Variation Of Optical Properties Research Articles

Effect of Calcination Temperature and Substitution of Erbium on Structural and Optical Properties of Nickel Zinc Ferrite Nanoparticles

A single composition of erbium-doped nickel zinc ferrite Ni0.5Zn0.5Fe1.95Er0.05O4 is synthesized by the sol-gel autocombustion process. The prepared composition was divided into five equal parts. One of the parts was an as-prepared sample, and remaining four other parts were calcinated at 600, 700, 800, and 900 ∘C to investigate the variation in structural and optical properties with the calcination temperature. The structural characterization was performed using XRD and SEM. Optical properties were analyzed using FTIR and UV-Visible spectral data. XRD patterns confirm the spinel cubic crystal structure and the Fd3m space group. The crystallite size was minimum for the as-prepared sample (17.9452 nm), and the crystallite size was maximum for the sample calcinated at 900 ∘C (29.8481 nm). SEM images revealed the grain size in the interval from 55.38 nm to 177.73 nm, and certain nanotubes were formed in the sample calcinated at 800 ∘C. Optical energy band gap was observed in the interval from 5.556 eV to 3.969 eV. All these testifies to the variations in structural and optical properties of Ni0.5Zn0.5Fe1.95Er0.05O4 with the calcination temperature.

An end-to-end seed vigor prediction model for imbalanced samples using hyperspectral image.

Hyperspectral imaging is a key technology for non-destructive detection of seed vigor presently due to its capability to capture variations of optical properties in seeds. As the seed vigor data depends on the actual germination rate, it inevitably results in an imbalance between positive and negative samples. Additionally, hyperspectral image (HSI) suffers from feature redundancy and collinearity due to its inclusion of hundreds of wavelengths. It also creates a challenge to extract effective wavelength information in feature selection, however, which limits the ability of deep learning to extract features from HSI and accurately predict seed vigor. Accordingly, in this paper, we proposed a Focal-WAResNet network to predict seed vigor end-to-end, which improves the network performance and feature representation capability, and improves the accuracy of seed vigor prediction. Firstly, the focal loss function is utilized to adjust the loss weights of different sample categories to solve the problem of sample imbalance. Secondly, a WAResNet network is proposed to select characteristic wavelengths and predict seed vigor end-to-end, focusing on wavelengths with higher network weights, which enhance the ability of seed vigor prediction. To validate the effectiveness of this method, this study collected HSI of maize seeds for experimental verification, providing a reference for plant breeding. The experimental results demonstrate a significant improvement in classification performance compared to other state-of-the-art methods, with an accuracy up to 98.48% and an F1 score of 95.9%.

Polarity-Induced Morphological Transformation with Tunable Optical Output of Terpyridine-Phenanthro[9,10-d]imidazole-Based Ligand and Its Zn(II) Complexes with I-V Characteristics.

Self-assembled nanostructures obtained from various functional π-conjugated organic molecules have been able to draw substantial interest due to their inherent optical properties, which are imperative for developing optoelectronic devices, multiple-color-emitting devices with color-tunable displays, and optical sensors. These π-conjugated molecules have proven their potential employment in various organic electronic applications. Therefore, the stimuli-responsive fabrication of these π-conjugated systems into a well-ordered assembly is extremely crucial to tuning their inherent optical properties for improved performance in organic electronic applications. To this end, herein, we have designed and synthesized a functional π-conjugated molecule (TP) having phenanthro[9,10-d]imidazole with terpyridine substitution at the 2 position and its corresponding metal complexes (TPZn and (TP)2Zn). By varying the polarity of the self-assembly medium, TP, TPZn, and (TP)2Zn are fabricated into well-ordered superstructures with morphological individualities. However, this medium polarity-induced self-assembly can tune the inherent optical properties of TP, TPZn, and (TP)2Zn and generate multiple fluorescence colors. Particularly, this property makes them useful for organic electronic applications, which require adjustable luminescence output. More importantly, in 10% aqueous-THF medium, TPZn exhibited H-type aggregation-induced white light emission and behaved as a single-component white light emitter. The experimentally obtained results of the solvent polarity-induced variation in optical properties as well as self-assembly patterns were further confirmed by theoretical investigation using density functional theory calculations. Furthermore, we investigated the I-V characteristics, both vertical and horizontal, using ITO and glass surfaces coated with TP, TPZn, and (TP)2Zn, respectively, and displayed maximum current density for the TPZn-coated surface with the order of measured current density TPZn > TP > (TP)2Zn. This observed order of current density measurements was also supported by a direct band gap calculation associated with the frontier molecular orbitals using the Tauc plot. Hence, solvent polarity-induced self-assembly behavior with adjustable luminescence output and superior I-V characteristics of TPZn make it an exceptional candidate for organic electronic applications and electronic device fabrication.

