Search

The heterogeneous land surface spanning the Yellow River irrigated oasis and the adjacent Kubuqi and Ulan Buh Desert (Hetao area) in Inner Mongolia, China, has been noted to frequently generate planetary boundary layer convergence line (BLCL), providing an important source of low-level lifting for convection initiation (CI). As the first field experiment to collect comprehensive observations of vegetation-contrast-resulting thermal circulations that consistently generate BLCLs and lead to CI, the Desert-Oasis Convergence Line and Deep Convection Experiment (DECODE) was conducted from 5 July to 9 August 2022 in the Hetao area. Two oasis and four desert observation sites were set up in the region that exhibits the highest frequency of BLCL and CI occurrences, equipped with a suite of advanced instruments probing land-atmosphere interactions, planetary boundary layer processes, and evolution of BLCLs and their associated CI, including Doppler lidars, microwave radiometers, soil temperature and moisture sensors, eddy covariance systems, portable radiosondes, C-band polarimetric Doppler radar, aircraft, and Geostationary High-speed Imager onboard FY-4B satellite. DECODE captured 29 BLCLs (16 with CI), 66 gust fronts, 12 horizontal convective rolls, and one tornado. The observations unveiled full thermal circulations spanning the desert-oasis boundary characterized by a horizontal width of ~25 km, a convergence height of ~1 km above ground level (AGL), and divergence from 2 to ~3.5 km AGL, with vertical wind speeds of up to 2 m [s.sup.-1]. Future publications stemming from DECODE will delve into a spectrum of scientific inquiries, including but not limited to land surface and boundary layer processes, BLCL dynamics, CI mechanisms, convective organization, predictability, and model evaluation. SIGNIFICANCE STATEMENT: The purpose of Desert-Oasis Convergence Line and Deep Convection Experiment (DECODE) is to collect intensive observations around desert-oasis divide to better understand the physical processes of boundary layer convergence lines (BLCLs), their associated thermal circulations, convection initiation (CI), and organization over heterogeneous land surfaces. This is important because deep convection initiation poses a major challenge for weather forecasting over heterogeneous land surfaces due to limited understanding of land-atmosphere interactions. In addition, the targeting divide between a desert and an irrigated oasis facilitates a unique situation where human activities can change the weather. This campaign captured 29 BLCLs (16 with CI), which provided a rich dataset for studies not only on convection dynamics and microphysics but also on land-atmosphere interactions, boundary layer processes, and even interdisciplinary studies such as wind farm impact and convective dust storms. KEYWORDS: Complex terrain; Convection lines; Convective-scale processes; Boundary layer; Vegetation; Orographic effects, 1. Background In early October 2016, by fortuitously clicking on a radar image folder labeled 'Linhe' on a computer at the Training Center of the China Meteorological Administration, the first [...]

Polar mesospheric clouds (PMCs) are ice crystal clouds formed in the mesosphere of high-latitude regions in both the northern (NH) and southern hemispheres (SH). Peak height is an important physical characteristic of PMCs. Satellite observation data from solar occultation for ice experiments (SOFIE) during seven PMC seasons from 2007 to 2014 show that the difference between the height of the mesopause and the peak height of the PMCs (Zmes-Zmax) were inversely correlated with the atmospheric mesopause temperature. The Zmes-Zmax averages for all seasons for the NH and SH were 3.54 km and 2.66 km, respectively. They were smaller at the starting and ending stages of each PMC season and larger in the middle stages. Analysis of the individual cases and statistical results simulated by the PMCs 0-D model also revealed the inverse correlations between the Zmes-Zmax and mesopause temperature, with correlation coefficients of −0.71 and −0.62 for the NH and SH, respectively. The corresponding rates of change of Zmes-Zmax with respect to mesopause temperature were found to be −0.21 km/K and −0.14 km/K, respectively. The formation mechanism of PMCs suggests that a lower temperature around the mesopause can lead to a greater distance and longer time for ice crystals to condense and grow in clouds. Thus, ice crystals sediment to a lower height, making the peak height of the PMCs further away from the mesopause. In addition, disturbances in small-scale dynamic processes tend to weaken the impact of temperature on the peak height of PMCs. [ABSTRACT FROM AUTHOR]

