Objective Absorbing aerosols, particularly black carbon (BC), exerts significant influence on the Earth's radiation budget by modifying both the amount and vertical distribution of solar radiation. Their climatic effects are especially pronounced in regions characterized by concentrated fossil fuel activities, such as large-scale coal mining areas. However, the spatial and temporal variability of their microphysical and optical properties introduces considerable uncertainty into regional radiative forcing assessments. The Zhundong Coalfield, located in eastern Xinjiang, China, is one such region where BC emissions from coal extraction and associated industrial activity are persistent yet under-characterized from a radiative perspective. This study aims to construct a rapid estimation framework for aerosol radiative forcing (ARF) over this region by integrating multi-band satellite observations with physically based scattering and radiative transfer models. The primary goal is to evaluate how aerosol optical depth (AOD), single scattering albedo (SSA), and particle size influence shortwave ARF at the top of the atmosphere (TOA), bottom of the atmosphere (BOA), and within the atmospheric column (ATM), and how ultraviolet-band data enhances the reliability of this estimation. Methods The research adopts a modular approach comprising aerosol property inversion and radiative transfer modeling. The aerosol inversion is based on a Mie scattering model incorporating a core-shell structure assumption, where BC forms the absorbing core and is coated by non-absorbing substances such as sulfate and nitrate. Satellite-derived aerosol products are used to constrain the model: MODIS provides AOD and SSA at visible wavelengths, while OMI contributes ultraviolet (UV) -band SSA and AOD information. Two experimental configurations are established-one based solely on MODIS data, and another integrating both MODIS and OMI-to assess the role of UV spectral information in constraining aerosol characteristics. Following inversion, the retrieved aerosol size and optical parameters are used as input to the SBDART (Santa Barbara DISORT Atmospheric Radiative Transfer) model to simulate instantaneous ARF at TOA, BOA, and ATM under clear-sky conditions. Radiative forcing is calculated as the difference in net shortwave flux with and without aerosols. Multiple linear regression models are then constructed using different combinations of AOD, SSA, and core radius to quantify the relationship between these parameters and simulated ARF. Regression performance is evaluated using R (2) and RMSE statistics across both single-source and combined-source scenarios. Results and Discussions First, the inclusion of OMI UV-band data significantly improves the inversion accuracy of aerosol particle size characteristics. When only MODIS data are used, the retrieved BC core sizes are relatively narrow, mostly centered around 120 nm, and the shell diameters exhibit limited variation. However, when OMI UV observations are incorporated, the core size distribution broadens, capturing particles ranging from 90 to 160 nm, while the shell diameter spans a wider interval of 300?700 nm. This improved resolution stems from the stronger sensitivity of UVs to absorption by fine-mode particles, which enhances the model's ability to distinguish subtle differences in particle morphology. The resulting total particle size distributions-core plus shell-are more consistent with reported field measurements in coal-intensive regions. These results confirm that UV data not only improve inversion detail but also reduce the uncertainty in the wavelength in the representation of aerosol mixing states. Second, the quantitative relationship between optical parameters and ARF demonstrates clear physical consistency across TOA, BOA, and ATM layers. In both MODIS-only and MODIS-OMI configurations, AOD exhibits a strong negative correlation with TOA and BOA radiative forcing (R=-0.77 and -0.78, respectively), indicating a cooling effect due to enhanced scattering and absorption of incoming solar radiation. SSA also shows a strong negative correlation with TOA and BOA forcing (R=-0.78 and -0.62, respectively), suggesting that as the aerosol becomes more scattering-dominant, its net radiative cooling effect intensifies. Conversely, AOD shows weaker but positive correlations with ATM forcing (R=0.43), suggesting an increase in atmospheric heating when aerosol loading or absorption increases. This pattern aligns with physical expectations: absorbing aerosols like BC trap energy in the atmosphere, contributing to vertical energy redistribution. The analysis confirms that SSA has a stronger explanatory power than AOD, emphasizing its role as a key driver of radiative uncertainty forcing. Third, regression model performance improves markedly with