Case Of Haze Research Articles

Using satellite multi-angle polarization measurements to characterize atmospheric aerosol above Bohai Bay

The paper analyzes data from the PARASOL optical multi-angle polarization radiometer over the waters of Bohai Bay under various atmospheric conditions and different seawater optical types. The study considered cases of clear atmosphere, haze, dust aerosol, and cloud coverage. The waters of Bohai Bay were categorized into areas heavily influenced by river inflows and relatively clear waters. By utilizing PARASOL data, the degree of polarization (DoP) values of optical radiation at scattering angles of about 90° between incident solar radiation and recorded radiation were determined. Appropriate scatterplots were created using measurements from the 490, 670, and 865 nm bands. Polarimetric pseudo-color maps were presented to classify various atmospheric states. The scatterplots successfully identified atmospheric dust, dust in clouds, haze, and water areas with high levels of suspended particles. The results obtained are consistent with the experience of using the Umov effect to study dust aerosol, which consists in the negative correlation between the maximum polarization of radiation and geometric albedo. The presence of suspended particles in water led to decrease in correlation coefficients between analyzed DoP at different wavelengths within the investigated sea area. The strong influence of river inflows on Bohai Bay in polarimetric data was observed only under clean atmospheric conditions.

A Survey of Deep Learning-Based Image Restoration Methods for Enhancing Situational Awareness at Disaster Sites: The Cases of Rain, Snow and Haze.

This survey article is concerned with the emergence of vision augmentation AI tools for enhancing the situational awareness of first responders (FRs) in rescue operations. More specifically, the article surveys three families of image restoration methods serving the purpose of vision augmentation under adverse weather conditions. These image restoration methods are: (a) deraining; (b) desnowing; (c) dehazing ones. The contribution of this article is a survey of the recent literature on these three problem families, focusing on the utilization of deep learning (DL) models and meeting the requirements of their application in rescue operations. A faceted taxonomy is introduced in past and recent literature including various DL architectures, loss functions and datasets. Although there are multiple surveys on recovering images degraded by natural phenomena, the literature lacks a comprehensive survey focused explicitly on assisting FRs. This paper aims to fill this gap by presenting existing methods in the literature, assessing their suitability for FR applications, and providing insights for future research directions.

Source apportionment and regional transport of PM2.5 during haze episodes in Beijing combined with multiple models

Atmospheric fine-particle (PM2.5) pollution is a prominent regional issue that is affected by local emissions, regional transport, and secondary formation and impacts human health, air quality, and climate. Identifying the origin and types of pollution sources that are transported to the receptor site is essential for the development of joint prevention and control measures. This study developed a combined method to explore the source-receptor relationship during haze episodes of the heating season in Beijing, by combining positive matrix factorization (PMF) model with Lagrangian particle model (FLEXPART-WRF) and chemical transport model (CAMx). Six source types identified by PMF with high-time-resolution online measurements were counted in different transport pathways including local, south, east, and north. The results showed that secondary source contributed the most to PM2.5, which was affected by regional transport of Baoding, Langfang, and Tangshan. Among major primary sources, vehicle source was concentrated locally. Coal combustion contributed a higher proportion locally (15.8%) and in the south (15.0%), and Baoding, Langfang, and Xingtai along the Taihang Mountains were predominant potential source regions. Biomass burning contributed a higher proportion in the south (19.0%) and northeast (22.6%), and adjacent southern Hebei and Northeastern areas were the predominant potential source regions. Moreover, the variations in PM2.5 sources, footprints, and source regions of two haze cases from pre-pollution to dissipation were analyzed. EP1, with a more southern transport, was caused by high secondary source and coal combustion, while EP2 was characterized by secondary source and biomass burning from Hebei and Liaoning Province transport. In particular, the emission distribution of surrounding cities along transport pathways had an important effect on PM2.5 sources in Beijing. This study demonstrated that the combined method can provide guidance for implementing effective emission mitigation measures and improving the regional air quality.

