Clouds affect Earth's energy balance, with high-altitude cirrus clouds contributing to atmospheric warming. While active satellite sensors are the most accurate for detecting cirrus clouds, they are not ideal for long-term studies. This study compares Moderate Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data, testing six MODIS methods, one MODIS-based test, and two International Satellite Cloud Climatology Project (ISCCP) tests. The all tests consolidation (ATC) was the most effective, achieving 72.98 % accuracy during daytime and 59.50 % at night, making it relatively accurate for creating a cirrus mask.

Global horizontal irradiance retrievals from satellite observations are affected by spatial displacements due to parallax and cloud shadows. We assess different approaches to correct for these displacements and quantify their added value by comparison with a network of ground-based pyranometer observations. The corrections are found to become increasingly important at higher spatial resolutions and are most relevant for variable cloud types.

This study presents, for the first time, the uncertainty analysis of the Ångström exponent assumption on the full set of retrievable optical properties obtained with Raman lidar. A quantitative comparison between the pure rotational and vibrational–rotational Raman lidar approaches is presented. A minor impact of a wrong Ångström exponent on the determined aerosol optical properties is found.

The chemical properties of aerosols in the atmosphere significantly influence their impact on global climate and human health. The current study constructed an instrumental system (HEAC (high-efficiency aerosol collector)/ESI (electrospray ionisation)-Orbitrap-MS (mass spectrometer)) for the real-time chemical analysis of aerosol samples. The combined system successfully identified over 30 chemical compounds in aerosol samples in real time, showing the robustness of the technique for the chemical characterisation of aerosols under atmospherically relevant conditions.

Clouds and aerosol are important for weather and climate. Typically, pure water cloud droplets stay liquid until around −35 °C, unless they come into contact with ice-nucleating particles (INPs). INPs are a rare subset of aerosol particles. Using uncrewed aerial vehicles (UAVs), it is possible to collect aerosol particles and analyse their ice-nucleating ability. This study describes the test and validation of a sampling set-up that can be used to collect aerosol particles onto a filter.

In this work, we describe the development of the Carbon monOxide Measurement from Ames (COMA) instrument for measurement of carbon monoxide (CO) and nitrous oxide (N₂O) aboard NASA's WB-57 high-altitude research aircraft. We detail the modifications and testing conducted as well as details of COMA's performance during research flights for NASA’s Asian summer monsoon Chemical & CLImate Project (ACCLIP) 2022 campaign.

Air pollution from airborne particles is a major health and environmental concern, especially in cities. Understanding the particles' sources is key to addressing this issue, but traditional methods require time-consuming sampling, delaying action. Our study introduces a real-time monitoring system that uses advanced instruments and software to track pollution instantly. This technology allows faster, more precise pollution analysis, helping cities create targeted strategies to improve air quality.

This is a reply to a recent article by Christoph Kiemle et al., critical of CO₂ measurements using continuous-wave (CW) lidar. We show CW lidar is not only capable of measuring range but also capable of measuring range to the required accuracy without the aid of an external altimeter.

Biomass-burning aerosols (BBAs) from Central Africa are transported above stratocumulus clouds. The absorption of solar energy by aerosols induces warming, altering the cloud dynamics. We developed an approach that combines polarimeter and lidar to quantify this. This methodology is assessed during the AEROCLO-sA (AErosol RadiatiOn and CLOud in Southern Africa) campaign. To validate it, we used irradiance measurements acquired during aircraft spiral descents. A major perspective is the generalization of this method to the global level.

Marine boundary layer (MABL) water vapor is among the key factors to couple the ocean and atmosphere, but it is also among the hardest to retrieve from a satellite remote sensing perspective. Here we propose a novel way to retrieve MABL specific humidity profiles using the GNSS (Global Navigation Satellite System) Level-1 signal-to-noise ratio. Using a machine learning approach, we successfully obtained a retrieval product that outperforms the ERA-5 reanalysis and operational Level-2 retrievals globally, except in the deep tropics.

Single-particle soot photometer (SP2) measures the mixing state (D_p/D_c) of coated black carbon (BC) using core-shell Mie theory and coating refractive index is set to 1.50+0i. The retrieved D_p/D_c contains error due to the non-sphericity of BC and coatings with various refractive indices. We reveal the remarkable effects of coatings on the D_p/D_c retrieval accuracy of SP2 based on optical simulation of fractal BC aerosols, and further evaluate the simple radiative forcing efficiency of coated BC.

This study evaluates PM_2.5 and NO₂ sensors for their use in health studies. Sensors were calibrated using data from reference instruments, and regression and machine learning models were evaluated, identifying opportunities and limitations in model transferability in both indoor and outdoor environments and showcasing the importance of integrating metadata such as activity logs and diffusive tubes to improve data validation and interpretation during deployment in the houses of the participants.

A large balloon was launched in summer 2021 in the Arctic to carry instruments for trace gas measurements up to 32 km, above the reach of aircraft. The main aims were to evaluate different techniques and atmospheric processes. We focus on halogenated greenhouse gases and ozone-depleting substances. For this, air was collected with the AirCore technique and a cryogenic air sampler and measured after the flight. A companion paper reports observations of major greenhouse gases.