The inversion of temperature by detecting the ratio of the intensity of airglow vibrational and rotational spectral lines is a traditional method for obtaining mesopause temperature. However, previous studies have shown that there is significant uncertainty in the temperature inversion using this technology. A spectrograph instrument called the Mesosphere Airglow Fine Spectrometer (MAFS) was previously developed by our research team. Based on the MAFS, this work systematically evaluated the impact of the spectral line extraction methods and residual background noise elimination methods on temperature inversion results of the OH (6-2) Q-branch as the target. The fitting of residual background noise using different numbers of sampling points can cause the inverted temperature to vary by 5 K to 10 K without changing the overall trend. The temperature inversion results obtained using the three-region single-fit method were generally 3 K to 5 K higher than those obtained using the two-region double-fit method. Moreover, the temperature obtained using the Gaussian fitting area varied by approximately 15 K, with changes in the residual background noise fitting method; however, when using a spectrum peak instead of the Gaussian fitting area, this variation decreased to approximately 10 K. When the temperature is higher, both the residual background noise fitting and the spectral line intensity extraction methods have a more significant impact on the uncertainty of temperature inversion. [ABSTRACT FROM AUTHOR]

The variation trends and characteristics of polar mesospheric clouds (PMCs) are important for studying the evolution of atmospheric systems and understanding various atmospheric dynamic processes. Through observation and analysis of PMCs, we can gain a comprehensive understanding of the mechanisms driving atmospheric processes, providing a scientific basis and support for addressing climate change. Ultraviolet (UV) imaging technology, adopted by the Cloud Imaging and Particle Size (CIPS) instrument on board the Aeronomy of Ice in the Mesosphere (AIM) satellite, has significantly advanced the research on PMCs. Due to the retirement of the AIM satellite, there is currently no concrete plan for next-generation instruments based on the CIPS model, resulting in a discontinuity in the observation data sequence. In this study, we propose a compact and cost-effective wide-field-of-view ultraviolet imager (WFUI) that can be integrated into various satellite platforms for future PMC observation missions. A forward model was built to evaluate the detection capability and efficiency of the WFUI. CIPS and Solar Occultation for Ice Experiment (SOFIE) data were fused to reconstruct a three-dimensional PMC scene as the input background. Based on the scattering and extinction characteristics of ice particles and atmospheric molecules, the radiative transfer was calculated using the solar radiation path through the atmosphere and PMCs. The optical system and satellite platform parameters of the WFUI were selected according to CIPS, enabling the calculation of the number of photons received by the WFUI. The actual detection signal is then simulated by photoelectric conversion, and the PMC information can be obtained by removing detector noise. Subsequently, a comparison with the input background field was conducted to compute and analyze the detection efficiency. Additionally, a sensitivity analysis of the instrument and platform parameters was conducted. Simulations were performed for both individual orbits and for the entire PMC seasons. The research results demonstrate that the WFUI performs well in PMC detection and has high detection efficiency. Statistical analysis of the detection efficiency using data from 2008 to 2012 revealed an exponential relationship between the ice water content (IWC) of PMCs and detection efficiency. During the initial and final durations of the PMC season, when the IWC was relatively low, the detection efficiency remained limited. However, as the season progressed and the IWC increased, the detection efficiency significantly improved. We note that regions at lower latitudes exhibited a lower IWC and, consequently, lower detection efficiency. In contrast, regions at higher latitudes, with a greater IWC, demonstrated better detection efficiency. Additionally, the sensitivity analysis results suggest that increasing the satellite orbit altitude and expanding the field of view (FOV) of the WFUI both contribute to improving the detection efficiency. [ABSTRACT FROM AUTHOR]

