Beijing-Tianjin-Hebei Research Articles

A Study on the Impact of Green Finance on the High-Quality Economic Development of Beijing–Tianjin–Hebei Region

China’s economy has shifted to a new stage of high-quality development, which means that economic development is no longer simply pursuing the increase of quantity, but a balance of quality and quantity. High-quality economic development (HQED) has become essential for China to achieve sustainable economic and social advancement. This paper explores the influence of green finance on HQED, along with the mediating roles of green innovation and industrial structure upgrading. A fixed-effects model is employed to assess the relationship between green finance and HQED and conduct an empirical test in the Beijing–Tianjin–Hebei (BTH) region of China. The findings reveal that green finance significantly contributes to the HQED of the BTH region, and green innovation and industrial structure upgrading have intermediary effects in this process. Based on these insights, this paper proposes several strategies to improve HQED in China, including the development of a green financial system, the promotion of green innovation, and the acceleration of industrial structure optimization and upgrading in the BTH region.

Influence of updated isoprene oxidation mechanisms on the formation of intermediate and secondary products in MCM v3.3.1

In this study, we developed an observation based photochemical box model with the measurement data collected at a suburban site (i.e., the Xianghe, XH site) of the Beijing-Tianjin-Hebei (BTH) region and the latest version of the Master Chemical Mechanism (MCM v3.3.1), which newly incorporated 498 reaction for the additional 155 species with the oxidation of isoprene by the OH radical. The influence of updated isoprene degradation on the radical budgets, formation of intermediate and secondary products by comparing the simulation results in the original version (MCM v3.2) was firstly analyzed to estimate whether the updates of precursors could influence the model performance on its evolution pathways and related products. The results demonstrated that though the input of isoprene could significantly decrease or increase the concentrations of OH and HO2 radicals in the model simulation, respectively, the difference in the simulated concentrations of these radicals with isoprene oxidation before and after the updates was not statistically significant. For intermediate products, the simulated concentrations of formaldehyde and methacrolein (MACR) did not significantly alter before and after the updates, while the abundance of methyl vinyl ketone (MVK) reduced obviously (the maximum reduction of 31%) due to lower reaction coefficient between ISOPBO2 and NO and the lower branching ratios caused by the newly added pathways involving CISOPA and TISOPA in the updated scheme. On the other hand, the simulation concentrations of acrolein (ACR), glyoxal (Gly) and methylglyoxal (Mgly) increased significantly after the model updates. The dominant pathway for the increment of ACR was the decomposition of CH2CHCH2O produced by PE4E2CO, while those of Gly and Mgly were associated with radicals of C537O and PACLOOA that were both from the new intermediate radical of CISOPC. In addition, 39 isoprene oxidation products among the 155 new added species were identified to partition in the formation of secondary organic aerosol (SOA), which were coupled in the gas-particle partitioning module to optimize the formation of SOA, contributing 1.15 μg m−3 to the increase of SOA mean concentration. The updates of isoprene degradation further resulted in the significant change for its sensitivity in SOA formation, making it as the secondary important SOA precursor at the XH site. Last but not the least, the influence on photochemical ozone formation related to updates of isoprene degradation was ignorable. Overall, the above results confirmed the insufficient description of the degradation of precursors indeed limited the simulation of the intermediate and secondary products, highlighting the needs of exploring and parameterizing the precursor degradation processes for better understanding of their behaviors and SOA formation in the atmosphere.

