxygen bands [O2-B (687 nm) and O2-A (760 nm)] of the vegetation radiance is modified by chlorophyll fluorescence as a result of the filling-in process. However, for far-range measurements, atmospheric effects also modify this shape. In this paper, measurements of the depth of O2-A and O2-B absorption bands have been performed at different altitudes, from 324 to 3123 m, over different targets, including bare soil and wheat fields. It is observed that bands depth increases significantly with altitude. In the O2-B band, the total magnitude of variation is on the same order of magnitude as the change induced by vegetation, while it is much greater in the O2-A band. Three main factors affect the measurements of band depth: 1) the transmittance of the air column between ground and sensor, 2) the path radiance, and 3) the additional contribution of the ground surface outside the field of view scattered by the atmosphere (adjacency effect). We used the MODerate spectral resolution atmospheric TRANsmittance algorithm (MODTRAN) 4 to compute separately these atmospheric and environmental terms, and we corrected airborne measurements to retrieve ground-level band depths. A study was conducted to assess the sensitivity of the absorption band depth to several atmospheric parameters. The magnitudes of these effects were compared to the band depth variation induced by fluorescence. We identified temperature, air pressure, and aerosols as the most critical parameters. After correction of airborne measurements from atmospheric effects, it is found that the variation of band depth with altitude is greatly reduced. The residual variation, particularly in the case of O2-B band over vegetation, is attributed to an inaccurate assessment of the environment contribution that is scattered by the atmosphere to the sensor. These results show that the MODTRAN 4 is able to simulate oxygen band depth variations at moderate spectral resolution (i.e., 0.5–1 nm) and can be used to compute atmospheric and environmental factors for corrections of airborne measurements of oxygen band profiles. We also showed that an accurate evaluation of the contribution of environment is needed to correct the band depth from atmospheric effects in the O2-B band. [ABSTRACT FROM PUBLISHER]

Due to the intermittency and randomness of solar photovoltaic (PV) power, it is difficult for system operators to dispatch PV power stations. In order to find a precise expectation for day-ahead PV power generation, conventional models have taken into consideration the temperature, humidity, and wind speed data for forecasting, but these predictions were always not accurate enough under extreme weather conditions. Aerosol index (AI), which indicates the particulate matter in the atmosphere, has been found to have strong linear correlation with solar radiation attenuation, and might have potential influence on the power generated by PV panels. A novel PV power forecasting model is proposed in this paper, considering AI data as an additional input parameter. Based on seasonal weather classification, the back propagation (BP) artificial neural network (ANN) approach is utilized to forecast the next 24-h PV power outputs. The estimated results of the proposed PV power forecasting model coincide well with measurement data, and the proposed model has shown the ability of improving prediction accuracy, compared with conventional methods using ANN. [ABSTRACT FROM PUBLISHER]

Due to the limitation of surface “dark-target,” in some regions and over certain surface types, Moderate Resolution Imaging Spectroradiometer (MODIS) standard aerosol algorithm does not work very well. In this paper, we developed and validated a robust algorithm, which combines the revised minimum reflectance technique and the technique of the synergy of Terra and Aqua MODIS to eliminate the dependence on surface conditions. The rationale of our algorithm is to first identify the “clearest” day observations in certain temporal window, assume that the aerosol optical depth (AOD) does not change during the limited period (0–3 h) between Terra and Aqua overpass in this day, subsequently obtain the relationships between visible bands and \bm 2.1\,\mu\mathbfm band surface reflectance, and finally retrieve the AOD of all observations in the temporal window. The algorithm was validated using year 2006 measurements from 13 Aerosol Robotic Network (AERONET) sites distributed in North China, Central Asia, eastern United States, and Western Europe. For AOD, 65.5% and 72.7% of retrievals within MOD04 expected error envelope for all levels of quality assurance confidence (QAC) and \mathbfQAC = 3, respectively, \mathbfR^2 of 0.87 and a less amount of gaps are found. In comparison to the MODIS aerosol products, the new algorithm on the whole shows similar accuracy over dark land surface, but gives a larger amount of retrievals over bright land surface. This indicates that the new algorithm can provide a more steady inversion for a variety of surface types. Especially over urban surface, such as Beijing in China, the inverted AOD is clearly better than that from MODIS aerosol products. Therefore, the new algorithm can provide an alternative way for AOD retrieving over regions where the standard dark target algorithm does not work well or higher spatial resolution is imperative. [ABSTRACT FROM PUBLISHER]

