Strong Inversion Layer Research Articles

Atom layer deposited TiO2 electron transport layer for silicon heterojunction solar cells to achieve high performance

Silicon/compound heterojunction (SCH) solar cells based on p-type and n-type c-Si wafers using atom layer deposition-TiO2 and low work function metal as the electron transport layer and rear electrode are fabricated. Efficiencies of 20.6 % and 21.6 % are achieved on p-type and n-type silicon solar cells, respectively. High Voc exceeding 700 mV have been realized on both kinds of Si wafers. Special attention has been paid to the SCH solar cells based on p-type c-Si wafers in which the TiO2 electron transport layer serves as the emitter. Carrier transport mechanisms and junction characteristics of the SCH solar cells are analyzed based on dark J-V measurement. The formation of a strong inversion layer at the Si surface region is determined, which implies the high Voc potential of the SCH solar cells based on p-type Si. An optical loss analysis is performed along with a possible solution to further improve the Jsc. The feasibility of TiO2 applied as an efficient electron transport layer (emitter) in p-type SCH solar cells with high performance has been showed.

Detection of Fe and Ti on the dayside of the ultrahot Jupiter MASCARA-1b with CARMENES

Ultrahot Jupiters are a type of gaseous exoplanet that orbit extremely close to their host star, resulting in significantly high equilibrium temperatures. In recent years, high-resolution emission spectroscopy has been broadly employed in observing the atmospheres of ultrahot Jupiters. We used the CARMENES spectrograph to observe the high-resolution spectra of the dayside hemisphere of MASCARA-1b in both visible and near-infrared. Through cross-correlation analysis, we detected signals of Fe I and Ti I. Based on these detections, we conducted an atmospheric retrieval and discovered the presence of a strong inversion layer in the planet’s atmosphere. The retrieved Ti and Fe abundances are broadly consistent with solar abundances. In particular, we obtained a relative abundance of [Ti/Fe] as −1.0 ± 0.8 under the free retrieval and −0.4−0.8+0.5 under the chemical equilibrium retrieval, suggesting the absence of significant titanium depletion on this planet. Furthermore, we considered the influence of planetary rotation on spectral line profiles. The resulting equatorial rotation speed was determined to be 4.4−2.0+1.6 km s−1, which agrees with the rotation speed induced by tidal locking.

The covariability between temperature inversions and aerosol vertical distribution over China

Temperature inversions (TI) have a unique impact on the regulation of aerosol distribution. However, it remains unclear the covariability of TI and aerosol vertical distribution. To address this issue, ten years CALIPSO observations and the fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis system (ERA5) data from January 2008 to December 2017 across China were collected. The aim was to explore the relationship between TI and the aerosol vertical distribution. The characteristics of TI and aerosol vertical distribution have been analysed in the Taklimakan Desert (TD), North China (NC), South China (SC) and Sichuan Basin (SB). The results demonstrate that the frequency of TI, inversion strength (ΔT), and TI height (TIH) follow a similar seasonal pattern across the four areas. Specifically, they are highest in winter, followed by spring and autumn, and the least in summer. Notably, NC exhibits a significantly higher average frequency (10.3%) of TI during summertime compared to the other regions. This may be a result of the heating effect of the elevated black carbon aerosol on the upper atmosphere. Moreover, the observations demonstrate that aerosol optical depth (AOD) above the TIH in the four areas is greater during spring and summer months compared to autumn and winter. It indicates that there is an obvious aerosol high-level transport over the Chinese mainland in spring and summer. In winter months, most of the aerosols are located below the TIH. This phenomenon occurs due to the influence of a strong inversion layer and adverse atmospheric ventilation conditions. In addition, the average AOD below TIH increases with the ΔT increased in TD region, supporting the hypothesis that a strong inversion can suppress surface aerosols below the TI. Conversely, in NC and SC regions, the average AOD below (above) TIH decreases (increases) as the ΔT increases. It indicates that the strong atmospheric stability forms a more effective transmission channel, resulting in the accumulation of aerosols above TIH. These findings have important support for studying aerosol transport.

