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Lake Erhai is a potentially phosphorus (P)-limited lake and its water quality may have been affected by atmospheric P deposition. However, there have been few studies on atmospheric P deposition in this lake. In this study, we established five wet deposition monitoring sites and two dry deposition monitoring sites around Lake Erhai to quantify the wet and dry deposition of total phosphorus (TP), including dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP) and particulate phosphorus (PP) from July 2022 to June 2023. Wet deposition fluxes of P species were collected by automatic rainfall collection instrument, and dry deposition fluxes were estimated using airborne concentration measurements and inferential models. The results reveal that among the different P components, DOP had the highest contribution (50%) to wet TP deposition (average all sites 12.7 ± 0.7 mg P m 2 /yr), followed by PP (40%) and DIP (10%). Similarly, DOP (51%) was the major contributor to dry TP deposition (average two sites 2.4 ± 0.9 mg P m 2 /yr), followed by DIP (35%) and PP (14%). Wet deposition dominated the annual total TP deposition (wet plus dry), accounting for approximately 83%. The key seasons for dry deposition were spring and autumn, which accounted for 64% of the annual total dry TP deposition. In comparison, wet deposition was significantly higher in the summer, accounting for 73% of the annual total wet TP deposition. The results of the potential source contribution function and concentration-weighted trajectories analysis indicate that local source emission and long-range transport from surrounding cities jointly exerted a substantial influence on aerosol P concentrations, particularly in the eastern and northwestern regions of the lake. These findings provide a comprehensive understanding of the different P components in atmospheric deposition, which is beneficial for developing effective strategies to manage the P cycle in Lake Erhai., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Peroxyl radicals (RO 2 ) are important components of atmospheric radical cycling and generation, but their formation, distribution and evolution mechanisms in the atmospheric environment have not been investigated. In this paper, we propose a novel atmospheric RO 2 radical trapping membrane that can trap low carbon number (Rc ≤ 5) RO 2 radicals and identify their R-group structures by fluorescence spectroscopy and chromatography. We also analyzed the composition and evolution mechanism of RO 2 species under different meteorological conditions in the atmospheric environment of Lanzhou, China, to provide scientific support for the treatment and research of atmospheric chemical pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

As carbon emission continue to rise and climate issues grow increasingly severe, countries worldwide have taken measures to reduce carbon emission. However, carbon dioxide is continuously flowing in the atmosphere and is easily influenced by neighboring cities' policies. Therefore, how to solve the problem of carbon emission spillover effect has become the key to improve policy efficiency. Cross-regional carbon governance provides a perspective on solving the carbon emission problem by regulating and guiding the cooperative behavior of cross-regional governance actors. Taking Chengdu-Chongqing area as an example, this study used the SDM to analyze the influencing factors and spatial spillover effects of emission. Then we used the system dynamics method to construct a dual-core carbon emission system, and simulated the spillover effect and emission reduction potential of Chengdu and Chongqing emission reduction policies under different policy schemes. The results reveal that the mobility of population and enterprises have a significant impact on carbon emission prediction. Carbon reduction policies exhibit the phenomena of "carbon transfer" and "free-riding." When Chengdu lowers its economic growth rate, it leads to the transfer of high energy-consuming enterprises to Chongqing, increasing carbon emission in Chongqing. The implementation of comprehensive carbon reduction policies in Chongqing has a positive effect on Chengdu. Emission reduction policies exhibit issues related to their temporal efficacy, as the effects of industrial structural policies in Chengdu yield opposite outcomes in the short and long term. Each city's unique circumstances necessitate tailored carbon reduction policies. In order to reduce carbon emissions, Chengdu and Chongqing require opposite population policies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Numerical weather prediction (NWP), when accessible, is a crucial input to short-term solar power forecasting. WRF-Solar, the first NWP model specifically designed for solar energy applications, has shown promising predictive capability. Nevertheless, few attempts have been made to investigate its performance under high aerosol loading, which attenuates incoming radiation significantly. The North China Plain is a polluted region due to industrialization, which constitutes a proper testbed for such investigation. In this paper, aerosol direct radiative effect (DRE) on three surface shortwave radiation components (i.e., global, beam, and diffuse) during five heavy pollution episodes is studied within the WRF-Solar framework. Results show that WRF-Solar overestimates instantaneous beam radiation up to 795.3 W m−2 when the aerosol DRE is not considered. Although such overestimation can be partially offset by an underestimation of the diffuse radiation of about 194.5 W m−2, the overestimation of the global radiation still reaches 160.2 W m−2. This undesirable bias can be reduced when WRF-Solar is powered by Copernicus Atmosphere Monitoring Service (CAMS) aerosol forecasts, which then translates to accuracy improvements in photovoltaic (PV) power forecasts. This work also compares the forecast performance of the CAMS-powered WRF-Solar with that of the European Centre for Medium-Range Weather Forecasts model. Under high aerosol loading conditions, the irradiance forecast accuracy generated by WRF-Solar increased by 53.2% and the PV power forecast accuracy increased by 6.8%. Significance Statement: Numerical weather prediction (NWP) is the "go-to" approach for achieving high-performance day-ahead solar power forecasting. Integrating time-varying aerosol forecasts into NWP models effectively captures aerosol direct radiation effects, thereby enhancing the accuracy of solar irradiance forecasts in heavily polluted regions. This work not only quantifies the aerosol effects on global, beam, and diffuse irradiance but also reveals the physical mechanisms of irradiance-to-power conversion by constructing a model chain. Using the North China Plain as a testbed, the performance of WRF-Solar on solar power forecasting on five severe pollution days is analyzed. This version of WRF-Solar can outperform the European Centre for Medium-Range Weather Forecasts model, confirming the need for generating high spatial–temporal NWP. [ABSTRACT FROM AUTHOR]

Green power trading is an institutional innovation proposed by China to promote green and sustainable development. This policy aims to relieve the serious debt pressure of renewable energy generation enterprises, thus laying the foundation for achieving carbon reduction targets. This paper empirically examines the role of green power trading by constructing the difference-in-differences (DID) model. Our findings indicate that green power trading significantly reduces the debt levels of policy-covered generation enterprises. This effect is more pronounced for state-owned enterprises, companies with better ESG performance, companies in regions with higher degree of marketization and companies specializing in renewable energy power generation. Further research discusses the impact mechanism of green power trading in terms of external and internal environmental channels. We find that a strong green development atmosphere, especially the external atmosphere, will significantly reinforce the weakening effect of green power trading on corporate debt. Our research provides empirical evidence for the success of green power trading policy in its pilot phase., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The GRAPES (Global/Regional Assimilation and Prediction System) global medium-range ensemble forecast system (GRAPES_GFS) is a new generation numerical weather forecast model developed by the China Meteorological Administration (CMA). However, the forecasts of surface latent heat fluxes and surface air temperature have systematic biases, which affect the forecasts of atmospheric dynamics by modifying the lower boundary conditions and degrading the application of GRAPES_GFS since the 2 m air temperature is one of the key components of weather forecast products. Here, we add a soil resistance term to reduce soil evaporation, which ultimately reduces the positive forecast bias of the land surface latent heat flux. We also reduce the positive forecast bias of the ocean surface latent heat flux by considering the effect of salinity in the calculation of the ocean surface vapor pressure and by adjusting the parameterizations of roughness length for the exchanges in momentum, heat, and moisture between the ocean surface and atmosphere. Moreover, we modify the parameterization of the roughness length for the exchanges in heat and moisture between the land surface and atmosphere to reduce the cold bias of the nighttime 2 m air temperature forecast over areas with lower vegetation height. We also consider the supercooled soil water to reduce the warm forecast bias of the 2 m air temperature over northern China during winter. These modified parameterizations are incorporated into the GRAPES_GFS and show good performance based on a set of evaluation experiments. This paper highlights the importance of the representations of the land/ocean surface and boundary layer processes in the forecasting of surface heat fluxes and 2 m air temperature. [ABSTRACT FROM AUTHOR]

