Qin Kai

• Ph.D
• Professor（Full） at China University of Mining and Technology

This work focuses on Changzhi, Shanxi, China, a city and surrounding rural region with one of the highest atmospheric concentrations of methane (CH4) worldwide (campaign-wide minimum, mean, standard deviation, and max observations: 2.0, 2.9, 1.3, and 16 ppm) due to a rapid increase in the mining, production, and use of coal over the past decade. An...

Black carbon (BC) emission estimates remain highly uncertain, especially in regions impacted by biomass burning (BB) and rapid urban expansion, where emissions are temporally variable and often misrepresented in bottom-up inventories(Liu, J.; Cohen, J. B.; He, Q.; Tiwari, P.; Qin, J. Accounting for NOx Emissions from Biomass Burning and Urbanizatio...

Carbon monoxide is a primary pollutant in energy-rich regions. Here we use a space-based mass-conserving framework based on observed carbon monoxide and formaldehyde columns to quantify carbon monoxide emissions over the energy-driven province of Shanxi, China. Annualized total emissions are seven times higher on average compared with some existing...

We propose a novel method for computing the effects of TROPOMI observational uncertainties on emissions calculation arising from the nonlinearity of the gradient terms and non-biased filtering in space and time. Application using TROPOMI XCH4 data in clean areas of Western China with long-term WMO background observations quantifies a minimum detect...

Global high-resolution emission inventories of trace gases require refinement to align with ground-based observations, especially for extreme events and changing sources. This study utilizes two satellites to globally quantify NO2 and CO concentrations on daily to weekly scales and estimate emissions with uncertainty bounds, grid-by-grid, for regio...

Methane (CH4) emissions in coal-energy-rich regions are characterized by hidden emission point sources and highly variable emission rates. While the Matched Filter (MF) method for detecting the CH4 point source using hyperspectral satellite sensors has been validated for high-emission concentrations, the accurate inversion of low-concentration emis...

This study applies a mass-conserving model-free analytical approach to daily observations on a grid-by-grid basis of NO2 from the Tropospheric Monitoring Instrument (TROPOMI) to rapidly and flexibly quantify changing and emerging sources of NOx emissions at high spatial and daily temporal resolution. The inverted NOx emissions and optimized underly...

Here we use multi-waveband single scattering albedo observations from ground-based instruments and satellite to constrain black carbon aerosol's physical properties and loading over Xuzhou, China, and Dhaka, Bangladesh. Our daily high-resolution findings reveal smaller black carbon cores and spatially variable morphology dominate both regions. Colu...

Dear Colleagues, We are pleased to announce to you the 2nd Atmospheric Environmental Remote Sensing Society (AERSS) Annual Meeting which will be held in Hong Kong, China, from 1 to 4 December 2024. The conference is organized by the Atmospheric Environmental Remote Sensing Society (AERSS) and The Hong Kong Polytechnic University. It is anticipated...

Remote sensing based on satellites can provide long-term, consistent, and global coverage of NO2 (an important atmospheric air pollutant) as well as other trace gases. However, satellites often miss data due to factors including but not limited to clouds, surface features, and aerosols. Moreover, as one of the longest continuous observational platf...

This study presents the first column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4) and carbon monoxide (XCO) in the coal mine aggregation area in Shanxi, China, using two portable Fourier transform infrared spectrometers (EM27/SUNs), in the framework of the Collaborative Carbon Column Observing Network (COCCON). The measu...

This work uses a mixture of observations from surface remote sensing (AERONET) and satellite remote sensing (OMI) to uniquely compute the atmospheric column loading of black carbon (BC) mass concentration density (MCD) and number concentration density (NCD) on a grid-by-grid, day-by-day basis at 0.25°x0.25° over rapidly developing and biomass burni...

Accurate estimation of nitrogen dioxide (NO2) levels at high spatio‐temporal resolution is crucial for atmospheric research and public health assessments. This study introduces a novel machine learning (ML) framework enhanced with uncertainty quantification (UQ) to predict hourly NO2 concentrations over East Asia. Benefiting from tropospheric NO2 c...