A case study of mesospheric frontal interaction and associated processes over the western Himalaya

An interesting event of interaction between a mesospheric bore and a front is observed in O(1S) 557.7 nm airglow images over the western Himalayan region on the night of 25 April 2022. The event is unique as it is the first report of a mesospheric bore interacting with a typical mesospheric front. The vertical profiles of temperature and Brunt Vaisala frequency indicate presence of a strong mesospheric inversion layer (MIL) which acts as a stable thermal duct for propagation of the mesospheric bore. Chemical heating is believed to be a causative mechanism for sustaining such strong MIL/thermal duct, although the presence of Doppler duct could not be verified due to a lack of wind measurement. The bore front shows an anti-clockwise rotation with time which is attributed to the differential phase speed between the extreme parts of the bore due to variation of duct depth. The bore propagation above is believed to push the underlying OH layer downward, resulting in a maximum horizontal slope of the peak height of the OH volume emission rate (VER) on the event day. The results highlight the characteristics of bore-front interaction, bore propagation supported by the thermal duct, and its effect on the vertical displacement of the airglow emission layers.

Response of sea surface heat fluxes to the South China Sea summer monsoon onset in 2021

By using the ship-based data collected over the South China Sea during the South China Sea summer monsoon (SCSSM) in 2021, the characteristics of near-surface meteorological conditions, surface heat budget, and atmospheric boundary layer structure are analyzed. We found that near-surface air temperature (relative humidity) decreased significantly during the developed monsoon period, while near-surface wind speed showed an obvious increase trend from the pre-monsoon period to the developed monsoon period. The significant reduction of solar radiation due to cloud cover led to the reverse of oceanic heat flux direction from downward to upward. The sea surface sensible and latent heat fluxes were restrained after the SCSSM onset. The atmospheric boundary layer height presented a positive (negative) correlation with near-surface air temperature (humidity). In addition, the vertical profiles of wind speed, virtual potential temperature, and air humidity revealed that: after monsoon onset, (i) the atmospheric circulation within the atmospheric boundary layer accelerated, with a strong low-level jet located below 500-m height; (ii) there was a strong inversion layer below 500-m height, especially at 1300 and 1900 local time (LT); (iii) the atmospheric humidity in low-level raised significantly.

Unveiling the role of ethylene glycol for enhanced performance of PEDOT:PSS/Silicon hybrid solar cells

Recently, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and n-silicon (n-Si) based hybrid solar cells (HSCs) are given significant attentions owing to their cost-effective processing and promising photovoltaic performances. Pristine PEDOT:PSS, however, due to its limited electrical conductivity, cannot yield highly efficient HSCs. Doping of ethylene glycol (EG) in PEDOT:PSS boosts its electrical properties. However, role of EG on the formation, working mechanism of PEDOT:PSS/n-Si heterojunction and the performance of the HSCs are rarely explained. Herein, influence of EG on the optical, structural, electrical, and passivation properties of PEDOT:PSS along with polymer/n-Si heterojunction formation is investigated. HSCs with significantly enhanced power conversion efficiency (by ∼3.5 fold) is achieved for an optimal EG concentration (as compared to pristine PEDOT:PSS) on micro-engineered thin n-Si wafers even in the simplest device design. Optimal EG induces a strong inversion layer (p+-n junction) in n-Si at the polymer/Si interface enabling efficient separation and transportation of photo-carriers and hence enhanced solar cell performances. Formation of EG dependent strong electric field at polymer/n-Si interface is confirmed by the results of minority carrier lifetime, J-V characteristics, quantum efficiency, electrochemical impedance and C-V measurements of the HSCs. Role of EG in making an efficient PEDOT:PSS/n-Si solar cell is explained which may pave the way for further advancement of the cost-effective hybrid solar cell technology.

Characterizing a Heavy Dust Storm Event in 2021: Transport, Optical Properties and Impact, Using Multi-Sensor Data Observed in Jinan, China

On 15 March 2021, the strongest sandstorm of the last 10 years occurred in China. The MODIS, MPL lidar, EDM 180, ADI 2080 and Meteorological observation instruments were used to observe the dust in Jinan, China, while the HYSPLIT model was also employed to find the source. It was found that the dust originated from Mongolia and the Gobi desert and was transported to Jinan at night on 14th March, lasting until the 18th. Multi-layer dust was observed, of which the dust below the height of 1 km was strongest with the VDR about 0.2 and the maximum extinction coefficient up to 3 km−1. The values of AOD and AE were greater than 2 and less than 0.25, respectively. The mass concentrations of PM10 and PM2.5 increased rapidly, and were up to 573 µg/m3 and 3406 µg/m3, respectively. Additionally, the mass concentration ratio decreased rapidly, with a minimum of 17%. The particle size of the dust was mainly distributed between 0.58–6.50 micros due to larger particles increasing dramatically; simultaneously, both the proportion and the value for calcium ions in PM2.5 went up. The dust had an obvious impact on the vertical structure of the air temperature, resulting in occurrence of a strong inversion layer.

