Preprints
There are 7785 Preprints listed.
Temporal Synchronization Determines the Accuracy of Sentinel-2 Turbidity Retrieval: Evidence from Community-Based Monitoring of the Buriganga River, Dhaka
Published: 2026-10-07
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
Community-based environmental organizations require continuous water quality data but are constrained by the cost and labor of physical sampling. Satellite remote sensing offers a free alternative, yet validation studies of inland waters frequently report weak agreement between satellite indices and ground measurements, and the cause of that disagreement is rarely isolated. This study analyzed 28 [...]
Segmenting submarine boulders with Random Forest and nnU-Net: from bathymetric rasters to survey-scale size distributions
Published: 2026-10-07
Subjects: Earth Sciences
In the soft-bottom-dominated southern Baltic Sea, geogenic hard substrates are biodiversity hotspots. The lack of open-source, pixel-level segmentation approaches for boulders in MBES data has made it difficult to advance the ecological understanding of boulder fields in the Baltic Sea. This study developed and evaluated two segmentation approaches. A deep learning model (nnU-Net) and a classical [...]
An Idealized Model of Buoyant Gas Spreading and Silt Release beneath Rough Cave Ceilings
Published: 2026-10-07
Subjects: Fluid Dynamics, Hydrology, Partial Differential Equations, Sedimentology, Statistical, Nonlinear, and Soft Matter Physics
Gas exhaled by open-circuit divers collects under the ceilings of submerged caves, migrates along the rock, and dislodges loose silt that then falls through the passage, a process that cave divers call percolation. This study develops an idealized model of the process. Buoyant gas under a self-affine rough ceiling is treated as a quasi-static sequence of pools that fill to their spill points, [...]
Lunar South Pole Resource Prospectivity: A Multi- Instrument Framework and a Testable Model for Heterogeneous Volatile Emplacement
Published: 2026-10-06
Subjects: Physical Sciences and Mathematics
Water ice and other volatiles in lunar south-polar permanently shadowed regions (PSRs) are established exploration targets, but their abundance, geometry, continuity, and depth distribution remain incompletely constrained. We present a physically informed, AI-assisted framework integrating neutron-derived hydrogen abundance, Diviner thermal stability, radar circular polarization ratio (CPR), [...]
Bottom-up estimation of CO2 emissions from container ships: a proof of concept using real operational data on the Brazil–Asia route
Published: 2026-10-06
Subjects: Sustainability
Granular quantification of greenhouse gas (GHG) emissions from maritime transport matters both for the assessment of decarbonisation strategies and for the attribution of the carbon footprint to logistics flows. This study proposes a bottom up approach that integrates operational reconstruction of the voyage, physical–energy modelling, Tank-to-Wake (TTW) and Well-to-Wake (WTW) assessment, and [...]
Ultramafic weathering in tropical volcanic arcs: Geochemistry and inverse modeling of rivers draining the Zambales Ophiolite Complex (ZOC), Philippines
Published: 2026-10-06
Subjects: Physical Sciences and Mathematics
Mafic and ultramafic rocks are highly susceptible to silicate weathering, a key negative feedback which modulates atmospheric CO2 over geological timescales. The tectonic exposure of these reactive lithologies, such as the Neogene uplift of the volcanic islands in maritime Southeast Asia, has been hypothesized to enhance this global feedback and contribute to long-term global cooling. However, [...]
Annual 30 m leaf-on daytime land surface temperature composites across China from 2000 to 2024
Published: 2026-10-06
Subjects: Geography, Remote Sensing
Long-term, spatially detailed land surface temperature (LST) records are needed to compare thermal environments across heterogeneous landscapes, but combining fine spatial detail with nationwide coverage over decades remains challenging. We present Chinatherm30, annual 30 m leaf-on daytime LST composites across China for 2000--2024. Quality-screened Terra MODIS thermal targets were combined with [...]
