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Development of long-term continues, consistent and high-quality satellite remote sensing aerosol and surface products is crucial to constrain climate models and improve our understanding on climate change. Particulate Observing Scanning Polarization (POSP) is the first space-borne multi-spectral (UV-VIS-NIR-SWIR) cross-track scanning polarimeter dedicated to complement Directional Polarimetric Camera (DPC) multi-angular polarimetric measurements and perform synergetic observations namely the Polarization Cross-Fire suite (PCF) onboard Chinese Gaofen series GF-5(02) satellite. The POSP unique single-viewing spectral (UV-VIS-NIR-SWIR) high-precision polarimetric measurements provide rich information for atmospheric aerosol and surface characterization. Here we developed aerosol and surface products from POSP/GF-5(02) based on the Generalized Retrieval of Atmosphere and Surface Properties (GRASP)/Models approach. The detailed retrieval approach and processing scheme are provided. The baseline level 2 product was generated for the first 18 months POSP measurements from December 2021 to May 2023 and publicly available and registered at doi.org/10.57760/sciencedb.14748. The obtained POSP/GF-5(02) aerosol and surface products are validated and intercompared with ground-based AERONET reference aerosol dataset and other independent satellite products, such as NOAA-20 VIIRS/DB aerosol product and MODIS MCD43 surface product. The results show generally good consistency of POSP products with AERONET, VIIRS/NOAA-20 aerosol dataset and MODIS surface product. Moreover, it is possible to conclude the developed POSP product includes reliable estimates of not only total Aerosol Optical Depth (AOD), but also detailed properties of aerosol such as aerosol size, absorption, layer height, type, etc., as well as full surface Bidirectional Reflectance Distribution Function (BRDF), Bidirectional Polarization Distribution Function (BPDF), and black-sky, white-sky albedos and Normalized Difference Vegetation Index (NDVI). These parameters are of high importance to constrain the Earth-atmosphere radiation budget. The retrieval of these properties seems to be possible due to the polarimetric capabilities and wide UV-VIS-NIR-SWIR spectral range of from POSP observations and advances of used GRASP/Models retrieval approach. Finally, some potential improvements for POSP level 1 to level 2 processing chain are identified, and limitations and lessons learned are discussed. [ABSTRACT FROM AUTHOR]

Background: Disanthus cercidifolius var. longipes is an ancient relic plant unique to China. However, the typical shade-loving plant is largely exposed to the sun, which poses a major challenge to its conservation. Methods: This study explored dynamic changes in primary and secondary metabolites in D. cercidifolius leaves at different stages of development, combining metabolomics and transcriptome analysis to discuss the differentially accumulated metabolites (DAMs) and differentially expressed genes (DEGs). Results: The DAMs and DEGs were enriched in pathways related to photosynthesis, carbon (C) metabolism, anthocyanin synthesis, plant hormone signal transduction, and flavonoid synthesis. At the initial stage of leaf development, many primary metabolites were synthesized in the leaves. Before leaf maturity, many primary metabolites were converted into secondary metabolites. Combined transcriptome and metabolome analysis showed that the metabolites and genes related to anthocyanin synthesis and flavonoid metabolism were upregulated. In contrast, the genes related to C metabolism and C fixation were downregulated. After leaf maturity, photosynthetic capacity increased, total flavonoid content peaked (implying the strongest photoprotection capacity), and the transformation of anthocyanins and flavonoids was weakened. Conclusions: Light intensity indirectly affects the accumulation of the primary and secondary metabolism of D. cercidifolius. With the enhancement of photoprotection, the photosynthetic energy capacity decreases. It is, therefore, inferable that D. cercidifolius has shading properties and achieves a stable nutrient supply during growth and development through these strategies. Thus, D. cercidifolius protection requires a shaded environment. [ABSTRACT FROM AUTHOR]

The virtually imaged phased array (VIPA) spectrometer uses the orthogonal dispersion method and has the advantages of compact structure, high spectral resolution, and wide wavelength coverage. It has been widely used in different fields. However, due to the non-linear dispersion of the VIPA etalon and the cross-dispersion structure of the VIPA spectrometer, simple and high-accuracy wavelength calibration remains a challenge. In this paper, a new and simple five-parameter spectrogram model is developed by simplifying the phase-matching equation of the VIPA etalon and considering the angle between the camera and dispersion direction, which can achieve a frequency accuracy better than one pixel. The performance of the model is demonstrated by measuring the CO2 absorption spectrum in the range of 1.42 to 1.45 μm using a self-designed near-infrared VIPA spectrometer. The reported method is simple and easy to solve with high accuracy, which is conducive to promoting the application of VIPA spectrometers in precision measurement. [ABSTRACT FROM AUTHOR]

