The study presents the results of investigating the impact of a new foundation on the stress-strain state of the soil base and the existing foundation of an adjacent structure. The aim of the research was to compare the efficiency and accuracy of the traditional analytical method—the corner point method—with numerical simulation performed in the LIRA-SAPR software package, which implements elastic-plastic soil model. The obtained results demonstrate that the analytical corner point method enables a rapid assessment of zones prone to additional settlements and the impact on adjacent structures. However, it does not account for the actual stress distribution in a heterogeneous soil mass or the interaction with the stiffness of foundation structures. In contrast, numerical simulation in the LIRA-SAPR software package provides a more detailed analysis of the stress-strain state of the soil, allowing for the consideration of complex geometry and the nonlinear behavior of materials. This is particularly crucial in cases involving challenging soil conditions and the presence of multiple adjacent foundations. The comparison of the results from the two approaches revealed consistency in predicting general trends of settlement and stress changes. However, discrepancies in the absolute values of displacements were observed, reaching 20–30% in some cases. The study results indicate that even in relatively stiff soil with a deformation modulus of E = 28 MPa, the mutual influence of foundations can be significant and requires consideration in design to prevent uneven deformations of the existing structure. The differences between the results of the two methods indicate that relying solely on the analytical approach may lead to an underestimation of the risk of uneven deformations in the existing structure. The study demonstrated that the new flat-plate foundation significantly affects the stress-strain state of the soil and the settlement of the existing foundation. The analytical corner point method allows for a rapid estimation of the approximate level of additional settlements and the zone of influence, but its results are averaged. In contrast, numerical simulation in the LIRA-SAPR software package with the Coulomb-Mohr model accurately reflects the actual stress distribution, local settlement maxima, and plastic soil deformations, thereby improving the precision of the predictions.
The paper considers the experience in implementing an innovative method of press-in impact loading (internationally known as Dynamic Load Test (DLT) in Ukraine when testing soils using full-scale piles, which is based on the principles of the wave theory of impact. The advantages and disadvantages of this test method for different types of piles are shown, and the issues that arise when testing soils using drilled piles, in particular CFA piles, are noted. The paper proposes for the first time the use of statistical methods to build a regression model that determines the bearing capacity of piles based on parallel soil tests by piles using the methods of static press-in loading (internationally known as Static Load Test, SLT) and impact (dynamic) press-in loading (DLT). The factors that significantly affect the mechanics of the interaction between the pile and the soil base when testing soils by piles using the DLT method were formulated and identified. Multiple linear regression models were developed to determine the ultimate resistance and bearing capacity from the elastic deformation of drilled piles based on the DLT results to predict the load-settlement relationship, which is essential for the design of pile foundations. Both correlation and regression analyses of the proposed models were performed; prospects for their improvement were suggested. At this stage of the development of correlation models, we have obtained sufficiently high statistical evaluation results, which indicate technically correct models with strong relationships between variables and high statistical significance. In 2024-2025, the proposed models were field-tested at a real construction site when testing piles using the DLT method, where the deviations of the determined values of Fe and Fu for CFA piles were within 5% of the values determined using the SLT method.