Short-term measures on air quality improvement have been commonly conducted for major events held in China, while their effectiveness was insufficiently analyzed due to deficient capability of tracking the fast-changing emissions of cities. Here we combined a machine learning algorithm, multiple satellite measurements, and an air quality model, and...

Due to relatively short lifetime and wide variability, global-scale high-resolution emission inventories of trace gasses need further improvement to match ground-based observations, especially with respect to extreme events and changing sources. This work uses two satellites in tandem to globally constrain daily to weekly emissions of NO x and CO g...

This study presents a top-down aerosol characterization by combining UV band information from TROPOMI and multi-waveband data from AERONET to constrain black carbon (BC) aerosol size and mixing state. The approach, applied to Xuzhou, China, and Dhaka, Bangladesh, reveals smaller BC cores and non-linear morphological influences in both cities. While...

This study quantifies methane emissions in clean areas of Western China using TROPOMI XCH4 observations and a mass conserving method, while explicitly considering observational uncertainty. All resulting physically unrealistic emissions values are successfully identified and filtered using a mixture of a threshold-based approach and a stochastic ap...

A space-based mass-conserving framework using observed carbon monoxide (CO) and formaldehyde (HCHO) columns quanti es day-today and grid-to-grid CO emissions over energy-consuming Shanxi. Annualized total emissions are 8 times higher than a priori datasets, especially over low emission areas, resulting in an at least 7% increase in CO 2 emissions....

A simple and flexible mass balance approach was applied to observations of XCH 4 from TROPOMI to estimate CH 4 emissions over Shanxi Province, including the impacts of advective transport, pressure transport, and atmospheric diffusion. High-frequency eddy-covariance flux observations were used to constrain the driving terms of the mass balance equa...

This study applies a mass-conserving model-free analytical approach to daily observations on a grid-by-grid basis of NO2 from TROPOMI, to rapidly and flexibly quantify changing and emerging sources of NOx emissions at high spatial and 10 daily temporal resolution. The inverted NOx emissions and optimized underlying ranges include quantification of...

This work focuses on Changzhi, Shanxi China, a city and surrounding rural region with one of the highest atmospheric concentrations of methane (CH4) world-wide (campaign-wide minimum/mean/standard deviation/max observations: 2.0, 2.9, 1.3, and 16 ppm) due to a rapid increase in the mining, production, and use of coal over the past decade. An intens...

Rapid economic and energy growth in Asia has led to change in the loadings of black carbon (BC) in the last two decades. This work uses remotely sensed column absorbing aerosol optical depth to quantify BC loading day-by-day and grid-to-grid. Variance maximization is used to uniquely compute an unbiased set of observations of remotely sensed NO 2 i...

Satellite-based remote sensing enables the quantification of tropospheric NO2 concentrations, offering insights into their environmental and health impacts. However, remote sensing measurements are often impeded by extensive cloud cover and precipitation. The scarcity of valid NO2 observations in such meteorological conditions increases data gaps a...

Remote sensing based on satellites can provide long-term, consistent, and global coverage of NO2 (an important atmospheric air pollutant) as well as other trace gases. However, satellite data often miss data due to factors including but not limited to clouds, surface features, and aerosols. Moreover, one of the longest continuous observational plat...

Rapid urbanization and broad use of biomass burning have led to important changes in NOx [sum of nitrogen dioxide and nitrous oxide] emissions across South, Southeast, and East Asia, frequently occurring on day-to-day time scales and over areas not identified by existing emissions databases. Here we compute NOx emissions using remotely sensed NO2 [...

China stands out as a major contributor to anthropogenic methane (CH4) emissions, with coal mine methane (CMM) playing a crucial role. To control and reduce CH4 emissions, China has made a dedicated commitment and formulated an ambitious mitigation plan. To verify the progress made, the consistent acquisition of independent CH4 emission data is req...