Spatial-temporal characteristics of particulate matters and different formation mechanisms of four typical haze cases in a mountain city

The mechanisms by which pollution forms and acts in mountain cities are unique and remain unclear owing to terrain and meteorological conditions in the mountains. This study investigates the pollution characteristics in Chongqing, a typical mountain city, over the period from 2013 to 2017. Routine observed surface meteorological data, CALIPSO data, ERA5 reanalysis data and the backward trajectory calculation were used for analysis and comparison among four typical pollution cases. The results can be summarized as follows: (1) Pollutants in firework and unfavorable weather condition case mainly originated from local emissions. Anthropogenic aerosols that were characterized by spherical and small particles were detected, which contributed to the higher atmospheric scattering ability. Meanwhile, high humidity was beneficial to hygroscopic growth, resulting in a mixture of haze and fog forming low-visibility conditions. The strong inversion of the upper-layer and the presence of high mountains meant that local pollutants became confined within the basin region, leading to the formation and maintenance of pollution. The important roles of the weather conditions that are associated with mountains, such as cold air damming, low-level jet, valley and gap wind, were also revealed by the variable pollution conditions. (2) Airflow originating from Guizhou, Guangxi, and Hunan, where numerous fire points were detected, transported pollutants that were released from straw burning through upper-lower layer transport to the basin during the straw burning case. The aerosols detected showed low depolarization but a high color ratio, which are the typical characteristics of smoke. The inversion layer did not cover the entire basin, indicating that smoke aerosols were transported by downdraft to mix with local pollutants. (3) During the dust case, large amounts of dust aerosols were detected reaching from the surface to the troposphere, with a special double-layer structure. A lower depolarization ratio but stronger scattering ability was observed for the dust aerosols above the study region, which was attributed to mixing with other aerosols and chemical processes. Secondary circulation occurred when the inversion layer was at around 700 hPa, bringing dust aerosols from around 850 hPa to the surface. This study provides an understanding of the optical properties of the various types of aerosols and highlights the importance of weather condition in the formation and maintenance of pollution events. The results emphasize the need for intense vertical measurement in mountain cities.

A new inverse modeling approach for emission sources based on the DDM-3D and 3DVAR techniques: an application to air quality forecasts in the Beijing–Tianjin–Hebei region

Abstract. We develop a new inversion method which is suitable for linear and nonlinear emission source (ES) modeling, based on the three-dimensional decoupled direct (DDM-3D) sensitivity analysis module in the Community Multiscale Air Quality (CMAQ) model and the three-dimensional variational (3DVAR) data assimilation technique. We established the explicit observation operator matrix between the ES and receptor concentrations and the background error covariance (BEC) matrix of the ES, which can reflect the impacts of uncertainties of the ES on assimilation. Then we constructed the inversion model of the ES by combining the sensitivity analysis with 3DVAR techniques. We performed the simulation experiment using the inversion model for a heavy haze case study in the Beijing–Tianjin–Hebei (BTH) region during 27–30 December 2016. Results show that the spatial distribution of sensitivities of SO2 and NOx ESs to their concentrations, as well as the BEC matrix of ES, is reasonable. Using an a posteriori inversed ES, underestimations of SO2 and NO2 during the heavy haze period are remarkably improved, especially for NO2. Spatial distributions of SO2 and NO2 concentrations simulated by the constrained ES were more accurate compared with an a priori ES in the BTH region. The temporal variations in regionally averaged SO2, NO2, and O3 modeled concentrations using an a posteriori inversed ES are consistent with in situ observations at 45 stations over the BTH region, and simulation errors decrease significantly. These results are of great significance for studies on the formation mechanism of heavy haze, the reduction of uncertainties of the ES and its dynamic updating, and the provision of accurate “virtual” emission inventories for air-quality forecasts and decision-making services for optimization control of air pollution.

Transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus.

Transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus.

