Glacier melt-induced ionic pulses significantly alter river physicochemistry and trigger cascading effects on aquatic communities. However, their impacts on multitrophic community structure and ecological networks remain insufficiently understood. In this study, environmental DNA (eDNA) metabarcoding was applied to explore how ionic pulses influence multitrophic communities in the Source Region of the Yangtze River. The results show that the ionic pulse caused a turnover of dominant taxa among algae, invertebrates, and fish. In addition, bacterial α-diversity declined during the pulse due to ionic stress but recovered afterward; the β-diversity of aquatic communities decreased during the pulse due to homogenization, then increased after the pulse as communities underwent reassembly driven by both species loss and replacement. Co-occurrence network analysis showed that networks were simplified during the pulse but became more complex and modular afterward, with an increase in keystone taxa across trophic levels; however, network stability declined. Water temperature, pH, electrical conductivity (EC), and nutrients are key drivers of these changes. The findings elucidate the important impacts of ionic pulses on aquatic communities in glacier-fed rivers and provide theoretical support for ecological protection and management in high-altitude regions.

The stratospheric Brewer-Dobson (B-D) circulation is a global-scale system that influences Earth's radiative energy balance, atmospheric chemistry, and atmospheric environment. However, its long-term variations are difficult to study due to a lack of appropriate proxies, and it remains unclear whether the B-D circulation was enhanced or weakened during the Last Glacial Maximum (LGM). Stratospheric water vapor exhibits a distinct oxygen-17 excess (17O-excess) due to the non-mass-dependent fractionation of oxygen isotopes during ozone-related photochemical reactions, making it a natural tracer for stratosphere-troposphere exchange. In this study, we integrate water 17O-excess records from multiple Antarctic ice cores, and estimate the strength of the B-D circulation based on a mass balance of water 17O-excess in the polar troposphere. Additionally, we develop a mixing model for 17O-excess at ice core site to further constrain the B-D strength. By combining our results with recent climate model simulations, we estimate that the B-D circulation during the LGM was approximately 19% weaker than its present state. Nevertheless, this estimation is subject to considerable uncertainty, owing to the limited availability of ice-core 17O-excess records and a lack of robust constrains of the climate models. The weaker B-D circulation during the LGM has important implications for interpreting polar ice-core chemical records on glacial-interglacial timescales and improving the accuracy of paleoclimate models.

Understanding elevation-dependent warming is essential for assessing risks to the cryosphere and water resources in mountainous regions. However, warming patterns above 5 km a.s.l. on the Tibetan Plateau are poorly understood due to data scarcity. Here, we integrate station observations with 12 ice core δ18O records to reconstruct annual and summer temperature records for the westerlies-dominated Tibetan Plateau since the 1950s, and systematically evaluate the three-dimensional structure and seasonal differences of elevation-dependent warming. Our results reveal a clear pattern of elevation-dependent warming in annual mean temperature between 2 and 7.5 km, primarily driven by snow albedo and cloud feedbacks. In contrast, summer temperatures show no elevation-dependent warming due to the competing effects of multiple feedback processes. Furthermore, we identified a warming peak between 2.5 and 3 km driven by radiative forcing and sensible heat, and muted warming between 6 and 6.5 km due to cloud-radiation-glacier feedbacks. “Annual mean temperatures in the Tibetan Plateau showed elevation-dependent warming at altitudes between 2 and 7.5 km, with a peak between 2.5 and 3 km, as reconstructed from station data and 12 ice core records back to the 1950s.”

Although the Tibetan Plateau (TP) is highly sensitive to biomass burning emissions, direct evidence of its long-term history remains limited. In this study, we reconstruct a history of biomass burning emissions in the western TP and surroundings for 1935-2012 CE, by using the first high-resolution ice core charcoal record from the Chongce ice cap. The record shows a fourfold increase in biomass burning emissions after the 1970s, which originated primarily from the northwestern Indian Peninsula. Although pre-1970s biomass burning was mostly modulated by climate-vegetation interactions, its post-1970s acceleration was decoupled from natural fuel and monsoon controls. This shift was primarily driven by anthropogenic activities, as evidenced by a concurrent rise in the charcoal-to-pollen ratio, which indicates regional agricultural intensification. In addition, biomass burning is identified as the dominant source of black carbon deposition in the ice core. This result suggests that anthropogenic fire, primarily from agricultural burning, increases the light-absorbing aerosols on Tibetan glaciers, potentially accelerating ice melt in the region.