Controlled dynamic variation of interfacial electronic and optical properties of lithium intercalated ZrO2/MoS2 vdW heterostructure

Efficient strategies for modifying the characteristics of van der Waals (vdW) layered materials in a precise and reversible mode remain challenging. Our suggested method for customization entails the implementation of layer-sliding and intercalation. In this work, a norm-conserving approach within the context of density functional theory has been used to examine the electronic and optical properties of two-dimensional (2D) van der Waals heterostructure (vdWHS), which is modeled by using 2D zirconium dioxide (1T-ZrO2) and molybdenum disulfide (1T-MoS2) monolayers of similar phase. Both contributing monolayers have similar lattice structures, with a minimum lattice mismatch of 0.83 %, and have corrugation on both sides that can successfully retain foreign species at the vdW-gap. In the next step, interfacial engineering through Li-intercalation and layer-sliding was employed to modify physical properties of the vdWHS. It is the worth mentioning that a narrow bandgap of 0.102 eV (0.22 eV) has been observed in the unintercalated ZrO2/MoS2 vdWHS when employing PW-LDA (hybrid-functional). Li-intercalation and sliding process significantly influenced the electronic properties of the studied vdWHS. Furthermore, un-slided and fully-slided Li-intercalated vdWHS exhibit an increase in the vdW-gap by 3.78 % and 27.14 %, respectively, as compared to unintercalated vdWHS. To further understand the electrical behaviour at the interface of contributing monolayers, a comparative study has also been made for the variation in the planar average charge density difference, charge transfer, and interface dipole moment for unintercalated and intercalated vdWHS. In the unintercalated vdWHS, the calculated values of ΔQ and μ(z) provide evidence of significant charge transfer from 1T-ZrO2 to 1T-MoS2 before sliding, whereas in the fully-slided vdWHS, there is 80.11 % more charge transfer from 1T-MoS2 to 1T-ZrO2. Li-intercalation increases the magnitude of ΔQ (by 90.27 %) near 1T-MoS2, indicating a sufficient quantity of charge transfer from the 1T-MoS2 monolayer. The results of the anisotropic analysis show that the calculated in-plane and out-of-plane components of the real and imaginary parts of the dielectric function differ significantly. The optical absorption and energy losses of Li-intercalated vdWHS experience a substantial decrease of about 90 % and 50 %, respectively, as compared to unintercalated vdWHS. Our employed method promotes the notion that interfacial engineering through simultaneous layer-sliding and intercalation approach can be used to regulate and modify the physical properties of 2D insulator/metal based vdWHS.