In this study, we combined the measured bulk particle number concentration (N CN ), particle number size distribution (PNSD) and bulk cloud condensation nuclei concentration (N CCN ) at various supersaturation (SS) levels to investigate competitive activation of aerosols in the marine atmospheres over the marginal seas of China during two winter campaigns Campaign A (December 9-19, 2019) and Campaign B (December 28, 2019-January 16, 2020). During the two campaigns, we observed various categories of aerosols, i.e., long-range transport continental aerosols, clean marine aerosols, grown new particles ranging from nucleation mode to larger sizes, and grown pre-existing particles ranging from Aitken mode to accumulation mode size, etc. We found that the measured N CCN increased by only approximately 30 % with increases in SS levels from 0.2 % to 1.0 %, e.g., (1.8 ± 1.4) × 10 3 cm -3 at SS = 0.2 % and (2.4 ± 1.4) × 10 3 cm -3 at SS = 1.0 % during Campaign A. We further calculated the hygroscopicity parameter kappa (κ) by combining simultaneously measured PNSD and bulk N CCN to explore the causes. The calculated κ values were below 0.1 at SS = 0.4 % during the 72 % (or 88 %) period of Campaign A (or Campaign B). When κ values below 0.1 (or 0.2) were excluded, the remaining κ values were apparently reasonable, with an average of 0.22 (or 0.36) and a standard deviation of 0.10 (or 0.21) at SS = 0.4 % during Campaign A (or Campaign B). The unexpectedly lower κ values were discussed in terms of competitive activation of aerosols in marine atmospheres together with its net contribution to lowering the measured bulk N CCN below the expected value., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Nitrous acid (HONO) is considered as one of the main sources of the hydroxyl radical (OH), the most relevant oxidant in the atmosphere. Multi-AXis-Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements were conducted to obtain the vertical profiles of aerosol and HONO from November 1, 2020 to January 31, 2021 at a suburb site of Shanghai, China. HONO was mainly distributed near the surface, but high values HONO occasionally occurred around 0.7 km, indicating an unaccounted source of daytime HONO at high altitudes. The positive correlation between HONO and aerosols suggested that the photo-enhanced heterogeneous reactions on the aerosol surface were an important source of daytime HONO at high altitudes. To obtain the vertical distribution of OH production by HONO photolysis (P(OH) HONO ), the vertical profiles of photolysis rate of HONO (J HONO ) were calculated by establishing a method of combining observations with empirical relationship based on heterogeneous atmospheric and radiative transfer models. The J HONO increased approximately linearly with increasing altitudes and the noontime averages value of J HONO near the ground were 6.68 × 10 -4 s -1 , which was strongly negatively affected by aerosols in the morning and afternoon. The P(OH) HONO profile varied in different months (November, December, January) that the changes were mainly affected by HONO and J HONO . P(OH) HONO was more positively affected by J HONO at high altitude and noon but greatly influenced by HONO concentrations in the morning and afternoon., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

An hourly scale precursor of inland earthquakes (EQs) is revealed in this paper. Several EQ cases in China have been reported. As indicated by a table listing 23 inland EQs and their shock time, epicenter location, magnitude, near-epicenter weather conditions, precursor start time and precursor duration, when the weather conditions are fair near the epicenter, an anomalously negative atmospheric electrostatic signal is readily observable approximately 2–48 h before the EQ occurs. Moreover, a successful single-station alarm for nearby moderate-magnitude EQs is demonstrated, and a possible mechanism for the precursor signal is proposed. The change in the electrostatic field during an EQ process is explained as the release of radioactive gases from the subsurface into the atmosphere via large (regional-scale) preexisting microfractures in the rock at the source depth. These gases considerably ionize the atmosphere, and the separated positive and negative ions establish a special macroscopic electric field. The final critical stage of 2–48 h before an EQ may indicate a stable tectonic process. [ABSTRACT FROM AUTHOR]

The southwest vortex (SWV) is a critical weather system in China, but our knowledge of this system remains incomplete. Here, we investigate the cloud properties in the SWV. First, we search for the SWVs with time steps and center locations that are consistent between the SWV yearbook and ERA-Interim reanalysis data. Second, we supplement these SWVs' life spans and movement paths. Third, we relocate the Fengyun (FY) satellite FY-4A cloud retrievals in the 10° × 10° region centered on each SWV and analyze the cloud occurrence frequency (COF), cloud-top height (CTH), and cloud optical thickness (COT). A distribution mode of cloud types is summarized from the COFs, with water clouds, supercooled clouds, mixed clouds, ice clouds, cirrus clouds, and overlap clouds occurring sequentially from west to east. The CTH probability density (PD) distribution features a significant north–south difference. In addition, the COT PD distributions exhibit a common trend: with increasing COT, the PD increases rapidly and then slowly before peaking, whereupon the PD decreases abruptly. From spring to summer, the region with the highest convective COF shifts from the northeast to the northwest, and an east–west gradient of the convective COF appears in autumn and winter. Furthermore, we investigate the cloud properties during SWV-related heavy rainfall. Heavy rain occurs mainly in the west of the SWV, and convective clouds are mainly in the northwest, partly in the southwest and near the SWV center. The average CTH in heavy rainfall is generally higher than 6 km, and the average COT is greater than 20. Significance Statement: The southwest vortex (SWV) is an important weather system in China. However, we do not yet comprehensively know this weather system. The cloud properties can indicate the structures of weather systems and are key parameters in numerical weather prediction (NWP) models. Thus, investigating cloud properties is necessary and meaningful to understand the SWV and accurately predict SWV-related precipitation in NWP models. In this paper, a typical distribution mode of six cloud types in the SWV is summarized from the cloud occurrence frequency, and the distribution features of convective clouds, cloud-top height, and cloud optical thickness in the SWV are analyzed. Furthermore, the cloud properties in SWV-related heavy rain are also studied. [ABSTRACT FROM AUTHOR]

Realistic modeling of high-resolution earth radiation signals in the visible-thermal spectral domain remains difficult, due to the complex radiation interdependence induced by the heterogeneous and rugged features of land surface. To find the trade-off between accuracy and efficiency for image simulation, this paper established a unified simulation framework for the entire visible-thermal spectral domain, based on the energy balance between solar-reflected and thermal radiation components over rugged surfaces. Considering the joint contributions of atmospheric and topographic adjacency effects, three spatial–spectral convolution kernels were uniformly designed to quantify the topographic irradiance, the trapping effect, and the atmospheric adjacency effect. Radiation signal simulation was implemented in three forms: land surface temperature (LST), bottom of atmosphere (BOA) radiance, and top of atmosphere (TOA) radiance. The accuracy was validated with onboard data from China's Gaofen-5 visual and infrared multispectral sensor (VIMS) over rugged desert. The simulation results demonstrate that the root mean square of relative deviations between the simulated and onboard TOA radiance are related to terrain, as 3–17% and 6–38% for the summer and winter scene, respectively. The evaluation of radiance components indicates the utility of the simulation framework to quantify the uncertainty associated with atmosphere and terrain coupling effects, in the sensor design and operation stages. [ABSTRACT FROM AUTHOR]

The relationship between government and enterprise has attracted extensive attention. Under the increasingly severe requirement of sustainable development, there is still a lack of research on the economic effect of political acuity from the perspective of enterprise's positive party value creation. We built a dictionary of political acuity and demonstrated reliability through machine learning algorithms such as K-Nearest Neighbor (KNN). Then, based on the annual reports of China's listed companies from 2013 to 2020, the relationship between political acuity, ESG atmosphere, and corporate performance is empirically discussed. Examination through the formal institutional perspective of informal institutionalization shows that the positive acuity of the Communist Party of China(CPC) and the democratic parties(DPC) will improve corporate performance, while the negative acuity will have an early warning effect on performance. Furthermore, the stronger ESG atmosphere synergized this relationship. The CPC's negative acuity has supervision effect on non-state-owned companies, and this supervisory effect still exists in the ESG atmosphere. However, whether the moderating effect is considered or not, the positive political acuity of state-owned enterprises doesn't significantly improve performance. We found that the CPC's embedding in corporate governance will lead to both economic and political benefits, and have thresholds. We constructed a political acuity dictionary and introduced text analysis and nonparametric estimation method in this paper, which provided a basis and reference for future research on political acuity at the enterprise level. Our findings also enrich the institutional theory and the embeddedness theory. Meanwhile, our research broadened the boundary of political parties, ESG, and enterprises, the integration of ideological values and formal institutions, and had practical implications for the green transformation of firms and the precise positioning of political party functions. • We build a dictionary of political acuity for the first time. This dictionary provides a new measurement perspective for the study of corporate political sentiment and sustainable development. • From the perspective of positive value creation, we examine the impact path of a company's party acuity, ESG atmosphere, and financial performance. This paper helps to expand the governance boundaries of ideology and formal institutions, political concepts, and corporate behavior. • We explored the accounting consequences of political acuity for different types of firms, and measured the economic and political effects thresholds. • We introduced machine learning, python crawler, text analysis, and nonparametric estimation methods into this paper, which helped to expand the technical approach to corporate governance and green transformation. [ABSTRACT FROM AUTHOR]