Chlorophyll-a (Chl-a) concentrations serve as a pivotal metric for assessing the biological content and eutrophication levels of waterbodies. In optical remote sensing, empirical and semi-analytical methods are commonly employed for Chl-a retrieval. Leveraging the Level-1B remote sensing data from the Directional Polarimetric Camera (DPC) aboard the Terrestrial Ecosystem Carbon Inventory Satellite (TECIS), this study amalgamates empirical algorithms (OC2, OC3, Aiken-P, and Aiken-C) and look-up-table (LUT) techniques to estimate Chl-a in open water. Test data acquired from DPC on 20 August 2022, are validated against the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite and AERONET-Ocean Color water-leaving radiance data for the same area and date. The results reveal that among the tested algorithms, particularly in the log10 scale space, the Aiken-P algorithm demonstrates the highest correlation coefficient (R2 = 0.6333), with the lowest bias of 1.0366 and a minimum mean absolute error (MAE) of 1.2097. This underscores the suitability and accuracy of the Aiken-P algorithm for water colour retrieval based on DPC-derived data, highlighting its practical applicability. [ABSTRACT FROM AUTHOR]

Semiliquidambar cathayensis is widely used in traditional Chinese medicine owing its high concentrations of polyphenol, triterpenoidic acid, and flavonoids. This study aimed to explore the impact of geographical origin and tissue type on the contents of chemical compounds of S. cathayensis , as determined by colorimetric and chromatographic methods. Therefore, we quantitively evaluated chemical compounds found in the tissues of various organs of plants collected in six different regions. Overall, we found that geographical origin affected the content of medicinal compounds in S. cathayensis leaves, with plants from Jingzhou county showing the best therapeutic potential. However, no specific correlation was observed with latitude. It is noteworthy that the amount of paeoniflorin and other compounds can be used as biomarkers of geographical origin and tissue type. Most medicinal compounds accumulated mainly in the leaves, whereas ursolic and oleanolic acids accumulated in the roots. These results show that the comprehensive medicinal value of the leaves of S. cathayensis in Jingzhou county is the highest, but the root should be selected first to collect oleanolic acid and ursolic acid., Competing Interests: The authors declare there are no competing interests., (©2023 Tian et al.)

The directional polarimetric camera (DPC) is a remote-sensing instrument for the characterization of atmospheric aerosols and clouds by simultaneously conducting spectral, angular, and polarimetric measurements. Polarization measurement accuracy is an important index to evaluate the performance of the DPC and mainly related to the calibration accuracy of instrumental parameters. In this paper, firstly, the relationship between the polarization measurement accuracy of DPC and the parameter calibration errors caused by the nonideality of the components of DPC are analyzed, and the maximum polarization measurement error of DPC in the central field of view and edge field of view after initial calibration is evaluated respectively. Secondly, on the basis of the radiometric calibration of the DPC onboard the GaoFen-5 satellite in an early companion paper [Opt. Express2813187 (2020)10.1364/OE.391078], a series of simple and practical methods are proposed to improve the calibration accuracy of the parameters-the diattenuation of the optics, absolute azimuth angle, and relative transmission corresponding to each pixel, thereby improving the polarization measurement accuracy of DPC. The calibration results show that, compared with the original methods, the accuracy of the diattenuation of the optics, relative azimuth angle, and relative transmission of three polarized channels obtained with the improved methods are improved from ±1%, 0.1 degree and ±2% to ±0.4%, 0.05 degree and ±0.2%, respectively. Finally, two verification experiments based on a non-polarized radiation source and a polarizing system were carried out in the laboratory respectively to verify the improvement of the parameters modified by the proposed methods on the polarization measurement accuracy of the DPC to be boarding the GaoFen-5 (02) satellite. The experimental results show that when the corrected parameters were employed, the average error in measuring the degree of linear polarization of non-polarized light source for all pixels in the three polarized bands and the maximum deviation of the degree of linear polarization between the values set by the polarizing system and the values measured by the DPC at several different field of view angles for each polarized spectral band are obviously reduced. Both the mean absolute errors and the root mean square errors of the degree of linear polarization obtained with the corrected parameters are much lower than those obtained with the original parameters. All of these prove the effectiveness of the proposed methods.