Synthesis and characterization of lithium-doped copper zinc tin sulfide (CZTS) thin films

The non-toxic nature and remarkable optoelectronic properties of kesterite (Cu2ZnSnS4 and CZTS) make CZTS a potential candidate for solar cell absorber layer material. Since alkali metal doping has shown a performance boost of active layers of solar cells, this work investigates the effects of significant lithium doping on sol-gel-produced CZTS thin films. CZTS- and lithium (Li)-doped CZTS thin films were prepared using the spin coating technique. The variation of structural, morphological, and optical properties of CZTS due to Li-doping has been studied by x-ray diffraction, scanning electron microscopy, and UV–visible spectroscopy techniques. All the synthesized LixCu2−xZnSnS4 (x = 0, 0.2, 0.4, 0.6) films showed fine crystallinity with average crystallite sizes of 4.745, 6.013, 6.255, and 6.404 nm, respectively. The average grain size decreases from 0.336 to 0.310 µm via increasing Li concentration. The inclusion of Li increased the bandgap energy ranges from 1.5 to 1.808 eV. The Li0.6Cu1.4ZnSnS4 thin showed the highest absorption coefficient of 3.505 × 104 cm−1 among all the prepared thin films. A high optical conductivity over 1014 s−1 was observed for CZTS, which further increased with an increased Li concentration. The synthesized structures showed enhanced characteristics suitable for solar cell application.

Study of Variation in Optical Properties and Dispersion Parameters of Fe-Doped TiO2 Nanopowders

Study of Variation in Optical Properties and Dispersion Parameters of Fe-Doped TiO2 Nanopowders

Imbedded Perovskite Nanocrystals in Metal Halide Microcrystal: Synthesis and Heterostructure

AbstractLead halide perovskite nanocrystals and other metal halides have received considerable attention due to their unique optoelectronic properties. A combined perovskite nanocrystal‐metal halide heterostructure can achieve desirable properties for enriched applications. However, the construction of such a heterostructure is challenging. In this study, a CsPbBr3/Cs2ZnBr4 heterostructured microcrystal with perovskite nanocrystals embedded in a metal halide matrix is successfully synthesized using a facile ultrasound‐assisted post‐processing method. The heterostructure of the perovskite‐metal halide composite materials is fully deciphered through ab initio calculations and multiscale characterizations. The heterostructure‐induced variation in optical properties is elucidated based on micro‐nano spectral and luminescence kinetic behaviors. This study provides new insights into the design of perovskite nanocrystal‐based heterostructured materials, improving the understanding of metal halides and extending their applications.

The effect of step-flow growth on the surface morphology and optical properties of thick diamond films

Thick diamond films are needed for high power device applications. One approach is to grow via the step-flow growth mode on miscut substrates. In this paper we correlate variations of surface morphology and optical properties of a 250 μm-thick undoped diamond layer, grown at a rate of 10.4 μm/h, on a (001) diamond substrate with a miscut angle of 10 degrees towards a <010> direction. The epilayer surface comprises regions with island growth on (001) planes, and regions parallel to the miscut substrate surface exhibiting step-bunching and faceting and resulting in various degrees of surface roughness. The optical properties exhibit a combination of sharp and broad luminescence peaks, which are found to be specific to growth morphology and to the nitrogen content in the near-surface region.

Optical Properties and Vertical Distribution of Aerosols Using Polarization Lidar and Sun Photometer over Lanzhou Suburb in Northwest China

To better understand aerosol vertical distribution and radiation effects, the seasonal variation and vertical distribution characteristics of aerosol optical properties were analyzed based on the aerosol extinction coefficient, depolarization ratio and backscatter Ångström exponent derived from the dual-wavelength polarization lidar at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from December 2009 to November 2012. Combining the CE-318 sun photometer, the microphysical, optical and vertical distribution characteristics of aerosol during a dust process were discussed comprehensively. The results revealed that the vertical profiles of the aerosol extinction coefficient and depolarization ratio clearly had seasonal variation characteristics. The aerosol optical depth (AOD) integrating with the aerosol extinction coefficient within 0–2 km in the spring, summer, autumn and winter accounted for 48%, 45%, 56% and 58% of the total AOD, respectively. The non-spherical feature was most distinctive in the spring, followed by the winter, autumn and summer. The particle size of aerosol in the lower layer was larger than that in the upper layer according to the vertical profile of the backscatter Ångström exponent. The cluster analysis of backward trajectory showed SACOL is dominated by dust aerosol in the spring and the mixtures of dust with anthropogenic pollution in the winter. A dust event in April 2010 was selected and the analysis showed that it mainly came from the high-altitude and long-range transportation from the Taklamakan Desert. During this period, the extinction coefficient increased up to 0.9 km−1, the maximum AOD was 2.21 and the SSA ranged from 0.92 to 0.99. The radiation force in the atmosphere reached 126.15 W/m2. It can be found that the influence of aerosol on the atmospheric radiation effect cannot be ignored.