Improvement of snow/haze confusion data gaps in MODIS Dark Target aerosol retrievals in East China

The MODerate resolution Imaging Spectroradiometer (MODIS) is one of the most widely used meteorological remote sensing instruments. Its Dark Target aerosol optical depth (AOD) product has been widely used in environment and meteorology researches, such as model evaluation and data assimilation. However, this product has a low coverage under conditions of heavy haze in China. This is because the haze can be misidentified as snow under some circumstances by the algorithm and therefore rejected, leading to large-scale data omission. In the most polluted regions, misidentified snow cover exceeded 8%. Regarding this issue, a new method combining the snow mask derived from the MODIS cloud mask product and Fisher discrimination analysis was developed to give a more accurate identification of snow and ice cover. Applying this new method increases the AOD data coverage significantly. Comparisons with AOD values from ground-based observations showed that the newly produced data under haze conditions had a similar accuracy with the original data in the MODIS AOD product. Because the newly supplemented data are more distributed at the seriously polluted regions, the average AOD increased significantly after data filling in many regions. In winter, AOD in the most severely polluted regions (average air quality index >130) increased by 0.2–0.3 after improvement, about 30–50% of the original value. In 49 haze cases with large-scale pollution, the increase reached 0.3–0.6, about 50%–70% of the original value. During the haze episodes, the data omission led to an underestimation of the regional average AOD by 19–40%. The improvement in AOD coverage helps to provide a better reflection of the air pollution condition in East China through the perspective of AOD.

MOPSS. II. Extreme Optical Scattering Slope for the Inflated Super-Neptune HATS-8b

Abstract We present results for the inflated super-Neptune HATS-8b from the Michigan Optical Planetary Spectra Survey (MOPSS). This program is aimed at creating a database of optical planetary transmission spectra all observed, reduced, and analyzed with a uniform method for the benefit of enabling comparative exoplanet studies. HATS-8b orbits a G dwarf and is a low-density super-Neptune with a radius of 0.873 R Jup, a mass of 0.138 M Jup, and a density of 0.259 g cm−3. Two transits of HATS-8b were observed in 2017 July and August with the Inamori-Magellan Areal Camera and Spectrograph (IMACS) instrument on the Magellan Baade 6.5 m telescope. We find an enhanced scattering slope on each night that agree within 2.3σ. This slope is stronger than one due only to Rayleigh scattering and cannot be fully explained by unocculted starspots. We explore the impact of condensates on the scattering slope and determine that MnS particulates smaller than 10−2 μm can explain up to 80% of our measured slope if the planet is warmer than equilibrium, or 50% of the slope at the equilibrium temperature of the planet for a low mean molecular weight atmosphere. The scattering slope that we observe is thus beyond even the most extreme haze case we consider. We suggest further follow up on this target and host star to determine if the temporal variation of the slope is primarily due to stellar or planetary effects, and to better understand what these effects may be.

Water-Soluble Ionic Characteristics of Aerosols in the Marine Boundary Layer over the Yellow Sea during the KORUS-AQ Campaign

Major compositions of water-soluble ionic species in particulate matter less than 10 and 2.5 μm in diameter (PM10 and PM2.5, respectively) over the Yellow Sea were collected during the Korea–United States Air Quality (KORUS-AQ) campaign in 2016 onboard the research vessel Gisang 1. The secondary ionic species (NH4+, nss-SO42−, and NO3−) in PM10 and PM2.5 accounted for 84% and 89% of the total analyzed species. NH4+ was strongly correlated with non-sea salt (nss) SO42− (nss-SO42−) in PM10 and PM2.5; NO3− was closely correlated with Na+, Mg2+, and nss-Ca2+ in PM10 and NH4+ in PM2.5. High mass concentrations of methane sulfonic acid (MSA, CH3SO3−), the main source of natural sulfates over the Yellow Sea, were observed. The concentrations of MSA were found to show an increasing trend over the Yellow Sea in recent years. Biogenic sulfur contributions to the total nss-SO42− (MSA/nss-SO42− ratio) over the Yellow Sea ranged from 1.4% to 9.2% in PM10 and from 0.68% to 9.5% in PM2.5 during the cruise. Thus, biogenic nss-SO42− must be included, especially in the spring and early summer seasons, when biological activities are elevated in Northeast Asia. We classified the high aerosol mass concentration cases such as Asian dust and haze cases. In Asian dust cases, the ratio of NO3− to nss-SO42− in the aerosols showed that mobile (stationary) sources mainly affected PM10 (PM2.5). The major chemical species for Asian dust cases over the Yellow sea were CaCO3, Ca(NO3)2, Mg(NO3)2, Na(NO3)2, and sea salt. In haze cases over the Yellow sea, the contributions from stationary sources are high and the major species were (NH4)2SO4 and NH4NO3 in PM10 and PM2.5, respectively.

