Hyperspectral Satellite Remote Sensing of Aerosol Parameters: Sensitivity Analysis and Application to TROPOMI/S5P

Precise knowledge about aerosols in the lower atmosphere (optical properties and vertical distribution) is particularly important for studying the Earth’s climatic and weather conditions. Measurements from satellite sensors in sun-synchronous and geostationary orbits can be used to map distributions of aerosol parameters in global or regional scales. The new-generation sensor Tropospheric Monitoring Instrument (TROPOMI) onboard the Copernicus Sentinel-5 Precursor (S5P) measures a wide variety of atmospheric trace gases and aerosols that are associated with climate change and air quality using a number of spectral bands between the ultraviolet and the shortwave infrared. In this study, we perform a sensitivity analysis of the forward model parameters and instrument information that are associated with the retrieval accuracy of aerosol layer height (ALH) and optical depth (AOD) using the oxygen (O2) A-band. Retrieval of aerosol parameters from hyperspectral satellite measurements requires accurate surface representation and parameterization of aerosol microphysical properties and precise radiative transfer calculations. Most potential error sources arising from satellite retrievals of aerosol parameters, including uncertainties in aerosol models, surface properties, solar/satellite viewing geometry, and wavelength shift, are analyzed. The impact of surface albedo accuracy on retrieval results can be dramatic when surface albedo values are close to the critical surface albedo. An application to the real measurements of two scenes indicates that the retrieval works reasonably in terms of retrieved quantities and fit residuals.

Network-Based Topological Exploration of the Impact of Pollution Sources on Surface Water Bodies

We developed a digital water management toolkit to evaluate the importance of the connections between water bodies and the impacts caused by pollution sources. By representing water bodies in a topological network, the relationship between point loads and basic water quality parameters is examined as a labelled network. The labels are defined based on the classification of the water bodies and pollution sources. The analysis of the topology of the network can provide information on how the possible paths of the surface water network influence the water quality. The extracted information can be used to develop a monitoring- and evidence-based decision support system. The methodological development is presented through the analysis of the physical-chemical parameters of all surface water bodies in Hungary, using the emissions of industrial plants and wastewater treatment plants. Changes in water quality are comprehensively assessed based on the water quality data recorded over the past 10 years. The results illustrate that the developed method can identify critical surface water bodies where the impact of local pollution sources is more significant. One hundred six critical water bodies have been identified, where special attention should be given to water quality improvement.

An Impact-Echo Experimental Approach for Detecting Concrete Structural Faults

For the current problem of detection of grouting defects in posttensioned prestressed concrete members, the paper takes a single-layer arrangement of prestressed pipes as the object of study. The influence law of the main factors such as pipe material, defect size, defect critical surface location, and prestressing reinforcement location on the results of the impact-echo method for detecting concrete grouting defects was studied. Firstly, the ABAQUS finite element software was used to simulate these factors to obtain the influence law on the detection results, and a modal test was conducted to verify them. The results show that the impact-echo method can effectively test the location of defects and the degree of burial depth, and the pipe material influences the test results, and the impact of corrugated metal pipe is smaller and more accurate than the PVC pipe. In addition, the greater the plate thickness frequency drift rate, the larger the transverse size of the defect, so the plate thickness frequency drift rate and the measured defect depth are combined to quantitatively determine the depth of the defect.

Field Treatment of Storage Sludge and Stability Analysis of Overlying Municipal Waste Landfilling

Storage sludge has high water content and low shear strength, which limits the capacity expansion of overlying municipal landfilling. Few studies have addressed the field treatment of large amounts of storage sludge due to the variability of the depth of geotechnical property. This paper proposes a stratified treatment method for storage sludge, based on the in situ characterization of layered sedimentary patterns of the storage sludge acquired from the Qizishan landfill in China. Additionally, the stability of the landfilling above the sludge pond is analyzed using the Morgenstern–Price and limit equilibrium slice method, which considers the layered strength properties of solidified sludge. The treated sludge has a significant decrease in average water content from 1398% to 88% and an increase in average cohesion to 23.52 kPa. The high content of clay particles, low amount of solidification products, and high water content together result in the high sensitivity to the water content of the strength of deep solidified sludge. For a 40-m high waste body, stability analysis suggests a sliding surface across the raw sludge pond, while the critical surface remains outside the treated sludge pond and the safety factor is increased from 0.934 to 1.464. The validated stratified treatment provides valuable references for the treatment of deep sludge.

Passive versus Active Transport of Saharan Dust Aerosols by African Easterly Waves

Theory and modeling are combined to reveal the physical and dynamical processes that control Saharan dust transport by amplifying African easterly waves (AEWs). Two cases are examined: active transport, in which the dust is radiatively coupled to the circulation; passive transport, in which the dust is radiatively decoupled from the circulation. The theory is built around a dust conservation equation for dust-coupled AEWs in zonal-mean African easterly jets. The theory predicts that, for both the passive and active cases, the dust transports will be largest where the zonal-mean dust gradients are maximized on an AEW critical surface. Whether the dust transports are largest for the radiatively passive or radiatively active case depends on the growth rate of the AEWs, which is modulated by the dust heating. The theoretical predictions are confirmed via experiments carried out with the Weather Research and Forecasting model, which is coupled to a dust conservation equation. The experiments show that the meridional dust transports dominate in the passive case, while the vertical dust transports dominate in the active case.