The westerlies moisture transport underpins water security for over two billion people dependent on the Asian water towers (AWTs). However, the mechanisms by which large-scale westerlies-advected moisture is integrated into the AWTs' atmospheric water budget remain poorly understood due to observational gaps. Here, we combine three-dimensional observations of atmospheric water vapor stable isotopes with isotope-enabled modeling. We identify the conveyor mechanism that regulates the vertical moisture transport under calm conditions during the winter-spring period when the westerlies are dominant. Sharp vertical isotopic gradients show that large-scale westerlies-advected moisture is predominantly confined aloft, while local residual moisture persists near the surface. Our results show the interplay of the westerlies' subsidence at night with thermodynamically distinct local residual air, yielding thermal inversions and condensation that suppresses vertical mixing and decouples moisture between the free troposphere and the atmospheric boundary layer. This process constitutes a primary pathway for integrating westerlies-advected moisture into the local moisture budget without precipitation, sustaining near-surface moisture accumulation. Our results provide critical benchmarks for improving atmospheric models, refining climate projections of the intensifying water cycle over the AWTs, and advancing interpretations of isotopic records in regional climatic archives.

During compound heatwave and drought events (CHDE), a significant amount of soil moisture is released into the atmosphere through evapotranspiration. In this study, we used multi-source atmospheric water vapor isotope data sets, including satellite and ground-based observations, to investigate the role of evapotranspired water vapor (EWV) during CHDE. We identified a vertical dipole pattern in water vapor isotopes, with depletion in the lower troposphere and enrichment in the middle troposphere. This pattern is primarily driven by vertically transported EWV, which can reach altitudes up to 500 hPa. More importantly, the upward transport of EWV plays a key role in the warming of the middle troposphere, creating a saddle-shaped temperature structure of the troposphere. This suggests that enhancing the forecasting capability of numerical weather prediction models for extreme CHDE should involve an adequate consideration of the warming effect of vertically transported EWV within the model framework.

Mass spectrometry and laser spectroscopy have been widely employed for precise water vapor isotope measurements. Nevertheless, these techniques are limited by logistical challenges in fieldwork, consequently constraining the temporal and spatial resolution of measurements. Specifically, water vapor isotope measurements are primarily limited to near-surface levels, while measurements in the free troposphere are notably scarce. Portable sampling devices, such as air bags and glass bottles, have therefore become necessary alternatives for collecting, storing, and transporting gaseous samples in diverse environments prior to analysis with less portable instruments. In drone-based high-altitude vapor sampling, air bags are preferred for their lighter weight and greater flexibility compared to glass bottles. Nevertheless, they present specific challenges, such as potential sample contamination and isotopic fractionation during storage, primarily due to the inherent permeability of air bags. Here, we developed a theoretical model for water vapor diffusion through the sampling bag surface, with parameters calibrated through laboratory experiments. This model enables the reconstruction of the initial isotopic composition of sampled vapor based on measurements obtained within the bag and from the surrounding environment. This diffusion model underwent rigorous validation through experiments conducted under varying humidity and isotopic composition differences between the inside and outside of the air bag, confirming its reliability. We applied this correction method to air samples collected at various pressures up to the upper troposphere using an air bag-mounted drone that we developed, thereby estimating the initial isotopic composition and uncertainty based on our observations. Our correction method enhances the reliability and applicability of water vapor isotope observations conducted using drones equipped with air bags, and provides a detailed assessment of all potential sources of error and quantifies the uncertainty range of the observations. This approach leverages the strengths of drone-based air bag sampling while mitigating its limitations, thus facilitating the convenient collection of isotopic data throughout the troposphere.