• The literatures on subterranean geopolitics have paid insufficient attention to issues of peace. • The concept of affective atmosphere helps to flesh out the elemental and embodied dimensions of subterranean geopolitics. • The paper uses the case study of the Zhaishan Tunnel to show how it serves as a rapprochement tourism site. • Visitors of Zhaishan Tunnel (re)negotiate peaceful China-Taiwan relations in this subterranean space. Geopolitical studies on the subterranean have tended to portray underground spaces (including tunnels and caves) as closely imbricated with warfare, violence and militarism. This paper departs from existing literatures insofar as it explores how peaceful ideas and relationships can similarly be fostered through the subterranean realm. Using the case of the Zhaishan Tunnel located on the Taiwanese island of Kinmen, we demonstrate how this site has converted from a defensive structure against the military antagonisms from mainland China to one that is largely associated with rapprochement tourism for the cultivation of benign China-Taiwan relations. Specifically, by drawing on the concept of affective atmosphere, we argue that the elemental and material aspects of the tunnel have been strategically deployed to affectively shore up Chinese and Taiwanese visitors' collective memories in order to re-orientate their dispositions towards peaceful cross-strait futures. In so doing, we demonstrate how affective atmosphere can be analytically productive in examining the elemental and embodied dimensions of subterranean geopolitics. It not only enables critical appreciation of the ways in which different elemental materialities impact upon subjective feelings in/of subterranean spaces. More crucially, it also encourages incisive reflections into the agency and politics behind the conjoining of the elemental and bodily for the (re)making of subterranean geopolitics. [ABSTRACT FROM AUTHOR]

Limiting the rise in global mean temperatures relies on reducing carbon dioxide (CO 2 ) emissions and on the removal of CO 2 by land carbon sinks. China is currently the single largest emitter of CO 2 , responsible for approximately 27 per cent (2.67 petagrams of carbon per year) of global fossil fuel emissions in 2017 1 . Understanding of Chinese land biosphere fluxes has been hampered by sparse data coverage 2-4 , which has resulted in a wide range of a posteriori estimates of flux. Here we present recently available data on the atmospheric mole fraction of CO 2 , measured from six sites across China during 2009 to 2016. Using these data, we estimate a mean Chinese land biosphere sink of -1.11 ± 0.38 petagrams of carbon per year during 2010 to 2016, equivalent to about 45 per cent of our estimate of annual Chinese anthropogenic emissions over that period. Our estimate reflects a previously underestimated land carbon sink over southwest China (Yunnan, Guizhou and Guangxi provinces) throughout the year, and over northeast China (especially Heilongjiang and Jilin provinces) during summer months. These provinces have established a pattern of rapid afforestation of progressively larger regions 5,6 , with provincial forest areas increasing by between 0.04 million and 0.44 million hectares per year over the past 10 to 15 years. These large-scale changes reflect the expansion of fast-growing plantation forests that contribute to timber exports and the domestic production of paper 7 . Space-borne observations of vegetation greenness show a large increase with time over this study period, supporting the timing and increase in the land carbon sink over these afforestation regions.

The nitrate radical (NO 3 ) and dinitrogen pentoxide (N 2 O 5 ) play an important role in the nocturnal atmosphere chemistry. Observations of NO 3 radicals and N 2 O 5 were performed in a semirural ground site at Tai'Zhou in polluted southern China using cavity ring down spectroscopy (CRDS) from 23 May to 15 June 2018. The observed NO 3 and N 2 O 5 concentrations were relatively low, with 1 min average value of 4.4 ± 2.2 and 26.0 ± 35.7 pptV, respectively. The N 2 O 5 uptake coefficient was determined to be from 0.027 to 0.107 based on steady state lifetime method. Fast N 2 O 5 hydrolysis was the largest contributor to the loss of NO 3 and contributed to substantial nitrate formation, with an average value of 14.83 ± 6.01 µg/m 3 . Further analysis shows that the N 2 O 5 heterogeneous reactions dominated the nocturnal NO x loss and the nocturnal NO x loss rate is 0.14 ± 0.02 over this region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

Lidar is an active remote sensing instrument, and it has been widely used in the detection of atmospheric environmental parameters and meteorological parameters. In recent years, climate change has been widely concerned by the public, and the corresponding atmospheric detection technology has also been developed rapidly. Atmospheric Lidar has been developed rapidly in China, and has achieved good research achievements. The research progress and development status of Lidar for atmospheric detection in recent years are introduced and summarized in this invited paper. The advantages and disadvantages of all kinds of atmospheric detection Lidars and their applications in different detection objects are comprehensively introduced in this article. Finally, the bottlenecks of Lidar technology are summarized, and the development trend of Lidar is also prospected. [ABSTRACT FROM AUTHOR]

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Atmospheric amines contribute to the nucleation and initial growth of new particles as well as secondary organic aerosol formation, influencing the radiative balance of the Earth's atmosphere. In this study, we develop an ion chromatography (IC) method for separating and quantifying the nine most abundant amines (methylaminium (MMAH + ), dimethylaminium (DMAH + ), trimethylaminium (TMAH + ), ethylaminium (MEAH + ), diethylaminium (DEAH + ), propylaminium (MPAH + ), butylaminium (MBAH + ), ethanolaminium (MEOH + ), and triethanolaminium (TEOH + )) from six common inorganic species in atmospheric aerosols. The retention times of the amines were altered by the addition of acetonitrile to the eluent because acetonitrile can reduce the adsorption of hydrophobic amines on the stationary phase. The developed method achieved the successful separation of DEAH + and TMAH + from inorganic cations, which often coelute with each other in established IC methods. The interference of K + on the determination of MEAH + was eliminated by the complexation of K + with 18-crown-6, which prolonged the retention time of K + . Finally, 9 target amines and 6 common inorganic cations were separated, with a resolution Rs ≥ 1.2 for DEAH + and MPAH + and Rs > 1.5 for other species. The detection limits varied in the range of 0.34-1.48 ng for the 9 amines and 0.19-0.56 ng for the inorganic cations. The developed method was successfully applied for the determination of low molecular weight amines and inorganic cations in PM 2.5 collected from an urban site in Shanghai and an isolated coast of Chongming Island. Eight amines were detected in the urban samples, in which MMAH + and DMAH + dominated. The average amine concentration in the urban aerosols was 76.3 ± 38.4 ng m -3 , which is approximately 4-fold higher than those in the marine samples collected from the coast., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Atmospheric bulk deposition samples were gathered month by month throughout a year at two sites in vicinity of a MSWI in Shanghai, to carry out an investigation on the atmospheric bulk deposition fluxes and seasonal variations of polychlorinated dibenzo-p-dioxinsand dibenzofurans (PCDD/Fs). The atmospheric bulk deposition fluxes of PCDD/Fs ranged from 23.5 to 560 pg m -2 ·d -1 (1.01-23.9 pg WHO-TEQ·m -2 ·d -1 ), with an average value of 136 pg m -2 ·d -1 (5.08 pg WHO-TEQ·m -2 ·d -1 ) in the Vicinity of the MSWI in Shanghai. The measured concentrations were well compared with those from urban or industrial sites in other regions in China and abroad. The seasonal trend of atmospheric bulk deposition fluxes of PCDD/Fs throughout a year exhibited as high levels in summer, moderate levels in winter, and low levels in spring and autumn. The principal component analysis (PCA) indicated not only the MSWI, but also vehicle emission was the indispensable source of PCDD/Fs in the vicinity of the MSWI, especially for the urban areas. The positive matrix factorization (PMF) apportioned 5 source categories: MSWI, diesel vehicles, atmosphere background, industrial combustion and un-leaded gas vehicles, accounting for 43.3%, 38.1%, 6.89%, 6.19% and 5.50% in average, respectively of PCDD/Fs in atmospheric bulk deposition in the vicinity of the MSWI in Shanghai, China., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The monitoring-blind area exists in the industrial park because of private interest and limited administrative power. As the atmospheric quality in the blind area impacts the environment management seriously, the prediction and inference of the blind area is explored in this paper. Firstly, the fusion network framework was designed for the solution of "Circumjacent Monitoring-Blind Area Inference". In the fusion network, the nonlinear autoregressive network was set up for the time series prediction of circumjacent points, and the full connection layer was built for the nonlinear relation fitting of multiple points. Secondly, the physical structure and learning method was studied for the sub-elements in the fusion network. Thirdly, the spatio-temporal prediction algorithm was proposed based on the network for the blind area monitoring problem. Finally, the experiment was conducted with the practical monitoring data in an industrial park in Hebei Province, China. The results show that the solution is feasible for the blind area analysis in the view of spatial and temporal dimensions.

