Accurate NO_x emission estimates are required to better understand air pollution. This study investigates and demonstrates the ability of the superposition column model in combination with TROPOMI tropospheric NO₂ column data to estimate city-scale NO_x emissions and lifetimes and their variabilities. The results of this work nevertheless confirm the strength of the superposition column model in estimating urban NO_x emissions with reasonable accuracy.

The Arctic region is subject to profound changes due to a warming climate. Ice-nucleating particles (INPs) in the seawater can get transported to the atmosphere and impact cloud formation. However, the sources of characteristics of INPs in the marine areas are poorly understood. We investigated the INPs in seawater from Greenlandic fjords and identified a seasonal variability, with highly active INPs originating from terrestrial sources such as glacial and soil runoff.

The height of the convective boundary layer (CBLH) is related to our health due to its crucial role in pollutant dispersion. The variance of vertical velocity from millimeter wave cloud radar (MMCR) can accurately capture the diurnal evolution of the CBLH, due to a small blind range and less impact by the residual layer. The CBLH is affected by radiation, humidity, cloud, and precipitation; thus, the MMCR is suitable for monitoring the CBLH, owing to its observation capability in various weather conditions.

To accurately represent the population exposure to outdoor concentrations of pollutants of interest to health (NO₂, PM_2.5, black carbon, and ultrafine particles), multi-scale modelling down to the street scale is set up and evaluated using measurements from field campaigns. An exposure scaling factor is defined, allowing  regional-scale simulations to be corrected to evaluate population exposure. Urban heterogeneities strongly influence NO₂, black carbon, and ultrafine particles but less strongly PM_2.5.

In this work, we utilized a volatility hygroscopicity tandem differential mobility analyzer (VH-TDMA) to investigate, for the first time, the hygroscopicity and volatility of submicron aerosols, as well as their hygroscopicity after heating, in urban Beijing during the autumn of 2023. We analyzed the size-resolved characteristics of hygroscopicity and volatility, the relationship between hygroscopic and volatile properties, and the hygroscopicity of heated submicron aerosols.

Many studies have identified an inverted-V relationship between the liquid water path (LWP) and droplet concentration (N_d), where LWP increases and then decreases with N_d. Using satellite observations and meteorological data, we demonstrate that the inverted V primarily reflects co-variability between LWP and N_d. We suggest taking a holistic approach that considers this co-variability when assessing the climatological sensitivity of LWP to anthropogenic aerosols.

This study highlights the unique capability of the ArcticShark, an uncrewed aerial system, in measuring vertically resolved atmospheric properties. Data from 32 research flights in 2023 reveal seasonal patterns and correlations with conventional measurements. The consistency and complementarity of in situ and remote sensing methods are highlighted. The study demonstrates the ArcticShark’s versatility in bridging data gaps and improving the understanding of vertical atmospheric structures.