Ammonia is an important atmospheric pollutant. This article presents version 4 of the algorithm which retrieves ammonia abundances from the infrared measurements of the satellite sounder IASI. A measurement operator is introduced that can emulate the measurements (so-called averaging kernels) and measurement uncertainty is better characterized. Several other changes to the product itself are also documented, most of which improve the temporal consistency of the 2007–2022 IASI NH₃ dataset.

We present air quality measurements in Kinshasa, Democratic Republic of the Congo, performed with a newly developed instrument which was installed on a roof of the University of Kinshasa in November 2019. The instrument records spectra of the scattered sunlight, from which we derive the abundances of nitrogen dioxide and formaldehyde, two important pollutants. We compare our ground-based measurements with those of the TROPOspheric Monitoring Instrument (TROPOMI).

Measurement methods are increasingly deployed to verify reported methane emissions of gas leaks. This study describes unique advantages and limitations of three methods. Two methods are rapidly deployed, but uncertainties and biases exist for some leak locations. In contrast, the suction method could accurately determine leak rates in principle. However, this method, which provides data for the German emission inventory, creates an overall low bias in our study due to non-random site selection.

Emission factor calculation was studied to provide models that do not use traditional CO₂-based calculation in exhaust plume analysis. Two types of models, one based on the physical dependency of dilution of the exhaust flow rate and speed and two based on the statistical, measured dependency of dilution of the exhaust flow rate, acceleration, speed, altitude change, and/or wind, were developed. These methods could possibly be extended to also calculate non-exhaust emissions in the future.

The potential ability of clear air radars to measure turbulence kinetic energy (TKE) dissipation rate ε in the atmosphere is a major asset of these instruments because of their continuous measurements. In the present work, we successfully tested the relevance of a model relating ε to the width of the Doppler spectrum peak and wind shear for shear-generated turbulence and we provide a physical interpretation of an empirical model in this context.

We combine observations from two scanning Doppler lidars to obtain new and unique insights into the dynamic processes inherent to atmospheric convection. The approach complements and enhances conventional methods to probe convection and has the potential to substantially deepen our understanding of this complex process, which is crucial to improving our weather and climate models.

We developed a portable spectrometer (EM27/SCA) that remotely measures greenhouse gases in the lower atmosphere above a target region. The measurements can deliver insights into local emission patterns. To evaluate its performance, we set up the EM27/SCA above the Los Angeles Basin side by side with a similar non-portable instrument (CLARS-FTS). The precision is promising and the measurements are consistent with CLARS-FTS. In the future, we need to account for light scattering.

Tropospheric ozone have been measured for more than a century. Highly quantitative ozone measurements have been made at monitoring stations. However, deficits have been reported for vertical sounding systems. Here, we report a thorough intercomparison effort between a differential-absorption lidar system and two types of balloon-borne ozone sondes, also using ozone sensors at nearby mountain sites as references. The sondes agree very well with the lidar after offset corrections.

Atmospheric measurements were completed for two total solar eclipses. An eclipse-specific weather model was utilized to model the atmosphere before, during, and after the eclipse events. These measurements have enabled further validation of the model's performance in simulating atmospheric responses to total solar eclipses. The paper concludes by recommending further scientific analyses to be explored utilizing the unique datasets presented.

We describe a device that allows one to produce a continuous stream of water vapour with a specified level of humidity. As a main innovation, we can mix waters with different water isotope composition. Through a series of tests we show that the performance characteristics of the device are in line with specifications. We present two laboratory applications where the device proves useful, first in characterizing instruments, and second for the analysis of water contained in stalagmites.

We introduce a novel method for simultaneous measurement of the viscosity and surface tension of metastable liquids. Our approach is based on the phase analysis of excited shape oscillations in levitated droplets. It is applicable to a wide range of atmospheric conditions and can monitor changes in real time. The technique holds great promise for investigating the effect of atmospheric processing on the viscosity and surface tension of solution droplets in equilibrium with water vapour.

