Large-area display textiles integrated with functional systems.

Displays are basic building blocks of modern electronics1,2. Integrating displays into textiles offers exciting opportunities for smart electronic textiles-the ultimate goal of wearable technology, poised to change the way in which we interact with electronic devices3-6. Display textiles serve to bridge human-machine interactions7-9, offering, for instance, a real-time communication tool for individuals with voice or speech difficulties. Electronic textiles capable of communicating10, sensing11,12 and supplying electricity13,14 have been reported previously. However, textiles with functional, large-area displays have not yet been achieved, because it is challenging to obtain small illuminating units that are both durable and easy to assemble over a wide area. Here we report a 6-metre-long, 25-centimetre-wide display textile containing 5 × 105 electroluminescent units spaced approximately 800 micrometres apart. Weaving conductive weft and luminescent warp fibres forms micrometre-scale electroluminescent units at the weft-warp contact points. The brightness between electroluminescent units deviates by less than 8 per cent and remains stable even when the textile is bent, stretched or pressed. Our display textile is flexible and breathable and withstands repeated machine-washing, making it suitable for practical applications. We show that an integrated textile system consisting of display, keyboard and power supply can serve as a communication tool, demonstrating the system's potential within the 'internet of things' in various areas, including healthcare. Our approach unifies the fabrication and function of electronic devices with textiles, and we expect that woven-fibre materials will shape the next generation of electronics.

Realizing Long Magnon Diffusion in Organic-Inorganic Hybrid Perovskite Film by the Universal Isotope Effect.

Organic-inorganic halide perovskite (OIHP) spintronics has become a promising research field, as it provides a new precisely manipulable degree of freedom. Recently, by utilizing the spin Seebeck effect and inverse spin-Hall effect measurements, we have discovered substantial magnon injection and transport in Pt/OIHP/Y3Fe5O12 nonlocalized structure. In theory, hyperfine interaction (HFI) is considered to have an important role in the magnon transport of OIHP, but there is no clear experimental evidence reported so far. We report increased spin Seebeck coefficient and lengthened magnon diffusion length in deuterated- (D-) OIHP films that have weaker HFI strength compared with protonated- (H-) OIHP. Consequently, D-MAPbBr3 film, as a non-ferromagnetic spacer, achieves long magnon diffusion length at room temperature (close to 120.3 nm). Our finding provides valuable insights into understanding magnon transport in OIHP films and paves the way for the use of OIHPs in multifunctional applications.

In-situ construction of fluorescent probes for hydrogen peroxide detection in mitochondria and lysosomes with on-demand modular assembling and double turn-on features.

Due to the diverse H2O2 distribution in organelles, fluorescent probes were usually required to be prepared separately, which limited the convenience and practicability. Herein, we reported a flexible strategy to in-situ construct H2O2 fluorescent probes in different organelles. A tetrazine fused probe TP was developed with rapid click reaction capacity and sensitive H2O2 response. When treated with H2O2, the turn-on fluorescence was effectively quenched by the tetrazine part. Only after click reaction with dienophiles, the fluorescence resumed. In application, cells were firstly treated with triphenylphosphorus tagged norbornene (TPP-NB) to label mitochondria, which was followed by the introduction of probe TP to trigger click reaction. The in-situ constructed probe P1 served as a local H2O2 sensor. In a similar way, probe P2 was in-situ constructed in lysosomes via probe TP and morpholine tagged norbornene (MP-NB). With this on-demand modular assembling and double turn-on features, our strategy to construct fluorescent probes presented high flexibility and anti-interference performance, which was expected to inspired more applications in biological studies.

Optimizing retrieval spaces of bio-optical models for remote sensing of ocean color.