Using reflectometry to minimize the dependence of fluorescence intensity on optical absorption and scattering.

The total diffuse reflectance RT and the effective attenuation coefficient µeff of an optically diffuse medium map uniquely onto its absorption and reduced scattering coefficients. Using this premise, we developed a methodology where RT and the slope of the logarithmic spatially resolved reflectance, a quantity related to µeff, are the inputs of a look-up table to correct the dependence of fluorescent signals on the media's optical properties. This methodology does not require an estimation of the medium's optical property, avoiding elaborate simulations and their errors to offer accurate and fast corrections. The experimental demonstration of our method yielded a mean relative error in fluorophore concentrations of less than 4% over a wide range of optical property variations. We discuss how the method developed can be employed to improve image fidelity and fluorochrome quantification in fluorescence molecular imaging clinical applications.

Influence of betalain natural dye from red beet in gum acacia biopolymer: optical and electrical perspective

Abstract In this study, the development and characterization of a plant-derived biopolymer, gum acacia, chemically modified by an herbal dye, red beetroot (Latin Beta vulgaris) has been presented. Red beetroot, a flowering plant with abundant phytochemicals, prevents diseases and produces colorful chromophores. Chromophores interact with incident intense electromagnetic field and thereby absorb radiation in ultraviolet and/or visible region of the spectrum, promoting low to high-level electron excitation between different energy states. Such transition influences variation in optical and electrical properties of the system. Optical properties of both biopolymer unmodified gum acacia specimen and after modification with red beet induced chromophore are investigated by UV–visible absorption spectroscopy. Pronounced light absorption is observed in the visible range of the spectrum compared to the unmodified specimen in which absorption is found to be observed in the deep ultraviolet range. Electrical characterization of the modified biopolymer with red beetroot extract suggests eviation from ideal dielectric relaxation obeying Debye mechanism. Electrical conductivity is found to be enhanced over pure specimen. These properties are eligible for application in energy storage devices, especially as a sensitizer in photovoltaic material which are ongoing extensive research area.

Exploring the effects of external stress on the crystal lattice of SrHfO3: Significance of variations in structural, electrical, optical, and mechanical properties

The electronic, optical, structural, elastic, and mechanical properties of cubic Strontium Hafnium Oxide SrHfO3 under variable stress conditions were examined using the Generalized Gradient Approximation (GGA) method. Density functional theory was employed to determine the influence of stress on the electronic properties of the oxide perovskite, resulting in changes in the electronic band gap 3.206–2.834 eV, partial density of states, and total density of states. Significant variations in various optical properties, including absorption, conductivity, reflectivity, as well as the real and imaginary components of the dielectric function, were observed. The differences were noted in the loss function and refractive index. The elastic properties revealed a linear increase in elastic constants such as C11 and C12, while C44 showed a declining trend. Likewise, an increase in mechanical properties, including Young's modulus, bulk modulus, and shear modulus, was found. Furthermore, variations were discovered in the Frantsevich ratio, Anisotropy, Poisson's ratio, and Pugh's ratio. These findings provided valuable intuitions into the properties of cubic SrHfO3, with potential implications for the development of semiconducting devices, thermal coatings, and dielectrics.