Co-occurrence of ozone and PM2.5 pollution in urban/non-urban areas in eastern China from 2013 to 2020: Roles of meteorology and anthropogenic emissions

We applied a three-dimensional (3-D) global chemical transport model (GEOS-Chem) to evaluate the influences of meteorology and anthropogenic emissions on the co-occurrence of ozone (O3) and fine particulate matter (PM2.5) pollution day (O3-PM2.5PD) in urban and non-urban areas of the Beijing-Tianjin-Hebei (BTH) and Yangtze River Delta (YRD) regions during the warm season (April–October) from 2013 to 2020. The model captured the observed O3-PM2.5PD trends and spatial distributions well. From 2013 to 2020, with changes in both anthropogenic emissions and meteorology, the simulated values of O3-PM2.5PD in the urban (non-urban) areas of the BTH and YRD regions were 424.8 (330.1) and 309.3 (286.9) days, respectively, suggesting that pollution in non-urban areas also warrants attention. The trends in the simulated values of O3-PM2.5PD were −0.14 and −0.15 (+1.18 and +0.81) days yr−1 in the BTH (YRD) urban and non-urban areas, respectively. Sensitivity simulations revealed that changes in anthropogenic emissions decreased the occurrence of O3-PM2.5PD, with trends of −0.99 and −1.23 (−1.47 and −1.92) days yr−1 in the BTH (YRD) urban and non-urban areas, respectively. Conversely, meteorological conditions could exacerbate the frequency of O3-PM2.5PD, especially in the urban YRD areas, but less notably in the urban BTH areas, with trends of +2.11 and +0.30 days yr−1, respectively, owing to changes in meteorology only. The increases in T2m_max and T2m were the main meteorological factors affecting O3-PM2.5PD in most BTH and YRD areas. Furthermore, by conducting sensitivity experiments with different levels of pollutant precursor reductions in 2020, we found that volatile organic compound (VOC) reductions primarily benefited O3-PM2.5PD decreases in urban areas and that NOx reductions more notably influenced those in non-urban areas, especially in the YRD region. Simultaneously, reducing VOC and NOx emissions by 50 % resulted in considerable O3-PM2.5PD decreases (58.8–72.6 %) in the urban and non-urban areas of the BTH and YRD regions. The results of this study have important implications for the control of O3-PM2.5PD in the urban and non-urban areas of the BTH and YRD regions.

Temperature-Dependent Evaporative Anthropogenic VOC Emissions Significantly Exacerbate Regional Ozone Pollution.

The evaporative emissions of anthropogenic volatile organic compounds (AVOCs) are sensitive to ambient temperature. This sensitivity forms an air pollution-meteorology connection that has not been assessed on a regional scale. We parametrized the temperature dependence of evaporative AVOC fluxes in a regional air quality model and evaluated the impacts on surface ozone in the Beijing-Tianjin-Hebei (BTH) area of China during the summer of 2017. The temperature dependency of AVOC emissions drove an enhanced simulated ozone-temperature sensitivity of 1.0 to 1.8 μg m-3 K-1, comparable to the simulated ozone-temperature sensitivity driven by the temperature dependency of biogenic VOC emissions (1.7 to 2.4 μg m-3 K-1). Ozone enhancements driven by temperature-induced AVOC increases were localized to their point of emission and were relatively more important in urban areas than in rural regions. The inclusion of the temperature-dependent AVOC emissions in our model improved the simulated ozone-temperature sensitivities on days of ozone exceedance. Our results demonstrated the importance of temperature-dependent AVOC emissions on surface ozone pollution and its heretofore unrepresented role in air pollution-meteorology interactions.

Ecological Vulnerability Assessment and Spatiotemporal Characteristics Analysis of Urban Green-Space Systems in Beijing–Tianjin–Hebei Region