An enhanced two-dimensional hole gas (2DHG) C\u2013H diamond with positive surface charge model for advanced normally-off MOSFET devices

Though the complementary power field effect transistors (FETs), e.g., metal–oxide–semiconductor-FETs (MOSFETs) based on wide bandgap materials, enable low switching losses and on-resistance, p-channel FETs are not feasible in any wide bandgap material other than diamond. In this paper, we propose the first work to investigate the impact of fixed positive surface charge density on achieving normally-off and controlling threshold voltage operation obtained on p-channel two-dimensional hole gas (2DHG) hydrogen-terminated (C-H) diamond FET using nitrogen doping in the diamond substrate. In general, a p-channel diamond MOSFET demonstrates the normally-on operation, but the normally-off operation is also a critical requirement of the feasible electronic power devices in terms of safety operation. The characteristics of the C–H diamond MOSFET have been analyzed with the two demonstrated charge sheet models using the two-dimensional Silvaco Atlas TCAD. It shows that the fixed-Fermi level in the bulk diamond is 1.7 eV (donor level) from the conduction band minimum. However, the upward band bending has been obtained at Al2O3/SiO2/C-H diamond interface indicating the presence of inversion layer without gate voltage. The fixed negative charge model exhibits a strong inversion layer for normally-on FET operation, while the fixed positive charge model shows a weak inversion for normally-off operation. The maximum current density of a fixed positive interface charge model of the Al2O3/C-H diamond device is − 290 mA/mm, which corresponds to that of expermental result of Al2O3/SiO2/C-H diamond − 305 mA/mm at a gate-source voltage of − 40 V. Also, the threshold voltage Vth is relatively high at Vth = − 3.5 V, i.e., the positive charge model can reproduce the normally-off operation. Moreover, we also demonstrate that the Vth and transconductance gm correspond to those of the experimental work.

Sub-stochiometric MoO x by radio-frequency magnetron sputtering as hole-selective passivating contacts for silicon heterojunction solar cells

The silicon heterojunction (SHJ) solar cell has long been considered as one of the most promising candidates for the next-generation PV market. Transition metal oxides (TMOs) show good carrier selectivity when combined with c-Si solar cells. This has led to the rapid demonstration of the remarkable potential of TMOs (especially MoO x ) with high work function to replace the p-type a-Si:H emitting layer. MoO x can induce a strong inversion layer on the interface of n-type c-Si, which is beneficial to the extraction and conduction of holes. In this paper, the radio-frequency (RF) magnetron sputtering is used to deposit MoO x films. The optical, electrical and structural properties of MoO x films are measured and analyzed, with focus on the inherent compositions and work function. Then the MoO x films are applied into SHJ solar cells. When the MoO x works as a buffer layer between ITO/p-a-Si:H interface in the reference SHJ solar cell, a conversion efficiency of 19.1% can be obtained. When the MoO x is used as a hole transport layer (HTL), the device indicates a desirable conversion efficiency of 17.5%. To the best of our knowledge, this current efficiency is the highest one for the MoO x film as HTL by RF sputtering.

P-type c-Si/SnO2/Mg heterojunction solar cells with an induced inversion layer

Crystalline silicon/compounds heterojunction (SCH) solar cells using oxides or fluorides as the electron or hole transport layers present great low-cost potential. In this paper, c-Si/SnO2 SCH solar cells are based on p-type c-Si substrates and use SnO2, prepared by atomic layer deposition, as the electron transport layers are investigated. By optimizing the SnO2 thickness and the device annealing process, a Voc of 718 mV and an efficiency of 20.1% are achieved on a champion SCH solar cell with an optimized SnO2 thickness of 3 nm. By analyzing the dark J–V curves, transport mechanisms of the silicon/compound heterojunction are investigated. It is proved that a strong inversion layer is induced in the p-type Si substrate, and a high hole barrier exists in the heterojunction region, which makes it a minority-carrier device. The induced inversion layer at the Si surface and the carrier selective transport effect of the SnO2 layer together enable the devices to achieve a high Voc.