Aerosol Optical Properties of Extreme Global Wildfires and Estimated Radiative Forcing With GCOM‐C SGLI

AbstractTo understand the climate impact of the wildfires, it is essential to monitor the aerosol emissions from biomass burning and to estimate their optical properties and radiative forcing. This study analyzed wildfires in Brazil, Angola, Australia, California, Siberia, and South‐east Asia that occurred after 2018 using data obtained with the Second‐generation GLobal Imager (SGLI) onboard Global Change Observation Mission—Climate which is a polar‐orbit satellite launched by JAXA on 23 December 2017. We showed the SGLI‐based 4‐year variation of the aerosol optical properties, Aerosol Optical Thickness, Ångström Exponent (AE), and Single Scattering Albedo (SSA) for each region complemented with other satellite‐ and ground‐based data. From the SSA and AE relationship analyses, we confirmed that their optical properties depend on the relative humidity and type of burned vegetation, which is consistent with the previous studies. Moreover, we estimated the net incoming radiation at the top of the atmosphere during the intense fire periods to understand the impact of the direct effect of biomass burning aerosols on radiative forcing. The estimates show a significant negative radiative forcing (i.e., a cooling effect) over the ocean (−78 and −96 Wm−2in Australia and California, respectively). In contrast, small values are observed over land (∼−10 Wm−2for all six regions). Therefore, taking the regional characteristics of the optical properties and surface reflectance into account is necessary to estimate the effect on radiative forcing and future impacts of a short‐lived climate forcer from wildfires.

Ultrafine particles in urban settings: A combined study of volatility and effective density revealed by VT-DMA-APM

Volatility and effective density of aerosol particles are complicatedly linked properties, undergoing dynamic temporal evolution in the ambient environment. However, the simultaneous investigation of these physicochemical characteristics remains unexplored in roadside environments that exhibit a significant proportion of motorcycles in the vehicle fleet - a common scenario in Southeast Asia. As such, we deployed an innovative in-situ measurement technique, specifically the Volatile Tandem Differential Mobility Analyzer and Aerosol Particle Mass Analyzer (VT-DMA-APM) system, to investigate ultrafine particles (UFPs) in an urban region of northern Taiwan. Our findings revealed that the UFPs predominant in this study area were largely soot aggregates interspersed with condensable materials. Traffic-related air pollutants (TRAPs), specifically condensable organic substances, emerged as key determinants of particle effective density and volatility. Intriguingly, the peculiar interrelation between aerosol physicochemical properties and particle size suggests that UFPs may represent an amalgamation of black carbon (BC) coated with condensable substances and non-BC-containing particles. We observed an inverse relationship between effective density and volatility, indicative of atmospheric aging processes. Moreover, concurrent measurements of Absorption Angstrom Exponent (AAE) and shape factor (Ks) provided valuable insights into variations in optical properties and morphology during aging. Peak AAE and minimal Ks values consistently occurred at noon, implying heightened particle aging during this period due to coating and morphological alterations.

A potential nonlinear optical material for crown-porphyrin complexes: Alkali metal doping and transition metal introducing

Crown ethers have inspired the rapid growth of research interest in the design and synthesis of functional materials due to their exceptional affinity for metal. In this work, a fascinating crown-porphyrin (Cr-Pr) complexes were studied with doping alkali metal (potassium, K atom) on the crown ether face and introducing transition metal (zinc, Zn atom) on the porphyrin face. The research reveals that the Cr-Pr complex with doped K and Zn atoms results in significant variations in nonlinear optical (NLO) properties. Interestingly, the crown ether ring with the K atom in the K@Cr-Pr complex leads to a remarkable first hyperpolarizability (βtot). On the contrary, when introducing the Zn atom in porphyrins, the Cr-Pr@Zn complex exhibits no significant change in NLO response. Further, the combination of the K and Zn atoms in crown-porphyrin complex (K@Cr-Pr@Zn) can result in significant enhancement of their NLO characteristics, which is much greater than that of the K@Cr-Pr and the Cr-Pr@Zn complexes. The natural population analysis (NPA) and the molecular electrostatic potential maps (ESP) show that the doping of the K atom regulates effectively charge distribution in the complexes. Moreover, the great βtot value can be further illustrated by their low transition energies and an obvious charge transfer (CT) transition in the main excited states. Therefore, the current work achieves that the NLO properties of crown ether derivatives can be regulated by doping alkali metals in the crown ether ring and provides a theoretical guide for developing high-performance NLO devices.

