Preprints
Filtering by Subject: Atmospheric Sciences
Spatially and temporally dense measurements reveal meteorological driver of atmospheric mercury variability
Published: 2026-06-02
Subjects: Atmospheric Sciences
The environmental fate of mercury (Hg) is determined by its atmospheric processing, yet the relative role of surface fluxes, chemistry, and transport on atmospheric loadings remains poorly understood. We use multiyear gaseous elemental Hg (Hg0) concentration measurements at two rural sites and two urban sites in the northeastern US coordinated by the National Atmospheric Deposition Program (NADP) [...]
Development and Evaluation of the High-Resolution MUSICA UK Domain: A Case Study of Global and Regional Biomass Burning Impacts
Published: 2026-05-29
Subjects: Atmospheric Sciences, Civil and Environmental Engineering, Environmental Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Regional air quality models provide insights into local pollution and exposure, but limitations in representing large-scale atmospheric processes and long-range transport can introduce inconsistencies across spatial scales, which can be addressed using multi-scale chemical transport models. We develop the first UK-specific regionally refined grid (UKne30×16; ∼7 km), alongside a global uniform [...]
Public Understanding of the Atmospheric River Scale
Published: 2026-05-27
Subjects: Atmospheric Sciences, Social and Behavioral Sciences
Atmospheric rivers (ARs) are long, narrow bands of moisture in the atmosphere that transport large amounts of water vapor, producing hazards ranging from heavy rain to high winds once they reach land. In 2019, researchers at the Center for Western Weather and Water Extremes, with partners including the National Weather Service and the California Department of Water Resources, developed the AR [...]
Wildfire smoke offsets decades of progress in reducing ozone exposure across the United States
Published: 2026-05-23
Subjects: Atmospheric Sciences, Climate, Environmental Sciences
Ground-level ozone (O3) pollution has declined in the U.S., yet the progress has stalled in recent years, coinciding with increasing wildfire smoke. Using ensemble machine learning models trained on surface observations, we develop a gridded daily smoke O3 dataset across the contiguous U.S. from 2006-2023. We estimate that wildfire smoke placed an additional 29 million people each year in areas [...]
Analysis of sub-regional climates in the European Alps based on the EEAR-Clim observational dataset
Published: 2026-05-22
Subjects: Atmospheric Sciences, Climate, Meteorology
The European Alps exhibit a complex geomorphology and undergo the influences of different climate regimes, resulting in high spatial variability of climatic variables and their changes. To provide a detailed analysis of climate regions and climatic changes occurring at a sub-regional scale during the 1961-2020 period, we exploited an updated regionalization of the European Alps that benefits from [...]
Deforestation Edge Effects on Soil Moisture Persistence in the Amazon Basin: Observational Evidence for Lateral Hydrological Degradation and Minimum Viable Restoration Scales
Published: 2026-05-22
Subjects: Atmospheric Sciences, Environmental Monitoring, Forest Sciences, Hydrology
Deforestation in the Amazon basin degrades not only the cleared land but also the hydrological function of adjacent intact forest. Here we combine 10 years of SMAP Level 4 root-zone soil moisture (9 km, 2015 to 2024) with Hansen Global Forest Change data (30 m) to quantify how proximity to deforestation edges affects soil moisture persistence in intact forest across the Amazon basin. We classify [...]
First Observational Evidence That Biological Giant CCN Control Urban Rainfall Character: A Natural Experiment from Islamabad's Paper Mulberry Removal
Published: 2026-05-22
Subjects: Atmospheric Sciences, Earth Sciences, Hydrology, Meteorology
Modeling studies predict that biological aerosol, specifically pollen acting as giant cloud condensation nuclei (GCCN), can modify precipitation character by initiating collision-coalescence and warm rain in shallow cloud (Steiner et al., 2015; Wozniak et al., 2018; Paukert et al., 2025). No observational study has tested this prediction. We exploit a natural experiment, the removal of ~29,000 [...]
Deep learning identification of SST teleconnections driving early-winter North Atlantic climate
Published: 2026-05-22
Subjects: Atmospheric Sciences, Climate, Meteorology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Seasonal predictability over the North Atlantic-European (NAE) sector is strongly modulated by the background climate state, particularly in early winter. In this season, different ENSO teleconnections have been reported before and after the 1990s. However, these studies rely on linear analysis, and the reasons for this lack of stationarity and its implications for seasonal forecasting have not [...]