It is worth noting that the influences of dust aerosol type and different aerosol loadings were not considered in the development of the generalized split-window (GSW) algorithm. However, numerical simulations showed that the influence of dust aerosol could lead to a maximum land surface temperature (LST) retrieval error of 5.12 K when the aerosol optical depth (AOD) in the atmosphere is 1.0 and viewing zenith angle (VZA) is 60°. This paper focuses on reducing the influence of dust aerosol on the LST retrieval error of the GSW algorithm. A linear function was developed to reduce such influence with respect to the AOD. The slope could be expressed as a function of the difference between the MODIS channel brightness temperatures \bmT\bf{31} and \bmT\bf{32} measured at the top of the atmosphere (TOA) and difference and mean of the two-channel emissivities, and the offset could be used as a constant value for each VZA. The results showed that the retrieval accuracy could be improved by approximately 4 K for \bfAOD = \bf1.0 and \bfVZA = \bf60^\circ. Sensitivity analysis in terms of the uncertainties of the input parameters showed that the maximum LST retrieval error is 1.15 K for \bfVZA = \bf0^\circ. Some of the in situ measurements observed at the Yingke site in northwest China and Arvaikheer site in south Mongolia were used to test the proposed method, respectively. The results showed that the proposed method could improve the LST retrieval accuracy by at least 1 K for the GSW algorithm in atmospheres with heavy dust aerosol loading. [ABSTRACT FROM PUBLISHER]

Sun photometric measurements are an important method of measuring the column amount and optical properties of atmospheric aerosols and are frequently used to better understand the impact of aerosols on the Earth's radiative budget. This paper assesses two calibration techniques used for multifilter rotating shadowband radiometers (MFRSRs) and presents the results obtained at Long Island, NY, during the July 2011 Aerosol Life Cycle Intensive Operational Period (IOP) campaign. The instrument calibration constants are validated internally against each other and against an independent quantitative technique based on the solar irradiance at the top of the atmosphere, convolved with the MFRSR filter response. In addition, the aerosol optical parameters obtained from the MFRSR are assessed against the same parameters retrieved with a recently calibrated CIMEL sun/sky radiometer collocated with the MFRSR instrument. These comparisons indicate generally good agreement between the two instruments for both calibration techniques. The advantages and disadvantages of the two techniques are presented. Additionally, an analysis of the optical and physical properties of aerosols from the MFRSR and their chemical compositions obtained by an in situ high-resolution time-of-flight aerosol mass spectrometer, together with back trajectories, indicate that the principal source of high concentrations of fine aerosols observed during July 18-24 was forest fires in western Canada. [ABSTRACT FROM PUBLISHER]

Atmospheric compensation (AC) is a fundamental and critical step for quantitative exploitation of hyperspectral data. It is the means by which the reflectance of an object/material is estimated from the measured at-sensor radiance. Such reflectance is the inherent signature that is used to identify various materials in a monitored scene. AC is quite complex and is hampered by the large amount of uncontrollable variables that play a role: just think about the spatial variability of some atmospheric constituents such as water vapor and aerosols, or to the rapidly spatially varying effects of the radiation coming from adjacent areas. Though, in principle, some atmospheric parameters and radiometric quantities such as solar irradiance and sky irradiance can be measured during the flight, in practice such measures are rarely available in an operational framework or are taken at a single point of the surface ignoring their spatial variation. Thus, a prompt quantitative exploitation of hyperspectral data for operational purposes, such as material identification and object detection, requires unsupervised and accurate AC procedures that can learn from the image itself the parameters of the inversion model and follow their variability within the scene. In this framework, we present a new unsupervised methodology for AC of airborne hyperspectral images in the visible and near-infrared spectral range. The proposed methodology relies on a radiative transfer model accounting for the adjacency effect and allows the estimation of relevant atmospheric parameters. Specifically, it embeds two new algorithms for the estimation of: 1) aerosol and atmospheric visibility and 2) the water vapor content of the atmosphere accounting for the spatial variability of such a parameter. The two algorithms significantly differ from those adopted by existing state-of-the-art approaches or in commercial packages such as fast line-of-sight atmospheric analysis of spectral hypercubes and airborne atmospheric and topographic correction algorithm. In this paper, we present the detailed description of the new AC methodology, and we analyze the results provided by the algorithm over real data. [ABSTRACT FROM AUTHOR]