The professional terminology of Ukrainian researchers and geotechnical specialists was previously formed in Russian within the framework established by the Soviet authorities, as both science and higher education were not allowed to use the Ukrainian language. Therefore, after the collapse of the Soviet Union, according to the Law on Higher Education, textbooks and national science of independent Ukraine were naturally formed by translation into Ukrainian. Meanwhile, during the Cold War, Soviet science developed behind the Iron Curtain from the West, with virtually no scientific and technical exchange. This led to significant differences in the development of entire fields of science. Now, on the way to integration into the European Union, cooperation with European colleagues has increased significantly, and mutual understanding in English is very important. The aim of this work is therefore to find ways of unifying national terminology in the field of civil engineering, particularly geotechnical engineering, to a level acceptable to our Western colleagues who are guided by European standards. The terms «civil engineering» and «geotechnics», which are relatively recent additions to our profession, are used incorrectly even in approved regulatory documents. From the point of view of English terminology, the terms «construction and civil engineering» and «geotechnics and foundation engineering» seem rather strange, because construction is a part of civil engineering and foundation engineering is a part of geotechnics. The difference between the terms «geotechnics» and «geotechnical engineering» should also be taken into account, as the former deals with the relevant scientific foundations and the latter with the application of these scientific foundations. The discipline of «soils and foundations» is known in Western universities as «foundations» and is an important component of «geotechnical engineering». At the same time, the research translation «Bases and Foundations» is never used in professional English literature, except by Russian-speaking scientists, although the word «base» is sometimes used, but not as often as in our country. Unfortunately, the misunderstanding of professional terminology has significant negative consequences, which are highlighted. The Order of the Ministry of Education and Science, Youth and Sports of Ukraine dated 14.09.2011 ¹ 1057 «On Approval of the List of Scientific Specialties» combines geotechnical and mining mechanics into the scientific specialty 05.15.09 and assigns it to the group of specialties «Development of mineral resources» 05.15.00, while geotechnical mechanics is actually the theoretical basis of geotechnics and a practical tool of geotechnical engineering. The scientific specialty 04.00.07 «Engineering Geology» is classified by the Order as a group of geological scientific specialties, although it is much more related to construction, and the specialty 03.00.18 «Soil Science» is generally classified as a group of biological scientific specialties. At the same time, the order does not include the group of specialties «Civil Engineering» at all, and the group of scientific specialties 05.23.00 «Construction» does not include the specialty «Geotechnical Engineering». It was suggested that on behalf of the Conference to address the Ministry of Education and Science of Ukraine with a proposal to introduce appropriate amendments to the Order of 14.09.2011 № 1057 «On Approval of the List of Scientific Specialities». Based on the analysis of the legislative regulation of the activities of public organisations, a new name of the national public organisation «Ukrainian Public Organisation of Soil Mechanics and Geotechnical Engineering» is proposed for discussion by the conference participants.
In today's conditions of the country's development, cities and suburban areas are being built up at a rapid pace, which causes its shortage, especially in cities with a large population. In such conditions, one of the possible solutions for the development of the city is the development of previously unsuitable areas that can be used for construction. Such areas include territories cut by ravines, gullies, wetlands or floodplains, which are flooded with water during floods. Due to the presence of water bodies near the indicated territories, it is possible to protect them from flooding by raising the absolute marks of their surface to non-flooded ones by using alluvial soil by means of hydromechanization. The properties of such new man-made formations differ significantly from natural ones, and sandy soils are used as alluvial soil. In this way, a large number of territories have been created in different countries of the world: Dubai, Japan, China, the USA, etc., which indicates the effectiveness of this method and its practical significance. The article highlights the features of the tectonic structure, geological and geomorphological zoning of the territory of the city of Kyiv. Much attention is paid to the floodplain areas of the Dnieper River, which were formed by alluvial. Such sites were created, as a rule, for new construction and were built up quite quickly with low-rise buildings, the basis for which was alluvial soils. The engineering and geological studies of the sites after alluvial soils and the observation of deformations of the base over time allowed us to establish the basic patterns and rules of construction in such territories. Today, the development of the city actively covers areas created by alluvial soils, on which high-rise buildings, shopping centers, and other buildings are being actively built, the loads from which must be transferred to reliable base. However, depending on the properties of the alluvial soils themselves and the quality and preparation of the base on which they are laid, different types of foundations can be used, the decision on their design is made in each individual case, taking into account the number of floors and the type of buildings or structures.
Viktor Shokarev, Andrii Shokarev, Iurii Kaliukh
et al.
