Yuanjian Yang

Nanjing University of Information Science & Technology · School of Atmospheric Physics

Air quality in China has been gradually improving because of recent emission control policies, but synoptic circulations in the planetary boundary layer have become increasingly conducive to haze formation. The effect of persistent synoptic circulation (PSC) on long-term variation in haze episodes remains to be fully elucidated. This study identifi...

Previous studies have reported boundary layer features related to air pollution. However, few studies have comprehensively evaluated the characteristics and mechanisms of vertical wind in the formation and evolution of heavy particulate matter pollution episodes (EP) in Hong Kong. In this study, we analyzed the vertical characteristics of heavy par...

Plain Language Summary A detailed understanding of the relationship between PM2.5 (particulate matter with aerodynamic diameter equal to or less than 2.5 μm) and the urban heat island (UHI) effect is significant for climate change adaption, planning, and sustainable development in urban regions. While the Beijing‐Tianjin‐Hebei (BTH) megalopolis of...

Studying precipitation diurnal variation characteristics is crucial to better understand their formation mechanism. Moreover, it is fundamental in assessing regional climate variability and to validate the effectiveness of cloud and precipitation parameterization schemes in weather and climate models. Based on observational data from 2008 to 2017,...

Studying the spatiotemporal variations of the urban heat island (UHI) effect and its cause is important towards understanding urban climate change, planning and green development, and disaster mitigation. In this paper, by using surface observations and reanalysis data with objective classification of synoptic weather patterns (SWPs), we analyze th...

The summertime air pollution events endangering public health in the Guangdong–Hong Kong–Macao Greater Bay Area are connected with typhoons. The wind of the typhoon periphery results in poor diffusion conditions and favorable conditions for transboundary air pollution. Random forest models are established to predict typhoon-associated air quality i...

Taking Lanzhou (a typical mountain-valley city in Northwest China) as an example, the diurnal and interannual variation characteristics of the canopy urban heat island (CUHI) and its relationship with heat waves (HWs), local climate zones (LCZs), mountain-valley wind circulation and aerosol pollution were explored. Results showed that the peak CUHI...

Precise and continuous monitoring on long-term carbon dioxide (CO2) and methane (CH4) over the globe is of great importance, which can help study global warming and achieve the goal of carbon neutrality. Nevertheless, the available observations of CO2 and CH4 from satellites are generally sparse, and current fusion methods to reconstruct their long...

Plain Language Summary Eddy covariance (EC) method is the well‐accepted technique to calculate turbulent flux under stationary conditions. However, the observational turbulence data sometimes show non‐stationarity, and in this case, the EC method is not applicable and wavelet analysis (WA) is frequently used. However, because turbulent fluxes are c...

Under the background of global warming, interaction between heat waves (HWs) and urban heat island (UHI) has led to trends of increase in the intensity, frequency, and duration of extreme heat events in urban areas, seriously threatening the health of urban populations. Taking Guangzhou (a tropical megacity in China) as an example, this study used...

Human-perceived thermal comfort (known as human-perceived temperature) measures the combined effects of multiple meteorological factors (e.g., temperature, humidity, and wind speed) and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being sev...

Mesoscale convective cloud systems have a small horizontal scale and a short lifetime, which brings great challenges to quantitative precipitation estimation (QPE) by satellite remote sensing. Combining machine learning models and geostationary satellite spectral information is an effective method for the QPE of mesoscale convective cloud, while th...

Compared with the urban boundary layer, air pollution–surface energy budget interactions in farmland areas are relatively sparse. To investigate the roles of local aerosol and transported dust pollution on the surface energy balance over farmland, a field experiment was conducted during spring 2016 in eastern China. The heavy pollution episodes dur...

Studying the long-term variations in warm and cold events and their causes under global warming is important for understanding urban climate change, planning, and green development, as well as for disaster prevention and mitigation. In this study, taking the megacity of Nanjing in China as an example, we analyzed the trends and characteristics of t...

Warm-sector heavy rainfall in South China is a frequent type of precipitation in summer in the Pearl River Delta region. The complexity of the mechanisms involved in the triggering of convection, especially the effects of urbanization, has greatly increased the uncertainty of numerical simulations of warm-sector heavy rainfall. In this study, five...

Human thermal comfort measures the combined effects of temperature, humidity, and wind speed, etc., and can be aggravated under the influences of global warming and local human activities. With the most rapid urbanization and the largest population, China is being severely threatened by aggravating human thermal stress. However, the variations of t...

The urban barrier effect is one possible physical mechanism by which the urbanization alters the spatial distribution of cloud‐to‐ground (CG) lightning activity in a city. There is a gap in the preceding research on an urban barrier effect to alter patterns of CG lightning in Beijing, and the urban morphology does not receive enough attention as an...