The variation trends and characteristics of polar mesospheric clouds (PMCs) are important for studying the evolution of atmospheric systems and understanding various atmospheric dynamic processes. Through observation and analysis of PMCs, we can gain a comprehensive understanding of the mechanisms driving atmospheric processes, providing a scientific basis and support for addressing climate change. Ultraviolet (UV) imaging technology, adopted by the Cloud Imaging and Particle Size (CIPS) instrument onboard the Aeronomy of Ice in the Mesosphere (AIM) satellite, has significantly advanced the research on PMCs. Due to the retirement of the AIM satellite, there is currently no concrete plan for next-generation instruments based on the CIPS model, resulting in a discontinuity in the observation data sequence. In this study, we propose a compact and cost-effective wide field-of-view ultraviolet imager (WFUI) that can be integrated into various satellite platforms for future PMCs observation missions. A forward model was built to evaluate the detection capability and efficiency of the WFUI. The fusion of CIPS and solar occultation for ice experiment (SOFIE) data was employed to reconstruct a three-dimensional PMCs scene as the input background. Based on the scattering and extinction characteristics of ice particles and atmospheric molecules, the radiative transfer was calculated using the solar radiation path through the atmosphere and PMCs. The optical system and satellite platform parameters of the WFUI were selected according to the CIPS, enabling the calculation of the number of photons received by the WFUI. The actual detection signal is then simulated by photoelectric conversion, and the PMCs information can be obtained by removing detector noise. Subsequently, a comparison with the input background field was conducted to compute and analyze the detection efficiency. Additionally, a sensitivity analysis of the instrument and platform parameters was conducted. Simulations were performed for both individual orbits and for the entire PMCs seasons. The research results demonstrate that using data from 2008 to 2012 revealed an exponential relationship between the ice water content (IWC) of PMCs and detection efficiency. During the initial and final durations of the PMCs season, when the IWC was relatively low, the detection efficiency the WFUI performs well in PMCs detection and has high detection efficiency. Statistical analysis of the detection efficiency remained limited. However, as the season progressed and the IWC increased, the detection efficiency significantly improved. We note that regions at lower latitudes exhibited a lower IWC and, consequently, lower detection efficiency. In contrast, regions at higher latitudes, with a greater IWC, demonstrated better detection efficiency. Additionally, the sensitivity analysis results suggest that increasing the satellite orbit altitude and expanding the field of view (FOV) of the WFUI both contribute to improving the detection efficiency. [ABSTRACT FROM AUTHOR]

Background: Pesticide formulations based on nanotechnology can effectively improve the efficiency of pesticide utilization and reduce pesticide residues in the environment. In this study, mesoporous silica nanoparticles containing disulfide bonds were synthesized by the sol–gel method, carboxylated and adsorbed with lufenuron, and grafted with cellulose to obtain a lufenuron‐loaded nano‐controlled release formulation (Luf@MSNs‐ss‐cellulose). Results: The structure and properties of Luf@MSNs‐ss‐cellulose were characterized. The results showed that Luf@MSNs‐ss‐cellulose exhibits a regular spherical shape with 12.41% pesticide loading. The highest cumulative release rate (73.46%) of this pesticide‐loaded nanoparticle was observed at 7 days in the environment of glutathione and cellulase, which shows redox‐enzyme dual‐responsive performance. As a result of cellulose grafting, Luf@MSNs‐ss‐cellulose had a small contact angle and high adhesion work on corn leaves, indicating good wetting and adhesion properties. After 14 days of spraying with 20 mg L−1 formulations in the long‐term control efficacy experiment, the mortality of Luf@MSNs‐ss‐cellulose against Ostrinia furnacalis larvae (56.67%) was significantly higher than that of commercial Luf@EW (36.67%). Luf@MSNs‐ss‐cellulose is safer for earthworms and L02 cells. Conclusion: The nano‐controlled release formulation obtained in this study achieved intelligent pesticide delivery in time and space under the environmental stimulation of glutathione and cellulase, providing an effective method for the development of novel pesticide delivery systems. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Composite materials with multi-layer structure were prepared by combining polyurethane film and waste polyphenylene sulfide filters by hot melting, which could be used as sound-absorbing materials to contribute to the noise control and reutilization of industrial waste. The structure, mechanical property, pore size distribution and stability of waste polyphenylene sulfide filters were investigated and could directly affect the quality of recycled products. The effects of layer numbers, layering sequence and polyurethane film thickness on sound absorption and insulation properties were also analyzed using an impedance tube absorption test system. The results showed that multi-layer materials had a better sound absorption effect than single-layer polyphenylene sulfide filters at low frequency. The sound absorption coefficients of the single-layer sample was only 0.081 at 1000 Hz, while the sound absorption coefficients of the five-layer sample could reach 0.26. The sound absorption properties of multi-layer materials were slightly affected by layering sequence, but polyurethane film thickness had a significant effect on sound absorption properties. The α of the SUS1 and USU1 samples were 0.151 and 0.170, while the α of the SUS3 and USU3 samples were only 0.076 and 0.056, respectively. Meanwhile, the sound insulation properties of multi-layer materials could be significantly influenced by the polyurethane film position. The sound transmission loss of the SUSUSU3 sample was just 32.83 dB, whereas that of the USUSU3 sample could reach 47.94 dB. Moreover, when polyurethane film was located on the sound facing side of multi-layer materials, the increase in polyurethane film thickness could cause the average sound reduction index of the USUSU sample to increase from 28.76 dB to 47.94 dB. [ABSTRACT FROM AUTHOR]

