Stratospheric influence on surface ozone pollution in China.

Events of stratospheric intrusions to the surface (SITS) can lead to severe ozone (O3) pollution. Still, to what extent SITS events impact surface O3 on a national scale over years remains a long-lasting question, mainly due to difficulty of resolving three key SITS metrics: frequency, duration and intensity. Here, we identify 27,616 SITS events over China during 2015-2022 based on spatiotemporally dense surface measurements of O3 and carbon monoxide, two effective indicators of SITS. An overview of the three metrics is presented, illustrating large influences of SITS on surface O3 in China. We find that SITS events occur preferentially in high-elevation regions, while those in plain regions are more intense. SITS enhances surface O3 by 20 ppbv on average, contributing to 30-45% of O3 during SITS periods. Nationally, SITS-induced O3 peaks in spring and autumn, while over 70% of SITS events during the warm months exacerbate O3 pollution. Over 2015-2022, SITS-induced O3 shows a declining trend. Our observation-based results can have implications for O3 mitigation policies in short and long terms.

Extending venous thromboembolism secondary prevention with apixaban in cancer patients. The EVE trial.

BACKGROUND: Cancer-associated venous thromboembolism (VTE) management guideline recommendations include continued therapeutic anticoagulation while active cancer persists. The Federal Drug Administration label for apixaban for secondary VTE prevention includes a dose reduction to 2.5 mg twice daily after 6 months of treatment. OBJECTIVES: The study's purpose was to determine whether this dose reduction is advisable for cancer-associated VTE. METHODS: A randomized, double-blind trial compared apixaban 2.5 mg with 5 mg twice daily for 12 months among cancer patients with VTE who had completed 6 to 12 months of anticoagulation therapy. The primary outcome was combined major bleeding plus clinically relevant nonmajor bleeding. RESULTS: Of 370 patients recruited, 360 were included in the intention-to-treat analyses. Major plus clinically relevant nonmajor bleeding occurred in 16 of 179 patients (8.9%) in the apixaban 2.5 mg group compared with 22 of 181 patients (12.2%) in the 5 mg group (hazard ratio [HR], 0.72; 95% CI, 0.38-1.37; P = .39). Major bleeding occurred in 2.8% of the apixaban 2.5 mg group and in 2.2% of the 5 mg group (HR, 1.26; 95% CI, 0.34-4.66; P = .73). Recurrent VTE or arterial thrombosis occurred in 9 of 179 patients (5.0%) in the apixaban 2.5 mg group and 9 of 181 patients (5.0%) in the 5 mg group (HR, 1.0; 95% CI, 0.40-2.53; P = 1.00). All-cause mortality rates were similar between groups, 13% vs 12% (HR, 1.14; 95% CI, 0.63-2.04; P = .67). CONCLUSION: For secondary prevention of cancer-associated VTE, apixaban 2.5 mg compared with 5 mg twice daily did not lower combined bleeding events (EVE trial NCT03080883).

Comparative assessment of leaf photosynthetic capacity datasets for estimating terrestrial gross primary productivity.