the inclusion of SSA and core size as input parameters. Under the MODIS-only scenario, models using AOD alone yield limited explanatory power, withR (2) values of 0.59 (TOA), 0.61 (BOA), and 0.18 (ATM). Adding SSA improves the fits substantially, increasingR (2) to 0.78 (TOA) and 0.67 (BOA), and to 0.21 in the ATM. Incorporating core radius into the model yields additional gains, raisingR (2) in the ATM layer to 0.23 and lowering RMSE values across all layers. In the MODIS-OMI fusion scenario, even though the number of valid observation days decreases significantly (eg, from 2589 to 954 days at the Wucaiwan site), model performance continues to improve. For example,R (2) for ATM forcing increases from 0.18 to 0.29, and RMSE decreases from 2.04 to 1.85. These results suggest that high-spectral-resolution UV data provide greater constraint on aerosol absorption properties, thereby enabling more physically consistent radiative forcing estimates, even with reduced samples. This finding supports the robustness of UV-enhanced satellite inversion strategies in regional ARF modeling. Conclusions This study presents a data-model integration framework for estimating ARF over coal mining regions using multi-source satellite observations and physically based scattering and radiative transfer models. The combination of MODIS visible and OMI ultraviolet aerosol products improves the inversion of absorbing aerosol particle size distributions and enhances the retrieval of SSA, especially under complex mixing conditions. The constructed regression models reveal that SSA exerts a greater influence on radiative forcing than AOD, and that including particle size parameters further strengthens model reliability. Despite a reduction in observational frequency due to OMI's narrower sampling, the incorporation of UV-band information leads to consistently improved model performance across all atmospheric layers, particularly in the atmospheric column. These results highlight the critical role of spectral diversity in satellite remote sensing for accurately characterizing the radiative impacts of absorbing aerosols, and demonstrate the feasibility of applying such approaches to high-emission, data-scarce environments like the Zhundong Coalfield.

Objective Xinjiang, recognized as a crucial coal resource area and strategic reserve in China, possesses abundant coal resources. The Zhundong coalfield, a large-scale open-pit mining area within this region, significantly contributes to increased concentrations of light-absorbing aerosols due to its coal production activities and associated industrial processes. These activities also produce substantial amounts of black carbon (BC), which, through atmospheric transport, mixes with snow and ice, influencing glacier ablation in the Tianshan Mountains. While previous studies on the Zhundong coalfield have predominantly concentrated on the ecological pollution resulting from mining activities, they have overlooked the implications for climate and radiative forcing in the area. In this context, it is crucial to employ satellite remote sensing technology to analyze and assess the optical properties and radiative forcing effects of light-absorbing aerosols in the Zhundong coalfield region. Such an approach is significant for understanding the regional environmental and climatic impacts associated with the development of open-pit coal resources in the arid regions of western China. Methods We investigate the temporal and spatial characteristics of aerosol optical depth (AOD) in the Zhundong coalfield by utilizing MODIS aerosol product (MOD04_L2) data spanning from 2005 to 2020. To simulate aerosol particle size information, a Mie scattering model is employed under the core-shell assumption. An uncertainty interval of 0.03 is selected to estimate the possible range of particle sizes within each grid, constrained by maximum and minimum values. The inter of these constraints is then used to calculate the optical parameters for various particle size combinations. Additionally, the influence of sand and dust aerosols is considered by setting the single scattering albedo (SSA) range for these aerosols between 0.93 and 0.96. The simulated extinction coefficient (sigma(ext)) is used as a threshold value; any portion smaller than this threshold is excluded to quantify the concentration of local BC columns. Finally, the radiative forcing effect of light-absorbing aerosols in the Zhundong coalfield over the past decade is evaluated using the SBDART radiative transfer model. Results and Discussions The AOD in the Zhundong coalfield exhibited pronounced spatial heterogeneity from 2005 to 2020, with high AOD values predominantly concentrated in the mining area and its surrounding regions (Fig. 2). Seasonal variations reveal the highest concentrations in spring and