Unprecedented urbanization in China has led to serious urban heat island (UHI) issues, exerting intense heat stress on urban residents. Based on the observed temperature and PM2.5 concentrations in Beijing over 2016–2020, we find diverse influences of aerosol pollution on urban heat island intensity (UHII) under different circulations. When norther...

A micro-pulse lidar system incorporating differential absorption lidar (DIAL) and coherent Doppler wind lidar (CDWL) is proposed and demonstrated. Due to the high signal-to-noise ratio (SNR) of the superconducting nanowire single-photon detector (SNSPD), the DIAL channel achieves high sensitivity in CO2 measurement. Meanwhile, the CDWL channel is u...

The summertime air pollution events endangering public health in the Guangdong–Hong Kong–Macao Greater Bay Area are connected with typhoons. The wind of the typhoon periphery results in poor diffusion conditions and favorable conditions for transboundary air pollution. Random Forest models are established to predict typhoon-associated air quality i...

A benchmark dataset of radiation, heat, and CO2 fluxes is crucial to land–atmosphere interaction research. Due to rapid urbanization and the development of agriculture, the land–atmosphere interaction processes over the Yangtze River Delta (YRD) of China, which is a typical East Asian monsoon region, are becoming various and complex. To understand...

Extreme torrential rainfall events are low-probability events. A “China-Record Extremely Heavy Rainfall” (CREHR) event with rain rate of 201.9 mm/h occurred on 20 July in Zhengzhou in North China. Using high-density meteorological observations, ERA5 reanalysis data, remote sensing data from China’s FY-4A satellite, and numerical simulation, we reve...

As a combination of temperature and humidity, wet-bulb temperature (WBT) is useful for assessing heat stress and its societal and economic impacts. However, spatial and temporal behaviors of summer WBT in China remain poorly understood. In this study, we investigate the dominant spatiotemporal modes of summer (June–July–August) WBT in the mainland...

Air pollution and extreme heat have been responsible for more than a million deaths in China every year, especially in densely urbanized regions. While previous studies intensively evaluated air pollution episodes and extreme heat events, a limited number of studies comprehensively assessed atmospheric hot-and-polluted-episodes (HPE) – an episode w...

Urban ventilation planning (UVP) are critically important to sustainable and green urban development. However, the climatic-environmental effects and benefits of urban ventilation corridors have yet to be fully understood. In this study, high-resolution simulation tests were carried out for winter of 2018 and summer of 2019 using the weather resear...

The monitoring and tracking of urban air pollution is a challenging environmental issue. The approach of synchronous 3-D detection of wind and pollution using a solo coherent Doppler wind lidar (CDWL) is developed and demonstrated. The 3-D distribution of pollutant is depicted by the backscatter coefficient based on signal intensity of CDWL. Then,...

A benchmark dataset of radiation, heat and CO2 fluxes is crucial to land–atmosphere interaction research. Due to the rapid urbanization and the development of agriculture, land–atmosphere interaction process over the Yangtze River Delta (YRD) of China, which is the typical East Asian monsoon region, is becoming various and complex. To understand th...

Heatwaves (HWs) paired with higher ozone (O3) concentration at the surface level pose a serious threat to human health. Their combined modulation of synoptic patterns and urbanization remains unclear. Using 5 years of summertime temperature and O3 concentration observation in Beijing, this study explored potential drivers of compound HWs and O3 pol...

The summertime atmospheric water vapor transport (WVT) of the Tibetan Plateau (TP) and surrounding regions is investigated based on the ERA5 reanalysis data during 1990–2019. It is found that the ascending motion on the south of the TP is conducive to the transport of water vapor from the low-latitude monsoon regions to the TP, showing strong WVT a...

China suffers from combined air pollution (CAP) comprising dual high O3 and PM2.5, particularly in the Beijing–Tianjin–Hebei (BTH) region, which is an urban agglomeration in the North China Plain. To characterize the seasonal changes in regional CAP, 82 CAP days were identified during the study period from 2015 to 2019 with the co-occurring polluti...

Unprecedented urbanization in China has led to serious urban heat island (UHI) issues, exerting intense heat stress on urban residents. Based on observed temperature and PM2.5 concentrations in Beijing over 2016–2020, we find diverse influences of aerosol pollution on urban heat island intensity (UHII) under different circulations. When northerly w...

A complex and varied terrain has a great impact on the distribution of wind energy resources, resulting in uncertainty in accurately assessing wind energy resources. In this study, three wind speed distributions of kernel, Weibull, and Rayleigh type for estimating average wind power density were first compared by using meteorological tower data fro...

Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high-spatial-resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evalua...

It is important to quantify changes in the local meteorological observational environment (MOE) around weather stations if we are to obtain accurate assessments of the regional warming of the surface air temperature (SAT) in relation to urbanization bias. Current studies often use two-dimensional parameters (e.g., the land surface temperature, land...