The maximum Rubisco carboxylation rate normalized to 25 °C (Vcmax25) is a key parameter in terrestrial biosphere models for simulating carbon cycling. Recently, global distributions of Vcmax25 have been derived through various methods and different data, including field measurements, ecological optimality theory (EOT), leaf chlorophyll content (LCC), and solar-induced chlorophyll fluorescence (SIF). However, direct validation poses challenges due to high uncertainty arising from limited ground-based observations. This study conducted an indirect evaluation of four Vcmax25 datasets by assessing the accuracy of gross primary productivity (GPP) simulated using the Biosphere-atmosphere Exchange Process Simulator (BEPS) at both site and global scales. Results indicate that, compared to utilizing Vcmax25 fixed by plant functional types (PFT) derived from field measurements, incorporating Vcmax25 derived from SIF and LCC (SIF + LCC), or solely LCC, into BEPS significantly reduces simulated errors in the annual total GPP, with a 23.2 %-25.1 % decrease in the average absolute bias across 196 FLUXNET2015 sites. Daily GPP for evergreen needleleaf forests, deciduous broadleaf forests, shrublands, grasslands, and croplands shows a 7.8 %-27.6 % decrease in absolute bias, primarily attributed to reduced simulation errors during off-peak seasons of vegetation growth. Conversely, the annual total GPP error simulated using EOT-derived Vcmax25 increases slightly (2.2 %) compared to that simulated using PFT-fixed Vcmax25. This is primarily due to a significant overestimation in evergreen broadleaf forests and underestimation in croplands, despite slight increased accuracy for other PFTs. The global annual GPP simulated using Vcmax25 with seasonal variations (i.e., LCC Vcmax25 and SIF + LCC Vcmax25) yields a 4.3 %-7.3 % decrease compared to that simulated using PFT-fixed Vcmax25. Compared to FLUXCOM and GOSIF GPP products, the GPP simulated based on SIF + LCC Vcmax25 and LCC Vcmax25 demonstrates better consistency (R2 = 0.91-0.93, RMSE = 314.2-376.6 g C m-2 yr-1). This study underscores the importance of accurately characterizing the spatiotemporal variations in Vcmax25 for the accurate simulation of global vegetation productivity.

Characteristics of Health Care Settings Where Adolescents and Young Adults Receive Care for ALL.

PURPOSE: Individuals diagnosed with cancer between 15 and 39 years (adolescent and young adult [AYA]) face unique vulnerability. Detail is lacking about care delivery for these patients, especially those with ALL. We address these knowledge gaps by describing AYA ALL care delivery details at National Cancer Institute Community Oncology Research Program (NCORP) (sub)affiliates by model of care. METHODS: Participating institutions treated at least one AYA with ALL from 2012 to 2016. Study-specific criteria were used to determine the number of unique clinical facilities (CFs) per NCORP and their model of care (adult/internal medicine [IM], pediatric, mixed [both]). Surveys completed by NCORPs for each CF by model of care captured size, resources, services, and communication. RESULTS: Among 84 participating CFs (adult/IM, n=47; pediatric, n=15; mixed, n=24), 34% treated 5-10 AYAs with ALL annually; adult/IM CFs more often treated <5 (adult/IM, 60%; pediatric, 40%; mixed, 29%). Referral decisions were commonly driven by an age/diagnosis combination (58%), with frequent ALL-specific age minimums (87%) or maximums (80%). Medical, navigational, and social work services were similar across models while psychology was available at more pediatric CFs (pediatric, 80%; adult/IM, 40%; mixed, 46%-54%). More pediatric or mixed CFs reported oncologists interacting with pediatric/adult counterparts via tumor boards (pediatric, 93%; adult/IM, 26%; mixed, 96%) or initiating contact (pediatric, 100%; adult/IM, 77%; mixed 96%); more pediatric CFs reported an affiliated counterpart (pediatric, 53%; adult, 19%). Most CFs reported no AYA-specific resources (79%) or meetings (83%-98%). CONCLUSION: System-level aspects of AYA ALL care delivery have not been examined previously. At NCORPs, these characteristics differ by models of care. Additional work is ongoing to investigate the impact of these facility-level factors on guideline-concordant care in this population. Together, these findings can inform a system-level intervention for diverse practice settings.

Elucidating drivers of severe wintertime fine particulate matter pollution episodes in the Yangtze River Delta region of eastern China.