winter, followed by fall, with the lowest levels observed in summer. During spring and winter, AOD values generally exceed 0.15, except in certain desert areas. Interannual fluctuations in AOD are frequent, marked by significant turning points in 2010, 2012, and 2017 (Fig. 3), which indicates that coal production, energy restructuring, and capacity reduction policies have a significant effect on air quality in mining regions. The inter-monthly variation displays a distinct U pattern (Fig. 3), with AOD peaking at 0.27 in February, which highlights the substantial influence of anthropogenic activities on regional air quality. Dusty weather in spring emerges as a dominant factor. Overall, the temporal variation in AOD in the Zhundong coalfield reflects the combined effects of natural factors and human activities. In the Wucaiwan and Dajing mining areas, the range of BC number density is (1?3)x10(18) grid(-1) (Fig. 6). In 2012, against the backdrop of China's coal economic performance, open-pit mining was less affected by the decline in production growth due to its larger production capacity and lower costs, influenced by mining methods, climatic conditions, and economic activities. In contrast, shaft mining is more heavily affected by safety risks and environmental constraints, which may lead to production limitations, especially under strengthened policy and regulatory measures. As a result, there are greater fluctuations in BC number density in the Dajing mining area (Fig. 6). The range of BC number density is 20?40 kg/grid, with seasonal variations largely consistent, although peak months differed. This suggests that BC mass concentration is closely related to particle aging and size (Fig. 7). Radiative forcing values at the top of the atmosphere, at the surface, and within the atmosphere showed varying degrees of decrease between 2011 and 2017, followed by a gradual increase. This suggests that reducing emissions of light-absorbing aerosols from mining sites can effectively lower regional radiative forcing values in the context of reduced coal production (Fig. 10). Radiative forcing values are higher in March and April during spring, when BC is aged and mixed with other aerosol components through mutual encapsulation, which results in more complex microphysical-chemical properties. This process enhances the absorption capacity of BC for both short- and long-wave radiations (Fig. 10). Conclusions We analyze the overall change in AOD in the Zhundong coalfield from 2005 to 2020 using the MODIS aerosol dataset. By integrating a meter scattering model to simulate optical parameters under various particle size combinations and constraining these simulations with single scattering albedo (SSA) observations from MODIS, this approach allows us to determine the eligible particle size information and optical parameters, enabling the calculation of BC mass concentration within the atmospheric column of the Zhundong coalfield. Subsequently, the area's radiative forcing is estimated using the SBDART radiative transfer model. The findings reveal several key insights. 1) The changes in AOD are closely linked to policy implementation and economic activities within the coal mining area. Interannual variations indicate that AOD peaked in 2012 and subsequently declined, which suggests that policies and economic activities significantly affect AOD levels. Seasonally, AOD is higher in spring and winter and lower in summer. The unique topographic and meteorological conditions facilitate the transport of BC from the mining area to other regions, which highlights the combined effects of seasonal meteorological conditions and human activities. 2) The column concentration of light-absorbing aerosols in the coal mine area is affected by both anthropogenic activities and meteorological conditions, particularly during sandy and dusty weather. A comparison of column concentrations between the Wucaiwan and Dajing mines shows that open-pit mining adapts more effectively in 2012, given the context of China's coal economic operations, whereas shaft mining may face greater challenges. 3) By examining the changes in AOD and light-absorbing aerosols, it is evident that reducing emissions of light-absorbing aerosols from coal mining areas can effectively decrease regional radiative forcing values in the short term. Inter-monthly variations reveal that atmospheric radiative forcing trends differ from those at the surface and the top of the atmosphere, with the latter two being closely related to the optical properties of light-absorbing aerosols. In spring, the frequent occurrence of sand and dust facilitates the mixing of BC with other substances, forming light-absorbing aerosols with a core-shell structure. This significantly enhances the light-absorbing capacity of BC, thereby increasing radiative forcing.