Large-scale wildfires are essential sources of black carbon (BC) and brown carbon (BrC), affecting aerosol-induced radiative forcing. This study investigated the impact of two wildfire plumes (Plume 1 and 2) transported to Moscow on the optical properties of BC and BrC during August 2022. During the wildfires, the total light absorption at 370 nm (b(abs_370nm)) increased 2.3-3.4 times relative to background (17.30 +/- 13.98 Mm(-)(1)), and the BrC contribution to total absorption increased from 14 % to 42-48 %. BrC was further partitioned into primary (BrCPri) and secondary (BrCSec) components. Biomass burning accounted for similar to 83-90 % of BrCPri during the wildfires. The b(abs_370nm) of BrCPri increased 5.6 times in Plume 1 and 11.5 times in Plume 2, due to the higher prevalence of peat combustion in Plume 2. b(abs_370nm) of BrCSec increased 8.3-9.6 times, driven by aqueous-phase processing, as evidenced by strong correlations between aerosol liquid water content and b(abs_370nm) of BrCSec. Daytime b(abs_370nm) of BrCSec increased 7.6 times in Plume 1 but only 3.6 times in Plume 2, due to more extensive photobleaching, as indicated by negative correlations with oxidant concentrations and longer transport times. The radiative forcing of BrCPri relative to BC increased 1.8 times in Plume 1 and Plume 2. In contrast, this increase for BrCSec was 3.4 times in Plume 1 but only 2.3 times in Plume 2, due to differences in chemical processes, which may result in higher uncertainty in its radiative forcing. Future work should prioritize elucidating both the emissions and atmospheric processes to better quantify wildfire-derived BrC and its radiative forcing.

The critical role of light-absorbing aerosol black carbon (BC) in modifying the Earth's atmosphere and climate system warrants detailed characterization of its microphysical properties. The present study examines the BC microphysical properties (size distributions and mixing state) and their impact on the light-absorption characteristics over a semi-urban tropical coastal location in Southern Peninsular India. The measurements of refractory BC (rBC) properties, carried out using the single particle soot photometer during 2018-2021, covering four distinct air mass conditions (Marine, Continental, Mixed-1, and Mixed-2), were used for this purpose. These were supported by measurements of non-refractory submicron particulate matter (NR-PM1) mass loadings and the core-shell Mie theory model for BC-containing particles. The results suggested that the BC particles exhibited varying sizes (mass median diameters from 0.181 +/- 0.079 mu m to 0.202 +/- 0.064 mu m) and relative coating thicknesses (RCT) (1.3-1.6) under distinct air mass conditions. These characteristics reflected varying source/sink strengths, aging processes of BC, and potential condensable coating material. The aerosol system during the Marine air mass period has lower BC (similar to 0.67 +/- 0.57 mu g m(-3)) and NR-PM1 (12.06 +/- 10.81 mu g m(-3)) mass concentrations, and the lowest RCT on BC (similar to 1.34 +/- 0.14). However, the other periods with continental influence depicted significant coatings on BC (mean RCT >1.5). The coatings on BC particles exhibited daytime enhancement, driven by photochemically produced condensable material, a contrasting diurnal pattern to that of other BC properties. Interestingly, the RCT on BC increased and/or remained invariant with increasing relative humidity (RH) until RH 85 %), indicating the potential role of secondary organics as coatings. The changes in the BC mixing state resulted in a significant alteration to its light-absorption properties. The mean light-absorption enhancement of BC (compared to uncoated BC) ranged from 1.36 +/- 0.14 for the Marine air mass periods to 1.58 +/- 0.15 for the Continental air mass periods, whereas the overall mass absorption cross-sections of BC varied between 7.91 +/- 0.91 to 9.03 +/- 0.84 m(2)/g at 550 nm. The key implication of this study is that changes to the BC mixing state, caused by multiple underlying processes unique to tropical atmospheric conditions, can lead to a significant enhancement in its light-absorption characteristics, which can lead to a notable increase in the positive radiative forcing of BC.

Climate warming has impacted the sustainability of freshwater supply in the global water tower unit (WTU) zone. The rainfall infiltration process, a key component of WTUs supply, is affected by freeze-thaw cycles, yet it remains uncertain whether it has undergone corresponding changes. We propose a temperature-mediated infiltration model considering changes in soil water holding, water potential, and hydraulic conductivity due to varying degrees of freezing under negative temperature. Using this model, we calculate the infiltration of 78 WTUs globally from 1980 to 2023. Our results indicate that global WTUs have a multi-year average infiltration of 26 similar to 2359 mm/year. Notably, WTUs in the key latitudinal zone (24 degrees S-42 degrees N) contribute 54 % of the total infiltration volume, showing expanding differences in infiltration characteristics compared to other regions. While rainfall primarily influences infiltration and infiltration capacity, soil temperature and initial soil water content also significantly impact these characteristics. Enhanced infiltration capacity promotes vegetation growth, though the relationship is not linear. Variations in infiltration characteristics threaten the water resource buffering and the stability of downstream living ecological water supply of WTUs. This study provides crucial references for the integrated management of water resources and ecological conservation amid changing infiltration characteristics.