The aim of the dissertation work is to create a new information technology for diagnosing the current state of multi-story building to eliminate its over-normative roll while simultaneously ensuring the reliable functioning of the multi-story building during the entire process of leveling without stopping the functioning of the multi-story building engineering networks, technological equipment (elevators) and the resettlement of residents, which will allow to improve the quality of estimates of the forecast of changes in the multi-story building vehicle in the controlled elimination of excessive tilting and to make responsible management decisions in conditions of uncertainty and the risk of construction accidents. Information technology for diagnosing the current state of multi-story building was developed for the first time to eliminate the tilting of the building in conditions of constant changes in its vertical position, the physical and mechanical properties of the foundation soils and the properties of the materials of individual building structures (cracking) during the entire time of leveling without stopping the operation of the engineering networks of the multi-story building, technological equipment (elevators) and the resettlement of residents, and sometime after its completion; the specialized Pendulum program for operational processing in online mode of experimental data from pre-trial inclinometric sensors distributed over the multi-story building (Digital Twins elements) in the process of eliminating its excessive roll, and graphical interpretation of the results for a better perception of information technology for diagnosing the current state of multi-story building information and is an element of feedback when support of operational management decisions in the process of liquidation of the above-standard bank roll. The mathematical-algorithmic apparatus of information technology for diagnosing the current state of multi-story building has been improved, which includes mathematical models of buildings and foundation soils that were used in the process of leveling the multi-story building, a mathematical model of drilling mixtures for fixing the foundations of the building after the leveling process is completed; precision sensitive inclinometric elements, a special stand has been developed for their testing and metrological research; continuous connection between the measurement results of the pre-screen sensitive inclinometric elements distributed over the multi-story building and the LIRA application program package for operational consideration of the change of the initial boundary conditions during the current calculations of the stressed - deformed state of the multi-story building during the entire alignment process and sometime after its completion. The system for transmitting digital experimental data from precision inclinometric sensors distributed over the multi-story building, with the help of modern cloud technologies (Internet of Things elements), received further development.
This study examines the performance of mat foundations in 13 blocks of eight-story concrete-walled residential buildings. Topographic monitoring bolts were used to monitor the slab’s construction, which was 0.35 m thick and comprised an area of 225 m2. Using the collected data, a retro-analysis of the modulus of elasticity was conducted to obtain the geotechnical parameters for forecasting the settlement using the elasticity theory. A nonlinear approach for construction modeling and soil–structure interactions showed that the earthworks at the start of construction had a significant role in settling. Blocks in landfills settled faster than those in land-cut zones. The partial execution of building levels was found to be critical in terms of angular distortions and stresses in the concrete slab. The partial lifting of the foundation plate was confirmed in blocks with partial building floor execution, demonstrating the importance of assessing the foundation’s behavior at this stage. The modulus of elasticity dropped as construction progressed, with landfill parts being particularly vulnerable. Creep settlements contributed significantly, accounting for about 20% of the total settlements in some blocks. The numerical staged construction model accurately replicated the behaviors observed in the monitoring data, confirming the hypothesis of the partial raising of the foundation during the building process, which resulted in higher angular distortions. Based on the results obtained, the authors strongly recommend that the simultaneous consideration of soil–structure interactions and construction effects be commonly used in foundation designs.
Expander decompositions form the basis of one of the most flexible paradigms for close-to-linear-time graph algorithms. Length-constrained expander de-compositions generalize this paradigm to better work for problems with lengths, distances and costs. Roughly, an $(h,s)$-length $\phi$-expander decomposition is a small collection of length increases to a graph so that nodes within distance $h$ can route flow over paths of length $hs$ with congestion at most $1/\phi$. In this work, we give a close-to-linear time algorithm for computing length-constrained expander decompositions in graphs with general lengths and capacities. Notably, and unlike previous works, our algorithm allows for one to trade off off between the size of the decomposition and the length of routing paths: for any $\epsilon > 0$ not too small, our algorithm computes in close-to-linear time an $(h, s)$-length $\phi$-expander decomposition of size $m\cdot\phi\cdot n^{\epsilon}$ where $s$ = exp(poly $(1/\epsilon)$). The key foundations of our algorithm are: (1) a simple yet powerful structural theorem which states that the union of a sequence of sparse length-constrained cuts is itself sparse and (2) new algorithms for efficiently computing sparse length-constrained flows.
The subgrade serves as the foundation of road construction, typically involving a significant amount of earthwork during its establishment. However, in coastal and desert areas, soil sources are often scarce. Local soil extraction significantly damages cultivated land, impacting the local ecological environment. Transporting soil over long distances inevitably raises construction costs. Fortunately, these regions often feature abundant fine sand distribution, presenting an opportunity to utilize it as subgrade filler in coastal regions. This review comprehensively introduces the properties of fine sand as a raw material, its engineering applications, and the associated construction technologies. It emphatically discusses the road use characteristics and treatment technology of fine sand filler and puts forward a prospect combining the characteristics and development trends of fine sand so as to provide a new perspective and basic material for the application of fine sand in the subgrade. To foster the adoption of fine sand in subgrade construction, it is recommended to advance research on the evaluation and treatment of fine sand foundations, analyze its suitability and structural behavior as a filler, and refine construction methodologies and quality control measures specific to fine sand subgrades.