The role of information in multilateral governance of environmental health risk: lessons from the Equatorial Asian haze case

A multilateral approach to the governance of environmental health risk could be regarded as a possible response to the complexity of current risk problems. Such multilateral governance is deemed advisable in consideration of the need to achieve an adaptive risk management approach and establish a dialogue among the stakeholders involved in or affected by a specific risk. However, whereas the benefits of multilateral risk governance are clear in theory, in practice – and specifically for the environmental health domain – there seems to be a shortage of successful cases where this multilateral approach has been actually applied. In particular, this article targets the necessity to understand ‘multilateral’ in a broad sense, thus also including the international community and civil society actors, both organized in collectives (e.g. NGOs) and wider civil society (e.g. on-the-ground citizens). The case of the Equatorial Asian haze is investigated to respond to a theoretical question, namely whether and how processes of deviating dynamics can trigger an improvement in risk governance, especially stimulating alternative information production and pushing for the release of key information held by the government. Access to information results in being a necessary step to achieve multilateral risk governance.

서울지역 PM2.5 오염원의 시계열적 기여도 평가와 헤이즈의 유형분류

Huge hourly PM2.5 datasets monitored at the Seoul Intensive Monitoring Station (SIMS) during Jan. 1, 2013 to Dec. 31, 2014 were obtained from the National Institute of Environmental Research (NIER). A total of 12,376 samples consisting of 24 chemical variables and 3 meteorological variables had been applied for the positive matrix factorization (PMF) modeling based on a dataset segmentation scheme in the previous study (Park et al., 2019). After performing the receptor model, 14 independent PM2.5 sources were successfully identified and quantified at the SIMS. In this study, based on the meteorological variables and the previous PMF results, we assessed intensively the PM2.5 source contributions by time sequential analyses such as hourly, daily, weekly, monthly, and seasonal analyses and further we classified haze patterns into 3 types such as foreign-oriented type, domestic-oriented type, and mixed type, judging from PM2.5 source contribution. According to our intensive study on wintertime haze cases, all the episode events in Seoul area initially began with rapid and big air temperature drop for several days and then high PM2.5 concentration appeared right after rapid and big air temperature rise until air temperature rose again, which forming frontal inversion with slower wind speed and then lowering a mixing height causing concentration buildup. The most dominant PM2.5 source among 14 identified sources in Seoul area was secondary aerosol source, which was considered to be transported distantly from overseas. The seasonal source contribution was summer 15.8 μg/m³, spring 14.4 μg/m³, winter 10.4 μg/m³, and fall 5.4 μg/m³ in mass order. On the other hand, secondary nitrate source as another secondary aerosol was identified as one of domestic sources. The range of seasonal source contribution was in the range of 1.0∼2.4 μg/m³ and further weekly and monthly variations were relatively small. However, its hour variation was greatly changed, up to 4.5 μg/m³ during nighttime. We hope that the results of the study can be used as basic information whenever establishing reasonable air quality management and policy in Korea.

A fast image dehazing method that does not introduce color artifacts

We propose a method for color dehazing with four main characteristics: it does not introduce color artifacts, it does not depend on inverting any physical equation, it is based on models of visual perception, and it is fast, potentially real time. Our method converts the original input image to the HSV color space and works in the saturation and value domains by: (1) reducing the value component via a global constrained histogram flattening; (2) modifying the saturation component in consistency with the previous reduced value; and (3) performing a local contrast enhancement in the value component. Results show that our method competes with the state-of-the-art when dealing with standard hazy images, and outperforms it when dealing with challenging haze cases. Furthermore, our method is able to dehaze a FullHD image on a GPU in 90 ms.