We investigated the optimal number of independent parameters required to accurately represent spectral remote sensing reflectances (R rs) by performing principal component analysis on quality controlled in situ and synthetic R rs data. We found that retrieval algorithms should be able to retrieve no more than four free parameters from R rs spectra for most ocean waters. In addition, we evaluated the performance of five different bio-optical models with different numbers of free parameters for the direct inversion of in-water inherent optical properties (IOPs) from in situ and synthetic R rs data. The multi-parameter models showed similar performances regardless of the number of parameters. Considering the computational cost associated with larger parameter spaces, we recommend bio-optical models with three free parameters for the use of IOP or joint retrieval algorithms.

Instantaneous photosynthetically available radiation models for ocean waters using neural networks.

Instantaneous photosynthetically available radiation (IPAR) at the ocean surface and its vertical profile below the surface play a critical role in models to calculate net primary productivity of marine phytoplankton. In this work, we report two IPAR prediction models based on the neural network (NN) approach, one for open ocean and the other for coastal waters. These models are trained, validated, and tested using a large volume of synthetic datasets for open ocean and coastal waters simulated by a radiative transfer model. Our NN models are designed to predict IPAR under a large range of atmospheric and oceanic conditions. The NN models can compute the subsurface IPAR profile very accurately up to the euphotic zone depth. The root mean square errors associated with the diffuse attenuation coefficient of IPAR are less than 0.011m-1 and 0.036m-1 for open ocean and coastal waters, respectively. The performance of the NN models is better than presently available semi-analytical models, with significant superiority in coastal waters.

The Antiviral Effects of Jasminin via Endogenous TNF-α and the Underlying TNF-α-Inducing Action.

Previous studies have reported that recombinant tumor necrosis factor (TNF)-α has powerful antiviral activity but severe systematic side effects. Jasminin is a common bioactive component found in Chinese herbal medicine beverage "Jasmine Tea". Here, we report that jasminin-induced endogenous TNF-α showed antiviral activity in vitro. The underlying TNF-α-inducing action of jasminin was also investigated in RAW264.7 cells. The level of endogenous TNF-α stimulated by jasminin was first analyzed by an enzyme-linked immunosorbent assay (ELISA) from the cell culture supernatant of RAW264.7 cells. The supernatants were then collected to investigate the potential antiviral effect against herpes simplex virus 1 (HSV-1). The antiviral effects of jasminin alone or its supernatants were evaluated by a plaque reduction assay. The potential activation of the PI3K-Akt pathway, three main mitogen-activated protein kinases (MAPKs), and nuclear factor (NF)-κB signaling pathways that induce TNF-α production were also investigated. Jasminin induces TNF-α protein expression in RAW264.7 cells without additional stimuli 10-fold more than the control. No significant up-expression of type I, II, and III interferons; interleukins 2 and 10; nor TNF-ß were observed by the jasminin stimuli. The supernatants, containing jasminin-induced-TNF-α, showed antiviral activity against HSV-1. The jasminin-stimulated cells caused the simultaneous activation of the Akt, MAPKs, and NF-κB signal pathways. Furthermore, the pretreatment of the cells with the Akt, MAPKs, and NF-κB inhibitors effectively suppressed jasminin-induced TNF-α production. Our research provides evidence that endogenous TNF-α can be used as a strategy to encounter viral infections. Additionally, the Akt, MAPKs, and NF-κB signaling pathways are involved in the TNF-α synthesis that induced by jasminin.

Atmospheric correction over the ocean for hyperspectral radiometers using multi-angle polarimetric retrievals.

We developed a fast and accurate polynomial based atmospheric correction (POLYAC) algorithm for hyperspectral radiometric measurements, which parameterizes the atmospheric path radiances using aerosol properties retrieved from co-located multi-wavelength multi-angle polarimeter (MAP) measurements. This algorithm has been applied to co-located spectrometer for planetary exploration (SPEX) airborne and research scanning polarimeter (RSP) measurements, where SPEX airborne was used as a proxy of hyperspectral radiometers, and RSP as the MAP. The hyperspectral remote sensing reflectance obtained from POLYAC is accurate when compared to Aerosol Robotic Network (AERONET), and Visible Infrared Imaging Radiometer Suite (VIIRS) ocean color products. POLYAC provides a robust alternative atmospheric correction algorithm for hyperspectral or multi-spectral radiometric measurements for scenes involving coastal oceans and/or absorbing aerosols, where traditional atmospheric correction algorithms are less reliable.