The evaluation and analysis of the ecological vulnerability of urban green-space systems are conducive to the sustainable development of urban green-space systems. Taking the urban green-space system in the Beijing–Tianjin–Hebei region in 2010, 2015, and 2020 as the research object, an ESSR model was first constructed, and a total of ten types of impact factors were integrated into the four dimensions of “Exposure, Sensitivity, State and Response”. The weight of the impact factors was objectively determined via spatial principal component analysis, and the ecological vulnerability of the urban green-space system was evaluated via superposition analysis; the evaluation’s results were graded. Moreover, the transfer matrix, center-of-gravity migration model, standard deviation ellipse, and spatial autocorrelation analysis were used to study the temporal and spatial variation characteristics of the evaluation results; then, the driving force of impact factors was analyzed based on a geographical detector. Finally, the rationality of the evaluation results was verified using the changing trend of the remote sensing ecological index (RSEI). The results show that the ecological vulnerability of the urban green-space system in the Beijing–Tianjin–Hebei region has decreased year by year for the past ten years. The distribution law of “Hebei surrounds Beijing and Tianjin” is presented in this space, and 2015 is the mutation node. In 2010, the moderately and severely vulnerable areas of Hebei surrounded the mildly vulnerability areas of Beijing and Tianjin. Moreover, in 2015 and 2020, the mildly vulnerable areas of Hebei surrounded the severely vulnerable areas of Beijing and Tianjin. Vulnerability expands slightly in the east–west direction and shrinks slightly in the north–south direction, and the center of gravity shifts towards Beijing year by year along the northeast direction. Moreover, the spatial distribution of vulnerability shows significant positive spatial autocorrelations and exhibits very obvious agglomeration. In addition, vulnerability is the result of the combined effect of various factors, and education degree, human disturbance index, and annual average precipitation are the dominant factors. The analysis results provide a reference for the effective application and sustainable development of urban green-space ecological functions.

Spatiotemporal evolutionary characteristics and driving forces of carbon emissions in three Chinese urban agglomerations

Assessing carbon emissions in urban agglomerations has emerged as a pivotal step towards achieving carbon neutrality. In this study, panel data from 75 cities within the three largest urban agglomerations in China—the Yangtze River Delta (YRD), Beijing-Tianjin-Hebei (BTH) region, and Pearl River Delta (PRD)—were constructed to analyse the spatiotemporal evolution of carbon emissions from 2005 to 2020. An indicator system was established, and the Spatial Durbin Model (SDM) was used to investigate the driving forces of carbon emissions. The findings revealed a gradual increase in carbon emissions within these agglomerations, with a notable shift in their spatial distribution from metropolitan areas to broader urban agglomerations, exhibiting significant spatial correlation. Additionally, variations in carbon emissions were observed across different development stages. The SDM indicated that several factors, such as economic conditions, industrialization levels, and population size, influenced the carbon emissions of urban agglomerations. Nevertheless, the impact of these driving factors on carbon emissions was not constant and could be altered by other elements, including green technologies and governmental policies, indicating a decoupling effect between economic growth and carbon emissions. The insights from this study can assist policymakers in formulating strategies to curb carbon emissions and foster sustainable development.

Urbanization effects on the food-water-energy nexus within ecosystem services: A case study of the Beijing-Tianjin-Hebei urban agglomeration in China

This research centers on the necessity for synchronized management of natural resources in urban agglomerations. This study utilizes the ecosystem services theory to analyze the interplay between land use and the Food-Water-Energy (F-W-E) nexus in the Beijing-Tianjin-Hebei (B-T-H) region from 2000 to 2030. Assessment of ecosystem services is conducted using InVEST models, which include Habitat Quality (HQ), Water Yield (WY), Carbon Sequestration (CS), Soil Retention (SDR), and Food Production (FP). The findings indicate an annual increase in construction land with a concurrent notable decrease in cultivated land. Furthermore, HQ, CS, and per capita FP show an annual decline until 2020, which is expected to continue until 2030. Conversely, WY and SDR have been growing annually, albeit projected to decline by 2030. Spearman coefficient analysis uncovers synergies between HQ and CS, SDR and CS, and SDR and HQ, alongside trade-offs between CS and WY and HQ and WY. Trade-offs are also observed between FP and SDR, CS, and HQ. Applying K-means clustering analysis facilitates county-based spatial planning for the F-W-E system, providing crucial insights and suggestions for sustainable resource management.