The thermal coupling between the atmosphere and the subsurface on the Qinghai-Tibetan Plateau (QTP) governs permafrost stability, surface energy balance, and ecosystem processes, yet its spatiotemporal dynamics under accelerated warming are poorly understood. This study quantifies soil-atmosphere thermal coupling ((3) at the critical 0.1 m root-zone depth using in-situ data from 99 sites (1980-2020) and a machine learning framework. Results show significantly weaker coupling in permafrost (PF) zones (mean (3 = 0.42) than in seasonal frost (SF) zones (mean (3 = 0.50), confirming the powerful thermal buffering of permafrost. Critically, we find a widespread trend of weakening coupling (decreasing (3) at 66.7 % of sites, a phenomenon most pronounced in SF zones. Our driver analysis reveals that the spatial patterns of (3 are primarily controlled by surface insulation from summer rainfall and soil moisture. The temporal trends, however, are driven by a complex and counter-intuitive interplay. Paradoxically, rapid atmospheric warming is the strongest driver of a strengthening of coupling, likely due to the loss of insulative snow cover, while trends toward wetter conditions drive a weakening of coupling by enhancing surface insulation. Spatially explicit maps derived from our models pinpoint hotspots of accelerated decoupling in the eastern and southern QTP, while also identifying high-elevation PF regions where coupling is strengthening, signaling a loss of protective insulation and increased vulnerability to degradation. These findings highlight a dynamic and non-uniform response of land-atmosphere interactions to climate change, with profound implications for the QTP's cryosphere, hydrology, and ecosystems.

The Himalayan glacier valleys are encountering escalating environmental challenges. One of the contributing factors is thought to be the rising amounts of light-absorbing carbonaceous aerosols, particularly brown carbon (BrC) and black carbon (BC), that are reaching glacier valleys. The present study examines the optical and radiative characteristics of BC at Bhojbasa, near Gaumukh (similar to 3800amsl). Real-time in-situ BC data, optical characteristics, radiative forcing, heating rate, several meteorological parameters, and BC transport pathways to this high-altitude site are investigated. The daily mean concentration of equivalent black carbon (eBC) was 0.28 +/- 0.21 mu g/m(3) over the research period, and the eBC from fossil fuel (BCFF) is dominant with 78 % with a daily mean of 0.22 +/- 0.19 mu g/m(3)(,) and eBC from biomass burning (BCBB) is 22 % with a daily mean of 0.06 +/- 0.08 mu g/m(3). Meteorological data, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) imaging, and backward air-mass trajectory analysis demonstrate the presence of BC particles and their plausible transit pathways from multiple source locations to the pristine Gangotri Glacier Valley. The estimated daily mean BC radiative forcing values are +6.71 +/- 1.80 W/m(2) in the atmosphere, +1.87 +/- 1.16 W/m(2) at the top of the atmosphere, and -4.84 +/- 1.01 W/m(2) at the surface with a corresponding atmospheric heating rate of 0.19 +/- 0.05 K/day. These findings highlight the critical role of ground-based measurements in monitoring the fluctuations of BC over such varied Himalayan terrain, as they offer important information on the localized trends and effects. Long-term measurements of glacier valleys are essential for a comprehensive evaluation of the impact of BC particles on Himalayan ecology and climate.

Central and Eastern European geography, shaped by its entanglement of natural and social sciences, provides a distinctive lens for rethinking the unity of the discipline. Its historical and institutional hybridity makes the region particularly well positioned to foster integrative geographical perspectives. The objective of this study was to evaluate the present, post-transitional state of the discipline in Central and Eastern Europe (CEE), to identify its future trajectory and to uncover the significant role of CEE geography in addressing global environmental, social and economic challenges. To facilitate this process, four significant geographical topics have been identified as potentially providing a conducive environment for the partial reintegration of geography. The aforementioned themes encompass a range of topics, including migrations, the green transition, anthropogenic climate change, global tipping points, wetland disturbance, peatland carbon sequestration and cryosphere degradation. Furthermore, we have sought to assess the perspective and significance of geographical unity in addressing global crises that impact human life on Earth. This analysis has enabled the identification of critical issues that necessitate integrated approaches. The necessity for enhanced collaboration between physical and human geography, as well as between nature studies and social and economic explorations, is emphasised. In this regard, it is acknowledged that a more inclusive approach is employed in the field of CEE geography, with contributions from other disciplines such as biology, ecology, physics, sociology and economics being welcomed. These disciplines address processes that span from local to global scales, as well as those that study long-term phenomena, such as history and archaeology. The establishment of robust interdisciplinary networks has the potential to enhance the scientific standing of integrated geography and to strengthen innovative connections between human and physical geography.

