Validation of global land-ocean aerosol products retrieved from the DPC-2/GF-5(02) on-orbit measurements

Pyrocumulonimbus (PyroCb) convection during the August 2024 North American wildfires injected smoke aerosols into the upper troposphere and lower stratosphere, altering cloud microphysics. These aerosols induced warming near fire sources and downwind over Western Europe, while producing contrasting effects over fire-source regions, cooling along the US West Coast and warming across North America, demonstrating strong wildfire-aerosol-cloud-radiation feedbacks with transcontinental impacts.

A global AOD product from Particulate Observing Scanning Polarimeter (POSP) has been proposed and validated using Aerosol Robotic Network (AERONET). Results show a high accuracy, with correlation coefficients (R) of 0.914, a root mean square error (RMSE) of 0.085, outperforming Moderate Resolution Imaging Spectroradiometer (MODIS). Error analysis reveals seasonal variation with lower accuracy in autumn/winter, and increased uncertainty with lower Normalized Difference Vegetation Index NDVI.

This study describes the analysis of time series of the MODIS-derived aerosol optical depth (AOD) over China between 2010 and 2024. Emission reduction policies were effective with respect to reducing the AOD until 2018. Thereafter, the overall reduction until the end of the study was very small due to unfavorable meteorological factors cancelling favorable anthropogenic effects and resulting in an AOD increase during extended periods. The variations over different areas in China are discussed.

Nitrogen dioxide (NO₂) is a major pollutant that, at high concentrations, may affect human health. We evaluated the remote sensing column NO₂ in relation to near-surface concentrations throughout the day and found that the prohibition of vertical transport in the morning and the mixing in the afternoon resulted in different relations between the near-surface (NS) and total column NO₂ concentrations. These different relationships have consequences for the use of satellite remote sensing to estimate NS NO₂ concentrations.

Particulate Observing Scanning Polarization (POSP) on board the second GaoFen-5 (GF-5(02)) satellite is the first space-borne ultraviolet–visible–near-infrared–shortwave-infrared (UV–VIS–NIR–SWIR) multi-spectral cross-track scanning polarimeter. Due to its wide spectral range and polarimetric capabilities, POSP measurements provide rich information for aerosol and surface characterization. We present the detailed aerosol/surface products generated from POSP's first 18 months of operation, including spectral aerosol optical depth, aerosol-size-/absorption-related properties, surface black-sky and white-sky albedos, etc.

We evaluate the long-term (2000–2020) variabilities of aerosol absorption optical depth, black carbon emissions, and associated health risks in China with an integrated framework that combines multiple observations and modeling techniques. We demonstrate the remarkable emission abatement resulting from the implementation of national pollution controls and show how human activities affected the emissions with a spatiotemporal heterogeneity, thus supporting differentiated policy-making by region.

A global gap-free high-resolution air pollutant dataset (LGHAP v2) was generated to provide spatially contiguous AOD and PM_2.5 concentration maps with daily 1 km resolution from 2000 to 2021. This gap-free dataset has good data accuracies compared to ground-based AOD and PM_2.5 concentration observations, which is a reliable database to advance aerosol-related studies and trigger multidisciplinary applications for environmental management, health risk assessment, and climate change analysis.

Nitrogen dioxide (NO₂) is a trace gas which is important for atmospheric chemistry and may affect human health. To understand processes leading to harmful concentrations, it is important to monitor NO₂ concentrations near the surface and higher up. To this end, a Pandora instrument has been installed in Beijing. An overview of the first year of data shows the large variability on diurnal to seasonal timescales and how this is affected by wind speed and direction and chemistry.

In order to conduct accurate aerosol retrieval over snow, the Remote Sensing of Trace Gases and Aerosol Products (RemoTAP) algorithm is extended with a bi-directional reflection distribution function for snow surfaces. The experiments with both synthetic and real data show that the extended RemoTAP maintains capability for snow-free pixels and has obvious advantages in accuracy and the fraction of successful retrievals for retrieval over snow, especially over surfaces with snow cover > 75 %.

The fractal black carbon was applied to re-evaluate the regional impacts of morphologies on aerosol–radiation interactions (ARIs), and the effects were compared between the US and China. The regional-mean clear-sky ARI is significantly affected by the BC morphology, and relative differences of 17.1 % and 38.7 % between the fractal model with a D_f of 1.8 and the spherical model were observed in eastern China and the northwest US, respectively.

A single model is difficult to represent various shapes of dust. We proposed a tunable model to represent dust with various shapes. Two tunable parameters were used to represent the effects of the erosion degree and binding forces from the mass center. Thus, the model can represent various dust shapes by adjusting the tunable parameters. Besides, the applicability of the spheroid model in calculating the optical properties and polarimetric characteristics is evaluated.

The Long-term Gap-free High-resolution Air Pollutant concentration dataset, providing gap-free aerosol optical depth (AOD) and PM_2.5 and PM₁₀ concentration with a daily 1 km resolution for 2000–2020 in China, is generated and made publicly available. This is the first long-term gap-free high-resolution aerosol dataset in China and has great potential to trigger multidisciplinary applications in Earth observations, climate change, public health, ecosystem assessment, and environment management.