On the order of the QCD chiral phase transition for different numbers of quark flavours

The nature of the QCD chiral phase transition in the limit of vanishing quark masses has remained elusive for a long time, since it cannot be simulated directly on the lattice and is strongly cutoff-dependent. We report on a comprehensive ongoing study using unimproved staggered fermions with Nf ∈ [2, 8] mass-degenerate flavours on Nτ ∈ {4, 6, 8} lattices, in which we locate the chiral critical surface separating regions with first-order transitions from crossover regions in the bare parameter space of the lattice theory. Employing the fact that it terminates in a tricritical line, this surface can be extrapolated to the chiral limit using tricritical scaling with known exponents. Knowing the order of the transitions in the lattice parameter space, conclusions for approaching the continuum chiral limit in the proper order can be drawn. While a narrow first-order region cannot be ruled out, we find initial evidence consistent with a second-order chiral transition in all massless theories with Nf ≤ 6, and possibly up to the onset of the conformal window at 9 ≲ $$ {N}_{\mathrm{f}}^{\ast } $$ N f ∗ ≲ 12. A reanalysis of already published $$ \mathcal{O} $$ O (a)-improved Nf = 3 Wilson data on Nτ ∈ [4, 12] is also consistent with tricritical scaling, and the associated change from first to second-order on the way to the continuum chiral limit. We discuss a modified Columbia plot and a phase diagram for many-flavour QCD that reflect these possible features.

Experimental Investigation on the Effect of Different Micro-Geometries on Cutting Edge and Wiper Edge on Surface Roughness and Forces in Face Milling

The significance of the micro-geometries on the cutting edge is known from numerous studies conducted in the past. However, the effect of micro-geometry on the wiper facet (also called the wiper edge) is not known. Hence, this paper investigates the effect of different micro-geometries with a focus on geometry variation on the wiper edge of a milling insert on surface roughness and forces in face milling of SAE1070 high-carbon steel. Milling inserts with sharp, rounded, chamfered edges and their combinations were manufactured on the cutting edge and wiper edge for the study. Critical surface quality parameters such as the average surface roughness (Ra), mean depth of surface roughness (Rz), and force components such as radial force (Fx), cutting force (Fy), and axial force (Fz) were evaluated. Metal cutting tests were performed at three different cutting speeds and three different feed rates to study the influence of cutting parameters and the effect of edge geometries on surface roughness. The results were correlated with the force values to understand the machining dynamics. Finite element analysis was performed to evaluate the high and low-stress zones on the insert, workpiece, and chip to understand the metal cutting mechanism of different micro-geometries. The novel finding from the study is that having identical micro-geometries on the cutting and wiper edge is the preferred combination, whereas dissimilar micro-geometries result in reduced surface quality, increased forces, and high stress on the workpiece and chip.

An Outright Success in Oil and Gas Production Arise from Surface Facility Modification – Story of Ujung Pangkah Field

The two most common challenges on the oil and gas production today are the flowing production under natural pressure depletion and the surface facility capacity limitation. Ujung Pangkah field is no exception regarding finding a method to overcome this problem. It compelled to embolden many strategies to ensure the continuity of oil and gas production. Production enhancement initiatives were delivered through both Subsurface and Surface sides. SAKA Energi Indonesia, as the operator of Pangkah PSC, proved that Surface Modification approach increased the oil and gas production. Historically, gas lift injection dependency in all production wells force a continuous operation of Gas Lift Compressor (GLC) unit to supply gas lift. However, GLC as a production backbone is no longer sustainable, it has reached its maximum limit and unable to fulfil the gas lift rate requirement for all wells. Furthermore, the changing flowing conditions – low gas feeding - from wells are relatable to most of the critical surface equipment. Considering all the challenges faced in Ujung Pangkah field, SAKA developed initiatives on MP Compressor and GLC configuration by performing compressors restaging. The equipment modifications started out with restaging the MP Compressor (MPC) that led to MP Separator operating pressure reduction – from 22 barg down to 16 barg. Pressure changes on MP Separator also directly affected the GLC system since it works on the same pipeline header. Technical assessment analysis for other corresponding equipment were performed to verify if each of the equipment's operating boundary could accommodate lower pressure at the facility. Compressor restaging has direct and indirect impacts. The direct impacts are decrease in suction pressure, increase in gas lift rates, and decrease in flowing of suction pressure due to the pressure at wellhead. The indirect impact is production gain from wells by lowering the wellhead pressure. Particularly in the pressure depletion case, this initiative could extend the lifetime of the wells. Production gain was quantified after compressor restaging and pressure system lower to 16 barg. The gain from this method was 3 MMscfd and ~400 BOPD.