Understanding the causes and sources responsible for severe fine particulate matter (PM2.5) pollution episodes that occur under conducive synoptic weather patterns (SWPs) is essential for regional air quality management. The Yangtze River Delta (YRD) region in eastern China has experienced recurrent severe PM2.5 episodes during the winters from 2013 to 2017. In this study, we employed an objective classification approach, the self-organizing map, to investigate the underlying impact of predominant SWPs on PM2.5 pollution in the YRD. We further conducted a series of source apportionment simulations using the Particulate Source Apportionment Technology (PSAT) tool integrated within the Comprehensive Air Quality Model with Extensions (CAMx) to quantify the source contributions to PM2.5 pollution under different SWPs. Here we identified six predominant SWPs over the YRD that are robustly connected to the evolution of the Siberian High. Considering the regional average PM2.5 anomalies, our results show that polluted SWPs favourable for the occurrence of regional PM2.5 pollution account for 61-78 %. The most conducive SWP, associated with the highest regional exceedance (46 %) of PM2.5 levels, is characterized by noticeable cyclonic anomalies at 850 hPa and stagnant surface weather conditions. Our source apportionment analysis emphasizes the pivotal role of local emissions and intra-regional transport within the YRD in shaping PM2.5 pollution in representative cities. Local emissions have the most significant impact on PM2.5 levels in Shanghai (32-48 %), while PM2.5 pollution in Nanjing, Hangzhou, and Hefei is more influenced by intra-regional transport (33-61 %). Industrial and residential emissions are the dominant sources, contributing 32-41 % and 24-38 % to PM2.5, respectively. Under specific SWPs associated with a stronger influence of inter-regional transport from northern China, there is a synchronously remarkable enhancement in the contribution of residential emissions. Our study pinpoints the opportunities for future air quality planning that would benefit from quantitative source attribution linked to prevailing SWPs.

A qualitative study to understand sociocultural beliefs around perinatal and neonatal health in rural areas of Mohali, Punjab, India.

Introduction: Globally, 600,000 mothers (15-49 years) die every year due to pregnancy and childbirth-related complications. Wide variations are seen in cultural practices and beliefs surrounding this period of a woman's life. The present study explores the cultural beliefs and practices of women and families during pregnancy and the postnatal period in order to understand what behavioral management strategies are required to improve maternal and infant outcomes during pregnancy and the postpartum period. Methods: The study was conducted in a rural area of Punjab, from December 2019 to March 2021. A total of 20 women (up to 3 months postpartum, age >18 years, were interviewed. Results: In general, women described eating varied and fairly healthy diets during pregnancy, especially nutritious warm food, following traditional practices. Other cultural practices included restrictions on movement and mobile phone use and the use of unsafe home remedies to promote infant safety and wellbeing, such as using gripe water, applying black pencil to the baby's eyes, and feeding the baby honey. A few were not inclined to engage with these and other cultural expectations, preferring instead to follow contemporary practices influenced by social media. These practices included being accompanied by a family member during delivery, celebrating the baby's birth regardless of sex, and early bathing post-delivery. Discussion: It can be concluded that while many traditional practices are still followed in India, there are new beliefs and behaviors arising from an intersection between culture and technology. Developing strategies that acknowledge older beliefs and modern approaches is essential to promoting better antenatal and postpartum care.

Modifiable fall risk factors among older adults with advanced cancer: Secondary analysis of a cluster-randomized clinical trial.

INTRODUCTION: Older adults with cancer have unique fall risk factors related to their disease and treatment such as polypharmacy and neurotoxic treatments. In this secondary analysis, we identified modifiable risk factors associated with future falls among older adults with advanced cancers. MATERIALS AND METHODS: Data were from the COACH study (ClinicalTrials.gov: NCT02107443; PI: Mohile). Patients were age ≥ 70, had stage III/IV solid tumor or lymphoma, ≥1 geriatric assessment impairment, and were receiving palliative intent treatment. Falls were self-reported at baseline (in the past six months), four to six weeks, three months, and six months. We generated inverse probability weights to account for mortality-related loss to follow-up and applied these in generalized linear mixed models to estimate incidence rate ratios. RESULTS: Of 541 patients (mean age: 77, standard deviation [SD]: 5.27), 140 (26%) reported prior falls at baseline, and 467 (86%) had falls data for ≥1 follow-up timepoint. Of those, 103 (22%) reported at least one fall during the follow-up period, and 112 (24%) had incomplete follow-up due to death. In fully adjusted models, prior falls and impaired Timed Up and Go score were associated with higher incidence of falls over 6 months. DISCUSSION: We identified several potentially modifiable fall risk factors in older adults with advanced cancers. Future studies should consider ways to integrate fall risk assessment into ongoing cancer care and intervene to reduce falls in this population.