Antarctic sea ice plays a crucial role in regulating regional and global climate, as well as ecosystem productivity of the Southern Ocean. Since sea ice data were rare before 1978C.E., reconstruction of past sea ice conditions is of vital importance for understanding their impact on past climate change. Methanesulfonate (MSA) in Antarctic ice cores is considered a potential proxy of sea ice extent (SIE). In this study, we tested this approach by measuring the variations of MSA flux (1950-2016C.E.) in samples collected from a snowpit at Dome A, the summit of Eastern Antarctic ice sheet, and investigating its relationship with the SIE in the Southern Ocean. The result shows a significant and positive correlation between the MSA flux and the observed mean SIE in the Indian Ocean sector of the Southern Ocean from 1979 to 2016C.E. In addition, our study shows that the MSA is mainly influenced by Southern Hemisphere westerly winds (zonal winds) and katabatic winds (flowing from inland to the coast). Enhanced winds in both systems promote sea ice production in the Southern Ocean. These wind systems significantly influence the MSA cycle, stronger westerlies and katabatic winds increase MSA production, whereas meridional winds facilitate the transport and subsequent deposition of MSA at Dome A. Our findings suggest that MSA recorded in snow from Dome A could serve as a reliable proxy or reconstruction for mean SIE. Consequently, MSA in deep ice cores from Dome A offers a valuable archive for investigating past sea ice conditions in the Indian Ocean sector of the Southern Ocean, biogenic sulfur, and their climatic impacts.

Vegetation greening on the Tibetan Plateau (TP) has profoundly changed the connection between terrestrial ecosystems and regional carbon, water, and energy cycling, but existing research on vegetation greenness can only be traced back to the 1980s, because of the scarcity of long-term remote sensing data. Here we present an ice-core record of pollen accumulation rates with a 3-year resolution during 1935–2012 AD for the western TP. Based on backward trajectory and wind data, we identified the pollen source region and transport mechanisms. We found that the 3-year total pollen accumulation rate (TPAR3a) is a good indicator of vegetation coverage of the source region, and our data showed that the greening of the western TP and surroundings began as early as 1935 AD, mostly due to regional warming and moistening. The greening trend became more significant after the 1970s, which is mostly related to the significant increase in temperature. Vegetation greening in the western Tibetan Plateau and its surroundings began in the early 20th century and became significant after the 1970s, according to an ice-core record of pollen accumulation rates with a 3-year resolution.

Glaciers, especially the small/local ones, are rapidly melting and disappearing due to their heightened sensitivity to climate change. A holistic understanding of the key criteria and fundamental challenges in developing materials for local glacier conservation is urgently needed, coupled with a call for interdisciplinary collaboration to effectively address the pressing issue of local glacier retreat.

The Guliya (Tibet) ice core drilled in 1992 (GP1992) has garnered special interest because of its exceptionally long timescale of ~760 thousand years. This timescale makes GP1992 currently the second oldest ice core in the world, much older than any other extrapolar ice cores. Here, we revisit the GP1992 timescale by dating a Guliya ice core (GP2021) that was drilled close to the GP1992 drilling site in 2021. All our data, including the absolute dates deduced from 210Pb, 39Ar, and 14C, confirmed an age of <3 thousand years at 175.1 meters depth of GP2021, compared with ~100 thousand years previously estimated at the stratigraphically equivalent depth in GP1992. Our results resolved several discrepancies between the GP1992 and other paleoclimate records in the region, leading to different insights in climate history of the Tibetan Plateau.

It is important to understand the mechanisms of heavy rainfall events, as such information could improve forecasting of these events and help mitigate their adverse impacts on life and property. In this study, we analyzed hourly stable isotopic compositions in water vapor (delta 18Ov and d-excessv) during heavy rainfall events in the summer monsoon season (June to September) from 2013 to 2023 in Nanjing, eastern China. These data were extracted from the longest data set of high-resolution and continuous in situ observations of water vapor isotopes globally. Based on these data, we identified four evolution patterns of delta 18Ov during heavy rainfall events, corresponding to different weather systems: slow-declining (tropical cyclone interacting with mid- and high-latitude system), W-shaped (tropical cyclone), U-shaped (cold vortex system), and inclined L-shaped (upper-level trough system). The isotopic variations suggest that heavy rainfall events in eastern China were mainly sustained by moisture from adjacent oceans (including the South China Sea and the East China Sea) and terrestrial environment rather than from the distant Indian Ocean as previously suggested. In addition, for some heavy rainfall events with an intermittent period, the nearby oceanic moisture transport alters before and after the intermittent period due to an intensity change or overall transition of low-level weather systems. This study serves as a benchmark for tracing heavy rainfall processes in East Asia using high-resolution water vapor isotopes.