Toward sustainable meteorological profiling in polar regions: Case studies using an inexpensive UAS on measuring lower boundary layers with quality of radiosondes

This study assessed the possibility of producing profiles of atmospheric parameters, including aerosol number concentration, using observations obtained by a conventional low-cost small rotary-wing Unmanned Aircraft Systems (UAS). A radiation shield for the meteorological sensor was developed to reduce the effects from heat exhaust from both the rotors and the body of the UAS and from solar radiation. Field experiments in northern Japan during winter confirmed that the continuous UAS-derived meteorological data obtained in the lower boundary layer were of quality equivalent to that of radiosonde observations in a cold environment (<− 20 °C), that is, better than other meteorological rotary-wing UASs. The continuous profiling of aerosols also demonstrated the capability for monitoring air quality below a very strong inversion layer during winter. Quality-controlled UAS meteorological profiles would be a potential observation data source for skillful numerical weather prediction, particularly in data-sparse regions such as the Arctic and Antarctic, contributing to the sustainable polar observing network.

Impacts of synoptic forcing and topography on aerosol pollution during winter in Shenyang, Northeast China

Northeast China frequently experiences aerosol pollution episodes in winter. In addition to the pollutant emissions, synoptic pattern and topography can impact the air quality in complex ways, which are still not well understood in Northeast China. Therefore, the impacts of synoptic forcing and topography on aerosol pollution in Shenyang were investigated combining surface observations, sounding measurements, and three-dimensional air quality simulations. The studied pollution episode occurred from January 1 to 5, 2020, along with poor meteorological dispersion conditions characterized by weak winds, strong thermal stabilities, and shallow planetary boundary layers (PBLs). During the formation of pollution, strong elevated thermal inversion layers were observed over Shenyang, induced by the large-scale synoptic pattern, which suppressed the PBL growth and the vertical dispersion of aerosols. Moreover, the blocking effect of mountains to the east of Shenyang further worsened the pollution when northwesterly/westerly flows prevailed in shallow PBLs. Numerical sensitive experiment was conducted to estimate the contribution of blocking effect of mountains to the near-surface PM2.5 concentration in Shenyang, and it was found that around one third of PM2.5 concentration during January 1–4 was relevant to the terrain effect. These findings can facilitate a comprehensive understanding of the physical formation of aerosol pollution in Northeast China and helpful for the pollution controls.

Formation mechanism of a severe air pollution event: A case study in the Sichuan Basin, Southwest China

The formation mechanism of air pollution events in the Sichuan Basin (SB), which is the fourth most heavily polluted area in China, has not been fully revealed. This study investigated the formation mechanism of a severe air pollution event over the SB using synoptic approaches and model simulations. The results can be summarized as follows: (1) Heavy air pollution in the SB was characterized by low visibility, low atmospheric boundary layer (ABL) height, high temperature, high relative humidity, strong temperature inversion layer, subsidence in the troposphere, high water vapor content between 500 and 900 hPa, southerly winds in the low troposphere, and surface winds with low speed and irregular direction. (2) Air quality in the SB was closely related to the weather system at 700 hPa over the basin. When the 700 hPa weather system affecting the SB was a high-pressure system, the subsidence and stable atmospheric stratification increased the air pollutant concentrations near the ground. When the 700 hPa weather system affecting the SB was a low-pressure system and the basin was in front of this low-pressure system, southwesterly warm and moist airflow and adiabatic subsidence warming formed the thick temperature inversion layer over the basin. As a result, the temperature inversion layer trapped air pollutants in the basin and induced the heavy air pollution event. When the 700 hPa weather system over the SB was a low-pressure system and the basin was behind the low-pressure system, the dry and cold airflow from the north invaded southward to the basin and broke the temperature inversion layer. Consequently, air pollutants dispersed vertically, resulting in decreased concentrations near the ground. (3) Air pollutants from December 17, 2017 to January 4, 2018 were mainly from local emissions. (4) The WRF-Chem model not only reproduced the variations in PM2.5 concentrations, the ABL height, and the height-time cross-sections of temperature, water vapor content, and wind over Chengdu during the air pollution event, but also revealed the formation mechanism of this heavy air pollution event. The results of this study reveal the formation mechanism of winter heavy air pollution events over the SB and help develop effective regional air quality management strategies to reduce the likelihood of local air pollution events and minimize the adverse impacts of air pollution.