Discordant pathologic diagnoses of myelodysplastic neoplasms and their implications for registries and therapies.

Myelodysplastic neoplasms (MDS) are a collection of hematopoietic disorders with widely variable prognoses and treatment options. Accurate pathologic diagnoses present challenges because of interobserver variability in interpreting morphology and quantifying dysplasia. We compared local clinical site diagnoses with central, adjudicated review from 918 participants enrolled in the ongoing National Heart, Lung, and Blood Institute National MDS Natural History Study, a prospective observational cohort study of participants with suspected MDS or MDS/myeloproliferative neoplasms (MPNs). Locally, 264 (29%) were diagnosed as having MDS, 15 (2%) MDS/MPN overlap, 62 (7%) idiopathic cytopenia of undetermined significance (ICUS), 0 (0%) acute myeloid leukemia (AML) with <30% blasts, and 577 (63%) as other. Approximately one-third of cases were reclassified after central review, with 266 (29%) diagnosed as MDS, 45 (5%) MDS/MPN overlap, 49 (5%) ICUS, 15 (2%) AML with <30%, and 543 (59%) as other. Site miscoding errors accounted for more than half (53%) of the local misdiagnoses, leaving a true misdiagnosis rate of 15% overall, 21% for MDS. Therapies were reported in 37% of patients, including 43% of patients with MDS, 49% of patients with MDS/MPN, and 86% of patients with AML with <30% blasts. Treatment rates were lower (25%) in cases with true discordance in diagnosis compared with those for whom local and central diagnoses agreed (40%), and receipt of inappropriate therapy occurred in 7% of misdiagnosed cases. Discordant diagnoses were frequent, which has implications for the accuracy of study-related and national registries and can lead to inappropriate therapy. This trial was registered at www.clinicaltrials.gov as #NCT05074550.

Exposure to Ionizing Radiation and Risk of Dementia: A Systematic Review and Meta-Analysis.

The number of people living with dementia is rising globally as life expectancy increases. Dementia is a multifactorial disease. Due to the ubiquity of radiation exposure in medical and occupational settings, the potential association between radiation and dementia, and its subtypes (Alzheimer's and Parkinson's disease), is of particular importance. There has also been an increased interest in studying radiation induced dementia risks in connection with the long-term manned space travel proposed by The National Aeronautics and Space Administration (NASA). Our aim was to systematically review the literature on this topic, and use meta-analysis to generate a summary measure of association, assess publication bias and explore sources of heterogeneity across studies. We identified five types of exposed populations for this review: 1. survivors of atomic bombings in Japan; 2. patients treated with radiation therapy for cancer or other diseases; 3. occupationally exposed workers; 4. those exposed to environmental radiation; and 5. patients exposed to radiation from diagnostic radiation imaging procedures. We included studies that considered incident or mortality outcomes for dementia and its subtypes. Following PRISMA guidelines, we systematically searched the published literature indexed in PubMed between 2001 and 2022. We then abstracted the relevant articles, conducted a risk-of-bias assessment, and fit random effects models using the published risk estimates. After we applied our eligibility criteria, 18 studies were identified for review and retained for meta-analysis. For dementia (all subtypes), the summary relative risk was 1.11 (95% CI: 1.04, 1.18; P = 0.001) comparing individuals receiving 100 mSv of radiation to those with no exposure. The corresponding summary relative risk for Parkinson's disease incidence and mortality was 1.12 (95% CI 1.07, 1.17; P <0.001). Our results provide evidence that exposure to ionizing radiation increases the risk of dementia. However, our findings should be interpreted with caution due to the small number of included studies. Longitudinal studies with improved exposure characterization, incident outcomes, larger sample size, and the ability to adjust for effects of potential confounders are needed to better assess the possible causal link between ionizing radiation and dementia.