A 10,000-Year Global Stochastic Tropical Cyclone Catalog with Wind-Dependent Track Transitions (WHITS)
Published: 2026-05-22
Subjects: Atmospheric Sciences, Risk Analysis
Reliable assessment of tropical cyclone risk is limited by the short and spatially uneven historical record, especially for rare, high-intensity landfalls that dominate insured loss. We present WHITS, the Wind-focused Hurricane Interactive Track Simulator, a non-parametric semi-Markov model that generates a 10,000-year global synthetic catalog of tropical cyclone tracks. WHITS builds new storms [...]
Pakistan's Orographic Ladder: Terrain-Constrained Water Potential and the Atmospheric Mechanism Suppressing It
Published: 2026-05-14
Subjects: Atmospheric Sciences, Climate, Hydrology
Pakistan's north-south topographic gradient, 0 m at the Arabian Sea coast rising to 8,611 m at K2 across five distinct ridge systems, represents one of the largest orographic condensation machines on the planet. The terrain's theoretical water yield, set by Arabian Sea moisture flux and ridge geometry alone, far exceeds what Pakistan currently captures. We show that a single atmospheric variable, [...]
Reduced geomagnetic shielding increased UV-B radiation at Earth’s surface during the Laschamps Event
Published: 2026-05-01
Subjects: Astrophysics and Astronomy, Atmospheric Sciences, Biochemistry, Biogeochemistry, Biology, Earth Sciences, Ecology and Evolutionary Biology, Environmental Chemistry, Environmental Sciences, Geology, Geophysics and Seismology, Life Sciences, Oceanography and Atmospheric Sciences and Meteorology, Other Life Sciences, Paleobiology, Physical and Environmental Geography, Physical Sciences and Mathematics, Planetary Geochemistry, Planetary Geology, Planetary Geophysics and Seismology, Planetary Sciences, Social and Behavioral Sciences, Statistics and Probability
Exposure to excess UV-B radiation can harm organisms through DNA damage and oxidative stress, and has likely been a key ecological and evolutionary driver throughout Earth’s history. Here, we show UV-B at Earth’s surface was significantly increased during the Laschamps Event, the last major geomagnetic excursion ca. 41ka BP. During the Laschamps, we find significant and prolonged (lasting [...]
Large climate model ensembles reveal underdispersion in seasonal Atlantic tropical cyclone counts
Published: 2026-04-29
Subjects: Atmospheric Sciences, Physical Sciences and Mathematics
Seasonal Atlantic tropical cyclone (TC) counts are commonly modeled as a conditional Poisson process, implying that the distribution of possible seasonal outcomes—the range of TC counts that could plausibly occur in a given year—exhibits equidispersion for a given climate state, with its variance equal to its mean. This assumption underlies many statistical frameworks used for seasonal TC [...]
Agricultural Fallowing Drives Extreme Anthropogenic Dust and Visibility Degradation During the October 2021 Dust Event in California’s Central Valley
Published: 2026-04-26
Subjects: Atmospheric Sciences
Anthropogenic dust aerosols from agricultural land affect regional air quality, visibility, and radiation, yet they are often ignored in atmospheric models. Here, we investigate the role of fallow croplands in driving anthropogenic dust emissions during the October 11, 2021, wind-driven dust event over California’s Central Valley (CV). The simulation without fallow croplands fails to reproduce [...]
Exploratory MPAS Sensitivity Experiments on Rainforest Biogenic Salt Aerosols, Tropical Rainfall, and Poleward Moisture Transport
Published: 2026-04-26
Subjects: Atmospheric Sciences, Climate, Planetary Hydrology
Equatorial rainforest trees and their associated fungi emit hygroscopic potassium-salt (K-salt) aerosols that activate readily as cloud condensation nuclei and can accelerate warm rain — a biogenic, vegetation-linked pathway not represented as a dedicated process in major climate models. We ask whether this source measurably modulates the poleward transport of latent heat, using MPAS-Atmosphere [...]
Assessing Causality in PM2.5 and NO2 Changes One Year After New York City’s Congestion Pricing Policy
Published: 2026-04-23
Subjects: Atmospheric Sciences, Climate, Environmental Sciences
On January 5, 2025, New York City implemented the Central Business District Tolling Program (CBDTP), a congestion pricing policy targeting lower Manhattan. We evaluate its air quality effects after one year using ground-based and satellite observations. Using New York City Community Air Survey (NYCCAS) real-time PM2.5 monitors, we compare PM2.5 concentrations during the first year of CBDTP [...]