China's Shanxi Province accounts for 12 % of global coal output and therefore is responsible for a very large fraction of the total global methane (CH4) emissions, as well as being a large source of uncertainty due to the lack of in situ and field measurements. This work introduces the first comprehensive attempt to compute the coal mine methane (C...

South East and East Asia are regions which have undergone rapid economic development, contributing a significant amount of urban and biomass burning emissions. While the connections between emissions, deposition, and impacts on the Earth System are theoretically understood, they are observationally and ill-constrained, especially with respect to th...

This work introduces the results of an intensive 15-day surface observation campaign of methane (CH4) and adapts a new analytical method to compute and attribute CH4 emissions. The selected area has a high atmospheric concentration of CH4 (campaign-wide minimum/mean/standard deviation/max observations: 2.0, 2.9, 1.3, and 16 ppm) due to a rapid incr...

Direct radiative forcing (DRF) of aerosols is driven by aerosol concentration, size, and mixing state, and solar radiation. This work introduces Core-Shell Mie model optimization (COSMO) to compute top of the atmosphere (TOA) forcing based on inversely constrained black carbon (BC) size and mixing state from AERONET, over two rapidly developing are...

China stands out as a major contributor to anthropogenic methane (CH4) emissions, with coal mine methane (CMM) playing a crucial role. To control and reduce CH4 emissions, China has made a dedicated commitment and formulated an ambitious mitigation plan. To verify the process made, the consistent acquisition of independent CH4 emission data is requ...

Rapid economic and energy growth in Asia has led to change in the loadings of black carbon (BC) the last two decades. This work uses remotely sensed column aerosol absorption (AAOD) to quantify BC loading day-by-day and grid-to-grid. An unbiased set of observations of remotely sensed NOx and variance maximization uniquely quantify the spatial and t...

Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2) retrieved from sun-synchronous satellite instruments have provided abundant NO2 data for environmental studies, but such data are limited by retrieval uncertainties and insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEM...

Direct radiative forcing (DRF) of aerosols is driven by aerosol concentration, size, and mixing state, and solar radiation. This work introduces Core-Shell Mie model optimization(COSMO) to compute top of the atmosphere (TOA) forcing based on inversely constrained BC size and mixing state from AERONET, over two rapidly developing areas: Lumbini and...

Current approaches to estimate NO x emissions fail to account for new and small sources, biomass burning, and sources which change rapidly in time, generally don't account for measurement error, and are either based on models, or do not consider wind, chemistry, and dynamical effects. This work introduces a new, model-free analytical environment th...

This work presents a new model-free inversion estimation framework (MFIEF) using daily TROPOspheric Monitoring Instrument (TROPOMI) NO2 columns and observed fluxes from the continuous emission monitoring system (CEMS) to quantify 3 years of daily scale emissions of NOx at 0.05∘×0.05∘ over Shanxi Province, a major world-wide energy-producing and ene...

China’s Shanxi Province accounts for 12 % of global coal output, and therefore is responsible for a very large fraction of the total global methane (CH4) emissions, as well as being a large source of uncertainty due to the lack of in-situ and field measurements. This work introduces the first comprehensive attempt to compute the coal mine methane e...

Nitrogen dioxide (NO2) air pollution provides valuable information for quantifying NOx (NOx = NO + NO2) emissions and exposures. This study presents a comprehensive method to estimate average tropospheric NO2 emission strengths derived from 4-year (May 2018–June 2022) TROPOspheric Monitoring Instrument (TROPOMI) observations by combining a wind-ass...

High spatial resolution soil moisture (SM) mapping is essential for a wide range of applications, especially for precision irrigation and crop management. This work proposes an SM estimation method combined with time series of L-band fully polarimetric synthetic aperture radar (PolSAR) and passive SM products over crop areas. Regarding the challeng...

Nitrogen dioxide (NO2) is a major air pollutant. Tropospheric NO2 vertical column densities (VCDs) retrieved from sun-synchronous satellite instruments have provided abundant NO2 data for environmental studies, but such data are limited by insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEMS...