Health-related quality of life and vulnerability among people with myelodysplastic syndromes: a US national study.

Health-related quality of life (HRQoL) and vulnerability are variably affected in patients with myelodysplastic syndromes (MDS) and other cytopenic states; however, the heterogeneity of these diseases has limited our understanding of these domains. The National Heart, Lung, and Blood Institute-sponsored MDS Natural History Study is a prospective cohort enrolling patients undergoing workup for suspected MDS in the setting of cytopenias. Untreated patients undergo bone marrow assessment with central histopathology review for assignment as MDS, MDS/myeloproliferative neoplasm (MPN), idiopathic cytopenia of undetermined significance (ICUS), acute myeloid leukemia (AML) with <30% blasts, or "At-Risk." HRQoL data are collected at enrollment, including the MDS-specific Quality of Life in Myelodysplasia Scale (QUALMS). Vulnerability is assessed with the Vulnerable Elders Survey. Baseline HRQoL scores from 449 patients with MDS, MDS/MPN, AML <30%, ICUS or At-Risk were similar among diagnoses. In MDS, HRQoL was worse for vulnerable participants (eg, mean Patent-Reported Outcomes Management Information Systems [PROMIS] Fatigue of 56.0 vs 49.5; P < .001) and those with worse prognosis (eg, mean Euroqol-5 Dimension-5 Level [EQ-5D-5L] of 73.4, 72.7, and 64.1 for low, intermediate, and high-risk disease; P = .005). Among vulnerable MDS participants, most had difficulty with prolonged physical activity (88%), such as walking a quarter mile (74%). These data suggest that cytopenias leading to MDS evaluation are associated with similar HRQoL, regardless of eventual diagnosis, but with worse HRQoL among the vulnerable. Among those with MDS, lower-risk disease was associated with better HRQoL, but the relationship was lost among the vulnerable, showing for the first time that vulnerability trumps disease risk in affecting HRQoL. This study is registered at www.clinicaltrials.gov as NCT02775383.

Meteorological impacts on interannual anomalies of O3 import over Twain-Hu Basin.

Prominent O3 pollution over Twain-Hu Basin (THB) is observed during 2014-2020, with the annual concentrations of near-surface O3 in the range of 49-65 µg·m-3, larger than those in Sichuan Basin (SCB) and Pearl River Delta (PRD) in China. The increasing rate of O3 over THB (1.9 µg·m-3·yr-1) is also higher than the counterparts in Yangtze River Delta (YRD), SCB and PRD. Besides, the exceeding rate of O3 levels in THB rises from 3.9 % in 2014 to 11.5 % in 2019, greater than those in SCB and PRD as well. Based on the GEOS-Chem simulations in summer over 2013-2020, we find that nonlocal O3 contributes dominantly to THB, with YRD being its principle source region, during regional O3 transport over the central and eastern China. Here, the imported O3 in THB is found to be mainly driven by the wind fields and the windward topography. The East Asia Summer Monsoon (EASM) circulations significantly regulate the interannual anomalies of imported O3 over THB. In the years with abnormally higher O3 import over THB, the EASM weakens, and the location of Western Pacific Subtropical High tends to more eastward compared with the years with abnormally lower O3 import. Particularly, an abnormal easterly winds at the surface of YRD region effectively favor the delivery of O3 from YRD to THB. In addition, the weak EASM promotes and undermines the regional transport of O3 from NCP and PRD to THB, respectively. Correspondingly, the O3 concentrations over THB can be fluctuated greatly depending on the degree of regional O3 transport regulated by the EASM circulations, which indicates a complex relationship between sources and receptors of O3 transport for air quality improvement.

Distinct seasonality in vertical variations of tropospheric ozone over coastal regions of southern China.