Comparison of Different Impact Factors and Spatial Scales in PM2.5 Variation

PM2.5 particles with an aerodynamic diameter of less than 2.5 μm are receiving increasing attention in China. Understanding how complex factors affect PM2.5 particles is crucial for the prevention of air pollution. This study investigated the influence of meteorological factors and land use on the dynamics of PM2.5 concentrations in four urban agglomerations of China at different scales from 2010 to 2020, using the Durbin spatial domain model (SDM) at five different grid scales. The results showed that the average annual PM2.5 concentration in four core urban agglomerations in China generally had a downward trend, and the meteorological factors and land use types were closely related to the PM2.5 concentration. The impact of temperature on PM2.5 changed significantly with an increase in grid scale, while other factors did not lead to obvious changes. The direct and spillover effects of different factors on PM2.5 in inland and coastal urban agglomerations were not entirely consistent. The influence of wind speed on coastal urban clusters (the Pearl River urban agglomeration (PRD) and Yangtze River urban agglomeration (YRD)) was not significant among the meteorological factors, but it had a significant impact on inland urban clusters (the Beijing–Tianjin–Hebei urban agglomeration (BTH) and Chengdu–Chongqing urban agglomeration (CC)). The direct effect of land use type factors showed an obvious U-shaped change with an increase in the research scale in the YRD, and the direct effect of land use type factors was almost twice as large as the spillover effect. Among land use type factors, human factors (impermeable surfaces) were found to have a greater impact in inland urban agglomerations, while natural factors (forests) had a greater impact in coastal urban agglomerations. Therefore, targeted policies to alleviate PM2.5 should be formulated in inland and coastal urban agglomerations, combined with local climate measures such as artificial precipitation, and urban land planning should be carried out under the consideration of known impacts.

Comparative Study of O3 Forecast Performance Using Multiple Models in Beijing–Tianjin–Hebei and Surrounding Regions

In order to systematically understand the operational forecast performance of current numerical, statistical, and ensemble models for O3 in Beijing–Tianjin–Hebei and surrounding regions, a comprehensive evaluation was conducted for the 30 model sets regarding O3 forecasts in June–July 2023. The evaluation parameters for O3 forecasts in the next 1–3 days were found to be more reasonable and practically meaningful than those for longer lead times. When the daily maximum 8 h average concentration of O3 was below 100 μg/m3 or above 200 μg/m3, a significant decrease in the percentage of accurate models was observed. As the number of polluted days in cities increased, the overall percentage of accurate models exhibited a decreasing trend. Statistical models demonstrated better overall performance in terms of metrics such as root mean square error, standard mean bias, and correlation coefficient compared to numerical and ensemble models. Numerical models exhibited significant performance variations, with the best-performing numerical model reaching a level comparable to that of statistical models. This finding suggests that the continuous tuning of operational numerical models has a more pronounced practical effect. Although the best statistical model had higher accuracy than numerical and ensemble models, it showed a significant overestimation when O3 concentrations were low and a significant underestimation when concentrations were high. In particular, the underestimation rate for heavy polluted days was significantly higher than that for numerical and ensemble models. This implies that statistical models may be more prone to missing high-concentration O3 pollution events.

Providing Enhanced Insights into Groundwater Exchange Patterns through Downscaled GRACE Data

The measurement of groundwater exchange between neighboring regions is a critical topic in water resource management and can usually be achieved through a combination of field investigations and the use of groundwater flow models. In this study, we employed the water balance and Darcy’s law methods, utilizing downscaled Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow On (GRACE-FO) data to assess groundwater exchange patterns in the Beijing-Tianjin-Hebei (BTH) region of China. Additionally, we determined the contributions of human activities and climate factors to the observed variations via residual analysis. The results revealed a consistent decrease in groundwater storage in the study area since 2008, especially in the spring and summer months. The groundwater exchange rates calculated by 1° and 0.05° groundwater storage anomalies (GWSAs) were basically consistent, and the downscaled GWSAs could better reflect the small-scale groundwater exchange characteristics. The groundwater exchange rate showed a decreasing trend from the Piedmont plain to the coastal areas. A notable trend of declining groundwater exchange between the Taihang Mountains and Piedmont plains was observed, and the downward trend gradually intensified from north to south between 2003 and 2007. After 2008, there was an increasing trend, and coastal areas exhibited the smallest amount of groundwater exchange. Human activities emerged as the predominant factor accounting for more than 90.9% of the overall reduction in groundwater storage, while climate change imposed a minimal influence on groundwater storage variations. The insights obtained in this study hold significant implications for groundwater resource planning and management in the region.