The continuous ground-based microwave radiometer profiler (MRP) observations of lower atmospheric temperature and humidity profiles are used to investigate the diurnal evolution of atmospheric boundary layer height (BLH) over a tropical coastal station. The BLH estimated from the MRP observations is compared with concurrent and collocated measurements of mixing layer height using a Micropulse Lidar and the BLH derived from radiosonde ascends. The monthly mean diurnal variation of the BLH derived from the multiyear (2010-2013) MRP observations exhibits strong diurnal variation with the highest around the local afternoon (~12:00-15:00 IST) and the lowest during the nighttime (~100-200 m). The daytime convective BLH is maximum during the premonsoon season (March-May) with the peak value (~1300 m) occurring in April and minimum in the month of July (~600 m). This paper presents the potential of MRP observations to investigate the continuous diurnal evolution of the BLH over a tropical coastal region manifested by a thermal internal boundary layer (TIBL) at much better time resolution, which is essential for understanding the rapid growth of the boundary layer and the TIBL during the forenoon period. [ABSTRACT FROM PUBLISHER]

The ScaRaB payload onboard the low-inclination Megha-Tropiques (MT) satellite has been making observations of radiative fluxes at the top of the atmosphere (TOA) for different local times (LTs) of the day over the tropics since October 2011. This provides a unique opportunity to investigate the diurnal variation of the regional instantaneous aerosol direct radiative effect efficiency (IADREE) at TOA, which is otherwise not possible using the available long-term satellite observations carried out using similar sensors onboard polar sun-synchronous satellites. In this paper, the diurnal variations of the IADREE over the Arabian Sea and the Atlantic Ocean during June–September, when both these regions are engulfed by large-scale mineral dust plumes transported from the adjoining deserts, are investigated using collocated multiyear (2012–2014) observations of the MT-ScaRaB measured shortwave fluxes and MODIS-derived aerosol optical depth. The estimates of the IADREE made using the MT-ScaRaB data at 13:30 LT are found to be in agreement with those derived from the Cloud and the Earth’s Radiant Energy System data at this LT, at which the latter observations are carried out. The IADREE derived from the MT-ScaRaB shows diurnal peak value of −53 ± 10 Wm $^{{{-2}}}\tau _{{{550}}}^{{{-1}}}$ and −40 ± 3 Wm $^{{{-2}}}\tau _{{{550}}}^{{{-1}}}$ at solar zenith angle of ~40° over the Arabian Sea and the Atlantic Ocean, respectively. Diurnal mean aerosol direct radiative effect efficiency at TOA during June–September is −22 ± 4.5 Wm $^{{{-2}}}\tau _{{{550}}}^{{{-1}}}$ over the Arabian Sea and −18 ± 3.6 Wm $^{{{-2}}}\tau _{{{550}}}^{{{-1}}}$ over the Atlantic Ocean. [ABSTRACT FROM PUBLISHER]

Suspended aerosols in the vicinity of discharged HVDC transmission lines will be charged by ions and deposit on the surface of the conductors. In order to obtain the conductors with different contamination conditions, a controllable accelerating contamination depositing method by introducing a controllable ionized field is proposed in the present paper. The conductor samples contaminated by 3 typical patterns were prepared and the morphology of the conductor surfaces was characterized by scanning electron microscopy (SEM). The photon counting rate of the conductors and the electric field strength on the ground electrode were also tested. The anticipatory contamination depositing results were obtained, specifically, the surface conditions of the conductors could be improved or deteriorated, therefore, the corona discharge could be suppressed or enhanced in corresponding patterns of the proposed contamination depositing method. [ABSTRACT FROM AUTHOR]

In this paper, a graph regularized nonlinear ridge regression (RR) model is proposed for remote sensing data analysis, including hyper-spectral image classification and atmospheric aerosol retrieval. The RR is an efficient linear regression method, especially in handling cases with a small number of training samples or with correlated features. However, large amounts of unlabeled samples exist in remote sensing data analysis. To sufficiently explore the information in unlabeled samples, we propose a graph regularized RR (GRR) method, where the vertices denote labeled or unlabeled samples and the edges represent the similarities among different samples. A natural assumption is that the predict values of neighboring samples are close to each other. To further address the nonlinearly separable problem in remote sensing data caused by the complex acquisition process as well as the impacts of atmospheric and geometric distortions, we extend the proposed GRR into a kernelized nonlinear regression method, namely KGRR. To evaluate the proposed method, we apply it to both classification and regression tasks and compare with representative methods. The experimental results show that KGRR can achieve favorable performance in terms of predictability and computation time. [ABSTRACT FROM PUBLISHER]