Soybean root rot is an important disease that has affected soybean crops in recent years, but the available control methods still do not provide good protection for soybeans. In this study, three biodegradable mulch films (HML@CMCS, HML@PVA, HML@CMCS/PVA) were prepared from carboxymethyl chitosan (CMCS) and polyvinyl alcohol (PVA), and hymexazol (HML) was loaded on them. The surface and cryofractured surface were compared via micromorphological observations using SEM, AFM, and 3D measurements. Mechanical, water barrier, and optical properties were compared between the different films, and the results showed that the composite film (HML@CMCS/PVA) had better tensile properties, lower water content (35%), and lower water solubility (28%), while water barrier properties were significantly improved. HML@CMCS/PVA also had better light transmission than commercial films (opacity at 600 nm of 1.92). Finally, the composite film was selected to study antifungal properties, soil degradability, and biosafety. The results showed that it exhibited significant inhibitory activity against Fusarium oxysporum and could effectively control soybean root rot, while degradation reached 58% after 7 d of soil burial, and the mortality of earthworms relative to the microplastics produced by the film within 7 d (23.33%) was much lower than that of the commercial film, demonstrating its excellent biosafety. This study provides a new approach for the on-farm management of soybean root rot and the reduction in soil microplastic pollution. [ABSTRACT FROM AUTHOR]

Residues of pyrethroid pesticides in aquatic environments seriously threaten aquatic organisms and the human health. Herein, a novel highly dispersed and recyclable composite ZIF-8 and SiO2 double-layer-modified Fe3O4 nanoparticle, named Fe3O4@ZIF-8@SiO2 nanoparticle, was synthesized via a layer-by-layer assembly method to remove pyrethroid insecticides (namely, fenvalerate, β-cyfluthrin, and tetramethrin) from water. The physical properties of the Fe3O4@ZIF-8@SiO2 nanoparticles were characterized via scanning electron microscopy, elemental mapping, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, dispersion analysis, and vibrating sample magnetometry. The prepared Fe3O4@ZIF-8@SiO2 nanoparticles exhibited excellent adsorption performance and high dispersibility and could be rapidly separated from water using an external magnetic field. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited the strongest adsorption effect at an adsorbent dosage of 10 mg, an adsorption time of 40 min, and a pH of 7. The fitted model for the adsorption process was consistent with the proposed secondary kinetic model and Sips isotherm model. The Fe3O4@ZIF-8@SiO2 nanoparticles exhibited maximum adsorption capacities of 316.23, 364.43, and 258.69 mg g–1 for fenvalerate, β-cyfluthrin, and tetramethrin, respectively. The Fe3O4@ZIF-8@SiO2 nanoparticles retained most of their adsorption capacity after five reuse cycles when acetone was used as an eluent for desorption. The mechanisms involved in the adsorption process included π–π stacking interactions, hydrogen bonds, hydrophobic interactions, and pore filling effects. This study provides a potential design for rapidly recoverable and reusable nanoparticles that can be used to effectively adsorb pyrethroid insecticides in wastewater. [ABSTRACT FROM AUTHOR]