This paper presents a study on long-term surface solar radiation (SSR) changes over China under clear- and all-sky conditions and analyzes the causes of the "dimming" and "brightening." To eliminate the nonclimatic signals in the historical records, the daily SSR dataset was first homogenized using quantile-matching (QM) adjustment. The results reveal rapid dimming before 2000 not only under all-sky conditions, but also under clear-sky conditions, at a decline rate of −9.7 ± 0.4 W m−2 decade−1 (1958–99). This is slightly stronger than that under all-sky conditions at −7.4 ± 0.4 W m−2 decade−1, since the clear-sky dimming stopped 15 years later. A rapid "wettening" of about 40-Pa surface water vapor pressure (SWVP) from 1985 to 2000 was found over China. It contributed 2.2% to the SSR decline under clear-sky conditions during the whole dimming period (1958–99). Therefore, water vapor cannot be the main cause of the long-term dimming in China. After a stable decade (1999–2008), an intensive brightening appeared under the clear-sky conditions at a rate of 10.6 ± 2.0 W m−2 decade−1, whereas a much weaker brightening (−0.8 ± 3.1 W m−2 decade−1) has been observed under all-sky conditions between 2008 and 2016. The remarkable divergence between clear- and all-sky trends in recent decades indicates that the clouds played two opposite roles in the SSR changes during the past 30 years, by compensating for the declining SSR under the cloud-free conditions in 1985–99 and by counteracting the increasing SSR under cloud-free conditions in 2008–16. Aerosols remain as the main cause of dimming and brightening over China in the last 60 years, although the clouds counteract the effects of aerosols after 2000. [ABSTRACT FROM AUTHOR]

Proposed in 2016, the Sky River Project promised to scale up China's weather modification practices by moving water vapour from the southern Tibetan Plateau to northern China, working as an 'aerial corridor' for the South-North Water Transfer Project. Although the engineering project has not come to fruition, the concept of a 'sky river' is itself noteworthy for its inventors' explicit goal of allowing surface and atmospheric waters to be managed together. Sky River is Promethean in that it advances a mechanistic and techno-optimist vision of the atmosphere as a set of relations to be modelled, modified, and optimised for human use.. [ABSTRACT FROM AUTHOR]

Ozone (O 3) pollution in the atmosphere is getting worse in many cities. In order to improve the accuracy of O 3 prediction and obtain the spatial distribution of O 3 concentration over a continuous period of time, this paper proposes a VAR-XGBoost model based on Vector autoregression (VAR), Kriging method and XGBoost (Extreme Gradient Boosting). China is used as an example and its spatial distribution of O 3 is simulated. In this paper, the O 3 concentration data of the monitoring sites in China are obtained, and then a spatial prediction method of O 3 mass concentration based on the VAR-XGBoost model is established, and finnally its influencing factors are analyzed. This paper concludes that O 3 features the highest correlation with PM 2.5 and the lowest correlation with SO 2. Among the measurement factors, wind speed and temperature are the most important factors affecting O 3 pollution, which are positively correlated to O 3 pollution. In addition, precipitation is negatively correlated with 8-hour ozone concentration. In this paper, the performance of the VAR-XGBoost model is evaluated based on the ten-fold cross-validation method of sample, site and time, and a comparison with the results of XGBoost, CatBoost (categorical boosting), ExtraTrees, GBDT (gradient boosting decision tree), AdaBoost (adaptive boosting), RF (random forest), Decision tree, and LightGBM (light gradient boosting machine) models is conducted. The result shows that the prediction accuracy of the VAR-XGBoost model is better than other models. The seasonal and annual average R2 reaches 0.94 (spring), 0.93 (summer), 0.92 (autumn), 0.93 (winter), and 0.95 (average from 2016 to 2021). The data show that the applicability of the VAR-XGBoost model in simulating the spatial distribution of O 3 concentrations in China performs well. The spatial distribution of O 3 concentrations in the Chinese region shows an obvious feature of high in the east and low in the west, and the spatial distribution is strongly influenced by topographical factors. The mean concentration is clearly low in winter and high in summer within a season. The results of this study can provide a scientific basis for the prevention and control of regional O 3 pollution in China, and can also provide new ideas for the acquisition of data on the spatial distribution of O 3 concentrations within cities. • VAR model estimate the dynamic relationships of all endogenous variables. • VAR-tree model estimate the spatial and temporal distribution of O 3. • The eight-tree model improve the accuracy of O 3 change prediction. • VAR-XGBoost method solve the problem of spatial heterogeneity of the study object. [ABSTRACT FROM AUTHOR]

This paper presents a method to homogenize China's surface solar radiation (SSR) data and uses the resulting homogenized SSR data to assess the SSR trend over the period 1958-2016. Neighboring surface sunshine duration (SSD) data are used as reference data to assess the SSR data homogeneity. A principal component analysis is applied to build a reference series, which is proven to be less sensitive to occasional data issues than using the arithmetic mean of data from adjacent stations. A relative or absolute test is applied to detect changepoints, depending on whether or not a suitable reference series is available. A quantile-matching method is used to adjust the data to diminish the inhomogeneities. As a result, 60 out of the 119 SSR stations were found to have inhomogeneity issues. These were mainly caused by changes in instrument and observation schedule. The nonclimatic changes exaggerated the SSR change rates in 1991-93 and resulted in a sudden rise in the national average SSR series, causing an unrealistically drastic trend reversal in the 1990s. This was diminished by the data homogenization. The homogenized data show that the national average SSR has been declining significantly over the period 1958-90; this dimming trend mostly diminished over the period 1991-2005 and was replaced by a brightening trend in the recent decade. From the homogenized SSR data, the 1958-90 and 1958-2005 dimming rate is estimated to be -6.13 ± 0.47 and -5.08 ± 0.27W m-2 decade-1, respectively, and the 2005-16 brightening rate is 6.13 ± 1.77W m-2 decade-1. [ABSTRACT FROM AUTHOR]

This paper analyzes the relationship between the 1000-850-hPa layer perturbation potential energy (LPPE) as the difference in local potential energy between the actual state and the reference state and the East Asian summer monsoon (EASM) using reanalysis and observational datasets. The EASM is closely related to the first-order moment term of LPPE (LPPE1) from the preceding March to the boreal summer over three key regions: the eastern Indian Ocean, the subtropical central Pacific, and midlatitude East Asia. The LPPE1 pattern (−, +, +), with negative values over the eastern Indian Ocean, positive values over the subtropical central Pacific, and positive values over East Asia, corresponds to negative LPPE1 anomalies over the south of the EASM region but positive LPPE1 anomalies over the north of the EASM region, which lead to an anomalous downward branch over the southern region but an upward branch over the northern region. The anomalous vertical motion affects the local meridional circulation over East Asia that leads to a southwesterly wind anomaly over East Asia (south of 30°N) at 850 hPa and anomalous downward motion over 100°-120°E (along 25°-35°N), resulting in a stronger EASM, more kinetic energy over the EASM region, and less boreal summer rainfall in the middle and lower reaches of the Yangtze River valley (24°-36°N, 90°-125°E). These LPPE1 anomalies in the eastern Indian Ocean and subtropical central Pacific appear to be connected to changes in local sea surface temperature through the release of latent heat. [ABSTRACT FROM AUTHOR]