Interaction of the N terminus of ADP-ribosylation factor with the PH domain of the GTPase-activating protein ASAP1 requires phosphatidylinositol 4,5-bisphosphate.

Arf GAP with Src homology 3 domain, ankyrin repeat, and pleckstrin homology (PH) domain 1 (ASAP1) is a multidomain GTPase-activating protein (GAP) for ADP-ribosylation factor (ARF)-type GTPases. ASAP1 affects integrin adhesions, the actin cytoskeleton, and invasion and metastasis of cancer cells. ASAP1's cellular function depends on its highly-regulated and robust ARF GAP activity, requiring both the PH and the ARF GAP domains of ASAP1, and is modulated by phosphatidylinositol 4,5-bisphosphate (PIP2). The mechanistic basis of PIP2-stimulated GAP activity is incompletely understood. Here, we investigated whether PIP2 controls binding of the N-terminal extension of ARF1 to ASAP1's PH domain and thereby regulates its GAP activity. Using [Δ17]ARF1, lacking the N terminus, we found that PIP2 has little effect on ASAP1's activity. A soluble PIP2 analog, dioctanoyl-PIP2 (diC8PIP2), stimulated GAP activity on an N terminus-containing variant, [L8K]ARF1, but only marginally affected activity on [Δ17]ARF1. A peptide comprising residues 2-17 of ARF1 ([2-17]ARF1) inhibited GAP activity, and PIP2-dependently bound to a protein containing the PH domain and a 17-amino acid-long interdomain linker immediately N-terminal to the first ß-strand of the PH domain. Point mutations in either the linker or the C-terminal α-helix of the PH domain decreased [2-17]ARF1 binding and GAP activity. Mutations that reduced ARF1 N-terminal binding to the PH domain also reduced the effect of ASAP1 on cellular actin remodeling. Mutations in the ARF N terminus that reduced binding also reduced GAP activity. We conclude that PIP2 regulates binding of ASAP1's PH domain to the ARF1 N terminus, which may partially regulate GAP activity.

Highly Selective Olefin Production from CO2 Hydrogenation on Iron Catalysts: A Subtle Synergy between Manganese and Sodium Additives.

Mn and Na additives have been widely studied to improve the efficiency of CO2 hydrogenation to valuable olefins on Fe catalysts, but their effects on the catalytic properties and mechanism are still under vigorous debate. This study shows that Fe-based catalysts with moderate Mn and Na contents are highly selective for CO2 hydrogenation to olefins, together with low selectivities for both CO and CH4 and much improved space-time olefin yields compared to state-of-the-art catalysts. Combined kinetic assessment and quasi in situ characterizations further unveil that the sole presence of Mn suppresses the activity of Fe catalysts because of the close contact between Fe and Mn, whereas the introduction of Na mediates the Fe-Mn interaction and provides strong basic sites. This subtle synergy between Na and Mn sheds light on the importance of the interplay of multiple additives that could bring an enabling strategy to improve catalytic activity and selectivity.

Connexin 40 regulates lung endothelial permeability in acute lung injury via the ROCK1-MYPT1- MLC20 pathway.

