Tropospheric gradients provide information on the moisture distribution, whereas zenith total delays provide the overall moisture information along the zenith. When both observations are used together, the model can actuate the moisture fields, correcting their dynamics. Our research shows that, in regions with very few stations, assimilating tropospheric gradients on top of zenith total delay observations can enhance the performance of existing improvements.

Humidity transport from the Earth's surface into the atmosphere is relevant for many processes. However, knowledge of the actual distribution of humidity concentrations is sparse – mainly due to technological limitations. With the lidar presented herein, it is possible to measure humidity concentrations and their vertical fluxes up to altitudes of > 3 km with high spatiotemporal resolution, opening new possibilities for detailed process understanding and, ultimately, better model representation.

Due to the scarcity of offshore in situ observations, alternative data sources are essential for a reliable understanding of offshore winds. Therefore, this study delves into the world of satellite remote sensing (ASCAT) and numerical models (ERA5), exploring their capabilities and limitations in characterising offshore winds. This investigation evaluates these two datasets against measurements from a floating ship-based lidar, collected during a novel measurement campaign in the Baltic Sea.

Ultrafine particles (diameter of less than 100 nm) are suspected to cause significant health effects. Accurately measuring their chemical composition and physical properties in real time is challenging due to their low mass and interference from larger particles. This study proposes a method for the continuous, automated measurement of their composition, tested in a pilot field study to explore their chemical characteristics, physical properties, and sources.

The two ozone instruments of IAGOS (In-service Aircraft for a Global Observation System) have been compared with the Ozone PhotoMeter (OPM) of the World Calibration Center of Ozone Sondes (WCCOS) in an atmospheric simulation chamber under realistic flight conditions of pressure, temperature, and ozone concentrations. The two IAGOS-instruments showed good agreement with the OPM within 5–6 %. The observed differences are small but systematic and reproducible during the intercomparison.

Air pollution management requires accurate determination of emissions and emission ratios of air pollutants. In this paper, we explore a new way to resolve excess mixing ratios in turbulent plumes, which allows aggregation of unbiased ensemble averages of air pollutant ratios that can be compared with emission models. The approach is tested in an urban environment and used to resolve emission patterns of nitrogen oxides and carbon dioxide.

Sea spray affects air–sea interaction, cloud microphysics, and the radiative budget. However, meteorological processes at the wind-gust level complicate the physical interpretation of measured aerosol particle properties. We used meter-scale models to track the life history of thousands of particles under different conditions to show that investigators must account for key factors to link observations at aircraft level to sea-spray emissions at the ocean's surface.

A new, low-cost instrument for measuring total column ozone was tested against a MK III Brewer spectrophotometer for six months. Using the "Global Irradiance" method from the Norwegian GUV network, it showed ozone values matching Direct Sun Brewer measurements with a 1.8 % standard deviation. Despite temperature and cloud dependencies, the instrument is robust and easy to use. Fully coverage of the UV-A/B spectrum allows for further UV-radiation analysis. Total cost is less than EUR 3000.

Tropospheric ozone from the three Infrared Atmospheric Sounding Interferometer (IASI) instruments is very consistent (<1 %). The validation against homogenized ozone sondes reveals an overall good agreement with slight biases (3 %–6 %) in tropospheric ozone and a possible temporal drift, but this is difficult to assess due to the limited number of sites. No specific trends are estimated for the tropospheric ozone column for the period 2008–2022, but persistent negative trends are observed in the lower troposphere.

The WIVERN (WInd Velocity Radar Nephoscope) conically scanning Doppler W-band radar has the potential, for the first time, to map the mesoscale and synoptic variability of cloud dynamics and precipitation microphysics. This study shows that the oblique angle of incidence will be advantageous compared to standard nadir-looking radars due to substantial clutter suppression over the ocean surface. This feature will enable the detection and quantification of light and moderate precipitation, with improved proximity to the surface.

In this work, we introduce WALL-E, a newly designed wall-free particle evaporator that enables real-time online aerosol analyses while minimizing wall interactions and fragmentation, offering a more accurate and efficient approach to studying aerosol properties. WALL-E provides molecular-level insights into aerosol composition, quantification, and volatility distributions.