With greater industrialization and urbanization, the amount of carbon dioxide (CO2) in the atmosphere has increased rapidly, and global warming has become a great challenge for humankind. Land is an important resource for human survival and development. The analysis of CO2 emissions from various land uses is crucial for controlling the level of land CO2 emissions and increasing the effectiveness of land use. This study develops a methodological framework to explore the spatiotemporal spillover effect and efficiency in regional land use carbon emissions (LUCE) and the change of land use structure efficiency (LUSE). The CO2 emissions of various land use types and the amount of indirect CO2 emissions of related industries from 1995 to 2015 were calculated. Based on CO2 emission measurement and spatial autocorrelation test, a spatial Durbin model is constructed to explore the spatial spillover effect (SSE) of LUCE. A Super-slack-based DEA model with undesirable outputs is proposed to measure the LUSE and the LUCE of various provinces from 1990 to 2015. Results show that the LUCE in China show an increasing trend overall, with emissions increasing nearly four times from 1990 to 2015. This increase is caused mainly by indirect CO2 emissions, that is, energy consumption generated by human activities. The local Moran's I showed a downward trend with the increase in years, indicating that regions with similar LUCE were gradually dispersed and that regional differences existed. The LUSE in China presents a mainly decreasing trend from 0.96 in 1990 to 0.69 in 2015. The spatial distribution of CO2 emissions is negatively correlated with land use efficiency. Economic growth, technological input and energy intensity are the core factors affecting regional LUCE and have significant spatial spillover characteristics. The 30 provinces are separated into three subareas by a comparison of the LUSE and the LUCE, and recommendations are made for how to improve the LUSE and CO2 emission reduction control of each subarea. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the surface solar radiation data from 1960 to 2000 gathered from 40 weather stations over China were reexamined, and the relationship of long-term trends of the solar radiation and climate factors were analyzed. The results indicate that the surface solar radiation in most regions of China begins to increase after 1990. Decreases in cirrus and cirrostratus clouds, which account for a larger percentage of the total cloud amount over China, have an important contribution to the increasing trend of the surface solar radiation. Further examination of the surface water vapor changes reveals that the surface solar radiation negatively correlates with the near surface water vapor in most region of China, and this negative correlation is more pronounced in higher latitudes of China where the atmosphere is compared to regions in southern China. [Copyright &y& Elsevier]

This paper explores the geometric performance of integration of aerial and QuickBird images. Different integration scenarios with different bias compensation schemes in the image space were studied, and the results showed that the introduction of the aerial images can improve the geopositioning accuracy of the QuickBird images to close to the aerial pixel level. In addition, methods of correcting biases in the object space were tested, and the results revealed the disadvantage of the bias compensation in the object space. An experiment was conducted for mapping ground objects such as inland rivers, buildings, and roads using the proposed integration method. [ABSTRACT FROM AUTHOR]

On the basis of NCEP/NCAR version I daily reanalysis data from 1971 to 2000 and by the methods of inverse calculation, correlation analysis and comparative analysis, the influences of atmospheric heat source (AHS) over the Tibetan Plateau on the large-scale AHS and the general circulation in summer are studied in this paper. The results show that AHS over the plateau in summer may trigger a heat source wavetrain propagating northeastward along the coast from the East Asian continent and West Pacific to Bering Strait-Arctic or even North Amend. In addition, if AHS over the eastern plateau is intense, South Asian High moves to southeast and West Pacific subtropical high moves to southwest; on the contrary, if AHS over the eastern plateau is weak, South Asian High moves to northwest and West Pacific subtropical high moves to northeast. Therefore, South Asian High and West Pacific sub tropical high move in the horizontally-opposite directions in terms of interannual variation, for which AHS over the e stern plateau seems to be thermodynamically responsible. [ABSTRACT FROM AUTHOR]

The absence of nationwide distribution data regarding heavy metal emissions into the atmosphere poses a significant constraint in environmental research and public health assessment. In response to the critical data deficiency, we have established a dataset covering Cr, Cd, As, and Pb emissions into the atmosphere (HMEAs, unit: ton) across 367 municipalities in China. Initially, we collected HMEAs data and covariates such as industrial emissions, vehicle emissions, meteorological variables, among other ten indicators. Following this, nine machine learning models, including Linear Regression (LR), Ridge, Bayesian Ridge (Bayesian), K-Neighbors Regressor (KNN), MLP Regressor (MLP), Random Forest Regressor (RF), LGBM Regressor (LGBM), Lasso, and ElasticNet, were assessed using coefficient of determination (R2), root-mean-square error (RMSE) and Mean Absolute Error (MAE) on the testing dataset. RF and LGBM models were chosen, due to their favorable predictive performance (R2: 0.58–0.84, lower RMSE/MAE), confirming their robustness in modelling. This dataset serves as a valuable resource for informing environmental policies, monitoring air quality, conducting environmental assessments, and facilitating academic research. [ABSTRACT FROM AUTHOR]

Atmosphere clearness is the single most essential parameter determining surface solar radiation. However, few studies have investigated the interannual variations in China's atmosphere clearness and the impacts of El Niño–Southern Oscillation on it. This study aims to fill the knowledge gap by calculating the clearness index using the China Meteorological Forcing Dataset version 1.7 and then analyzing the correlations between the interannual anomaly and the Niño-3.4 index. The results show that there is a significantly negative correlation in the southeastern coastal regions, northern Xinjiang, northeastern Xizang, and areas from northern Hebei to middle Inner Mongolia. In these areas, the higher the ENSO index, the lower the clearness index, and, coincidingly, positive precipitation anomalies are reported in previous studies. The impacts of El Niño and La Niña vary with seasons. The ENSO events have generally opposite impacts in the seasons other than summer. El Niño tends to decrease the clearness index, while La Niña tends to decrease the atmosphere clearness in most territories of China. The impacts are different in the places of statistical significance. The negative impacts of El Niño are significant in the southeastern coastal regions of China in winter and in northeast China in autumn. The positive impacts of La Niña are significant in the southwestern and northeastern China in the autumn. In these seasons, ENSO's impacts scale with the strength of the event. Stronger events amplify the magnitude of the anomalies, while the spatial patterns of the anomalies are kept almost invariant. In summer, ENSO's impacts exhibit different characteristics than in the other seasons and between the El Niño and La Niña events. For the El Niño events, the impacts are insignificant in most territories of China, even for the strong ones. La Niña has a larger influence on the summertime clearness than El Niña, and the spatial pattern of the La Niña's impacts varies with the event strength. The anomalies during strong La Niña events have a tripolar pattern with a positive anomaly in south and north China and a negative anomaly in between. The pattern suggests that the relationship between the clearness index and precipitation is different during strong La Niña events. These findings would provide valuable insights into the interannual variations of atmosphere clearness in China and could be clues to further investigation. The revealed impacts of El Niño–Southern Oscillation should be important for developing solar energy. [ABSTRACT FROM AUTHOR]

The land surface model (LSM) is extensively utilized to simulate terrestrial processes between land surface and atmosphere in the Earth system. Hydrology simulation is the key component of the model, which can directly reflect the capability of LSM. In this study, three offline LSM simulations were conducted over China using the Community Land Model version 5.0 (CLM5) driven by different meteorological forcing datasets, namely China Meteorological Forcing Dataset (CMFD), Global Soil Wetness Project Phase 3 (GSWP3), and bias-adjusted ERA5 reanalysis (WFDE5), respectively. Both gridded and in situ reference data, including evapotranspiration (ET), soil moisture (SM), and runoff, were employed to evaluate the performance levels of three CLM5-based simulations across China and its ten basins. In general, all simulations realistically replicate the magnitudes, spatial patterns, and seasonal cycles of ET over China when compared with remote-sensing-based ET observations. Among ten basins, Yellow River Basin (YRB) is the basin where simulations are the best, supported by the higher KGE value of 0.79. However, substantial biases occur in Northwest Rivers Basin (NWRB) with significant overestimation for CMFD and WFDE5 and underestimation for GSWP3. In addition, both grid-based or site-based evaluations of SM indicate that systematic wet biases exist in all three CLM5 simulations for shallower soil layer over nine basins of China. Comparatively, the performance levels in simulating SM for deeper soil layer are slightly better. Moreover, all three types of CLM5 simulate reasonable runoff spatial patterns, among which CMFD can capture more detailed information, but GSWP3 presents more comparable change trends of runoff when compared to the reference data. In summary, this study explored the capacity of CLM5 driven by different meteorological forcing data, and the assessment results may provide important insights for the future developments and applications of LSM. [ABSTRACT FROM AUTHOR]