Case study of spring haze in Beijing: Characteristics, formation processes, secondary transition, and regional transportation

Continuous haze monitoring was conducted from 12:00 3 April to 12:00 8 April 2016 in Beijing, China to develop a more detailed understanding of spring haze characteristics. The PM2.5 concentration ranged from 6.30 to 165 μg m−3 with an average of 63.8 μg m−3. Nitrate was the most abundant species, accounting for 36.4% of PM2.5, followed by organic carbon (21.5%), NH4+ (19.3%), SO42− (18.8%), and elemental carbon (4.10%), indicating the key role of nitrate in this haze event. Species contribution varied based on the phase of the haze event. For example, sulfate concentration was high during the haze formation phase, nitrate was high during the haze, and secondary organic carbon (SOC) had the highest contribution during the scavenging phase. The secondary transition of sulfate was influenced by SO2, followed by relative humidity (RH) and Ox (O3+NO2). Nitrate formation occurred in two stages: through NO2 oxidation, which was vulnerable to Ox; and by the partitioning of N (+5) which was susceptible to RH and temperature. SOC tended to form when Ox and RH were balanced. According to hourly species behavior, sulfate and nitrate were enriched during haze formation when the mixed layer height decreased. However, SOC accumulated prior to the haze event and during formation, which demonstrated the strong contribution of secondary inorganic aerosols, and the limiting contribution of SOC to this haze case. Investigating backward trajectories showed that high speed northwestern air masses following a straight path corresponded to the clear periods, while southwesterly air masses which traversed heavily polluted regions brought abundant pollutants to Beijing and stimulated the occurrence of haze pollution. Results indicate that the control of NO2 needs to be addressed to reduce spring haze. Finally, the correlation between air mass trajectories and pollution conditions in Beijing reinforce the necessity of inter-regional cooperation and control.

The characteristics of atmospheric phthalates in Shanghai: A haze case study and human exposure assessment

While phthalates in indoor environments are extensively studied, reports on phthalates in outdoor air, particularly their associations with haze weather events are rare. Phthalates, especially dimethyl phthalate, are known to react with criteria air pollutants contributing to the formation of secondary organic aerosols. This study investigated phthalates levels in the atmosphere in Shanghai with a focus on their associations with different air quality weather events. The air quality during the study period was classified into three levels: non-haze, light pollution and moderate pollution. Phthalates levels were found to be lower in non-haze weather events (236 ng/m3) and higher in moderate pollution weather events (up to 700 ng/m3). Meteorological factors of relative humidity and wind speed had an inverse relationship with phthalates levels. Particulate matter had a positive correlation with phthalates levels. Hydroxyl radical initiated photo-reaction of dimethyl phthalate was evident by its inverse relationship with total atmospheric oxidant (O3 + NO2), indicating that dimethyl phthalate could be one of the precursors of secondary organic aerosol causing haze weather events. Daily intake of phthalates through exposure to outdoor air is estimated to be relatively minor; children intake remains higher on a body weight basis. This is the first study demonstrating the relationship of phthalates and different air quality conditions in haze weather events. The knowledge contributes to our understanding on the cause of haze weather events in China and elsewhere.