Increased pulmonary vascular permeability is a hallmark of acute lung injury (ALI). Connexin 40 (Cx40) is a gap junctional protein abundantly present in the lung microvascular endothelium. Yet, the role of Cx40 in the regulation of lung vascular permeability and its underlying mechanisms are unclear. Here, we tested the hypothesis that Cx40 participates in regulation of lung endothelial permeability via a mechanism involving a Rho-associated protein kinase (ROCK) dependent regulation of myosin light chain (MLC). In murine models of intratracheal acid- or LPS-induced lung injury, genetic deficiency of Cx40 attenuated key features of ALI including vascular barrier failure. In human pulmonary microvascular endothelial cells (PMVECs), thrombin-induced loss of transendothelial electrical resistance was attenuated by a Cx40-inhibiting mimetic peptide (40GAP27), Cx40-specific shRNA, or ROCK inhibitor Y27632. In isolated perfused mouse lungs, platelet-activating factor-induced lung weight gain was abrogated by gap junction blocker carbenoxolone, 40GAP27, Y27632, or genetic deficiency of Cx40. Phosphorylation of MLC20 increased drastically in both LPS-treated PMVECs and HCl-treated mouse lungs. Expression of ROCK1 was increased in both LPS-treated PMVECs and HCl-treated mouse lungs, and paralleled by phosphorylation of MLC20. Coimmunoprecipitation experiments revealed protein-protein interaction between ROCK1 and Cx40. LPS-induced upregulation of ROCK1 and phosphorylation of MLC20 were blocked by knockdown of Cx40. LPS caused phosphorylation of myosin phosphatase targeting subunit 1, which could be abrogated by Y27632 or Cx40-shRNA. Our findings reveal a role of Cx40 in regulation of ROCK1 and MLC20 that contributes critically to lung vascular barrier failure in ALI.

An Air Knife-Assisted Recrystallization Method for Ambient-Process Planar Perovskite Solar Cells and Its Dim-Light Harvesting.

The photovoltaic performance of perovskite solar cells is highly dependent on the control of morphology and crystallization of perovskite film, which usually requires a controlled atmosphere. Therefore, fully ambient fabrication is a desired technology for the development of perovskite solar cells toward real production. Here, an air-knife assisted recrystallization method is reported, based on a simple bath-immersion to prepare high-quality perovskite absorbers. The resulted film shows a strong crystallinity with pure domains and low trap-state density, which contribute to the device performance and stability. The proposed method can operate in a wide process window, such as variable relative humidity and bath-immersion conditions, demonstrating a power conversion efficiency over 19% and 27% under 1 sun and 500-2000 lux dim-light illumination respectively, which is among the highest performance of ambient-process perovskite solar cells.

Characterizing Structural Changes With Devolving Remyelination Following Experimental Demyelination Using High Angular Resolution Diffusion MRI and Texture Analysis.

BACKGROUND: Changes in myelin integrity are associated with the pathophysiology of many neurological diseases, including multiple sclerosis. However, noninvasive measurement of myelin injury and repair remains challenging. Advanced MRI techniques including diffusion tensor imaging (DTI), neurite orientation dispersion and density index (NODDI), and texture analysis have shown promise in quantifying subtle abnormalities in white matter structure. PURPOSE: To determine whether and how these advanced imaging methods help understand remyelination changes after demyelination using a mouse model. STUDY TYPE: Prospective, longitudinal. ANIMAL MODEL: Demyelination was induced in the thoracic spinal cord of 21 mice using the chemical toxin lysolecithin. FIELD STRENGTH/SEQUENCES: 9.4T ASSESSMENT: Imaging was done at day 7 (demyelination) and days 14 to 35 (ongoing remyelination) postsurgery, followed by histology. Image analysis focused on both lesions and peri-lesional areas where remyelination began. In histology, we quantified the complexity of tissue alignment using angular entropy, in addition to staining area. STATISTICAL ANALYSIS: Two-way analysis of variance was performed for assessing differences between tissue types and across timepoints, followed by post-hoc analysis to correct for multiple comparisons (P < 0.05). RESULTS: All diffusion and texture parameters were worse in lesions than the control tissue (P < 0.05) except orientation dispersion index (ODI) and neurite density index (NDI) over late remyelination. Longitudinally, ODI decreased and NDI increased persistently in both lesions and peri-lesion regions (P < 0.05). Fractional anisotropy showed a mild decrease at day 35 after increase, when lesion texture heterogeneity showed a trend to decrease (P > 0.05). Both lesion size and angular entropy decreased over time, and no change in any measure in the control tissue. DATA CONCLUSION: Diffusion and MRI texture metrics may provide compensatory information on myelin repair and ODI and NDI could be sensitive measures of evolving remyelination, deserving further validation. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1750-1759.