Because human modification has been significant enough to alter the atmospheric chemistry, some scholars argue that our planet Earth is going beyond the Holocene and coming into a new geological epoch, the Anthropocene. While the Anthropocene concept is widely acknowledged, some key issues, such as the starting point of this epoch and how humans influenced climate, are unclear. This paper provides an overview of the long-term, broad-scale interactions between climate evolution and increasingly intensive human activities (mainly farming) in Early China. It firstly reviews both the traditional "climate in charge" hypothesis and Ruddiman's "anthropogenic greenhouse gases" hypothesis. Then pollen and isotope data on paleo-climate is summarized to shed light on the climatic history in China from ~3500 BCE to ~220 CE. It is followed by an overview of the cultural history within the same time span. Finally, by integrating these two lines of evidence, the dynamic process of the interplay of human activity (particularly farming) and climate is synthetically discussed. Based on the evidence, I argue that the onset of the Anthropocene is a prolonged process with a notable mark in the early centuries CE. [ABSTRACT FROM AUTHOR]

Brominated flame retardants (BFRs) were measured in eucalyptus leaves and pine needles as well as the leaf surface particles (LSPs) of the two species at an e-waste site in southern China in 2007-2008. The monthly concentrations of total BFRs in the eucalyptus leaves and pine needles were in range of 30.6-154 and 15.1-236 ng/g dry weight, respectively, and relatively higher concentrations were observed in winter and spring. Correlation analysis of BFR concentrations and comparison of PBDE compositions between the plants and LSPs, air (gaseous and particle-bound phases), and ambient variables were conducted. The results revealed that BFRs in the plants, especially for less brominated BFRs, showed positive relationships with BFRs in the LSPs and negative relationships with the gaseous BFRs and ambient temperature. The PBDE profiles in the plants were similar to the gaseous profile for low brominated BDEs (di- through hexa-BDEs) and to the LSP profiles for highly brominated BDEs (hepta- through deca-BDEs). Applying McLachlan's framework to our data suggests that the uptake of BFRs was controlled primarily by gaseous partitioning equilibrium for compounds with log octanol-air partition coefficients (K(OA)) < 12 and by particle-bound deposition for compounds with log K(OA) > 13. Different relationships between the plant/air partition coefficient (K(PA)) and K(OA), which depend on the uptake mechanisms, were observed for polybrominated diphenyl ethers (PBDEs). This paper adds to the current knowledge of the factors and mechanisms governing plant uptake of semivolatile organic compounds with relatively high K(OA) in the environment.

Subseasonal to seasonal (S2S) predictions, which bridge the gap between weather forecasts and climate outlooks, have the great societal benefits of improving water resource management and food security. However, there are tremendous disparities in the forecasting skills of subseasonal precipitation prediction products. This study investigates the spatiotemporal variations in the precipitation forecasting skill of three subseasonal prediction products from the CMA, ECMWF, and NCEP over China. Daily precipitation predictions with lead times ranging from 1 to 30 days and cumulative precipitation predictions over 1-30 days were evaluated in nine major river basins. The daily prediction skill rapidly declines with lead time. In contrast, the correlation coefficient between the cumulative precipitation predictions and corresponding observations increases at first and peaks at 0.7-0.8 after 3-5 days, then gradually decreases and settles at approximately 0.2-0.6. Among the three evaluated models, the ECMWF model demonstrates the best skill, maintaining a correlation coefficient of approximately 0.5 for 2-week cumulative precipitation. Moreover, the correlation coefficient of the model's prediction is 0.2-0.5 higher than that of the climatological prediction over a large domain for the 30-day cumulative precipitation during the rainy summer. Similarly, the equitable threat score for forecasting below- and above-normal precipitation events presents good results in eastern China but is affected by biases of raw predictions. The variations in the subseasonal prediction skill at different time scales reveal the potential values of cumulative precipitation predictions. The findings of this study can provide practical information for applications that prioritize the long-term aggregation of hydrometeorological variables. [ABSTRACT FROM AUTHOR]

A regional analysis of soil temperature (ST) is essential for improving our understanding of the soil thermal regime and its link with the atmosphere. This study attempts to assess trends in the Poyang Lake Basin (PLB) ST magnitude during 1960–2016 from station observations at multiple depths. The Mann–Kendall, Thiel-Sen, linear regression, and probability density statistics (PDF) are used for ST trend assessment with a significance level of 95%. The ST seasonal variability shows minimum values in winter (8℃) and maximum in the summer season (32 ℃). On an interannual scale, spring and winter seasons exhibited a significant increase in both land surface temperature (LST) (0.4℃, 0.4℃) and ST (0.3 °C, 0.15℃) magnitude than summer (LST − 0.1℃, ST 0.2℃) and autumn seasons (LST 0.3℃, ST 0.2℃). The northern basin exhibited a significant increase in LST, and ST magnitude, especially during the cold seasons (spring, winter) than the warm seasons. The maximum and minimum temperature trend and their diurnal difference infer an increase in the minimum temperature, especially during the summer, autumn, and winter seasons. The PDF further inferred that extreme cold events' frequency decreased, and a significant increase in extreme warm events is obvious in the recent decade. The increasing trend in soil temperature magnitude is more in the northern basin than the high-altitude southern basin. Large-scale global warming and regional water and energy cycle changes can be the leading factors of such a warming trend. [ABSTRACT FROM AUTHOR]

The ionosphere is a crucial factor affecting Global Navigation Satellite System positioning. The Global Ionosphere Map (GIM) or the International Reference Ionosphere (IRI) model can be used for regional ionospheric correction. Since southern China is located near the electron density equatorial anomaly, this study evaluates the performance of the Wuhan University GIM (WHU‐GIM) and the IRI‐2020 from 2008 to 2020 over the China region. The comparison indicates that the Total Electron Content (TEC) from IRI‐2020 is lower than that from WHU‐GIM overall, the discrepancy is more obvious in high solar conditions and low‐latitude regions. The differential Slant TEC (dSTEC) during a phase‐arc with about 0.1 TECU accuracy derived from Global Positioning System (GPS) observations is used for model validation, the results show that the accuracies of WHU‐GIM and IRI‐2020 are 3.14 and 4.57 TECU, respectively. The dSTEC error is larger at low latitudes and decreases with increasing latitude. GPS‐derived TEC is taken for reference to evaluate the model reliability. Results show that both models can reproduce the diurnal TEC variations, but IRI‐2020 is more influenced by geomagnetic activities. The TEC correction percentage for IRI‐2020 is about 60%–80% under different ionospheric conditions, while for WHU‐GIM is 80%–90%. The Single‐Frequency Precise Point Positioning is performed with the ionosphere delay corrected by the two models, respectively. The positioning errors show that using IRI‐2020 has a lower accuracy, and the TEC discrepancy of the IRI‐2020 can cause a large bias in the up direction, especially at low‐latitude regions. Plain Language Summary: The ionosphere is a part of the Earth's atmosphere within an altitude of 60–1,000 km from the ground. The ionized molecules and free electrons that exist in the ionosphere will affect the Global Navigation Satellite System signals, and reduce the positioning accuracy finally. Ionospheric models such as the Global Ionospheric Map (GIM) and the International Reference Ionosphere (IRI) model provide the Total Electron Content (TEC) which is always used to mitigate ionospheric errors. The China region is close to the equator where the ionosphere is more active and disturbed, and is important to assess the performance of these two models in this area. This study evaluates the Wuhan University GIM (WHU‐GIM) and the IRI‐2020 model for 13 years according to the differential Slant TEC data, Global Positioning System TEC and Single‐Frequency Precise Point Positioning (SF‐PPP) technique. The results indicate that the TEC from the IRI‐2020 model is lower than that from the WHU‐GIM, especially under high solar conditions and in low‐latitude regions. According to the result of the SF‐PPP, the accuracy of the IRI‐2020 model is worse than WHU‐GIM, and the low TEC of the IRI‐2020 could cause a large bias in the up direction at the low‐latitude regions over China. Key Points: An assessment of Wuhan University Global Ionosphere Map (WHU‐GIM) and International Reference Ionosphere (IRI)‐2020 was conducted from 2008 to 2020 over the China region, with an overall better performance of WHU‐GIMCompared to WHU‐GIM, the Total Electron Content (TEC) derived from IRI‐2020 model is lower, such discrepancies are more obvious under the high solar conditionIRI‐2020 can be more influenced by geomagnetic storms, and its low TEC is reflected in a larger bias in the up component resulting from Single‐Frequency Precise Point Positioning [ABSTRACT FROM AUTHOR]