In light of a series of recent fatal landslides in Alaska, we set out to determine 1) the history of Alaskan landslides and 2) if the number of associated fatalities has increased with time. To answer our research questions, we searched a combination of 24 digital newspapers and online media sources, including historic digitized Alaskan newspapers, seeking landslides that affected people and/or infrastructure. This resulted in an inventory of 281 landslides occurring in Alaska since 1883. Our database includes the date on which the landslide occurred, its location and probable trigger, any reported injuries and/or fatalities, other reported damage, and the media source. Our inventory indicates that the number of reported landslides started to increase in the 1980's, and has increased dramatically in recent decades. We correlate the increase in landslides to a 1.2 degrees C to 3.4 degrees C increase in average annual air temperature and a 3% to 27% increase in precipitation over the last 50 years across Alaska. This change in climate is degrading permafrost, increasing the number of annual freeze/thaw events, and contributing to larger and more intense precipitation events - such as atmospheric rivers, all of which increase landslide susceptibility in various parts of the state. Alaska's last four fatal landslides occurred in Southeast Alaska, which has experienced the greatest increase in the number of landslides per capita. Our landslide database can serve as the initial inventory for analyses of landslides related to specific extreme weather events, as well as a resource to determine costs incurred from landslide-related damage.

Ensuring the accuracy of free-field inversion is crucial in determining seismic excitation for soil-structure interaction (SSI) systems. Due to the spherical and cylindrical diffusion properties of body waves and surface waves, the near-fault zone presents distinct free-field responses compared to the far-fault zone. Consequently, existing far-fault free-field inversion techniques are insufficient for providing accurate seismic excitation for SSI systems within the near-fault zone. To address this limitation, a tailored near-fault free-field inversion method based on a multi-objective optimization algorithm is proposed in this study. The proposed method establishes an inversion framework for both spherical body waves and cylindrical surface waves and then transforms the overdetermined problem in inversion process into an optimization problem. Within the multi-objective optimization model, objective functions are formulated by minimizing the three-component waveform differences between the observation point and the delayed reference point. Additionally, constraint conditions are determined based on the attenuation property of propagating seismic waves. The accuracy of the proposed method is then verified through near-fault wave motion characteristics and validated against real downhole recordings. Finally, the application of the proposed method is investigated, with emphasis on examining the impulsive property of underground motions and analyzing the seismic responses of SSI systems. The results show that the proposed method refines the theoretical framework of near-fault inversion and accurately restores the free-field characteristics, particularly the impulsive features of near-fault motions, thereby providing reliable excitation for seismic response assessments of SSI systems.

Char and soot represent distinct types of elemental carbon (EC) with varying sources and physicochemical properties. However, quantitative studies in sources, atmospheric processes and light-absorbing capabilities between them remain scarce, greatly limiting the understanding of EC's climatic and environmental impacts. For in-depth analysis, concentrations, mass absorption efficiency (MAE) and stable carbon isotope were analyzed based on hourly samples collected during winter 2021 in Nanjing, China. Combining measurements, atmospheric transport model and radiative transfer model were employed to quantify the discrepancies between char-EC and soot-EC. The mass concentration ratio of char-EC to soot-EC (R-C/S) was 1.4 +/- 0.6 (mean +/- standard deviation), showing significant dependence on both source types and atmospheric processes. Case studies revealed that lower R-C/S may indicate enhanced fossil fuel contributions, and/or considerable proportions from long-range transport. Char-EC exhibited a stronger light-absorbing capability than soot-EC, as MAE(char) (7.8 +/- 6.7 m(2)g(-1)) was significantly higher than MAE(soot) (5.4 +/- 3.4 m(2)g(-1))(p < 0.001). Notably, MAE(char) was three times higher than MAE(soot) in fossil fuel emissions, while both were comparable in biomass burning emissions. Furthermore, MAE(soot) increased with aging processes, whereas MAE(char) exhibited a more complex trend due to combined effects of changes in coatings and morphology. Simulations of direct radiative forcing (DRF) for five sites indicated that neglecting the char-EC/soot-EC differentiation could cause a 10 % underestimation of EC's DRF, which further limit accurate assessments of regional air pollution and climate effects. This study underscores the necessity for separate parameterization of two types of EC for pollution mitigation and climate change evaluation.

Thawing permafrost alters climate not only through carbon emissions but also via energy-water feedback and atmospheric teleconnections. This review focuses on the Tibetan Plateau, where strong freeze-thaw cycles, intense radiation, and complex snow-vegetation interactions constitute non-carbon climate responses. We synthesize recent evidence that links freeze-thaw cycles, ground heat flux dynamics, and soil moisture hysteresis to latent heat feedback, monsoon modulation, and planetary wave anomalies. Across these pathways, both observational and simulation studies reveal consistent signals of feedback amplification and nonlinear threshold behavior. However, most Earth system models underrepresent these processes due to simplifications in freezethaw processes, snow-soil-vegetation coupling, and cross-seasonal memory effects. We conclude by identifying priority processes to better simulate multi-scale cryosphere-climate feedback, especially under continued climate warming in high-altitude regions.