Immunomodulatory effects of Trichinella spiralis excretory-secretory antigens on macrophages.

Helminths and their products can suppress the host immune response and other immunopathologies which may benefit parasite survival. Parasitic nematode Trichinella spiralis (T. spiralis) exert immunomodulatory effect on the host immune response through excretory-secretory (ES) products. However, the immunomodulatory mechanism is not yet completely understood or defined. Macrophages play a key role in modulating the host immune response to helminth parasite infection. Here, we focus on the effect of T. spiralis ES antigens on the immune response by studying the effect of ES antigens on RAW264.7 macrophages in vitro. RAW264.7 macrophages were incubated with ES antigens either alone or in combination with LPS. The cytokine production (TNF-α, IL-10 and IL-12 p70) and the expression of TLR were measured. Moreover, the nuclear translocation of MyD88 and NF-кB was assessed by Western blot analysis. Results indicate that ES products had impacts on reducing the expression of TLRs in LPS-induced macrophages. In addition, ES products inhibited the cytokine production of IL-12 p70 and TNF-α and alone boosted the expression of cytokine IL-10 in RAW264.7 macrophages. In conclusion, our results implied that T. spiralis ES antigens may regulate host immune response at the macrophages level in vitro.

Insights into Interfacial Synergistic Catalysis over Ni@TiO2- x Catalyst toward Water-Gas Shift Reaction.

The mechanism on interfacial synergistic catalysis for supported metal catalysts has long been explored and investigated in several important heterogeneous catalytic processes (e.g., water-gas shift (WGS) reaction). The modulation of metal-support interactions imposes a substantial influence on activity and selectivity of catalytic reaction, as a result of the geometric/electronic structure of interfacial sites. Although great efforts have validated the key role of interfacial sites in WGS over metal catalysts supported on reducible oxides, direct evidence at the atomic level is lacking and the mechanism of interfacial synergistic catalysis is still ambiguous. Herein, Ni nanoparticles supported on TiO2- x (denoted as Ni@TiO2- x) were fabricated via a structure topotactic transformation of NiTi-layered double hydroxide (NiTi-LDHs) precursor, which showed excellent catalytic performance for WGS reaction. In situ microscopy was carried out to reveal the partially encapsulated structure of Ni@TiO2- x catalyst. A combination study including in situ and operando EXAFS, in situ DRIFTS spectra combined with TPSR measurements substantiates a new redox mechanism based on interfacial synergistic catalysis. Notably, interfacial Ni species (electron-enriched Niδ- site) participates in the dissociation of H2O molecule to generate H2, accompanied by the oxidation of Niδ--O v-Ti3+ (O v: oxygen vacancy) to Niδ+-O-Ti4+ structure. Density functional theory calculations further verify that the interfacial sites of Ni@TiO2- x catalyst serve as the optimal active site with the lowest activation energy barrier (∼0.35 eV) for water dissociation. This work provides a fundamental understanding on interfacial synergistic catalysis toward WGS reaction, which is constructive for the rational design and fabrication of high activity heterogeneous catalysts.

Single scattering properties of non-spherical hydrosols modeled by spheroids.

The single scattering properties of hydrosols play an important role in the study of ocean optics, ocean color remote sensing, and ocean biogeochemistry research. Measurements show that hydrosols can be of various sizes and shapes, suggesting general non-spherical models should be considered for the study of single scattering properties of hydrosols. In this work, light scattering by non-spherical hydrosols are modeled by randomly oriented spheroids with the Amsterdam discrete dipole approximation (ADDA) code. We have defined two new parameters to quantify the degree of optical non-sphericity (DONS) and investigated the dependence of DONS on refractive index, size, and aspect ratio. For particles with non-unitary aspect ratios, the magnitude of DONS increases as the refractive index and particle size increase. The dependence of the backscattering fraction on the non-sphericity, size, and refractive index of hydrosols is also studied. It is found that the backscattering fraction is larger for smaller particles as well as for particles with higher refractive indices. Absorptive hydrosols generally have a lower backscattering fraction than non-absorptive hydrosols. This study of light scattering by non-spherical hydrosols would lead to better radiative transfer models in ocean waters and new remote sensing techniques of hydrosol compositions.