As Advanced Very High Resolution Radiometer (AVHRR) lacks a 2.1-\mu\textm band, the widely used “dark target” algorithm cannot be used to retrieve aerosol optical depth (AOD) from AVHRR over land. Instead, a multiple regression algorithm has been developed to process a time series of AVHRR Level_1b measurements over China (15°–45° N, 75°–135° E) for AOD retrieval. As the apparent reflectance of AVHRR is closely related to AOD, which can be provided by Moderate Resolution Imaging Spectroradiometer (MODIS), spatially and temporally collocated Aqua/MODIS AOD and AVHRR Level_1b measurements from four years (January 2008–December 2011) were used to generate the regression coefficients. Angle information, normalized difference vegetation index, water vapor, and surface elevation are chosen in addition to the apparent reflectance as predictors for different surface types. By applying the regression coefficients to AVHRR, the AOD product from independent AVHRR Level_1b measurements (May 2003–December 2007) was generated. Validation with AErosol RObotic NETwork (AERONET) AOD and comparison with MODIS AOD products have been conducted to evaluate the uncertainty of the AVHRR AOD from May 2003 to December 2007. The distribution pattern of the seasonal mean AOD from AVHRR is consistent with that of the MODIS AOD. Taking regions with rapid economic development, for example, the regional monthly mean AOD for these two data sets agrees well, with a consistent tendency and high correlation coefficients. When compared with AERONET from four sites in China, the results are also encouraging. Results show that the multiple regression method offers the potential to generate an AOD climatology data record from a long-term AVHRR Level_1b data set over land. [ABSTRACT FROM PUBLISHER]

Polarization response is an important factor influencing the accuracy of radiance measurement for satellite ocean color sensors, which would change with on-orbit time. In this paper, a practical method is proposed for on-orbit estimation of polarization response. First, the linear polarization components of the Stokes vector entering the sensor are estimated by a vector radiative transfer model of the coupled ocean–atmosphere system. Second, the real radiance entering the sensor is estimated by another high-accuracy ocean color sensor using the cross-calibration method. Finally, based on the estimated linear polarization components and real radiance, the polarization response coefficients are derived by the least squares method. The proposed method is tested by applying it to the Moderate Resolution Imaging Spectroradiometer on board the Aqua satellite, and the derived polarization factors are consistent with the prelaunch values, indicating the reliability of the proposed method. In addition, our results reveal that the contribution of aerosol scattering should be included in the estimation of the linear polarization components of the Stokes vector at the top of atmosphere, particularly for long wavelengths. [ABSTRACT FROM PUBLISHER]

Multispectral satellite images are often contaminated by haze and/or cirrus. A previous paper presented a haze removal method that calculates a haze thickness map (HTM) based on a local search of dark objects. The haze-free signal is restored by subtracting the HTM from the hazy image assuming an additive model of the haze influence. The HTM method is substantially improved by employing the 1.38- \mu\mboxm cirrus band. The top-of-atmosphere reflectance cirrus band is used as an additional source of information. The method restores the information in highly inhomogeneous surfaces attenuated by a low-altitude haze and high-altitude cirrus, improving the interpretation of the scene content while preserving the shape of the spectral signatures. The new enhanced HTM method is successfully applied to Landsat-8 OLI and Sentinel-2 real and simulated scenes. [ABSTRACT FROM PUBLISHER]

Saharan dust outbreaks are one of the major aerosol sources in Southern Europe. Dust affects the radiative balance of the Earth–atmosphere system and impacts health. The assessment of Saharan outbreaks requires information about the vertical distribution of dust in the atmosphere, usually obtained from lidar measurements, such as the ones performed by the spaceborne Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) sensor. In this paper, we have used CALIOP level-1 daytime data in combination with aerosol optical depth (AOD) measurements from Aerosol Robotic Network (AERONET) ground-based photometers to obtain aerosol profiles during 23 dust outbreaks over Southern Europe. These profiles are used for two main purposes: analyzing the lidar ratio values and vertical distribution of dust and evaluating the performance of version 3 of CALIOP algorithms. The mean lidar ratio obtained from the synergic method ranged between 47.7 and 49.0 sr, depending on the criterion used to average CALIOP signal. The dust layers traveled at a wide range of altitudes, from surface level up to 7.6 km. We found that the AOD values retrieved from CALIOP level 2 (version 3) and AERONET were not correlated (r < 0.2). In addition, we observed that the mean AOD obtained by satellite retrievals, between 0.16 and 0.18, was lower than the mean AERONET value, i.e., 0.33, by 50%. These differences in the AOD were found to be caused by two main reasons: misclassification of dense dust layers as clouds by CALIOP algorithms, mainly over 4 km, and limitations of CALIOP algorithms to detect weak aerosol layers, particularly between 1.5 and 2.5 km. [ABSTRACT FROM PUBLISHER]