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Currently, ozone pollution is one of the key environmental concerns, and to provide more effective strategies for ozone control, this paper proposes the use of the Geostationary Environmental Monitoring Spectrometer (GEMS) in conjunction with MAX-DOAS for observations and ozone sensitivity analysis. Compared to traditional polar-orbiting satellites, GEMS, launched by South Korea in 2019, offers superior spatiotemporal resolution. However, there is a lack of ground validation for GEMS data related to ozone and its precursors. In this study, we conducted validation in the Jing-Jin-Ji (Beijing-Tianjin-Hebei) region using two typical MAX-DOAS sites and the China National Environmental Monitoring Center (CNEMC) sites, confirming the accuracy of GEMS data. Analysis of the seasonal horizontal distribution results from GEMS and vertical distribution results from MAX-DOAS in 2022 reveals that the concentrations of NO 2 , HCHO, O 3 , and ozone sensitivity not only display seasonality and regional variations but also exhibit distinct characteristics at different altitudes and times, influenced by local climatic conditions, human activities, and topography. When formulating ozone control policies, it becomes imperative to consider factors such as time, regional characteristics, and seasonality. Comparisons between daily results from TROPOMI and GEMS indicate that polar-orbiting satellites may overlook high-pollution periods within a single day, and their measurements may not provide a comprehensive representation of an entire day's data. Consequently, relying solely on polar-orbiting satellite data for shaping ozone prevention and control policies may inadvertently encourage ozone formation during specific time periods, rendering these policies ineffective. Therefore, leveraging GEMS is essential for the development of comprehensive, around-the-clock ozone control policies. Finally, we used monitoring data from Beijing on October 6, 2022, to illustrate how the combination of GEMS and MAX-DOAS enables three-dimensional monitoring of pollutant transport processes on an hourly scale. [Display omitted] • Validation of the accuracy of ozone and its precursor data from GEMS. • Analysis of hourly ozone sensitivity level distribution using GEMS. • Limitations of polar orbit satellites in O 3 sensitivity analysis compared to GEMS. • Observation of the transport of pollutants combining GEMS and MAX-DOAS. [ABSTRACT FROM AUTHOR]

The most mature directional dark matter experiments at present all utilize low-pressure gas Time Projection Chamber (TPC) technologies. We discuss some of the challenges for this technology, for which balancing the goal of achieving the best sensitivity with that of cost effective scale-up requires optimization over a large parameter space. Critical for this are the precision measurements of the fundamental properties of both electron and nuclear recoil tracks down to the lowest detectable energies. Such measurements are necessary to provide a benchmark for background discrimination and directional sensitivity that could be used for future optimization studies for directional dark matter experiments. In this paper we describe a small, high resolution, high signal-to-noise GEM-based TPC with a 2D CCD readout designed for this goal. The performance of the detector was characterized using alpha particles, X-rays, gamma-rays, and neutrons, enabling detailed measurements of electron and nuclear recoil tracks. Stable effective gas gains of greater than 1 × 10 5 were obtained in 100 Torr of pure CF 4 by a cascade of three standard CERN GEMs each with a 140 µm pitch. The high signal-to-noise and sub-millimeter spatial resolution of the GEM amplification and CCD readout, together with low diffusion, allow for excellent background discrimination between electron and nuclear recoils down below ∼10 keVee (∼23 keVr fluorine recoil). Even lower thresholds, necessary for the detection of low mass WIMPs for example, might be achieved by lowering the pressure and utilizing full 3D track reconstruction. These and other paths for improvements are discussed, as are possible fundamental limitations imposed by the physics of energy loss. [ABSTRACT FROM AUTHOR]

Many properties of concrete are related to its pore volume and pore structure. This paper describes an approach to predict gel and capillary pore volumes and other hardened properties of pastes using the pore partitioning model, and scaling these calculated properties to concrete by including entrained and entrapped air and aggregates. This paper focuses on illustrating how parameters that can be used for determining the freeze-thaw performance can be computed using a critical saturation model. Specifically, the degree of saturation and formation factor of the concrete are predicted when the matrix pores are saturated. Based on the model simulations, the secondary rate of sorption can be estimated using the formation factor to predict the potential for reaching a critical degree of saturation which is a measure of concrete's resistance to freeze-thaw damage. This approach allows for the evaluation of the performance of concrete mixtures with a wide variety of binder compositions and mixture proportions. The model predicts the saturated formation factor with a maximum error of 13% and the matrix saturation with a maximum error of 7%. The model can also be used to provide insight into the amount of entrained air needed for a given replacement and reactivity of binder. [ABSTRACT FROM AUTHOR]