Retrieval of aerosol properties and water-leaving reflectance from multi-angular polarimetric measurements over coastal waters.

Ocean color remote sensing is an important tool to monitor water quality and biogeochemical conditions of ocean. Atmospheric correction, which obtains water-leaving radiance from the total radiance measured by satellite-borne or airborne sensors, remains a challenging task for coastal waters due to the complex optical properties of aerosols and ocean waters. In this paper, we report a research algorithm on aerosol and ocean color retrieval with emphasis on coastal waters, which uses coupled atmosphere and ocean radiative transfer model to fit polarized radiance measurements at multiple viewing angles and multiple wavelengths. Ocean optical properties are characterized by a generalized bio-optical model with direct accounting for the absorption and scattering of phytoplankton, colored dissolved organic matter (CDOM) and non-algal particles (NAP). Our retrieval algorithm can accurately determine the water-leaving radiance and aerosol properties for coastal waters, and may be used to improve the atmospheric correction when apply to a hyperspectral ocean color instrument.

MetaComp: comprehensive analysis software for comparative meta-omics including comparative metagenomics.

BACKGROUND: During the past decade, the development of high throughput nucleic sequencing and mass spectrometry analysis techniques have enabled the characterization of microbial communities through metagenomics, metatranscriptomics, metaproteomics and metabolomics data. To reveal the diversity of microbial communities and interactions between living conditions and microbes, it is necessary to introduce comparative analysis based upon integration of all four types of data mentioned above. Comparative meta-omics, especially comparative metageomics, has been established as a routine process to highlight the significant differences in taxon composition and functional gene abundance among microbiota samples. Meanwhile, biologists are increasingly concerning about the correlations between meta-omics features and environmental factors, which may further decipher the adaptation strategy of a microbial community. RESULTS: We developed a graphical comprehensive analysis software named MetaComp comprising a series of statistical analysis approaches with visualized results for metagenomics and other meta-omics data comparison. This software is capable to read files generated by a variety of upstream programs. After data loading, analyses such as multivariate statistics, hypothesis testing of two-sample, multi-sample as well as two-group sample and a novel function-regression analysis of environmental factors are offered. Here, regression analysis regards meta-omic features as independent variable and environmental factors as dependent variables. Moreover, MetaComp is capable to automatically choose an appropriate two-group sample test based upon the traits of input abundance profiles. We further evaluate the performance of its choice, and exhibit applications for metagenomics, metaproteomics and metabolomics samples. CONCLUSION: MetaComp, an integrative software capable for applying to all meta-omics data, originally distills the influence of living environment on microbial community by regression analysis. Moreover, since the automatically chosen two-group sample test is verified to be outperformed, MetaComp is friendly to users without adequate statistical training. These improvements are aiming to overcome the new challenges under big data era for all meta-omics data. MetaComp is available at: http://cqb.pku.edu.cn/ZhuLab/MetaComp/ and https://github.com/pzhaipku/MetaComp/ .

Electric-Field-Tunable Conductivity in Graphene/Water and Graphene/Ice Systems.

This study demonstrates that the application of an external electrical potential to a phenyl-sulfonic functionalized graphene (SG)/water suspension distinctly enhances its electrical conductivity via the structural transition from isolated clusters to a 3D SG network. Microstructural and alternating current impedance spectroscopy studies indicate that the surface charge plays an important role in the state of dispersion and connectivity of the SG in the suspension due to the potential-dependent interactions with functional groups on the SG surface in the presence of an external electrical potential. In addition, the conductive SG/ice can be produced via liquid-solid phase transition of the SG/water suspension in the presence of an external electrical potential, which shows a one-order magnitude improvement in electrical conductivity compared with pure ice. The electric-field-tunable property advances the understanding of nanofluid systems and has many potential applications.