Atmospheric age reflects how long particles have been suspended in the atmosphere, which is closely associated with the evolution of air pollutants. Severe regional haze events occur frequently in China, influencing air quality, human health, and regional climate. Previous studies have explored the characteristics of mass concentrations and compositions of fine particulate matter (PM 2.5) during haze events, but the evolution of atmospheric age remains unclear. In this study, the age-resolved University of California, Davis/California Institute of Technology (UCD/CIT) model was developed and applied to simulate the concentration and age distribution of PM 2.5 during a severe regional haze episode in eastern China. The results indicated that PM 2.5 concentrations in the North China Plain (NCP) gradually accumulated due to stagnant weather conditions during the beginning stage of the haze event. Accordingly, the atmospheric age of elemental carbon (EC), primary organic aerosol (POA), sulfate (SO42-), and secondary organic aerosol (SOA) gradually increased. The subsequent PM 2.5 concentration growth was driven by the local chemical formation of nitrate (NO3-) under high relative humidity. The newly formed NO3- particles led to a decrease in the mean atmospheric age of NO3- particles. During the regional transport stage, aged particles from the NCP moved to the downwind Yangtze River Delta (YRD) region, leading to a sharp increase in PM 2.5 concentrations and the average age of EC, POA, SO42- , and SOA in YRD. In contrast, the average age of NO3- and ammonium remained unchanged or even slightly decreased due to continuous local formation in the YRD region. Different evolution of the atmospheric age among these components provides a unique perspective on the formation of PM 2.5 components during the regional haze event. The information can also be used for designing effective control strategies for different components of PM 2.5. [ABSTRACT FROM AUTHOR]

Current process-based research mainly uses box models to evaluate photochemical ozone production and destruction rates, and it is unclear to what extent the photochemical reaction mechanisms are elucidated. Here, we modified and improved a net photochemical ozone production rate (NPOPR, P (O 3) net) detection system based on the current dual-channel reaction chamber technique, which makes the instrument applicable to different ambient environments, and its various operating indicators were characterized, i.e., "airtightness", light transmittance, wall losses of the reaction and reference chambers, conversion rate of O 3 to NO 2 , air residence time, and performance of the reaction and reference chambers. The limits of detection of the NPOPR detection system were determined to be 0.07, 1.4, and 2.3 ppbv h -1 at sampling flow rates of 1.3, 3, and 5 L min -1 , respectively. We further applied the NPOPR detection system to field observations at an urban site in the Pearl River Delta (China). During the observation period, the maximum value of P (O 3) net was 34.1 ppbv h -1 , which was ∼ 0 ppbv h -1 at night within the system detection error and peaked at approximately noon local time. The daytime (from 06:00–18:00 LT) average value of P (O 3) net was 12.8 (± 5.5) ppbv h -1. We investigated the detailed photochemical O 3 formation mechanism in the reaction and reference chambers of the NPOPR detection system using a zero-dimensional box model. We found that the photochemical reactions in the reaction chamber were very close to those in ambient air, but there was not zero chemistry in the reference chamber because the reaction related to the production and destruction of RO 2 (= HO 2 + RO 2) continued in the reference chamber, which led to a small amount of P (O 3) net. Therefore, the P (O 3) net measured here can be regarded as the lower limit of the real P (O 3) net in the atmosphere; however, the measured P (O 3) net was still ∼ 7.5 to 9.3 ppbv h -1 higher than the modeled P (O 3) net value depending on different modeling methods, which may be due to the inaccurate estimation of HO 2 / RO 2 radicals in the modeling study. Short-lived intermediate measurements coupled with direct P (O 3) net measurements are needed in the future to better understand O 3 photochemistry. Our results show that the NPOPR detection system can achieve high temporal resolution and continuous field observations, which helps us to better understand photochemical O 3 formation and provides a key scientific basis for continuous improvement of air quality in China. [ABSTRACT FROM AUTHOR]

Recently, atmospheric distribution, transport, and reaction of persistent organic pollutants (POPs) in remote areas are getting more attention. Based on the passive air sampler, the networks are established for studying the temporal and spatial distribution of atmospheric POPs in remote areas. The results suggest that the atmospheric concentrations of POPs display a peak value in the 1980s. As the use of POPs has been forbidden after 1980s, concentrations of POPs in air are generally reduced. Concentration of POPs in atmosphere is influenced by temperature and seasonal usage. High concentration of organochlorine pesticides is observed in summer and the comparatively low level is detected in winter. For PAHs, the trend is contrary. High volatility and long-range transport of POPs lead to the global distribution of POPs and accumulation of POPs in remote areas. High mountain is the "acceptor" of atmospheric POPs and cold condensation plays the main role in capturing POPs in high elevation areas. Distribution, transport, exchange direction and exchange flux of POPs among air/water, air/soil, air/snow and air/vegetation interfaces are mainly controlled by temperature, precipitation and characteristics of POPs. Models were developed on the basis of the effect of these factors. Taken together the transport model and source analysis of POPs, transport mechanism of POPs seems to be clearer. This paper reviewed the progress about the above-mentioned scientific topics and discussed the deficiencies of current researches. Furthermore, it pointed out the further work needed for the study of atmospheric POPs in remote areas.

With eleven garden plant species in Beijing as test materials, this paper determined the adhesion density of atmospheric particles on leaf surface, observed the micro-configurations of leaf epidermis, and measured the particle size distribution of the particles. The results showed that the particles were mainly adhered on upside leaf surface, and the adsorbed amount was about six times higher than that on underside leaf surface. The particle-retaining capability of the micro-configurations of leaf epidermis was decreased in the order of groove> vein + cell > cell > strip protuberance. The capability of particle-retaining was higher when the micro-configurations were denser and the fall between them was larger. The mean value and the mean percentages of PM2.5 and PM10 on upside leaf surface were 66.7% and 98.3%, while those on underside leaf surfaces were 43.4% and 92.9%, respectively.

By the method of static chamber-gas chromatography, this paper studied the nitrous oxide flux in three typical wetlands (perennial waterlogged Carex lasiocarpa marsh, seasonal waterlogged Deyeuzia angustifolia wet meadow, and perennially over-wet brushwood wetland) of Sanjiang Plain from 2002 to 2004. The results showed that the nitrous oxide flux in test wetlands presented obvious seasonal and annual variation, suggesting that these three typical wetlands were all the sources of atmosphere nitrous oxide during plant growth season, and the weak sink in winter. The annual average flux in C. lasiocarpa marsh, D. angustifolia and brushwood wetland was 53.928, 21.408 and 657.120 mg x m(-2) x yr(-1), respectively. No diurnal variation of nitrous oxide flux was observed in three typical wetlands, and there was no significant correlation between nitrous oxide flux and temperature.

In this paper, various correction methods were compared, based on the observation data of the CO2 and water fluxes above the canopy of a tropical seasonal rainforest in Xishuangbanna during 1-9 March, 2003. The results showed that it was necessary to correct the observation data when calculating the carbon flux, though various correction methods contributed differently to the results. For daytime data, WPL made the most important contribution, while sonic temperature correction did the least. t test indicated that no significant difference was found between the carbon fluxes corrected by WPL and the standard values. Cluster analysis showed that triple-rotation correction was helpful to improve the precision of the data. For nighttime data, it was the triple-rotation correction that made the most important contribution, and sonic temperature correction also did the least. There existed significant differences between the carbon fluxes corrected by WPL, planar-fit correction and their combination and the standard values, while the differences between the carbon fluxes corrected by double-or triple-rotation and the standard values were not significant. Cluster analysis showed that the data corrected orderly by coordinate axes-rotated correction and WPL would be propitious to improve the precision. The results would provide a basis for calculating the fluxes within tropical rainforest in the future, and supply reference to the fluxes calculation for other areas.