First observation of atmospheric electric field at Kashmir valley North Western Himalayas, Srinagar (India)

Preliminary results from the measurement of potential gradient (PG) for the period of March 2018–February 2019 at the University of Kashmir, Srinagar, (34° 03′ N, 74° 51’ E, 1585 m amsl) India is reported. The annual mean diurnal variation of PG represents typical double-maxima pattern with the primary maximum at 0900–1000 LT and the secondary maximum at 1900–2000 LT which is in accordance with the measurements at different continental stations. The primary maximum of PG and its extended duration is explained by the sunrise effect due to increasing surface temperature, the development of surface convection and hence the boundary layer probably favour the uplifting of the surface aerosols. The higher PG values measured at Kashmir valley were explained with the height of the measurement from the surface and the role of mountain-valley winds circulation. Monthly mean PG showed the higher value during December and minimum in June and the amplitude variations were attributed to the local PM concentrations. PG is found to be highly influenced by PM2.5 compared to PM10, due to the high suspension duration in the ambient air. Measurement of PM2.5 to Srinagar showed higher values in December followed by the November and January under the strong inversion layer formation in Kashmir valley with the westerly winds apart from an increase in the local tourist activity. The measured PG values and its observed variations are explained considering the role of aerosol concentration, atmospheric mixing and mountain-valley wind circulations. The present results are comparable with measurements of PG at different continental stations. The level of aerosols and site location shows variation in amplitude as well as temporal shift.

Performance enhancement of organic/Si solar cell using CNT embedded hole selective layer

In this work, we present a simple and solution-based synthesis approach to combine the virtues of PEDOT:PSS and carbon nanotube (CNT) by developing a composite film and their application as a hole selective layer (HSL) in organic-silicon hybrid heterojunction solar cell. The heterojunction solar cell with the optimised PEDOT: PSS-CNT HSL showed a notable open-circuit voltage (Voc) of 588.6 mV, short circuit current density (Jsc) of 25.3 mA/cm2 and fill factor (FF) of 60.79% yielding a photo-conversion efficiency (η) of 9.05%. The pristine PEDOT:PSS/Si device obtained an η of 6.2% with a Voc of 502 mV. The role of CNT in the charge transport mechanism and improving Voc was corroborated by employing various characterisation methods such as J-V, C-V, and electrochemical impedance spectroscopy. The composite layer induced a strong inversion layer in silicon and enhanced the device performance. The application of PEDOT:PSS-CNT composite film is not limited to c-Si solar cells, but can also be used to fabricate flexible organic and perovskite solar cells.

Contribution of Northeastern Asian stratospheric warming to subseasonal prediction of the early winter haze pollution in Sichuan Basin, China

Predicting the interannual (IA) variability of the early winter haze pollution (HP) in Sichuan Basin (SCB) and analyzing the contribution of the complex terrain are of great significance and challenge as well. For one thing, this study finds that the second mode of early winter IA variations of the HP in Central Eastern China (CEC) is dominated by the pollutant pattern of SCB, characterized by an extreme value center located over SCB. For another, the mode accounts for 15.1% of the total variance and well represents the IA variability of the areal mean HP in SCB. Furthermore, the anomalous circulations conducive to the severe HP in SCB consist of the strengthened (weakened) north (south) branch of Tibetan Plateau (TP) bypassing westerlies at 700 hPa, enhanced descents over SCB, and a strong inversion layer at 750 hPa, suppressing the precipitation and the development of the planetary boundary layer (PBL) in SCB. As a result, dispersion and wet deposition conditions are poor, favorable for the occurrence of the HP in SCB.Observed evidences show that the regional warming in the upper stratosphere over Northeastern Asia in November can be a possible subseasonal precursory signal for the SCB mode. Above all, the warming at upper stratosphere will propagate downward and arrive at the lower stratosphere in 3–4 weeks. Followed by the southward and downward propagation through the longitudinal tilted isothermal surface, the warming arrives at the tropospheric mid-low latitudes in 2–3 weeks, leading to anomalous warming and descents over TP and SCB. Consequently, SCB sees the aforementioned three-dimensional anomalous circulations. For this reason, a physical-empirical subseasonal prediction model for the IA variability of the early winter HP in SCB is established in terms of the regional stratospheric temperature in November. Apparently, the hindcast shows a promising prediction skill.

Influence of Intermittent Turbulence on Air Pollution and Its Dispersion in Winter 2016/2017 over Beijing, China

With rapid urbanization in recent years, severe air pollution has emerged as a major issue for many regions of China, especially in some metropolises. A persistent pollution case during 6 December 2016–8 January 2017 was selected to investigate the relations between turbulent intermittency and frequent PM2.5 (particulate matters with diameter less than 2.5 μm) pollution events over the metropolitan region of Beijing, China. The accumulation of PM2.5 near the surface frequently occurred as a combined result of strong inversion layers, stagnant winds, high ambient humidity levels, and stable stratification during this case. Arbitrary-order Hilbert spectral analysis indicated that steep decreases in the PM2.5 concentration were simultaneous with the occurrence of intermittent turbulence and strong vertical mixing. A wind profiler observation revealed existence of low-level jets (LLJs) at the end of the polluted periods, suggesting that the upper-level turbulent mixing accompanied by the wind shear of LLJ was transported downward and enhanced the vertical mixing near the surface, which might have caused an abrupt reduction in PM2.5 and improvement in air conditions.