The Potential of Using SDGSAT-1 TIS Data to Identify Industrial Heat Sources in the Beijing–Tianjin–Hebei Region

It is crucial to detect and classify industrial heat sources for sustainable industrial development. Sustainable Development Science Satellite 1 (SDGSAT-1) thermal infrared spectrometer (TIS) data were first introduced for detecting industrial heat source production areas to address the difficulty in identifying factories with low combustion temperatures and small scales. In this study, a new industrial heat source identification and classification model using SDGSAT-1 TIS and Landsat 8/9 Operational Land Imager (OLI) data was proposed to improve the accuracy and granularity of industrial heat source recognition. First, multiple features (thermal and optical features) were extracted using SDGSAT-1 TIS and Landsat 8/9 OLI data. Second, an industrial heat source identification model based on a support vector machine (SVM) and multiple features was constructed. Then, industrial heat sources were generated and verified based on the topological correlation between the identification results of the production areas and Google Earth images. Finally, the industrial heat sources were classified into six categories based on point-of-interest (POI) data. The new model was applied to the Beijing–Tianjin–Hebei (BTH) region of China. The results showed the following: (1) Multiple features enhance the differentiation and identification accuracy between industrial heat source production areas and the background. (2) Compared to active-fire-point (ACF) data (375 m) and Landsat 8/9 thermal infrared sensor (TIRS) data (100 m), nighttime SDGSAT-1 TIS data (30 m) facilitate the more accurate detection of industrial heat source production areas. (3) Greater than 2~6 times more industrial heat sources were detected in the BTH region using our model than were reported by Ma and Liu. Some industrial heat sources with low heat emissions and small areas (53 thermal power plants) were detected for the first time using TIS data. (4) The production areas of cement plants exhibited the highest brightness temperatures, reaching 301.78 K, while thermal power plants exhibited the lowest brightness temperatures, averaging 277.31 K. The production areas and operational statuses of factories could be more accurately identified and monitored with the proposed approach than with previous methods. A new way to estimate the thermal and air pollution emissions of industrial enterprises is presented.

Future Ozone Changes and Their Impacts on Vegetation and Human Health in China Under the Shared Socio‐Economic Pathways

AbstractOzone concentrations in China are increasing in recent years and future changes of ozone and their impacts have attracted much attention. We use global chemical transport model (GEOS‐Chem) to simulate the surface ozone concentrations in China in 2020 and 2050 under four Shared Socio‐economic Pathways and evaluate the impacts of future ozone pollution on vegetation and premature mortality in four polluted regions (Beijing–Tianjin–Hebei, BTH; Yangtze River Delta, YRD; Pearl River Delta, PRD; Sichuan Basin, SCB) and three major crop growing areas (Huang–Huai–Hai, HHH; Northeast Plain, NEP; middle and lower reaches of Yangtze River, MLRY) in China. The changes of simulated seasonal maximum daily 8‐hr average (MDA8) ozone from 2020 to 2050 (−15.5 to +11.9 ppbv) are significant under SSP126 (low forcing pathway) and SSP245 (medium forcing pathway) scenarios in all regions due to large changes of emissions. MDA8 ozone in summer 2050 will be above the WHO guidelines (100 μg/m3) in BTH, YRD, HHH and MLRY under four scenarios. By 2050, W126 (vegetative ozone exposure index) in summer will be much above the maximum of US secondary standard (21 ppm‐h) in HHH under SSP245, SSP370 (medium to high forcing pathway) and SSP585 (high forcing pathway) scenarios, and in MLRY under SSP370 and SSP585 scenarios. Annual ozone‐related deaths for people over 30 years old will mainly decrease in four polluted areas from 2020 to 2050 under SSPs scenarios, but only increase much under SSP245 scenario in BTH (+3.1 to +4.2 thousand) and YRD (+1.1 to +1.6 thousand).

