Preprints
Filtering by Subject: Physical Sciences and Mathematics
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 [...]
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 [...]
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 [...]
Bulk iron-sulfur ratio (Fe/S) conditional proxy for sulfurized, TOC-rich sediments: insights and comparison of compositional model with real data utilizing the Pyrite-TOC-Fe-S compositional space
Published: 2026-10-04
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics
Bulk iron-sulfur (Fe/S) ratio can be a proxy for sulfurized organic matter in organic-rich shales, particularly those prone to be siliceous or carbonate. First part uses a theoretical model of a compositional system consisting solely of iron, sulfur, TOC, and pyrite to demonstrate how the Fe/S ratio can indicate the presence of sulfurized organic matter using the model’s assumption of sulfur [...]
Climate resilience from long-term low till adoption in US farms
Published: 2026-10-03
Subjects: Agriculture, Environmental Sciences, Life Sciences, Physical Sciences and Mathematics, Sustainability
Low-intensity tillage (low till) has expanded rapidly in the United States since 2000. Evidence on its yield impacts has come mainly from field experiments and has been limited to short time horizons. Using satellite-based observations from more than 40 million field-year pairs across the U.S. Corn Belt from 1999-2023, we demonstrate that yield gains continue to accrue with longer duration of [...]
Improvement of Daily Temperature Forecasts from a Prediction Market
Published: 2026-10-03
Subjects: Applied Statistics, Atmospheric Sciences, Climate, Meteorology, Natural Resource Economics, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Probability, Statistical Methodology, Statistical Models, Statistics and Probability
Prediction markets aggregate and distill the collective views of participants who have a financial stake in being correct. They have been shown to produce more accurate forecasts in realms like election results, which are not easily amenable to mechanistic modeling because they entail forecasting human behavior. It is far less clear that prediction markets should improve the accuracy of [...]
Fixed-ground multisensor monitoring resolves longitudinal vegetation condition and fuel-state structure in Southern California chaparral and oak scenes
Published: 2026-10-03
Subjects: Ecology and Evolutionary Biology, Environmental Monitoring, Environmental Sciences, Forest Sciences, Geography, Life Sciences, Physical Sciences and Mathematics, Plant Sciences, Remote Sensing, Social and Behavioral Sciences, Terrestrial and Aquatic Ecology
Wildfire-relevant vegetation and fuel conditions evolve through interacting changes in vegetation condition, three-dimensional fuel structure, thermal response, and atmospheric drying, yet these dimensions are commonly monitored separately. This study evaluated repeated fixed-ground multisensor monitoring at two fixed vegetation scenes in Placerita Canyon, California. Multispectral imaging, [...]
Novel Mechanism of Abiotic Ammonium Oxidation Triggers Nitrous Oxide Bursts Upon Soil Rewetting
Published: 2026-10-02
Subjects: Physical Sciences and Mathematics
Drought-rewetting cycles (DWC) in soil are accompanied by a rapid burst of nitrous oxide (N2O) emission within minutes without reactivation of dormant microbes. Here we present a manifold of evidence for a previously unrecognized abiotic mechanism connecting soil ammonium (NH4+) to N2O with hydroxylamine (NH2OH) as a key intermediate. DWC experiments in the Negev Desert soil revealed comparable [...]
The relation of ENSO with global surface temperature
Published: 2026-10-02
Subjects: Physical Sciences and Mathematics
Here we examined the seasonal structure of the El Niño–Southern Oscillation (ENSO)–global surface temperature relation in monthly observations for June 1979–May 2026. Neglecting seasonality, correlations of Niño-3.4 with global mean surface temperature (GMST) and tropical mean surface temperature (TMST) are largest at lags of three and two months, respectively; without detrending, GMST [...]
Understanding Earthquake Physics with On-Fault Observatories
Published: 2026-10-02
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes often strike without warning. Current fault monitoring infrastructure is not sensitive enough to detect signals such as accelerating fault creep or dilation, which laboratory experiments and numerical models predict may precede large earthquakes. Here we argue that a paradigm shift is needed and technically achievable: from inferring faulting processes from a distance with surface [...]
Assessment of adjacency effect correction methods for Sentinel-2 MSI observations over mid-latitude lakes
Published: 2026-10-01
Subjects: Earth Sciences, Environmental Sciences, Fresh Water Studies, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Accurate retrieval of remote-sensing reflectance (Rrs) from lakes requires separating water-leaving radiance from atmospheric, surface and adjacency contributions. We assessed adjacency effect correction (AEC) methods for Sentinel-2 MultiSpectral Instrument (MSI) imagery using 329 satellite--insitu matchups from four mid-latitude lakes: Greifensee, Lake Geneva, Lake Garda and Lake Trasimeno. The [...]
Training-Free Monitoring of Kenya with Pre-computed Satellite Embeddings: Lake Expansion, Construction Dating and Crop Retrieval with TESSERA
Published: 2026-10-01
Subjects: Earth Sciences, Physical Sciences and Mathematics
Pre-computed embeddings from geospatial foundation models turn the most expensive step of satellite analysis into shared data. We test how much analysis this enables for one country, using TESSERA, which publishes a 128-dimensional embedding for every 10 m pixel and year. An audit of Kenya shows that all 4,766 tiles centred in the country carry all nine years (2017–2025), but that the landmask [...]
Can recovered data-centre heat supply solid-sorbent direct air capture regeneration? A thermodynamic and carbon-accounting review of the proposed DACR–HSDC coupling, with falsifiable deployment gates
Published: 2026-09-30
Subjects: Education, Engineering, Life Sciences, Physical Sciences and Mathematics
Abstract Background. Direct air capture (DAC) using temperature-vacuum swing adsorption requires electricity and low- to medium-temperature regeneration heat. Data centres reject heat that may be available for this purpose, but the temperature, timing and emissions intensity of that heat determine whether integration produces additional net atmospheric removal. An earlier design document by the [...]
Metal Toxin Signatures in the Smoke of Wildland–Urban Interface Fires
Published: 2026-09-30
Subjects: Medicine and Health Sciences, Physical Sciences and Mathematics, Social and Behavioral Sciences
Wildland–urban interface (WUI) fires burn natural and built environments simultaneously, generating smoke from vegetation, soil, buildings, vehicles, and infrastructure. Airborne metals can provide source signatures and pose inhalation hazards, yet the sources and physicochemical properties of these metals in WUI fire smoke remain poorly resolved. This uncertainty limits identification of burned [...]
Earthquake damage mapping from Sentinel-1 modeling against coherence damage proxy
Published: 2026-09-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
This paper tests whether a supervised model that uses the same Sentinel-1 signal as the coherence damage proxy can rank earthquake damage better than the proxy itself. Damage grades from Copernicus EMS for four earthquakes are joined to 783 635 OpenStreet- Map footprints over 28 assessed areas, and the coherence drop is aggregated to buildings, morphological blocks and cells of 50 m to 400 m. A [...]