<p>Mitigating the global climate crisis and its consequences, such as more frequent and severe droughts, is one of the major challenges for future agriculture. Therefore, identifying land use systems and management practices that reduce greenhouse gas (GHG) emissions and promote water use efficiency (WUE) is crucial. This, however, requires accurate and precise measurements of carbon dioxide (CO<span class="inline-formula"><sub>2</sub></span>) fluxes and evapotranspiration (ET). Despite that, commercial systems to measure CO<span class="inline-formula"><sub>2</sub></span> and ET fluxes are expensive and thus often exclude research in ecosystems within the Global South. This is especially true for research and data of agroecosystems in these areas, which are to date still widely underrepresented. Here, we present a newly developed low-cost, non-dispersive infrared (NDIR)-based CO<span class="inline-formula"><sub>2</sub></span> and ET flux measurement device (<span class="inline-formula">∼</span> EUR 200) that provides reliable, accurate and precise CO<span class="inline-formula"><sub>2</sub></span> and ET flux measurements in conjunction with manually operated closed chambers. To validate the system, laboratory and field validation experiments were performed, testing multiple different low-cost sensors. We demonstrate that the system delivers accurate and precise CO<span class="inline-formula"><sub>2</sub></span> and ET flux measurements using the K30 FR NDIR (CO<span class="inline-formula"><sub>2</sub></span>) and SHT31 (RH, relative humidity) sensor. An additional field trial application demonstrated its longer-term stability (<span class="inline-formula">></span> 3 months) and ability to obtain valid net ecosystem C balances (NECBs) and WUE. This was the case, even though environmental conditions at the field trial application site in sub-Saharan Africa were rather challenging (e.g., extremely high temperatures, humidity and rainfall). Consequently, the developed low-cost CO<span class="inline-formula"><sub>2</sub></span> and ET flux measurement device not only provides reasonable results but also might help with democratizing science and closing current data gaps.</p>
<p>To reveal the spatiotemporal distributions of atmospheric CO<span class="inline-formula"><sub>2</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> mixing ratios and regulation mechanisms over the China shelf sea, two field surveys were conducted in the southern Yellow Sea in China in November 2012 and June 2013, respectively. The results observed showed that mean background atmospheric CO<span class="inline-formula"><sub>2</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> mixing ratios were 403.94 (<span class="inline-formula">±13.77</span>) ppm and 1924.8 (<span class="inline-formula">±27.8</span>) ppb in November 2012 and 395.90 (<span class="inline-formula">±3.53</span>) ppm and 1918.0 (<span class="inline-formula">±25.7</span>) ppb in June 2013, respectively. An improved data-filtering method was optimised and established to flag atmospheric CO<span class="inline-formula"><sub>2</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> emission from different sources in the survey area. We found that the spatiotemporal distributions of atmospheric CO<span class="inline-formula"><sub>2</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> mixing ratios over the southern Yellow Sea were dominated by land–sea air mass transport, which was mainly driven by seasonal monsoon, while the influence of air–sea exchange was negligible. In addition, atmospheric CO<span class="inline-formula"><sub>2</sub></span> and CH<span class="inline-formula"><sub>4</sub></span> mixing ratios over the southern Yellow Sea could be elevated remarkably at a distance of approximately 20 km offshore by land-to-sea air mass transportation from the Asian continent during the early-winter monsoon.</p>
<p>Cloud droplet number concentration (<span class="inline-formula"><i>N</i><sub>d</sub></span>) is of central importance to observation-based estimates of aerosol indirect effects, being used to quantify both the cloud sensitivity to aerosol and the base state of the cloud. However, the derivation of <span class="inline-formula"><i>N</i><sub>d</sub></span> from satellite data depends on a number of assumptions about the cloud and the accuracy of the retrievals of the cloud properties from which it is derived, making it prone to systematic biases.</p>