Vertical Evolution of Ozone Formation Sensitivity Based on Synchronous Vertical Observations of Ozone and Proxies for Its Precursors: Implications for Ozone Pollution Prevention Strategies.

Photochemical ozone (O3) formation in the atmospheric boundary layer occurs at both the surface and elevated altitudes. Therefore, the O3 formation sensitivity is needed to be evaluated at different altitudes before formulating an effective O3 pollution prevention and control strategy. Herein, we explore the vertical evolution of O3 formation sensitivity via synchronous observations of the vertical profiles of O3 and proxies for its precursors, formaldehyde (HCHO) and nitrogen dioxide (NO2), using multi-axis differential optical absorption spectroscopy (MAX-DOAS) in urban areas of the Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD) regions in China. The sensitivity thresholds indicated by the HCHO/NO2 ratio (FNR) varied with altitude. The VOC-limited regime dominated at the ground level, whereas the contribution of the NOx-limited regime increased with altitude, particularly on heavily polluted days. The NOx-limited and transition regimes played more important roles throughout the entire boundary layer than at the surface. The feasibility of extreme NOx reduction to mitigate the extent of the O3 pollution was evaluated using the FNR-O3 curve. Based on the surface sensitivity, the critical NOx reduction percentage for the transition from a VOC-limited to a NOx-limited regime is 45-72%, which will decrease to 27-61% when vertical evolution is considered. With the combined effects of clean air action and carbon neutrality, O3 pollution in the YRD and PRD regions will transition to the NOx-limited regime before 2030 and be mitigated with further NOx reduction.

Comparing the mechanisms of two types of summer extreme precipitation in Beijing-Tianjin-Hebei region, China: Insights from circulation patterns and moisture transports

Beijing-Tianjin-Hebei (BTH) is undergoing huge risks from severe precipitation extremes, but their climate features and underlying mechanisms are not fully understood and warrant in-depth investigations. Here, the summer extreme precipitation events in BTH are objectively divided into two types according to the spatial distribution i.e., Northeast precipitation (NEP) and Southwest precipitation (SWP) and their underlying mechanisms are revealed and compared from perspectives of circulation patterns and moisture transports. In the case of Type NEP, the anomalous deep low-pressure (high-pressure) systems respectively cover over the west (east) of BTH, which jointly induce strong anomalous southwesterly and southerly airflows converging over BTH. The converging airflows strengthen water vapor transports from the western and southern boundaries of BTH and result in a strong convection over northeastern BTH, thereby triggering Type NEP precipitation. Compared with Type NEP, the circulation pattern of Type SWP is characterized by an anomalous deep (shallow) high-pressure (low-pressure) system over northeast (southwest) of BTH, respectively. The circulation patterns could induce strong anomalous southerly and easterly airflows converging over BTH and thus strengthen water vapor transports from the southern and eastern boundaries of BTH, resulting in a strong convection over southwestern BTH. Over the long-term period, the summer extreme precipitation days with multiple return periods extracted by the Generalized extreme value distribution theory show significantly increasing trends in Beijing-Tianjin and surrounding areas, particularly in urban regions, indicating that summer extreme precipitation events are becoming more frequent. These findings provide theoretical basis for summer extreme precipitation forecasting and scientific insight for taking effective measures to mitigate the corresponding disasters in BTH.