Investigating the relationship between tree growth within a year and environmental factors is crucial for understanding how climate change affects seasonal tree growth patterns. In this study, high‐resolution point dendrometers were used to monitor the stem radial changes of Oak trees (Quercus acutissma) over two years (2020 and 2021) in the eastern subtropical monsoon region of China. We find that the main growth period of Oak trees spans from March to September, and air temperature significantly affects the growth onset of Oak trees but with no clear impact on their growth cessation. The observations show that precipitation substantially affects daily stem radial increment (SRI), but the frequency of precipitation days plays a more crucial role in enhancing seasonal growth than the total precipitation amount. In the growing season, the stem radius of the Oak trees shows obvious diurnal cycles with shrinkage during the day and expansion at night, reflecting a delicate balance between canopy water loss and soil water absorption. The diurnal variations of the stem radius during the cold period (January and December) show an opposite pattern to that of the growing season, due to the sap's freezing under the condition of low air temperature at night as well as no or weak transpiration in the daytime. Because the temporal dynamics and intensity of tree activities significantly affect the timing and mechanisms of carbon assimilation in terrestrial ecosystems, our results are helpful to evaluate the carbon sequestration capacity of subtropical forests under the global climate change.

The isotope-enabled general circulation models (GCM) have been widely applied to simulate the variability of stable isotopes in meteoric water at various time scales. The in-situ observations of water vapour isotopes are an important basis for assessing the performance of isotope-enabled GCMs, although they are still limited. Here we compiled the observations of near-surface water vapour isotopes on a daily scale at 17 stations in East Asia, and assessed the skill and the association between isotope error and meteorological errors on a daily scale. Generally, the spatial pattern and seasonal variability can be well simulated in the isotope-enabled GCMs. The models show better skill for warm and humid backgrounds, which also corresponds to the monsoonal regions with lower latitudes in East Asia. As spatial resolution is finer, the skill of models is better, which can be seen from the two GCMs. According to the correlation coefficient, the improvement of resolution is more obvious in summer than in winter, especially for IsoGSM. In addition, the correlation coefficient in winter is usually larger than that in summer. The daily modelling has good potential to investigate the daily or synoptic climate information in water isotopes. The findings are useful for understanding the applicability of isotope-enabled models in East Asia and the climate factors influencing the skill of isotope-enabled models on a daily basis.

In global hydrological circulation, evaporation widely occurs from the land, the oceans, and other water surfaces. Compared to the evaporation from open water, the below-cloud evaporation of falling raindrops is more difficult to quantify. As an alternative to the traditional microphysical model, the difference in stable water isotopes between water vapour and precipitation provides a new perspective to estimate the raindrop mass loss. According to the recent observations of stable isotopes in near-surface water vapour and precipitation in five sampling stations from humid to arid climates in East Asia, we quantified the below-cloud evaporation of raindrops using both a microphysical model and an isotope inversion model. The results indicate that the isotope inversion model, relative to the microphysical model, usually underestimates the impact of below-cloud evaporation on precipitation, especially in arid inland. The sensitivity test of the two models to errors in climatic factors shows that the microphysical model was more sensitive to errors in temperature and relative humidity than the isotope inversion model. We also plot the ranges that the isotope inversion model has solutions under various meteorological and isotope inputs. The findings are useful for understanding the atmospheric processes below the cloud base and the comparability of different methods in quantifying below-cloud evaporation.

Understanding the impact of meltwater discharge during the final stage of the Laurentide Ice Sheet (LIS) has important implications for predicting sea level rise and climate change. Here we present a highresolution ice-core isotopic record from the central Tibetan Plateau (TP), where the climate is sensitive to the meltwater forcing, and explore possible signals of the climate response to potential LIS meltwater discharges in the early to mid-Holocene. The record shows four abrupt large fluctuations during the 7-9 ka BP (kiloannum before present), reflecting large shifts of the mid-latitude westerlies and the Indian summer monsoon (ISM) over this period, and they corresponded to possible LIS freshwater events documented in other paleoclimate records. Our study suggests that multiple rapid meltwater discharge events might have occurred during the final stage of LIS. The finding implies the possibility of rapid sea level rise and unstable climate in the transition zone between the mid-latitude westerlies and the ISM due to fast polar ice retreat under the anthropogenic global warming. (c) 2023 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Fluoride contamination poses great threat to ecosystems and human health, and has caused widespread concern. Large gaps in knowledge still exist regarding the distribution, sources of fluoride and the influence of atmospheric transport on its dispersal, particularly at high altitudes because of a lack of data due to geographic constraints. Tibetan ice cores are a natural archive for chemical depositions from the atmosphere, and can be used to reconstruct past variations of atmospheric fluoride in remote environment. In this study, we investigate the trends, sources and controlling factor of atmospheric fluoride during 1951–2008 AD using high-resolution chemical deposition records derived from the Zangser Kangri (ZK) ice core, central Tibetan Plateau (TP). Our data shows that the concentration peaks of F− coincide with those of typical crustal species (e.g., Ca2+, Mg2+), indicating that variation of F− in the ZK ice core is largely driven by dust activities, and dust emission from soil is the primarily natural source of F−. F− sources and transport pathways were further investigated by using the empirical orthogonal function (EOF) analysis, excess (Ex) concentration, in combination with airmass backward trajectory analysis. Ex F− in the ZK ice core record could be attributed to anthropogenic emissions, and its significant increase since 1990 was likely related to increased industrial and agricultural activities in the northwestern Indian peninsula. In addition, the strength of the South Asian monsoon is also a key factor in the transport of anthropogenic fluoride to the ZK glacier. This study provides valuable data for understanding the past atmospheric fluoride budget in the central TP.