<p>A number of sampling strategies have been proposed to address these biases by selecting the most accurate <span class="inline-formula"><i>N</i><sub>d</sub></span> retrievals in the satellite data. This work compares the impact of these strategies on the accuracy of the satellite retrieved <span class="inline-formula"><i>N</i><sub>d</sub></span>, using a selection of in situ measurements. In stratocumulus regions, the MODIS <span class="inline-formula"><i>N</i><sub>d</sub></span> retrieval is able to achieve a high precision (<span class="inline-formula"><i>r</i><sup>2</sup></span> of 0.5–0.8). This is lower in other cloud regimes but can be increased by appropriate sampling choices. Although the <span class="inline-formula"><i>N</i><sub>d</sub></span> sampling can have significant effects on the <span class="inline-formula"><i>N</i><sub>d</sub></span> climatology, it produces only a 20 % variation in the implied radiative forcing from aerosol–cloud interactions, with the choice of aerosol proxy driving the overall uncertainty. The results are summarised into recommendations for using MODIS <span class="inline-formula"><i>N</i><sub>d</sub></span> products and appropriate sampling.</p>
<p>Source functions for mechanically driven coarse-mode sea spray and dust aerosol particles span orders of magnitude owing to a combination of
physical sensitivity in the system and large measurement uncertainty. Outside special idealized settings (such as wind tunnels), aerosol particle
fluxes are largely inferred from a host of methods, including local eddy correlation, gradient methods, and dry deposition methods. In all of these
methods, it is difficult to relate point measurements from towers, ships, or aircraft to a general representative flux of aerosol particles. This
difficulty is from the particles' inhomogeneous distribution due to multiple spatiotemporal scales of an evolving marine environment. We
hypothesize that the current representation of a point in situ measurement of sea spray or dust particles is a likely contributor to the
unrealistic range of flux and concentration outcomes in the literature. This paper aims to help the interpretation of field data: we conduct a
series of high-resolution, cloud-free large eddy simulations (LESs) with Lagrangian particles to better understand the temporal evolution and
volumetric variability of coarse- to giant-mode marine aerosol particles and their relationship to turbulent transport. The study begins by
describing the Lagrangian LES model framework and simulates flux measurements that were made using numerical analogs to field practices such as the
eddy covariance method. Using these methods, turbulent flux sampling is quantified based on key features such as coherent structures within the
marine atmospheric boundary layer (MABL) and aerosol particle size. We show that for an unstable atmospheric stability, the MABL exhibits large
coherent eddy structures, and as a consequence, the flux measurement outcome becomes strongly tied to spatial length scales and relative sampling of
crosswise and streamwise sampling. For example, through the use of ogive curves, a given sampling duration of a fixed numerical sampling instrument is
found to capture 80 % of the aerosol flux given a sampling rate of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>z</mi><mi>f</mi><mo>/</mo><msub><mi>w</mi><mo>∗</mo></msub><mo>∼</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="42pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="495ebe3122088c076ea98d5bc4c1986c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-7171-2022-ie00001.svg" width="42pt" height="14pt" src="amt-15-7171-2022-ie00001.png"/></svg:svg></span></span> 0.2, whereas a spanwise moving instrument results in a
95 % capture. These coherent structures and other canonical features contribute to the lack of convergence to the true aerosol vertical flux at
any height. As expected, sampling all of the flow features results in a statistically robust flux signal. Analysis of a neutral boundary layer
configuration results in a lower predictive range due to weak or no vertical roll structures compared to the unstable boundary layer
setting. Finally, we take the results of each approach and compare their surface flux variability: a baseline metric used in regional and global
aerosol models.</p>
<p>Space profiling lidars offer a unique insight into cloud
properties in Earth's atmosphere and are considered the most reliable