Spectral sea surface reflectance of skylight.

In examining the dependence of the sea surface reflectance of skylight ρs on sky conditions, wind speed, solar zenith angle, and viewing geometry, Mobley [Appl. Opt.38, 7442 (1999).10.1364/AO.38.007442] assumed ρs is independent of wavelength. Lee et al. [Opt. Express18, 26313 (2010).10.1364/OE.18.026313] showed experimentally that ρs does vary spectrally due to the spectral difference of sky radiance coming from different directions, which was ignored in Mobley's study. We simulated ρs from 350 nm to 1000 nm by explicitly accounting for spectral variations of skylight distribution and Fresnel reflectance. Furthermore, we separated sun glint from sky glint because of significant differences in magnitude, spectrum and polarization state between direct sun light and skylight light. The results confirm that spectral variation of ρs(λ) mainly arises from the spectral distribution of skylight and would vary from slightly blueish due to normal dispersion of the refractive index of water, to neutral and then to reddish with increasing wind speeds and decreasing solar zenith angles. Polarization moderately increases sky glint by 8 - 20% at 400 nm but only by 0 - 10% at 1000 nm. Sun glint is inherently reddish and becomes significant (>10% of sky glint) when the sun is at the zenith with moderate winds or when the sea is roughened (wind speeds > 10 m s-1) with solar zenith angles < 20°. We recommend a two-step procedure by first correcting the glint due to direct sun light, which is unpolarized, followed by removing the glint due to diffused and polarized skylight. The simulated ρs(λ) as a function of wind speeds, sun angles and aerosol concentrations for currently recommended sensor-sun geometry, i.e., zenith angle = 40° and azimuthal angle relative to the sun = 45°, is available upon request.

Water-leaving contribution to polarized radiation field over ocean.

The top-of-atmosphere (TOA) radiation field from a coupled atmosphere-ocean system (CAOS) includes contributions from the atmosphere, surface, and water body. Atmospheric correction of ocean color imagery is to retrieve water-leaving radiance from the TOA measurement, from which ocean bio-optical properties can be obtained. Knowledge of the absolute and relative magnitudes of water-leaving signal in the TOA radiation field is important for designing new atmospheric correction algorithms and developing retrieval algorithms for new ocean biogeochemical parameters. In this paper we present a systematic sensitivity study of water-leaving contribution to the TOA radiation field, from 340 nm to 865 nm, with polarization included. Ocean water inherent optical properties are derived from bio-optical models for two kinds of waters, one dominated by phytoplankton (PDW) and the other by non-algae particles (NDW). In addition to elastic scattering, Raman scattering and fluorescence from dissolved organic matter in ocean waters are included. Our sensitivity study shows that the polarized reflectance is minimized for both CAOS and ocean signals in the backscattering half plane, which leads to numerical instability when calculating water leaving relative contribution, the ratio between polarized water leaving and CAOS signals. If the backscattering plane is excluded, the water-leaving polarized signal contributes less than 9% to the TOA polarized reflectance for PDW in the whole spectra. For NDW, the polarized water leaving contribution can be as much as 20% in the wavelength range from 470 to 670 nm. For wavelengths shorter than 452 nm or longer than 865 nm, the water leaving contribution to the TOA polarized reflectance is in general smaller than 5% for NDW. For the TOA total reflectance, the water-leaving contribution has maximum values ranging from 7% to 16% at variable wavelengths from 400 nm to 550 nm from PDW. The water leaving contribution to the TOA total reflectance can be as large as 35% for NDW, which is in general peaked at 550 nm. Both the total and polarized reflectances from water-leaving contributions approach zero in the ultraviolet and near infrared bands. These facts can be used as constraints or guidelines when estimating the water leaving contribution to the TOA reflectance for new atmospheric correction algorithms for ocean color imagery.