Comparison of 5468 retreatments after laser in situ keratomileusis by lifting the flap or performing photorefractive keratectomy on the flap

Abstract Purpose To assess visual outcomes of retreatment after laser in situ keratomileusis (LASIK) by lifting the flap or performing photorefractive keratectomy (PRK) on the flap, as well as to establish whether there was an increased risk of epithelial ingrowth (EIG) when LASIK and lifting of the flap are separated by a long time interval and to determine the incidence of corneal haze after PRK. Methods Retrospective study of 4077 patients (5468 eyes) who underwent LASIK and subsequent retreatment were reviewed in order to study their visual results and identify cases of EIG and corneal haze. Results Enhancements included 5196 eyes from 3876 patients that were retreated by lifting the flap, and 272 eyes from 201 patients that were retreated by PRK on the flap. No statistically significant differences were found between the retreatments in terms of predictability, efficacy, and safety. A total of 704 cases of EIG were found after lifting the flap, for which surgical cleansing was necessary in 70. Surgical cleansing decreased the efficacy index when compared with patients with EIG who did not need cleansing ( p = 0.01). Differences in terms of safety and predictability were not statistically significant. The incidence of corneal haze after ablation of the surface of the previous flap was 14.34%, although none of these cases were clinically relevant. Conclusions Visual outcomes were similar between patients who were retreated by lifting the flap and those who underwent PRK. The incidence of EIG when the flap was lifted was 13.55%. The incidence of EIG increases with the time elapsed between the primary procedure and retreatment.

Comparación de 5.468 retratamientos tras láser in situ queratomileusis levantando el lentículo o mediante queratectomía fotorrefractiva sobre el lentículo

PurposeTo assess visual outcomes of retreatment after laser in situ keratomileusis (LASIK) by lifting the flap or performing photorefractive keratectomy (PRK) on the flap, as well as to establish whether there was an increased risk of epithelial ingrowth (EIG) when LASIK and lifting of the flap are separated by a long time interval and to determine the incidence of corneal haze after PRK. MethodsRetrospective study of 4077 patients (5468 eyes) who underwent LASIK and subsequent retreatment were reviewed in order to study their visual results and identify cases of EIG and corneal haze. ResultsEnhancements included 5196 eyes from 3876 patients that were retreated by lifting the flap, and 272 eyes from 201 patients that were retreated by PRK on the flap. No statistically significant differences were found between the retreatments in terms of predictability, efficacy, and safety. A total of 704 cases of EIG were found after lifting the flap, for which surgical cleansing was necessary in 70. Surgical cleansing decreased the efficacy index when compared with patients with EIG who did not need cleansing (P=.01). Differences in terms of safety and predictability were not statistically significant. The incidence of corneal haze after ablation of the surface of the previous flap was 14.34%, although none of these cases were clinically relevant. ConclusionsVisual outcomes were similar between patients who were retreated by lifting the flap and those who underwent PRK. The incidence of EIG when the flap was lifted was 13.55%. The incidence of EIG increases with the time elapsed between the primary procedure and retreatment.

Visibility effect on the availability of a terrestrial free space optics link under a tropical climate

Haze, fog and rain limit the visibilities and acts as dominant parameter for free space optics availability estimation. Low visibilities increase atmospheric attenuation and reduce the availability of optical signals from free space optics (FSO) links. Thus, this study determines the effect of visibility on FSO link availability in a tropical climate. Visibility data were measured in Malaysia for three years and used to estimate availability of FSO links. Rain and haze are two phenomena which reduces the visibility in tropical climate like Malaysia. Hence three cases were considered for measured data analysis: rain with dense haze, dense haze, and normal haze cases. In Malaysia, seasonal dense haze is mainly attributed to forest fires in Indonesia and in parts of Malaysia. The atmospheric attenuations predicted based on measured visibility (km) were compared across the three cases. The attenuations in the first two cases are found severe (almost 155dB/km); while in the third case it is very low (almost 6dB/km). The worst case (dense haze) is equivalent to a thick fog in temperate regions and must be examined carefully with respect to FSO deployment in a tropical environment.