source of total (column-integrated) cloud amount (CA), and true
(geometrical) cloud top height (CTH). However, lidar-based cloud
climatologies suffer from infrequent sampling: every <span class="inline-formula"><i>n</i></span> days, and only along
the ground track. This study therefore evaluated four lidar missions, namely
CALIPSO (revisit every <span class="inline-formula"><i>n</i>=16</span> d), EarthCARE (<span class="inline-formula"><i>n</i>=25</span>), Aeolus (<span class="inline-formula"><i>n</i>=7</span>), and
ICESat-2 (<span class="inline-formula"><i>n</i>=91</span>), to test the hypothesis that each mission provides accurate
data on CA and CTH. CA/CTH values for a hypothetical daily revisit mission
were used as reference (data simulated with Meteosat 15 min cloud
observations, assumed to be a proxy for ground truth). Our results
demonstrated that this hypothesis is invalid, unless individual lidar
transects are averaged over an area <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">10</mn><mo>×</mo><mn mathvariant="normal">10</mn><msup><mi/><mo>∘</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="42pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="4ec6dc02ec3e5bbcc6653dd76da67955"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-4307-2022-ie00001.svg" width="42pt" height="11pt" src="amt-15-4307-2022-ie00001.png"/></svg:svg></span></span> in longitude
and latitude (or larger). If this is not the case, the required accuracy of
1 % (for CA) or 150 m (for CTH) cannot be met, either for a single-year
annual or monthly mean, or for a <span class="inline-formula">>10</span> year climatology. A
CALIPSO-focused test demonstrated that the annual mean CA estimate is very
sensitive to infrequent sampling, and that this factor alone can result in
14 % or 7 % average uncertainty with 1 or 2.5<span class="inline-formula"><sup>∘</sup></span>
resolution data, respectively. Consequently, applications that use gridded
lidar data should consider calculating confidence intervals, or a similar
measure of uncertainty. Our results suggest that CALIPSO, and its follow-on
mission EarthCARE, are very likely to produce consistent cloud records
despite the difference in sampling frequency.</p>
<p>The observing system design of multidisciplinary field
measurements involves a variety of considerations on logistics, safety, and
science objectives. Typically, this is done based on investigator intuition
and designs of prior field measurements. However, there is potential for
considerable increases in efficiency, safety, and scientific success by
integrating numerical simulations in the design process. Here, we present a
novel numerical simulation–environmental response function (NS–ERF)
approach to observing system simulation experiments that aids
surface–atmosphere synthesis at the interface of mesoscale and microscale
meteorology. In a case study we demonstrate application of the NS–ERF
approach to optimize the Chequamegon Heterogeneous Ecosystem Energy-balance
Study Enabled by a High-density Extensive Array of Detectors 2019
(CHEESEHEAD19).</p>
<p>During CHEESEHEAD19 pre-field simulation experiments, we considered the
placement of 20 eddy covariance flux towers, operations for 72 h of
low-altitude flux aircraft measurements, and integration of various remote
sensing data products. A 2 h high-resolution large eddy simulation
created a cloud-free virtual atmosphere for surface and meteorological
conditions characteristic of the field campaign domain and period. To
explore two specific design hypotheses we super-sampled this virtual
atmosphere as observed by 13 different yet simultaneous observing system
designs consisting of virtual ground, airborne, and satellite observations.
We then analyzed these virtual observations through ERFs to yield an optimal
aircraft flight strategy for augmenting a stratified random flux tower
network in combination with satellite retrievals.</p>
<p>We demonstrate how the novel NS–ERF approach doubled CHEESEHEAD19's
potential to explore energy balance closure and spatial patterning science
objectives while substantially simplifying logistics. Owing to its modular
extensibility, NS–ERF lends itself to optimizing observing system designs also
for natural climate solutions, emission inventory validation, urban air
quality, industry leak detection, and multi-species applications, among other
use cases.</p>
J. S. Wilzewski, J. S. Wilzewski, A. Roiger
et al.