The surface ozone pollution is strongly coupled with ozone variations above the ground. Using sufficient airborne ozone profiles during 2012-2018, this study reveals the tropospheric ozone distributions over four cities located in coastal regions of southern China. The 7-year mean tropospheric ozone profiles in the four cities consistently show a double-maxima profile, with a local maximum at 1 km altitude and the other in the middle-to-upper troposphere. Seasonally, springtime ozone is larger than the annual mean throughout the troposphere, while ozone in summer is high in the middle-to-upper troposphere, leading to largest vertical variations among seasons. Ozone in the middle-to-upper troposphere is lower in autumn than in spring and summer. The winter ozone is characterized with a minimum in the lower troposphere, and low values in the middle-to-upper troposphere, leading to least vertical variations among seasons. We untangle the causes for these complicated vertical ozone variations using the GEOS-Chem model. The tropospheric ozone over southern China is partitioned into locally produced ozone, regionally transported native ozone, imported ozone from outside of China (foreign ozone) and natural stratospheric ozone. The results suggest that the springtime ozone abundance is due to the enhanced import of foreign and stratospheric ozone and the intensified regional transport processes of native ozone. In summer, local ozone production is enhanced and regional transport of ozone in the middle-to-upper troposphere is strengthened due to upward air motions, while such transport becomes weaker in autumn leaving low ozone in the middle-to-upper troposphere. In winter, the intensive westerly jets promote foreign and stratospheric ozone again in the middle-to-upper troposphere, but the local ozone production and regional transport are sharply reduced, resulting in low ozone near the surface. This study provides new insights into regional ozone profiles and reveals the significance of vertical ozone variations on surface ozone prevention strategy.

Microbial diversity and antimicrobial resistance in faecal samples from acute medical patients assessed through metagenomic sequencing.

Antimicrobial resistance (AMR) is a threat to global public health. However, unsatisfactory approaches to directly measuring the AMR burden carried by individuals has hampered efforts to assess interventions aimed at reducing selection for AMR. Metagenomics can provide accurate detection and quantification of AMR genes within an individual person's faecal flora (their gut "resistome"). Using this approach, we aimed to test the hypothesis that differences in antimicrobial use across different hospitals in the United Kingdom will result in observable differences in the resistome of individual patients. Three National Health Service acute Hospital Trusts with markedly different antibiotic use and Clostridioides difficile infection rates collected faecal samples from anonymous patients which were discarded after C. difficile testing over a period of 9 to 15 months. Metagenomic DNA was extracted from these samples and sequenced using an Illumina NovaSeq 6000 platform. The resulting sequencing reads were analysed for taxonomic composition and for the presence of AMR genes. Among 683 faecal metagenomes we found huge variation between individuals in terms of taxonomic diversity (Shannon Index range 0.10-3.99) and carriage of AMR genes (Median 1.50 genes/cell/sample overall). We found no statistically significant differences in diversity (median Shannon index 2.16 (IQR 1.71-2.56), 2.15 (IQR 1.62-2.50) and 2.26 (IQR 1.55-2.51)) or carriage of AMR genes (median 1.37 genes/cell/sample (IQR 0.70-3.24), 1.70 (IQR 0.70-4.52) and 1.43 (IQR 0.55-3.71)) at the three trusts respectively. This was also the case across the sample collection period within the trusts. While we have not demonstrated differences over place or time using metagenomic sequencing of faecal discards, other sampling frameworks may be more suitable to determine whether organisational level differences in antibiotic use are associated with individual-level differences in burden of AMR carriage.

Utility of targeted gene sequencing to differentiate myeloid malignancies from other cytopenic conditions.