Previous studies found depletion of precipitation 18O (18Op) during the late or post Asian monsoon season when precipitation amount is much lower. This is inconsistent with the amount effect of precipitation isotopes commonly found in tropical regions. It is still unclear whether this late/post season abnormal 18Op depletion also occurs in other monsoon regions, and what are the possible underlying mechanisms. In this paper, we examined seasonal variations of observed and modeled isotopic composition in precipitation (& ocirc;18Op) across the global monsoon regions, and their relationship with atmospheric circulations. We found that this abnormal 18Op depletion occurs in all monsoon regions globally, and it is largely caused by strong rainout along the global trade wind moisture transport pathway. The finding suggests that tropical cyclones are not the only mechanism to deplete 18Op during the late or post monsoon seasons, as suggested by previous studies. We should interpret such low & ocirc;18O values in the high-resolution paleoclimate records with more caution.

KAGRA is a newly built gravitational wave observatory, a laser interferometer with a 3 km arm length, located in Kamioka, Gifu prefecture, Japan. In this article, we describe the KAGRA data management system, i.e., recording of data, transfer from the KAGRA experiment site to computing resources, as well as data distribution to tier sites, including international sites in Taiwan and Korea. The amount of KAGRA data exceeded 1.0 PiB and increased by about 1.5 TB per day during operation in 2020. Our system has succeeded in data management, and has achieved performance that can withstand observations after 2023, that is, a transfer rate of 20 MB s-1 or more and file storage of sufficient capacity for petabyte class. We also discuss the sharing of data between the global gravitational-wave detector network with other experiments, namely LIGO and Virgo. The latency, which consists of calculation of calibrated strain data and transfer time within the global network, is very important from the view of multi-messenger astronomy using gravitational waves. Real-time calbrated data delivered from the KAGRA detector site and other detectors to our computing system arrive with about 4-15 seconds of latency. These latencies are sufficiently short compared to the time taken for gravitational wave event search computations. We also established a high-latency exchange of offline calibrated data that was aggregated with a better accuracy compared with real-time data.

Short-duration heavy rainfall causes severe urban flooding, threatening urban security and socio-economic development. The lower reaches of the Yangtze River are one of the regions with the highest frequency of short-duration heavy rainfalls in China. In this study, hourly stable isotope compositions in water vapor (818Ov and d-excessv) are analyzed for nine short-duration heavy rainfall events during the summer monsoon season (June to September) from 2013 to 2021 in Nanjing, eastern China. The circulation patterns that lead to these events can be divided into four types: tropical cyclone, low-pressure vortex, cold front, and western North Pacific subtropical high. During these events, 818Ov is enriched, ranging from -18.8 %o to -13.7 %o with a pre-storm increasing trend. This is largely caused by strongly isolated meso- and small-scale convections and the close proximity of oceanic moisture sources. The d-excessv shows three different variation patterns during rainfall events: increasing, decreasing, and irregular fluctuations. They each correspond to the increasing contribution of terrestrial moisture from eastern China, proximal oceanic moisture from China's offshore waters (including the South China Sea, East China Sea, and Yellow Sea), and the mixing influence of these two moisture sources. Multiple patterns of the d-excessv variations reflect both importance of terrestrial moisture from eastern China and oceanic moisture from China's offshore waters for summer short-duration heavy rainfall events in eastern China.