A vertical vegetation structure model of the Earth
Published: 2026-10-06
Subjects: Computer Sciences, Earth Sciences, Environmental Sciences, Forest Biology, Forest Management, Forest Sciences, Other Forestry and Forest Sciences, Research Methods in Life Sciences, Wood Science and Pulp, Paper Technology
Knowing the global distribution of vegetation structure is an essential prerequisite to better quantify, model, and manage carbon, water, energy, and biodiversity in the Earth system. Despite its recognized importance, vertical structure measurements remain sparse at global scales, limiting our understanding of the links between structure and ecosystem functions and resilience. Here we present [...]
Impact of Soil Data Representation on Streamflow Modelling: A Contiguous-Object Connectivity Approach Case Study in Switzerland
Published: 2026-10-05
Subjects: Hydrology, Water Resource Management
Hydrological models often rely on soil data to represent water partitioning, storage and release within a catchment. However, differences in soil data representation may be obscured by calibration when performance is evaluated primarily against streamflow. This study investigates how alternative soil datasets influence streamflow performance, internal hydrological processes, and parameter [...]
Separating measurement from definition: an object-based workflow for national forest mapping
Published: 2026-10-05
Subjects: Engineering, Life Sciences
Forest is defined rather than observed, and definitions are written to serve different management objectives. In Norway, four authoritative datasets place forest between 35 and 43% of the mainland because each encodes a different rule. Categorical forest maps inherit this problem, since each serves only the definition it was built on. We present a documented object-based workflow that separates [...]
Physics-Informed Machine Learning in Hydrology and Water Resources: A Systematic Bibliometric Analysis
Published: 2026-10-05
Subjects: Civil and Environmental Engineering
This study presents a systematic bibliometric review of Physics-Informed Machine Learning (PIML) research in hydrology and water resources, examining the field's evolution in response to the limitations of traditional process-based models and data-driven approaches. Using a PRISMA-guided framework and a curated dataset from the Scopus database, the analysis evaluated publication trends, leading [...]
Hydrogen gas (H₂) artificially generated during soil-gas sampling - Technical report
Published: 2026-10-05
Subjects: Physical Sciences and Mathematics
Surface gas geochemistry methods, including soil gas measurements, are widely used for natural hydrogen (H₂) exploration. It is known that H₂ can be artificially generated by mechanical friction during installation of soil-gas probes. However, it is frequently considered that artificial H₂ is produced only by drill bit rotation, although there are no systematic studies about its generation during [...]
COVID-19 Emission Reductions Reveal the Efficiency and Warming Impact of Short-Lived Greenhouse Gases
Published: 2026-10-05
Subjects: Physical Sciences and Mathematics
The COVID-19 response provided a natural experiment to quantify the climate forcing efficiency of short-lived pollutants. Using satellite-constrained reanalysis and chemistry-climate simulations, we isolate the radiative impacts of anthropogenic NOₓ reductions through two modes: a rapid ozone decrease and a slower methane-driven adjustment that dominates the net effect. Globally, these responses [...]
A Stable Column ΔXCH₄/ΔXCO₂ Ratio over Los Angeles (2011–2025): An Inventory-Independent Test of Urban Methane Policy
Published: 2026-10-05
Subjects: Physical Sciences and Mathematics
We extend the column-averaged CH₄ and CO₂ (XCH₄, XCO₂) record from the California Laboratory for Atmospheric Remote Sensing (CLARS) through July 2025, spanning 15 years over the Los Angeles megacity. CLARS retrievals show persistent enhancements of both gases above the free-tropospheric background, with a strong excess correlation (R = 0.93) and an emission ratio ΔXCH₄/ΔXCO₂ ≈ 5.1 ppb ppm⁻¹ that [...]
Natural aerosol variability can reverse the apparent air-quality response to abrupt emission reductions
Published: 2026-10-05
Subjects: Physical Sciences and Mathematics
Abrupt societal disruptions, including economic shocks, pandemic lockdowns, and armed conflicts, are widely used as natural experiments for attributing changes in air quality to changes in emissions. Such attribution commonly rests on observed concentrations: combustion tracers fall, and the resulting improvement is credited to reduced emissions. Here we show that coincident natural aerosol [...]