Although many severe pollution events in Central and East China have been analyzed in recent years, the heavy PM2.5 pollution episode happened on persistent foggy days from January 13 to 18, 2018 was unique, characterized by explosive increase and sharp decrease in PM2.5 (particles with kinetic equivalent diameter less than or equal to 2.5 microns)...

The regime-dependence of aerosol-cloud interaction has recently been highlighted and explored using idealized cloud-resolving models in previous studies. We further utilized synergistic observations from satellites and LiDARs to reinforce understandings of this interaction, and then examined and clarified the regime dependence of aerosol indirect e...

Observation of a melting layer using a 1.55 µm coherent Doppler lidar (CDL) is first presented during a stratiform precipitation event. Simultaneous radar measurements are also performed by co-located 1.24 cm micro rain radar (MRR) and 10.6 cm Doppler weather radar (DWR). As a well-known bright band in radar reflectivity appears during precipitatio...

Heatwaves (HWs) paired with higher ozone (O3) concentration at surface level pose a serious threat to human health. Their combined modulation of synoptic patterns and urbanization remains unclear. By using five years of summertime temperature and O3 concentrations observation in Beijing, this study explored potential drivers of compound HWs and O3...

The correlations between the planetary boundary layer height (PBLH) and surface meteorological factors, including the surface wind speed (RWS), temperature (RTS), specific humidity (RSH), pressure (RPS), and lower tropospheric stability (RLTS), are investigated using hourly profiles from the Aircraft Meteorological Data Reports at 54 major airports...

The macro- and microphysical properties of clouds can reflect their vertical physical structure and evolution and are important indications of the formation and development of precipitation. We used four-year merged CloudSat-CALIPSO-MODIS products to distinguish the macro- and microphysical properties of precipitating and non-precipitating clouds o...

Using the ERA5 (the fifth major global reanalysis produced by the European Centre for Medium-Range Weather Forecasts) data and the T-PCA (Principal Component Analysis in T-mode) objective classification method to classify the 850-hPa geopotential height, we summarize four conceptual models of large-scale synoptic weather types over East Asia. By co...

A complex and varied terrain has a great impact on the distribution of wind energy resources, resulting in uncertainty in accurately assessing wind energy resources. In this study, three wind speed distributions of kernel, Weibull, and Rayleigh type for estimating average wind power density were first compared by using meteorological tower data fro...

Deriving large-scale and high-quality precipitation products from satellite remote-sensing spectral data is always challenging in quantitative precipitation estimation (QPE), and limited studies have been conducted even using China's latest Fengyun-4A (FY-4A) geostationary satellite. Taking three rainstorm events over South China as examples, a mac...

Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high spatial resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evalua...

Despite advances in remote sensing–based gross primary productivity (GPP) modeling, the calibration of the Moderate Resolution Imaging Spectroradiometer (MODIS) GPP product (GPPMOD) is less well understood over rice–wheat-rotation cropland. To improve the performance of GPPMOD, a random forest (RF) machine learning model was constructed and employe...

Tridacna spp. usually have annual and even daily growth bands, and thus provide great potential to be the high-resolution recorders of past climate and environmental changes of the ocean. However, current studies mainly focus on the geochemical records of Tridacna shells, the environmental and climatic implications of long time sequenced daily grow...

Satellite-based measurements are of crucial importance for the accurate global-scale estimation of precipitation at fine spatiotemporal resolutions. Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) (IMERG) represents a milestone in precipitation monitoring and integrates observations from multiple satellites with ana...

Synoptic weather conditions can modulate short-term variations in the marine biophysical environment. However, the impact of large-scale synoptic circulation patterns (LSCPs) on variations in chlorophyll-a (chl-a) and sea surface temperature (SST) in the South China Sea (SCS) remains unclear. Using a T-mode principal component analysis method, four...

As one of the aridest regions in the mid‐latitudes, arid Northwest China (ANC) has scarce water resources year‐round, its annual total precipitation is mainly contributed by summer extreme precipitation events, which may also cause disastrous flash floods. However, the physical mechanism and climatic features of extreme precipitation events in ANC...

Deriving large-scale and high-quality precipitation products from satellite remote sensing spectral data is always challenging in quantitative precipitation estimation (QPE), and limited studies have been conducted even using the China’s latest Fengyun-4A (FY-4A) geostationary satellite. Taking three rainstorm events over South China as examples, a...

The ocean surface and subsurface biophysical responses and their feedbacks to super typhoon Nida were comprehensively investigated based on a substantial dataset of multiple-satellite observations, Argo profiles, and reanalysis data. Nida experienced two Category 5 stages: a rapid intensification stage that was fast moving along a straight-line tra...

Rapid increases in urban sprawl affect the observational environment around meteorological stations by changing the land use/land cover (LULC) and the anthropogenic heat flux (AHF). Based on remote sensing images and GIS technology, we investigated the impact of changes in both LULC and AHF induced by urbanization on the meteorological observationa...