An instrumented container laboratory is operated on regular commercial passenger flights to obtain a long-term representative dataset on the composition of the upper troposphere and lower stratosphere. Here we report on the development of a fully automated aerosol mass spectrometer for this project. We present technical specifications, necessary modifications for the automation, instrument calibration and comparisons, detection limits, and the first in-flight data.

Entrainment is key in understanding temperature and moisture changes within the boundary layer, but it is difficult to observe using ground-based observations. This work used simulations to verify an assumption that simplifies entrainment estimations from ground-based observational data, recognizing that entrainment is the combination of the transfer of heat and moisture from above the boundary layer into it and the change in concentration of heat and moisture as boundary layer depth changes.

Current knowledge of the link between clouds and climate is limited by a lack of observations of the drop size distribution (DSD) within clouds, especially for the smallest drops. We demonstrate a method of retrieving DSDs down to small drop sizes using observations of drizzling marine layer clouds captured by the CloudCube millimeter-wave Doppler radar. We compare the shape of the observed spectra to theoretical expectations of radar echoes to solve for DSDs at each time step and elevation.

A new technique for the end-to-end calibration of weather radars is introduced. Highly precise artificial radar targets are generated with a radar target simulator and serve as a calibration reference for weather radar observables like reflectivity and Doppler velocity. The system allows investigating and correcting any biases associated with weather radar observations.

This study proposes a new technique to augment polarimetric radar measurements of the national German operational radar network with vertically looking cloud radars. The method is tested in two different case studies by comparison to dedicated scanning radars revealing promising results. Future usage of the method is motivated by analyzing the coverage of the operational radar network finding advantageous locations with good radar coverage.

This study presents an approach that enables the detection of the shape and orientation of multiple types of co-located hydrometeors in mixed-phase cloud systems. This information is key for improving the understanding of these clouds, as they do contain ice and liquid water simultaneously, making them relevant for the precipitation budget and radiative balance of the Earth's atmosphere. The retrieval is based on elevation scans of polarimetric cloud radars and can therefore be flexibly applied.

Ice-nucleating particles (INPs) are important for cloud formation and properties affecting weather and climate. This article presents a method coupling an offline ice nucleus counter to an electron microscope to obtain information, not only about INP number concentrations but also about physico-chemical properties (e.g., size and chemical composition) relevant to ice nucleation on single particles. The method was evaluated on the basis of a case study at the high-altitude research station Jungfraujoch.

Greenhouse gases like CO₂ and CH₄ drive climate change. Satellites enable monitoring of these emissions from space. Our simulations show that the upcoming Twin ANthropogenic Greenhouse gas Observers (TANGO) mission can detect about 500 targets per 4 d cycle under clear skies, but cloud cover reduces detection. Integrating cloud forecasts into TANGO’s manoeuvering boosts detection, highlighting its potential for improving global emission monitoring.

This study used Polarimetric radio occultation (PRO) observations to evaluate simulations of cloud hydrometeors with five microphysics schemes for three typhoons from 2019 and 2021. The simulated cloud hydrometeors distributions varied significantly depending on model initial conditions, typhoon structures, and microphysics schemes. Results in this study demonstrate the potential for using PRO observation to evaluate the performance of different microphysics schemes in numerical models.

This work presents a new simplified ground-based thermal infrared (TIR) system capable of detecting and retrieving volcanic emissions during both the day and the night. Knowing the location of the instrument and the crater, it is possible to compute the geometry (height and thickness) of a volcanic plume. Furthermore, thanks to a specific filter positioned in front of one of the TIR cameras, it is possible to compute the sulfur dioxide (SO₂) content emitted by the volcano at a safe distance from the vent.

This research aimed to improve our understanding of cloud structure using spaceborne measurements. The study applied an optimal estimation method to determine how cloud droplet sizes change with height, using satellite data and coincident aircraft measurements for validation. It found that current space-borne spectrometers lack the accuracy to fully resolve this vertical structure, but upcoming instruments like CLARREO (Climate Absolute Radiance and Refractivity Earth Observatory) Pathfinder will significantly enhance this capability.