This paper analyzes the similarities and differences of electronic engineering majors in Chinese and American universities from the aspects of undergraduate teaching operation and management, professional curriculum setting, and teaching and evaluation methods. Point, Image Retrieval Model DSHB in Deep Semantic Hashing. Designing end-to-end deep le...

The effective integration of ideological and political education into college English curriculum is an important part of the reform of English teaching for public courses in higher vocational colleges, and also an important way to implement moral cultivation and realize the education of all employees, the whole process and all directions. Under the...

Absorbing aerosols, consisting of smoke (black carbon (BC) and other organics) and dust (from windblown sources), can have a strong warming effect on the climate and impact atmospheric circulation due to localized heating. To investigate the spatiotemporal and vertical changes of absorbing aerosols across Asia, collocation data from OMI, MODIS, and...

This work presents a new model free inversion estimation framework using daily TROPOMI NO2 columns and observed fluxes from the continuous emissions monitoring systems (CEMS) to quantify three years of daily-scale emissions of NOx at 0.05°×0.05° over Shanxi Province, a major world-wide energy producing and consuming region. The NOx emissions, day-t...

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...

Nitrogen dioxide (NO2) at the ground level poses a serious threat to environmental quality and public health. This study developed a novel, artificial intelligence approach by integrating spatiotemporally weighted information into the missing extra-trees and deep forest models to first fill the satellite data gaps and increase data availability by...

Nitrogen dioxide (NO2) air pollution provides valuable information for quantifying NOx emissions and exposures. This study presents a comprehensive method to estimate average tropospheric NO2 emission strengths derived from three-year (April 2018 – March 2021) TROPOMI observations by combining a wind-assigned anomaly approach and a Machine Learning...

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...

Based on air quality station data and satellite remote sensing data, the interannual variation characteristics and seasonal variation trends of near-surface ozone (O3) in Henan province were studied, and the variation in O3 sensitivity was analyzed. The results showed that the O3 concentration near the surface of Henan province increased first and...

Air pollution, as important environmental problem, directly affects daily life and physical health of public. The gradual maturity of polluted gas and particulate matter observation technology has rapidly developed the monitoring of air pollutants near the surface based on satellite platforms. This study aims to clarify the collaborative observatio...

Ground-based measurements of downwelling surface solar irradiance (DSSI) play an important role in many topics, such as the design and operation of solar energy systems, the study of the Earth radiation budget, and the validation of gridded DSSI products such as those derived from satellite imagery and reanalyses. For our purpose of validating sate...

Satellite retrievals of columnar nitrogen dioxide (NO 2 ) are essential for the characterization of nitrogen oxides (NO x ) processes and impacts. The requirements of modeled a priori profiles present an outstanding bottleneck in operational satellite NO 2 retrievals. In this work, we instead use neural network (NN) models trained from over 360,000...

Vegetation plays an important role in the dry deposition of particles with significant spatial variability, but the magnitude remains unclear at the global scale. With the aid of satellite products, this study estimated the vegetation-related dry deposition of fine particulate matter (PM2.5). Methodologically, dry deposition was first calculated us...

Rapid industrialization and urbanization have caused frequent haze pollution episodes during winter in eastern China. Considering that the vertical profile of the aerosol properties changes significantly with altitude, investigating aerosol aloft information via satellite remote sensing is essential for studying regional transport, climate radiativ...

This paper aims to determine the factors which introduce more errors to mountainous aerosol optical depth (AOD) in the hope that such results can guide aerosol inversion over mountainous areas. AODs retrieved by the GRASP algorithm from POLDER-3 are compared with those obtained from AERONET over global mountainous areas between 2005 and 2013. Compa...

Quantifying the concentration of absorbing aerosol is essential for pollution tracking and calculation of atmospheric radiative forcing. To quickly obtain absorbing aerosol optical depth (AAOD) with high-resolution and high-accuracy, the Gradient Boosted Regression Trees (GBRT) method based on the joint data from OMI, MODIS and AERONET is used for...