Tunable Non-Kasha Behaviors and Excited-State Dynamics of Quadrupolar Squaraine Aggregates.

Versatile coupling theories have been developed for rationalizing unusual aggregation phenomena of multipolar chromophores. Here, diverse excitonic couplings of a quadrupolar squaraine dye protonated by trifluoroacetic acid could be achieved and tuned unprecedentedly in different solvation media. Subtle changes of the solvent and ion pair influenced the aggregation of the donor-acceptor-donor (D-A-D)-type SQC6 and led to significant variations in optical properties. In contrast to conventional H/J aggregates, strong spectroscopic evidence of nonfluorescent and red-shifted hJ aggregation was obtained. Assumptions of the excitonic interplay with variable strength stabilized by the synergic contributions of π-π stacking and electronic interaction were addressed. Comparative excited-state dynamics in the aggregates clarified the distinctive excitonic coupling of adjacent quadrupolar molecules and the nature of the excited state beyond the dimers. Meanwhile, dominant two-photon absorption transitions could be elucidated by a resonance-enhanced mechanism. The present unusual molecular interplay provides a strategy to fine tune the optical properties of multipolar aggregates.

Morphology Transition with Temperature and its Effect on Optical Properties of Colloidal MoS2 Nanostructures.

Morphology plays a crucial role in determining the chemical and optical properties of nanomaterials due to confinement effects. We report the morphology transition of colloidal molybdenum disulfide (MoS2) nanostructures, synthesized by a one-pot heat-up method, from a mix of quantum dots (QDs) and nanosheets to predominantly nanorods by varying the synthesis reaction temperature from 90 to 160 °C. The stoichiometry and composition of the synthesized QDs, nanosheets, and nanorods were quantified to be MoS2 using energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses. A nanostructure morphology transition due to variation in the reaction temperature resulted in a photoluminescence quantum yield enhancement from 0 to 4.4% on increasing the temperature from 90 to 120 °C. On further increase in the temperature to 160 °C, a decrease in the quantum yield to 3.06% is observed. Red-shifts of ≈18 and ≈140 nm in the emission maxima and absorption edge, respectively, are observed for the synthesized nanostructures with an increase in the reaction temperature from 90 to 160 °C. The change in the quantum yield is attributed to the change in shape and hence confinement of charge carriers. To the best of our knowledge, microscopic analysis of variation in shape and optical properties of colloidal MoS2 nanostructures with temperature, explained by a nonclassical growth mechanism is presented here for the first time.

An operational model for separating the absorption of optically active constituents from SeaWiFS measurements

ABSTRACT To analytically or semi-analytically convert satellite-measured remote sensing reflectance (R rs) to widely used biogeochemical variables from the global oceans, it is common to first determine the total absorption coefficient from satellite R rs data and then separate the total absorption coefficient into the absorption coefficients of phytoplankton (a ph ) and non-phytoplankton (a dg ) pigments. While still considering the spectral characteristics of a ph and a dg , we developed an operational model to improve the accuracy of estimating a ph and a dg products from satellite R rs data. Our results show that our model effectively separates a ph and a dg from the total absorption coefficient spectrum, which decreases the uncertainty by 6.81% to 17.52% compared to a widely used quasi-analytical algorithm. Moreover, after applying the new model to SeaWiFS satellite images, we present the spatial and temporal variations of a ph (443) and a dg (443) for the global oceans from 1997 to 2010, further confirming that coastal zones exhibited higher a ph (443) and a dg (443) than the open oceans during that time. In addition, a ph (443) and a dg (443) declined in the tropical Indian Ocean Gyre over those 13 years. Our results improve our knowledge of the spatiotemporal variations of optical properties of the global oceans, and also demonstrate the potential of our model in separating the total absorption.