The National Heart, Lung, and Blood Institute-funded National MDS Natural History Study (NCT02775383) is a prospective cohort study enrolling patients with cytopenia with suspected myelodysplastic syndromes (MDS) to evaluate factors associated with disease. Here, we sequenced 53 genes in bone marrow samples harvested from 1298 patients diagnosed with myeloid malignancy, including MDS and non-MDS myeloid malignancy or alternative marrow conditions with cytopenia based on concordance between independent histopathologic reviews (local, centralized, and tertiary to adjudicate disagreements when needed). We developed a novel 2-stage diagnostic classifier based on mutational profiles in 18 of 53 sequenced genes that were sufficient to best predict a diagnosis of myeloid malignancy and among those with a predicted myeloid malignancy, predict whether they had MDS. The classifier achieved a positive predictive value (PPV) of 0.84 and negative predictive value (NPV) of 0.8 with an area under the receiver operating characteristic curve (AUROC) of 0.85 when classifying patients as having myeloid vs no myeloid malignancy based on variant allele frequencies (VAFs) in 17 genes and a PPV of 0.71 and NPV of 0.64 with an AUROC of 0.73 when classifying patients as having MDS vs non-MDS malignancy based on VAFs in 10 genes. We next assessed how this approach could complement histopathology to improve diagnostic accuracy. For 99 of 139 (71%) patients (PPV of 0.83 and NPV of 0.65) with local and centralized histopathologic disagreement in myeloid vs no myeloid malignancy, the classifier-predicted diagnosis agreed with the tertiary pathology review (considered the internal gold standard).

[Temporal and Spatial Variations in Black Carbon Aerosol in Different Atmospheric Background Stations in China from 2006 to 2020].

Black carbon (BC) aerosol emissions are complex and have important environmental and meteorological effects. In China, the temporal and spatial variations in BC in different atmospheric environmental conditions need to be fully understood. Based on the long-term observational BC data in seven atmospheric background stations in China from 2006 to 2020, combined with meteorological data, emission source data, enhanced vegetation index (EVI) data, and aerosol optical depth (AOD) data, we comprehensively analyzed the characteristics of temporal and spatial variations, long-term evolution, and influencing factors of BC in China. The results showed that the BC and AOD values of different atmospheric environments in China were quite different, and BC positively contributed to AOD. The spatial distribution was high in the east and low in the west owing to the differences in emission sources and meteorological conditions. The ρ(BC) and AOD values were higher to the east of the "Hu Huanyong" line, such as at the Mt. Longfeng, Shangdianzi, Lin'an, and Jinsha stations, where the average values were (1699±2213)-(3392±2131) ng·m-3 and 0.36±0.32-0.72±0.37, respectively. These values were lower to the west of the "Hu Huanyong" line, such as at the Akedala, Mt. Waliguan, and Shangri-La stations, where the average values were (287±226)-(398±308) ng·m-3 and 0.20±0.13-0.22±0.19, respectively. The interannual variability in BC included differences between different atmospheric background stations, which could be divided into four categories:low interannual variability, such as at the Akedala station; an initial increase followed by a decrease and subsequent stabilization, such as at the Mt. Waliguan station; an initial decrease followed by stabilization, such as at the Shangri-La station; and an initial stabilization followed by a decrease, such as at the Mt. Longfeng, Shangdianzi, Jinsha, and Lin'an stations. Seasonal variations in BC included differences in different atmospheric background stations. The BC mass concentrations were lowest in autumn and higher in winter and spring west of the "Hu Huanyong" line and were highest in winter and lowest in summer east of the "Hu Huanyong" line. BC contributed to the AOD being larger in all stations in the spring and summer and contributed less at the stations west of the "Hu Huanyong" line in autumn and the stations east of the "Hu Huanyong" line in winter. The diurnal variations in BC were mainly bimodally distributed in the different atmospheric background stations, but the peak times varied in different stations and seasons.

Exploring the ozone pollution over the western Sichuan Basin, Southwest China: The impact of diurnal change in mountain-plains solenoid.