Study on the Vertical Distribution and Transport of Aerosols in the Joint Observation of Satellite and Ground-Based LiDAR

The mechanism of aerosol pollution transport remains highly elusive owing to the myriad of influential factors. In this study, ground station data, satellite data, ground-based LiDAR remote sensing data, sounding data, ERA5 reanalysis and a backward trajectory model were combined to investigate the formation process and optical properties of winter aerosol pollution in Beijing and surrounding areas. The analysis of ground station data shows that compared to 2019 and 2021, the pandemic lockdown policy resulted in a decrease in the total number of pollution days and a decrease in the average concentration of particulate matter in the Beijing area in 2020. The terrain characteristics of the Beijing-Tianjin-Hebei (BTH) made it prone to northeast and southwest winds. The highest incidence of aerosol pollution in Beijing occurs in February and March during the spring and winter seasons. Analysis of a typical heavy aerosol pollution process in the Beijing area from 28 February to 5 March 2019 shows that dust and fine particulate matter contributed to the primary pollution; surface air temperature inversion and an average wind speed of less than 3 m/s were conducive to the continuous accumulation of pollutants, which was accompanied by the oxidation reaction of NO2 and O3, forming photochemical pollution. The heavy aerosol pollution was transmitted and diffused towards the southeast, gradually eliminating the pollution. Our results provide relevant research support for the prevention and control of aerosol pollution.

Differential response of various pollutant-meteorology factors on O3 in key regions of China: Based on multiple methods and datasets

Scientific control is urgently required to address O3 pollution in key regions of China. Therefore, based on air pollutant concentrations and meteorological datasets, the methods including distributed lag nonlinear models, Kolmogorov–Zurbenko filter and stepwise multiple linear regression (SMLR) were applied to analyze and clarify the response of pollution and meteorological factors to O3, as well as the comprehensive impact under different time dimensions in Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD) and Chengdu-Chongqing regions (CY). Results indicate O3 concentrations in the study area fluctuated at high pollution levels. The effects of various air pollutants and meteorological factors on O3 varied among cities. Temperature is the dominant driver for O3, followed by solar radiation and relative humidity. The influence of wind vector indicates different transport sources of O3 and its precursors. Direct photochemical process based on SMLR fitting coefficient calculation is the main pathway for O3 generation, with contribution of 68.7%–93.8%. In terms of air-pollutant factors, U-shaped response between PM2.5 and O3 in all cities highlighted the interaction of the two air pollutants. The undeniable impact of NO2 on O3 is reflected in its range of effect. Meteorological adjustments led to −10.4–15.1 μg/m3 variations on O3 during 2014–2021, but performed obvious spatiotemporal differences. The changes in anthropogenic emissions deteriorated O3 pollution from 2014 to 2017, while have fluctuated effect since 2018. From the actual cases in special periods, in order to alleviate O3 pollution, it is necessary to strengthen the understanding of the synergistic contribution of meteorology and anthropogenic emissions.

Research on regional terrestrial carbon storage based on the pattern-process-function

The evolution of ecological pattern caused by human activities has altered the terrestrial carbon cycle process, and it is important to explore systematic approaches to study the relationship between ecological pattern and carbon sequestration function within regions. From the new perspective of the pattern-process-function in landscape ecology, this study couples NPP-InVEST, GeoDa, MOP-PLUS, and GeoDetector models to construct a conceptual cascade framework of “Land use pattern-Evolution process-Carbon sequestration function” (LEC), which provides a new epistemology and methodology for increasing carbon sink and mitigating down carbon source. Based on natural and socioeconomic elements, the use of LEC is illustrated in the Beijing-Tianjin-Hebei (BTH) region, the land use pattern, evolution process, and carbon sequestration function from 2000 to 2020 were analyzed, the trends of carbon storage in 2030 under four development scenarios were simulated, the driving mechanism of carbon sequestration function was studied, and the carbon sequestration function enhancement strategy based on the LEC was proposed. The results indicate that the land use pattern determines the spatial distribution and aggregation of carbon sequestration function, and the evolution process forms a low-carbon zone with construction land expansion, leading to a reduction in carbon storage. However, the ecological protection simulation scenario increases the high-carbon zone, which effectively slows down the decreasing trend of carbon sequestration function. Based on a comprehensive understanding of LEC, regional carbon storage can be enhanced through scientific allocation, priority protection, and efficient utilization of land use pattern. LEC contributes to the sustainability of complex natural-social-economic systems and provides an innovative approach for regional landscape pattern optimization policy formulation and carbon sequestration function enhancement.