Snow-corrected vegetation indices for improved gross primary productivity assessment in North American evergreen forests

North American evergreen forests cover large areas and influence the global carbon cycle. Satellite remote sensing has been used to track the phenology of ecosystem photosynthesis of these forests by detecting variation in vegetation optical properties associated with physiological and structural features, and most of these methods have been closely tied to vegetation greenness. However, in evergreens, the application of satellite data to monitor photosynthetic phenology is often limited by the lack of sensitivity of greenness-based indices. In this study, we identified 47 evergreen forest flux sites in North America that had MODIS observation overlapping with the flux tower records. We then calculated four vegetation indices using MODIS MAIAC data (MCD19A1), including NDVI, CCI, NIRv, and kNDVI, for the 47 flux sites and evaluated relationships between gross primary productivity (GPP) and vegetation indices across the North American evergreen forests. Our results showed that snow had substantial effects on the performance of all vegetation indices in tracking GPP phenology, particularly in the early spring when rapid changes occurred to both GPP and snow cover. Different vegetation indices were affected differently, indicating contradictory and confounding effects of snow on these indices. After correcting for the snow effects, both CCI and NIRv performed well in tracking GPP phenology, albeit for different reasons. CCI is sensitive to seasonal changes in the relative levels of chlorophyll and carotenoid pigments, which are closely tied to GPP phenology in evergreens. NIRv is sensitive to the absorbed photosynthetically active radiation and to the contribution of deciduous components to the overall optical properties. We also found that correlations between GPP and vegetation indices varied among ecoregions and climate classes. In general, regions with pronounced seasonal GPP patterns had stronger correlations between GPP and greenness-based indices than regions with weaker seasonal GPP patterns. These biome differences were less pronounced for CCI. The snow artifacts and complementary vegetation index effects reported here should be considered in any large-scale studies of GPP using reflectance-based indices from optical satellites.

Optical and Physical Characteristics of Aerosol Layers in Australia Based on CALIPSO

Atmospheric aerosols have important impacts on global radiative forcing, air pollution, and human health. This study investigated the optical and physical properties of aerosol layers over Australia from 2007 to 2019 using the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) Level 2 aerosol products. Australia was divided into three sub-regions (western highlands, central plains, and eastern ranges). Interannual and seasonal optical property variations in aerosol layers in the three sub-regions were analyzed and compared. Results showed that annual mean values of AODL (lowest aerosol layer AOD) and AODT (total AOD of all aerosol layers) were always higher in the eastern ranges region than the other two regions from 2007 to 2019. The reason could be that Australian population was predominantly located in the eastern ranges region, where more human activities could bring significant aerosol loadings. BL (base height of the lowest aerosol layer), HL (top height of the lowest aerosol layer), and HH (top height of the highest aerosol layer) all showed trends of “western highlands &gt; eastern mountains &gt; central plains”, indicating that the higher the elevation, the higher the BL, HL, and HH. TL (thickness of the lowest aerosol layer) was higher during the day than at night, which might account for increased diurnal atmospheric convection and nocturnal aerosol deposition. DRL (depolarization ratio of the lowest aerosol layer) was higher in the western highlands and central plains than the eastern mountains, probably because these two regions have large deserts with more irregularly shaped dust aerosols. CRL (color ratio of the lowest aerosol layer) had slightly higher values in the eastern ranges than the other two regions, probably due to the wet climate of the eastern ranges, where aerosols were more hygroscopic and had larger particle sizes. This study can provide technical support for the control and management of regional air pollutants.