A heavy haze episode in Beijing in February of 2014: Characteristics, origins and implications

More than half Chinese cities are suffering from severe air pollution due to the rapid development of industry and urbanization. Beijing, as a political and cultural center of China, has frequently suffered from severe haze. However, the precise sources of air pollution in Beijing still remain uncertain. In this study, the observational data (PM2.5, PM10, O3, NO2, CO and SO2) at ten monitoring stations from February 8 to 28, 2014, in Beijing were used to analyze air pollution. The satellite observations for aerosol optical thickness were also used. Backward trajectory model and receptor models were used to identify the sources of air pollution in Beijing. On the basis of PM2.5 concentrations, we separated the whole data into three categories: relatively clean air (PM2.5 concentrations less than 75 μg m–3), haze (PM2.5 concentrations greater than 75 μg m3 but less than 200 μg m3) and heavy haze (PM2.5 concentrations greater than 200 μg m3). The results show that the average concentrations of PM2.5 are 29.5 μg m3, 136.6 μg m3 and 311.2 μg m3 for relatively clean air, haze and heavy haze cases, respectively. The back trajectory cluster analysis reveals that the predominant clusters are east and south for the heavy haze case. The results of the receptor models show that for the haze case, pollutants mainly originated from south of Beijing such as Dezhou, Liaocheng and Heze in Shandong province, while for the heavy haze case, pollutants were mainly from southwest of Beijing such as Baoding, Hengshui and Handan in Hebei province. These results indicate that the emissions in the surrounding provinces made a significant contribution to Beijing's air pollution. Thus, it is necessary to implement air pollution control for all surrounding areas, especially for the industrial zones in the south/southwest regions of Beijing.

Spatial and Temporal Variability of Aerosol Vertical Distribution Based on Lidar Observations: A Haze Case Study over Jinhua Basin

The impacts of haze emphasized significance of hazards for human activities and importance of observations of aerosol vertical distribution. This study aimed to analyze the aerosol vertical distribution during a haze case at temporal and spatial aspects, using space-borne and ground-based Lidar observations over Jinhua Basin, Zhejiang province, as well as the Hybrid Single-Particle Lagrangian Integrated Trajectory (HSPLIT) model and optical situ monitoring at Jinhua site. The results highlight three pollution peaks above the surface located in the upper and lower boundary layer in Jinhua Basin. The trajectory analysis shows the pollutants inside and outside the planetary boundary layer from different sources. Planetary boundary layer height (PBLH) obtained from the space-borne Lidar observations was compared with that from ground-based Lidar observations. The absolute error between the two instruments is about 0.193 km. It is illustrated that the space-borne Lidar is an effective instrument for obtaining regional aerosol pollution in vertical section. Pollution transport near the ground is closely related with the terrain condition.

Textural interface opacity after Descemet-stripping automated endothelial keratoplasty

To describe cases of interface haze, also known as textural interface opacity, after Descemet-stripping automated endothelial keratoplasty (DSAEK). Department of Cornea, External Disease, and Refractive Surgery Service, Duke Eye Center, Durham, North Carolina, USA. Retrospective case series. Patients' clinical and demographic characteristics, cornea donor information, surgical technique, histopathology, and anterior segment optical coherence tomography (OCT) were reviewed retrospectively and clinical outcomes reported. The interface haze that developed after DSAEK comprised 2 types of textural interface opacity; that is, total (11 cases) and partial (3 cases). The time of onset of textural interface opacity ranged from 1 day to 7 weeks postoperatively. Although most patients with textural interface opacity showed improvement, with a corrected distance visual acuity better than 20/50, 3 had persistent decreased visual acuity and required repeat DSAEK. Seven eyes had concurrent phacoemulsification with intraocular lens implantation and DSAEK. The corneal graft was inserted with an Endoserter device in 11 eyes, an insertion forceps in 2 eyes, and a cystotome needle in 1 eye. Histopathology of the grafts of eyes that required repeat DSAEK showed no inflammation, no foreign-body deposit, and no fibrosis. Anterior segment OCT showed increased hyperreflectivity in the interface. Although the etiology of textural interface opacity is unclear, it may be related to retained ophthalmic viscosurgical device (OVD) or an adhesive property of the OVD used during the surgery. Although most cases resolve with time, repeat DSAEK may be an effective treatment for refractory cases. Dr. Kim is a consultant to Ocular Systems, Inc. No other author has a financial or proprietary interest in any material or method mentioned.