On the contribution of chemical oscillations to ozone depletion events in the polar spring

Abstract. This paper presents a numerical study of the oscillations (or recurrences) of tropospheric ozone depletion events (ODEs) using the further-developed one-dimensional KInetic aNALysis of reaction mechanics with Transport (KINAL-T) chemistry transport model. Reactive bromine is the major contributor to the occurrence of ODEs. After the termination of an ODE, the reactive bromine in the air is deposited onto aerosols or on the snow surface, and the ozone may regenerate via NOx-catalyzed photochemistry or by turbulent transport from the free troposphere into the boundary layer. The replenished ozone then is available for the next cycle of autocatalytic bromine release (bromine explosion) leading to another ODE. The oscillation periods are found to be as short as 5 d for the purely chemically NOx-driven oscillation and 30 d for a diffusion-driven oscillation. An important requirement for oscillation of ODEs to occur is found to be a sufficiently strong inversion layer. In a parameter study, the dependence of the oscillation period on the nitrogen oxides' concentration, the inversion layer strength, the ambient temperature, the aerosol density, and the solar radiation is investigated. Parameters controlling the oscillation of ODEs are discussed.

Regional stratification at the top of Earth's core due to core–mantle boundary heat flux variations

Earth’s magnetic field is generated by turbulent motion in its fluid outer core. Although the bulk of the outer core is vigorously convecting and well mixed, some seismic, geomagnetic and geodynamic evidence suggests that a global stably stratified layer exists at the top of Earth’s core. Such a layer would strongly influence thermal, chemical and momentum exchange across the core–mantle boundary and thus have important implications for the dynamics and evolution of the core. Here we argue that the relevant scenario is not global stratification, but rather regional stratification arising solely from the lateral variations in heat flux at the core–mantle boundary. Using our extensive suite of numerical simulations of the dynamics of the fluid core with heterogeneous core–mantle boundary heat flux, we predict that thermal regional inversion layers extend hundreds of kilometres into the core under anomalously hot regions of the lowermost mantle. Although the majority of the outermost core remains actively convecting, sufficiently large and strong regional inversion layers produce a one-dimensional temperature profile that mimics a globally stratified layer below the core–mantle boundary—an apparent thermal stratification despite the average heat flux across the core–mantle boundary being strongly superadiabatic.

Synoptic pattern and planetary boundary layer structure associated with aerosol pollution during winter in Beijing, China

The day-to-day variations in the planetary boundary layer (PBL) structure and air quality are closely governed by large-scale synoptic forcings. Partly due to the lack of long-term PBL observations during the winter in Beijing, the complex relationships between the large-scale synoptic patterns, local PBL structures/processes, and PM2.5 pollution have not been fully understood. Thus, this study systematically investigated these linkages by combining aerosol measurements, surface meteorological observations, radiosonde data, reanalysis, long-term three-dimensional meteorological simulations, and idealized meteorology-chemistry coupled simulations. Based on the validated long-term simulation results, the boundary layer height (BLH) in Beijing during two winters from 2013 to 2015 was calculated and compared with PM2.5 measurements. A significant anti-correlation was found between the daily BLH and PM2.5 concentration in Beijing, indicating the importance of the PBL structure on the variations in the aerosol pollution levels. Those days with low BLHs are often accompanied by a strong elevated thermal inversion layer. Based on the daily 900-hPa geopotential height fields, seven synoptic patterns were identified using an objective approach, in which two types were found to be associated with heavy PM2.5 pollution in Beijing. One pattern was characterized by weak northwesterly prevailing winds and a strong elevated thermal inversion layer over Beijing, and the local emissions of aerosols played a decisive role in the formation of heavy pollution. The other pattern was associated with southerly prevailing winds, which could transport the pollutants emitted from southern cities to Beijing. According to the meteorology-chemistry coupled simulations, southerly regional transportation can contribute approximately 56% of the PM2.5 in Beijing. The results of this study have important implications for understanding the crucial roles that multiscale meteorological factors play in modulating the aerosol pollution in Beijing during the winter.