Plain Language Summary Black Carbon strongly absorbs visible radiation, leading to unique impacts on atmospheric radiation, climate, the water cycle, and PM2.5. This work attributes different aerosol source characteristics, and further specifies the size distribution and concentration of aerosol black carbon cores and refractive shells. This work u...

Nitrogen dioxide (NO2) at the ground level poses a serious threat to environmental quality and public health. This study developed a novel, artificial intelligence approach by integrating spatiotemporally weighted information into the missing extra-trees and deep forest models to first fill the satellite data gaps and increase data availability by...

The representation of landform element varies over multiple scales, or multiresolution digital elevation model (DEM) and its derivatives. When more details of land surfaces are available to be characterized based on the existing high spatial resolution elevation products, the influence of scale variation might become more significant. This poses a...

Near-surface NO2 (NS-NO2) is closely related to human health and the atmospheric environment. While top-down approaches have been widely applied to estimate NS-NO2 using satellite-based NO2 column measurements, there still exist significant defects, resulting in a low overall fit and significant amount of bias. This paper combines GOME-2B and OMI s...

The value of the high-resolution data lies in the high-precision information discovery. The fine-detailed landform element extraction is thus the basis of high-fidelity application of the high-resolution digital elevation models (DEMs). However, the results of landform element extraction generated by classical methods might be ungrounded on high-re...

Soil moisture (SM) plays a critical role in the water and energy cycles of the Earth system; consequently, a long-term SM product with high quality is urgently needed. In this study, five SM products, including one microwave remote sensing product – the European Space Agency's Climate Change Initiative (ESA CCI) – and four reanalysis data sets – Eu...

The contribution of biomass burning to the total aerosol loading over Monsoon Asia is both significant and continuing to increase. To better match the spatio-temporal distribution of aerosols and trace gasses observed in the free troposphere, this work applied a 3-D constrained emission inventory based on top-down remotely sensed NO2 measurement to...

Urban functional fragmentation plays an important role in assessing Nitrogen Dioxide (NO 2 ) emissions and variations. While the mediated impact of anthropogenic-emission restriction has not been comprehensively discussed, the lockdown response to the novel coronavirus disease 2019 (COVID-19) provides an unprecedented opportunity to meet this goal....

The massive lockdown of global cities during the COVID-19 pandemic is substantially improving the atmospheric environment, which for the first time, urban mobility is virtually reduced to zero, and it is then possible to establish a baseline for air quality. By comparing these values with pre-COVID-19 data, it is possible to infer the likely effect...

With increasing interest in understanding the contribution of secondary organic aerosol (SOA) to particulate air pollution in urban areas, an exploratory study was carried out to determine levels of carbonaceous aerosols and polycyclic aromatic hydrocarbons (PAHs) in the city of Kuala Lumpur, Malaysia. PM2.5 samples were collected using a high-volu...

Numerous statistical models have established the relationship between ambient fine particulate matter (PM2.5, with an aerodynamic diameter of less than 2.5 μm) and satellite aerosol optical depth (AOD) along with other meteorological/land-related covariates. However, all the models assumed that all covariates affect the PM2.5 concentration at the s...

The unavoidable noise often present in synthetic aperture radar (SAR) images, such as speckle noise, negatively impacts the subsequent processing of SAR images. Further, it is not easy to find an appropriate application for SAR images, given that the human visual system is sensitive to color and SAR images are gray. As a result, a noisy SAR image f...

The anomalies associated with the 12 May, 2008 Ms8.0 Wenchuan earthquake have been widely reported. Nevertheless, so far, these anomalies have not been synergically analyzed to interpret or prove the potential geosphere physical coupling process. Moreover, the 14 April, 2010 Ms7.1 Yushu earthquake with similar active tectonic background is less stu...

With increasing interest in understanding contribution of secondary organic aerosol (SOA) to particulate air pollution in urban areas, an exploratory study was carried out to determine levels of carbonaceous aerosols and polycyclic aromatic hydrocarbons (PAHs) in the City of Kuala Lumpur, Malaysia. PM2.5 samples were collected using a high-volume s...