Nonlinear Variations in PM2. 5 Concentration in the Three Major Urban Agglomerations in China

ITA and Beast methods were used to quantitatively analyze the nonlinear process of a PM2.5 concentration time series based on the PM2.5 concentration data of the three major urban agglomerations in China. The results showed that： ① the degree of the PM2.5 pollution in the three major urban agglomerations had decreased， and the high-concentration areas had noticeably shrunk. The degree of spatial polarization of PM2.5 concentration was reduced， and the spatial difference was narrowed. The PM2.5 concentration in most areas showed downward trends， but the degree of change was not the same. Compared with the YRD and PRD， the concentration of PM2.5 in the BTH was still at a relatively high level. ② The concentration of PM2.5 in the three major urban agglomerations had seasonal variation characteristics that were high in winter and spring and low in summer and autumn. There were obvious differences in PM2.5 concentration between winter and summer， and the convergence of PM2.5 concentration in summer was greater than that in winter. Areas with high PM2.5 concentration also had obvious downward trends， but the downward trends of PM2.5 concentration in the PRD were not obvious compared with those in the YRD and BTH. ③ The PM2.5 concentration time series of the three major urban agglomerations all had significant downward trends： Beijing-Tianjin-Hebei （BTH） > the Yangtze River Delta （YRD） > the Pearl River Delta （PRD）. The PM2.5 concentration had the largest downward trends in winter. The higher the PM2.5 pollution level， the greater the downward trends. ④ The trend component of the PM2.5 concentration time series in the BTH had two change points， and there was one change point in the seasonal component. The trend and seasonal components of the PM2.5 concentration time series in the YRD had no change point. There was no change point in the seasonal component but one change point in the trend component of the PM2.5 concentration time series in the PRD. These results can provide scientific references for regional air pollution control.

The Spatial Role and Influencing Mechanism of the Digital Economy in Empowering High-Quality Economic Development

Based on the data from 2012 to 2022, this paper comprehensively uses exploratory spatial data analysis, the panel threshold model, and the spatial Durbin model to explore the spatiotemporal evolution characteristics and mechanisms of digital economy and high-quality economic development. The results show that the center of gravity of China’s digital economy development has gradually concentrated in the southeast region, and the level of high-quality economic development has improved rapidly, gradually forming a pattern of radiation driving the development of the central and western regions with the Beijing–Tianjin–Hebei region, the Yangtze River Delta, and the Pearl River Delta. The digital economy can significantly improve the level of high-quality economic development, but this effect has a lag effect, and it can be extended to the fifth stage. There is a single threshold for high-quality economic development of the digital economy, and the two stages of its development can significantly promote the high-quality development of the economy, but the effect of the latter stage is weakened, showing the nonlinear characteristics of first strong and then weak. The digital economy has a notable positive spatial spillover impact, and its development dividend will raise this province’s and its bordering provinces’ levels of high-quality economic development.

Locally opposite responses of the 2023 Beijing–Tianjin–Hebei extreme rainfall event to global anthropogenic warming

The effect of anthropogenic warming on extreme rainfall events is a hot topic in this era of global warming, and increasing attention is being paid to its impact at regional and local scales. We explore the localized response of precipitation during the high-impact “23·7” extreme rainfall event in the Beijing–Tianjin–Hebei region under anthropogenic warming using ensemble convective-permitting simulations. We identify two sub-regions with opposite responses: anthropogenic warming decreased (increased) precipitation in the northern (southern) sub-region of the Beijing–Tianjin–Hebei area. Further analysis shows that anthropogenic warming intensified the remnant of Typhoon Dusuari and increased rainfall in its inner core but decreased rainfall in the peripheral spiral rain band. These are the main reasons for the locally inconsistent responses of extreme rainfall to anthropogenic warming. We emphasize that anthropogenic warming, as a global background signal, directly affects the intensity and structure of specific weather systems rather than local precipitation. A high-impact extreme rainfall event, therefore, cannot always be simply attributed to climate warming enhancing precipitation at every location in a particular region.