Abstract: Over twenty modeling groups are participating in the Air Quality Model Evaluation International Initiative (AQMEII) in which a variety of mesoscale photochemical and aerosol air quality modeling systems are being applied to continental-scale domains in North America and Europe for 2006 full-year simulations for model inter-comparisons and evaluations. To better understand the reasons for differences in model results among these participating groups, each group was asked to use the same source of emissions and boundary concentration data for their simulations. This paper describes the development and application of the boundary concentration data for this AQMEII modeling exercise. The European project known as GEMS (Global and regional Earth-system Monitoring using Satellite and in-situ data) has produced global-scale re-analyses of air quality for several years, including 2006 (http://gems.ecmwf.int). The GEMS trace gas and aerosol data were made available at 3-hourly intervals on a regular latitude/longitude grid of approximately 1.9° resolution within 2 “cut-outs” from the global model domain. One cut-out was centered over North America and the other over Europe, covering sufficient spatial domain for each modeling group to extract the necessary time- and space-varying (horizontal and vertical) concentrations for their mesoscale model boundaries. Examples of the impact of these boundary concentrations on the AQMEII continental simulations are presented to quantify the sensitivity of the simulations to boundary concentrations. In addition, some participating groups were not able to use the GEMS data and instead relied upon other sources for their boundary concentration specifications. These are noted, and the contrasting impacts of other data sources for boundary data are presented. How one specifies four-dimensional boundary concentrations for mesoscale air quality simulations can have a profound impact on the model results, and hence, this aspect of data preparation must be performed with considerable care. [Copyright &y& Elsevier]

Abstract: This paper addresses several aspects related to ultraviolet (UV) measurements from an upcoming geostationary orbit (GEO) satellite mission. First, using simulated cloud coverage based on the MTSAT (Multi-functional Transport Satellite 1R) 650nm channel as a proxy, we find that GEO observations can increase clear-sky coverage by ~4 times. Secondly, we examine the feasibility of improved ozone detection with GEO observations, using synthetic GEMS spectra with GEO geometries along with the TOMS total ozone algorithm and an ozone profile algorithm based on the optimal estimation method. The sensitivity of ozone retrievals to the lower troposphere is limited at large solar and satellite zenith angles, especially above 70° under clear-sky conditions. Third, we evaluate two new ideas for improving ozone retrieval sensitivity in the troposphere at large angle geometries; (1) a geosynchronous orbit with an inclination-angle of 30°, with smaller values of viewing zenith angles than those from a geostationary orbit; (2) a combination of UV measurements at multiple solar zenith angles to improve the accuracy of ozone profile retrievals. [Copyright &y& Elsevier]

The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) instrument is an airborne hyperspectral spectrometer measuring backscattered solar radiation in the ultraviolet (290–400 nm) and visible (415–695 nm) wavelength regions. This paper presents high-resolution sulfur dioxide (SO 2) maps over the Korean Peninsula, produced by SO 2 retrievals from GeoTASO measurements during the Korea–United States Air Quality Field Study (KORUS-AQ) from May to June 2016. The highly sensitive GeoTASO instrument with a spatial resolution of ~250 m × 250 m can detect point emission sources of SO 2 within its fields of view, even without merging multiple overlapping observations. To retrieve SO 2 vertical columns from the GeoTASO measurements, we apply an algorithm based on principal component analysis (PCA), which is effective in suppressing noise and biases in SO 2 retrievals. The retrievals successfully capture SO 2 plumes and various point sources such as power plants, a petrochemical complex, and a steel mill, located in South Chungcheong Province, some of which are not detected by a ground-based in situ measurement network. Spatial distributions of SO 2 from GeoTASO observations in source areas are consistent with those from the Stack Tele-Monitoring System reports and airborne in situ SO 2 measurements. Comparisons of SO 2 retrievals from GeoTASO and existing satellite sensors demonstrate the significance of high-resolution SO 2 observations, by indicating that GeoTASO detects small SO 2 emission sources that are not precisely resolved by single overpasses of satellites. To assess future geostationary SO 2 observations having a higher spatial resolution, we upscale the GeoTASO SO 2 retrievals to a spatial resolution of the Geostationary Environment Monitoring Spectrometer (GEMS). Since the upscaled GeoTASO retrievals also detect SO 2 plumes clearly, we expect from GEMS to identify even small SO 2 emission sources over Asia. • SO 2 columns are retrieved from airborne remote sensing by an algorithm based on PCA. • Retrieved SO 2 columns successfully detect SO 2 sources in the Korean Peninsula. • Distributions of SO 2 columns are consistent with those of known SO 2 point sources. • Comparisons with spaceborne SO 2 data highlight the significance of high-resolution. • Upscaled airborne SO 2 retrievals allow assessing future geostationary observations. [ABSTRACT FROM AUTHOR]