<p>Verifying anthropogenic carbon dioxide (<span class="inline-formula">CO<sub>2</sub></span>) emissions globally is essential to inform about the progress of institutional efforts to mitigate anthropogenic climate forcing. To monitor localized emission sources, spectroscopic satellite sensors have been proposed that operate on the <span class="inline-formula">CO<sub>2</sub></span> absorption bands in the shortwave-infrared (SWIR) spectral range with ground resolution as fine as a few tens of meters to about a hundred meters. When designing such sensors, fine ground resolution requires a trade-off towards coarse spectral resolution in order to achieve sufficient noise performance. Since fine ground resolution also implies limited ground coverage, such sensors are envisioned to fly in fleets of satellites, requiring low-cost and simple design, e.g., by restricting the spectrometer to a single spectral band.</p>
<p>Here, we use measurements of the Greenhouse Gases Observing Satellite (GOSAT) to evaluate the spectral resolution and spectral band selection of a prospective satellite sensor with fine ground resolution. To this end, we degrade GOSAT SWIR spectra of the <span class="inline-formula">CO<sub>2</sub></span> bands at 1.6 (SWIR-1) and 2.0 <span class="inline-formula">µ</span>m (SWIR-2) to coarse spectral resolution, without a further addition of noise, and we evaluate single-band retrievals of the column-averaged dry-air mole fractions of <span class="inline-formula">CO<sub>2</sub></span> (<span class="inline-formula">XCO<sub>2</sub></span>) by comparison to ground truth provided by the Total Carbon Column Observing Network (TCCON) and by comparison to global “native” GOSAT retrievals with native spectral resolution and spectral band selection. Coarsening spectral resolution from GOSAT's native resolving power of <span class="inline-formula">>20 000</span> to the range of 700 to a few thousand makes the scatter of differences between the SWIR-1 and SWIR-2 retrievals and<span id="page732"/> TCCON increase moderately. For resolving powers of 1200 (SWIR-1) and 1600 (SWIR-2), the scatter increases from 2.4 (native) to 3.0 ppm for SWIR-1 and 3.3 ppm for SWIR-2. Coarser spectral resolution yields only marginally worse performance than the native GOSAT configuration in terms of station-to-station variability and geophysical parameter correlations for the GOSAT–TCCON differences. Comparing the SWIR-1 and SWIR-2 configurations to native GOSAT retrievals on the global scale, however, reveals that the coarse-resolution SWIR-1 and SWIR-2 configurations suffer from some spurious correlations with geophysical parameters that characterize the light-scattering properties of the scene such as particle amount, size, height and surface albedo. Overall, the SWIR-1 and SWIR-2 configurations with resolving powers of 1200 and 1600 show promising performance for future sensor design in terms of random error sources while residual errors induced by light scattering along the light path need to be investigated further. Due to the stronger <span class="inline-formula">CO<sub>2</sub></span> absorption bands in SWIR-2 than in SWIR-1, the former has the advantage that measurement noise propagates less into the retrieved <span class="inline-formula">XCO<sub>2</sub></span> and that some retrieval information on particle scattering properties is accessible.</p>
<p>Scanning transmission X-ray microscopy coupled with near-edge X-ray
absorption and fine structure (STXM-NEXAFS) spectroscopy can be used to
characterize the morphology and composition of aerosol particles. Here, two
inorganic <span class="inline-formula">∕</span> organic systems are used to validate the calculation of
organic volume fraction (OVF) and determine the level of associated error by
using carbon K-edge STXM data at 278, 285.4, 288.6, and 320 eV. Using the
mixture of sodium chloride and sucrose as one system and ammonium sulfate and
sucrose as another, three solutions were made with <span class="inline-formula">10:1</span>, <span class="inline-formula">1:1</span>, and <span class="inline-formula">1:10</span>
mass ratios (inorganic to organic). The OVFs of the organic-rich aerosols of
both systems deviated from the bulk OVF by less than 1%, while the
inorganic-rich aerosols deviated by approximately 1 %. Aerosols from the
equal mass mixture deviated more (about 4 %) due to thick inorganic
regions exceeding the linear range of Beer's law. These calculations were
performed after checking the data for poor image alignment, defocusing issues, and
particles too thick to be analyzed. The potential for systematic error in the
OVF calculation was also tested by assuming the incorrect composition. There
is a small (about 0.5 %) OVF difference if the organic is erroneously
assumed to be adipic acid rather than the known organic, sucrose. A much
larger difference (up to 25 %) is seen if sodium chloride is assumed
instead of ammonium sulfate. These results show that the OVF calculations are
fairly insensitive to the organic while being much more sensitive to the
choice of inorganic.</p>