Atmosphere remote sensing using GNSS radio occultation provides a highly valuable basis for atmospheric and climate science. For the highest-quality demands, the Wegener Center set up a rigorous system for processing low-level measurement data. This excess-phase processing setup includes integrated quality control and uncertainty estimation. It was successfully evaluated and inter-compared, ensuring the capability of producing reliable long-term data records for climate applications.

Homogenized atmospheric water vapor data are an important prerequisite for climate analysis. Compared to other techniques, GPS has an inherent homogeneity advantage but requires reprocessing and homogenization to eliminate impacts of applied strategy and observation environmental changes. The low-elevation cut-off angles are suggested for the best estimates of zenith tropospheric delay (ZTD) reprocessing time series when compared to homogenized radiosonde data or ERA5 reference time series.

Quantification of a wide range of volatile organic compounds by proton-transfer-reaction mass spectrometry (PTR-MS) can be achieved with direct calibration of only a subset of compounds, characterization of instrument response, and simple reaction kinetics. We characterized our Vocus PTR-MS and developed a toolkit as a guide through this process. A catalytic zero air generator provided the lowest detection limits, and short, frequent calibrations informed variability in instrument response.

Satellite retrievals of trace gases require prior knowledge of the vertical distribution of the pollutant, which is usually obtained from models. Using aircraft-measured vertical NO₂ profiles over the North Sea in summer 2021, we evaluate the Transport Model 5 profiles used in the TROPOMI NO₂ retrieval. We conclude that driven by the low horizontal resolution and the overestimated vertical mixing, resulting NO₂ columns are 20 % too low. This has important implications for emission estimates.

Near-infrared satellite images have information on clouds that is complementary to what is available from the visible and infrared parts of the spectrum. Using this information for data assimilation and model evaluation requires a fast, accurate forward operator to compute synthetic images from numerical weather prediction model output. We discuss a novel, neural-network-based approach for the 1.6 µm near-infrared channel that is suitable for this purpose and also works for other solar channels.

The Earth Cloud, Aerosol and Radiation Explorer mission (EarthCARE) is a multi-instrument cloud–aerosol–radiation-oriented satellite for climate and weather applications. For this satellite mission to be successful, the development and implementation of new techniques for turning the measured raw signals into useful data is required. This paper describes how atmospheric model data were used as the basis for creating realistic high-resolution simulated data sets to facilitate this process.

We have released version 8 of MIPAS IMK–IAA temperatures and pointing information retrieved from MIPAS Middle and Upper Atmosphere mode version 8.03 calibrated spectra, covering 20–115 km altitude. We considered non-local thermodynamic equilibrium emission explicitly for each limb scan, essential to retrieve accurate temperatures above the mid-mesosphere. Comparisons of this temperature dataset with SABER measurements show excellent agreement, improving those of previous MIPAS versions.

A new database is constructed from over 20 years of satellite records that comprises millions of deep convective clouds and spans the global tropics and subtropics. The database is a collection of clouds ranging from isolated cells to giant cloud systems. The cloud database provides a means of empirically studying the factors that determine the spatial structure and coverage of convective cloud systems, which are strongly related to the overall radiative forcing by cloud systems.

A camera-based imager and convolutional neural network (CNN) were used to estimate ground cloud cover. Image data from 2019 were used for training and validation, and those from 2020 were used for testing. The CNN model exhibited high performance, with an accuracy of 0.92, RMSE of 1.40 tenths, and 93% agreement with observed cloud cover within ±2 tenths' difference. It also outperformed satellites and ceilometers and proved to be the most suitable for ground-based cloud cover estimation.

Low-cost sensors are becoming increasingly important in air quality monitoring due to their affordability and ease of deployment. While low-cost sensors have the potential to democratize air quality monitoring, their use must be accompanied by careful interpretation and validation of the data. Analysis of their long-term data record clearly shows that the reported data from low-cost sensors may not be equally sensitive to all emission sources, which can complicate policy-making.

This study assesses the effectiveness of two geostationary satellite-based sunshine duration datasets over Brazil. Statistical parameters were used to evaluate the performance of the products. The results showed generally good agreement between satellite and ground observations, with some regional discrepancies. Overall, both satellite products offer reliable data for various applications, which benefit from their high spatial resolution and low time latency.