The irrigated areas in the northern region of China are important food production areas. Therefore, studies on the variability of the carbon balance in these agro-ecosystems are fundamental for the management of carbon sequestration. This paper simulated the long-term variability of the carbon balance in a typical irrigated area along the lower Yellow River from 1984 to 2006, using a process-based ecosystem model called the Simple Biosphere Model, version 2. The mean annual gross primary production (GPP), mean annual net assimilation rate (NAR), mean annual soil respiration ( R), and mean annual net ecosystem exchange (NEE) were 1733, 1642, 1304, and −338 g C m a, respectively. A significant increasing trend in the seasonal total NAR during the wheat growing season, and a significant decreasing trend in the seasonal total NAR during the maize growing season were detected. However, no significant trend was found in the annual NAR, R, and NEE. The average carbon sequestration was 1.93 Tg C a when the grain harvest was not taken into account, and the carbon sequestration amount during the maize season was higher than that during the wheat season. However, the agro-ecosystem was a weak carbon source with a value of 0.23 Tg C a, when the carbon in the grain was assumed emitted into the atmosphere. [ABSTRACT FROM AUTHOR]

Deserts are one of the most important dust sources in the world. Because dust content changes as a function of height at low levels in the atmosphere, this affects long-term dust transport. In this paper, field data measured above shifting sands in the south-eastern Tengger Desert were used to analyse the vertical distribution of sediment fluxes in the near-surface layer (0 to 48 m). It was possible to express horizontal sediment flux as a power function, but aeolian deposition as a function of height could be expressed as an exponential function. There are two curve types for the particle size distributions in the horizontal sediment flux and aeolian deposition: bimodal and unimodal curves. For the horizontal sediment flux and aeolian deposition, heights of 24 m and 32 m, respectively, were the key heights in the size distribution curve; below these heights, the curve was bimodal, whereas above these heights, it was unimodal. At heights of 4 to 16 m, and especially between 8 m and 12 m, the data were particularly interesting because the sediment size, transport mode, degree of sorting, and the skewness and kurtosis change. For the horizontal sediment flux, wind turbulence moved saltating particles higher than expected. [ABSTRACT FROM AUTHOR]

The atmospheric boundary layer (ABL) is an important physical characteristic of the Earth's atmosphere. Compared with the typical ABL, the ABL in arid regions has distinct features and is formed by particular mechanisms. In this paper, the depth of the diurnal and nocturnal ABLs and their related thermodynamic features of land surface processes, including net radiation, the ground-air temperature difference and sensible heat flux, under typical summer and winter conditions are discussed on the basis of comprehensive observations of the ABL and thermodynamic processes at the land surface carried out in the extreme arid zone of Dunhuang. The relationships of the ABL depth in the development and maintenance stages with these thermodynamic features are also investigated. The results show that the depth of the ABL is closely correlated with the thermodynamic features in both development and maintenance stages and more energy is consumed in the development stage. Further analysis indicates that wind velocity also affects ABL development, especially the development of a stable boundary layer in winter. Taken together, the analysis results indicate that extremely strong thermodynamic processes at the land surface are the main driving factor for the formation of a deep ABL in an arid region. [ABSTRACT FROM AUTHOR]

Fast and accurate retrieval of lightning sources is crucial to the early warning and quick repairs of lightning disaster. An algorithm for computing the location and onset time of cloud-to-ground lightning using the time-of-arrival (TOA) and azimuth-of-arrival (AOA) data is introduced in this paper. The algorithm can iteratively calculate the leastsquares solution of a lightning source on an oblate spheroidal Earth. It contains a set of unique formulas to compute the geodesic distance and azimuth and an explicit method to compute the initial position using TOA data of only three sensors. Since the method accounts for the effects of the oblateness of the Earth, it would provide a more accurate solution than algorithms based on planar or spherical surface models. Numerical simulations are presented to test this algorithm and evaluate the performance of a lightning detection network in the Hubei province of China. Since 1990s, the proposed algorithm has been used in many regional lightning detection networks installed by the electric power system in China. It is expected that the proposed algorithm be used in more lightning detection networks and other location systems. [ABSTRACT FROM AUTHOR]

Based on homogenized land surface air temperature (SAT) data (derived from China Homogenized Historical Temperature (CHHT) 1.0), the warming trends over Northeast China are detected in this paper, and the impacts of urban heat islands (UHIs) evaluated. Results show that this region is undergoing rapid warming: the trends of annual mean minimum temperature (MMIT), mean temperature (MT), and mean maximum temperature (MMAT) are 0.40 C decade−1, 0.32 C decade−1, and 0.23 C decade−1, respectively. Regional average temperature series built with these networks including and excluding “typical urban stations” are compared for the periods of 1954–2005. Although impacts of UHIs on the absolute annual and seasonal temperature are identified, UHI contributions to the long-term trends are less than 10% of the regional total warming during the period. The large warming trend during the period is due to a regime shift in around 1988, which accounted for about 51% of the regional warming. [ABSTRACT FROM AUTHOR]

This paper examines variations of the surface air temperature (SAT) over China and the globe in the twentieth century simulated by 19 coupled climate models driven by historical natural and anthropogenic forcings. Most models perform well in simulating both the global and the Northern Hemispheric mean SAT evolutions of the twentieth century. The inclusion of natural forcings improves the simulation, in particular for the first half of the century. The reproducibility of the SAT averaged over China is lower than that of the global and hemispheric averages, but it is still acceptable. The contribution of natural forcings to the SAT over China in the first half of the century is not as robust as that to the global and hemispheric averages. No model could successfully produce the reconstructed warming over China in the 1920s. The prescribed natural and anthropogenic forcings in the coupled climate models mainly produce the warming trends and the decadal- to interdecadal-scale SAT variations with poor performances at shorter time scales. The prominent warming trend in the last half of the century over China and its acceleration in recent decades are weakly simulated. There are discrepancies between the simulated and observed regional features of the SAT trend over China. Few models could produce the summertime cooling over the middle part of eastern China (27°–36°N), while two models acceptably produce the meridional gradients of the wintertime warming trends, with north China experiencing larger warming. Limitations of the current state-of-the-art coupled climate models in simulating spatial patterns of the twentieth-century SAT over China cast a shadow upon their capability toward projecting credible geographical distributions of future climate change through Intergovernmental Panel on Climate Change (IPCC) scenario simulations. [ABSTRACT FROM AUTHOR]

Most standalone atmospheric models do not perform well in simulations of coastal boundary layer jets (BLJs), important weather processes that can trigger heavy rain in coastal areas by supplying both moisture and dynamic lifting. We compared 33‐year simulations with a coupled atmosphere–ocean model and its standalone atmospheric component, the REgional atmosphere MOdel (REMO), forced by the prescribed sea surface temperature (SST). We validated our results using the Tropical Rainfall Measuring Mission SST and the ERA5 hourly reanalysis data set. We found that the coupled model gave a more realistic SST standard deviation than the REMO on BLJ days and corrected the overestimated air temperature over land during the day. The coupled atmosphere–ocean model showed a lower land–sea thermal contrast in the boundary layer. This increased the effects of inertial oscillation, which caused the ageostrophic flows to veer southwest, which is the direction of the maximum wind speed on BLJ days. This reproduced a more reasonable land–sea thermal contrast in the boundary layer as a result of strong air–sea mixing in coastal weather processes, which led to a more robust inertial oscillation and a larger SST standard deviation over the central South China Sea. These findings deepen our understanding of the influence of a fully mixed air–sea boundary on coastal weather processes. These results show that operational numerical weather prediction models can be improved by applying atmosphere–ocean coupling to advance their ability to forecast the weather (e.g., BLJ events) in coastal areas. Plain Language Summary: Coastal boundary layer jets (BLJs) are important coastal weather processes and, because they are precursor signals of heavy rain, they can be used to improve operational numerical weather forecasts. Coupled atmosphere–ocean models improve the predictability of BLJs in South China, but we still need a deeper understanding of the mechanism leading to their occurrence. We compared 33‐year simulations with a coupled atmosphere–ocean model and its standalone atmospheric component forced by the prescribed sea surface temperature (SST). Through validation against remote sensing SSTs and ERA5 hourly reanalysis data, we found that the coupled model gave a more realistic SST standard deviation and corrected the overestimated air temperature over land surfaces. These improvements helped the coupled atmosphere–ocean model to reproduce a more reasonable land–sea thermal contrast in the boundary layer as a result of strong air–sea mixing in coastal weather processes, which led to a more robust inertial oscillation and a larger SST standard deviation over the central South China Sea. We conclude that the impact of the influence of a fully mixed air–sea boundary on coastal weather processes is larger than previously recognized. Key Points: The use of atmosphere‐ocean coupling can improve the predictability of coastal boundary layer jets in South ChinaThe coupled model gave a more realistic sea surface temperature standard deviation and corrected the overestimated air temperatureStrong air‐sea mixing led to a more robust inertial oscillation, veering the ageostrophic flows toward the direction of the maximum wind [ABSTRACT FROM AUTHOR]