The Sichuan Basin (SCB), to the east of the Tibetan Plateau (TP), experiences severe ozone (O3) pollution. Unfavorable atmospheric diffusion conditions are considered the main causes of heavy air pollution over the basin. However, the meteorological impact of thermally driven mountain-plains solenoid (MPS) between the TP and SCB on O3 pollution has not been reported. Here we show the MPS driving the diurnal O3 changes in the atmospheric boundary layer over the SCB based on surface and high-resolution vertical observations, ERA5 reanalysis data, and the WRF-Chem model. The MPS shifts between upslope and easterly flows along the eastern slope of the TP and SCB during the day and downslope westerly flows to the western SCB at night. The daytime MPS flows drive the westward transport of O3-rich air mass in the atmospheric boundary layer from the polluted SCB and accumulate high O3 levels from the western edge of the SCB to the eastern slope of TP, subsequently aggravating O3 pollution in this region. After sunset, the MPS drainage flows carry air containing elevated O3 eastward downslope along the eastern slope of the TP into the nocturnal residual layer, enhancing the O3 concentrations aloft over the western SCB. The high-level O3 in the residual layer is transported downstream by nocturnal prevailing winds and contributes significantly to the next-day surface O3 buildup in the downwind region through daytime vertical mixing (~30 µg m-3 h-1). The present study reveals a transport mechanism driven by the MPS with coupling diurnal changes in the atmospheric boundary layer, which redistributes O3 over the basin and exacerbates O3 pollution along the western edge of the basin. This study has important implications for understanding meteorological drivers on atmospheric environment underlying the complex terrain.

Teleconnections between large-scale oceanic-atmospheric patterns and interannual surface wind speed variability across China: Regional and seasonal patterns.

Great attention has been paid to the long-term decline in terrestrial near-surface wind speed (SWS) in China. However, how the SWS varies with regions and seasons and what modulates these changes remain unclear. Based on quality-controlled and homogenized terrestrial SWS data from 596 stations, the covarying SWS patterns during the Asian Summer Monsoon (ASM) and the Asian Winter Monsoon (AWM) seasons are defined for China using empirical orthogonal function (EOF) analysis for 1961-2016. The dominant SWS features represented by EOF1 patterns in both seasons show a clear decline over most regions of China. The interannual variability of the EOF1 patterns is closely related to the Northeast Asia Low Pressure (NEALP) and the Arctic Oscillation (AO), respectively. The EOF2 and EOF3 patterns during ASM (AWM) season describe a dipole mode of SWS between East Tibetan Plateau and East China Plain (between East Tibetan Plateau and Northeast China), and between Southeast and Northeast China (between Northeast China and the coastal areas of Southeast China), respectively. These dipole structures of SWS changes are closely linked with the oceanic-atmospheric oscillations on interannual scale.

Atmospheric transport drives regional interactions of ozone pollution in China.

In recent years, ozone pollution becomes a serious environmental issue in China. A good understanding of source-receptor relationships of ozone transport from aboard and inside China is beneficial to mitigating ozone pollution there. To date, these issues have not been comprehensively assessed, especially for highly polluted regions in the central and eastern China (CEC), including the North China Plain (NCP), Twain-Hu region (THR), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SCB). Here, based on simulations over 2013-2020 from a well-validated chemical transport model, GEOS-Chem, we show that foreign ozone accounts for a large portion of surface ozone over CEC, ranging from 25.0% in THR to 39.4% in NCP. Focusing on transport of domestic ozone between the five regions in CEC, we find that atmospheric transport can largely modulate regional interactions of ozone pollution in China. At the surface, THR receives the largest amount of ozone from the other four regions (54.2% of domestic ozone in the receptor region, the same in below), followed by PRD (32.3%), SCB (26.7%), YRD (21.1%), and NCP (18.0%). Meanwhile, YRD exports largest amount of ozone to the other regions, ranging from 8.9% in SCB to 28.4% in THR. Although SCB is relatively isolated and thus impacts NCP, YRD, and PRD weakly (< 2.2%), export of SCB ozone to THR reaches 9.3%. The regional ozone transport over CEC, occurring mostly in the lower troposphere, is mainly modulated by the East Asian monsoon circulations, proximity between source and receptor regions, seasonal changes of ozone production, and topography.