Optical receivers for solar spectral actinic radiation are designed for angle-independent sensitivities within a hemisphere. Remaining imperfections can be compensated for by receiver-specific corrections based on laboratory characterizations and radiative transfer calculations of spectral radiance distributions. The corrections cover a wide range of realistic atmospheric conditions and were applied to ground-based and airborne measurements in a wavelength range 280–660 nm.

Atmospheric networks are used for monitoring air quality and greenhouse gases and can provide essential information about the sources and sinks. The design of the network, specifically where to place the observations, is a critical question in order to maximize the information provided while minimizing the cost. Here, a novel method of designing atmospheric networks is presented with two examples, one on monitoring sources of methane and the second on monitoring fossil fuel emissions of CO₂.

We present a new, highly sensitive technique for measuring atmospheric ammonia, an important trace gas that is emitted mainly by agriculture. We deployed the instrument on an aircraft during research flights over rural Oklahoma. Due to its fast response, we could analyze correlations with turbulent winds and calculate ammonia emissions from nearby areas at 1 to 2 km resolution. We observed high spatial variability and point sources that are not resolved in the US National Emissions Inventory.

The ground-based FTIR measurements at Xianghe provide carbon monoxide (CO), acetylene (C₂H₂), ethane (C₂H₆), formaldehyde (H₂CO), and hydrogen cyanide (HCN) total columns between June 2018 and November 2021. The retrieval strategies, information, and uncertainties of these five important trace gases are presented and discussed. This study provides insight into the time series, variations, and correlations of these five species in northern China.

Weather radar data are the backbone of a lot of meteorological products. In order to obtain a better low-level coverage with radar data, additional systems have to be included. The frequency range in which radars are allowed to operate is limited. A potential radar-to-radar interference has to be avoided. The paper derives guidelines on how additional radars can be included into a C-band weather radar network and how interferences can be avoided.

Strateole-2 is an French–US initiative designed to study atmospheric events in the tropical upper troposphere–lower stratosphere. In this work, data from several superpressure balloons, capable of staying aloft at an altitude of 18–20 km for over 3 months, were used. The present article describes methods to detect the occurrence of atmospheric turbulence – one efficient process impacting the properties of the atmosphere composition via stirring and mixing.

Influenced by the representativeness of ice crystal scattering models, the existing terahertz ice cloud remote sensing inversion algorithms still have significant uncertainties. We developed an ice cloud remote sensing retrieval algorithm of the ice water path and particle size from aircraft-based terahertz radiation measurements based on the Voronoi model. Validation revealed that the Voronoi model performs better than the sphere and hexagonal column models.

We present a new method to extract the gases from ice cores and measure their greenhouse gas composition. The ice is sublimated continuously with a near-infrared laser, releasing the gases, which are then analyzed on a laser absorption spectrometer. The main advantage over previous efforts is a low effective resolution of 1–2 cm. This capability is crucial for the analysis of highly thinned ice, as expected from ongoing drilling efforts to extend ice core history further back in time.

We report in situ measurements of air pollutant concentrations within the planetary boundary layer on board a Zeppelin NT in Germany. We highlight the in-flight evaluation of electrochemical sensors that were installed inside a hatch box located on the bottom of the Zeppelin. Results from this work emphasize the potential of these sensors for other in situ airborne applications, e.g., on board unmanned aerial vehicles (UAVs).

Measurements of atmospheric O₂ can help constrain the carbon cycle processes and quantify fossil fuel CO₂ emissions; however, measurement of atmospheric O₂ is very challenging, and existing analysers are complex systems to build and maintain. We have tested a new O₂ analyser (Picarro Inc. G2207-i) in the laboratory and at Weybourne Atmospheric Observatory. We have found that the G2207-i does not perform as well as an existing O₂ analyser from Sable Systems Inc.

The depolarization ratio of hematite, silica, Arizona and Asian dust is evaluated in a lab with a π-polarimeter operating at lidar 180 ° and at (355, 532) nm wavelengths. The hematite depolarization equals (10±1) % at 355 nm for coarser particles, while that of silica is (33±1) %. This huge difference is explained by accounting for the high imaginary part of the hematite complex refractive index, thus revealing the key role played by light absorption in mineral dust lidar depolarization.

The T-matrix theory was used to compute the backscatter and depolarization of mixed-phase PSC, assuming that particles are solid (NAT or possibly ice) above a threshold radius R and liquid (STS) below, and a single shape is common to all solid particles. We used a dataset of coincident lidar and balloon-borne backscattersonde and OPC measurements. The agreement between modelled and measured backscatter is reasonable and allows us to constrain the parameters R and AR.

Profile observations of the atmospheric boundary layer now allow for layer heights and characteristics to be derived at high temporal and vertical resolution. With novel high-density ground-based remote-sensing measurement networks emerging, horizontal information content is also increasing. This review summarises the capabilities and limitations of various sensors and retrieval algorithms which need to be considered during the harmonisation of data products for high-impact applications.

Nitrogen dioxide (NO₂) is an important trace gas for both air quality and climate. NO₂ affects satellite ocean color products. A new ocean color instrument – OCI (Ocean Color Instrument) – will be launched in 2024 on a NASA satellite. We show that it will be possible to measure NO₂ from OCI even though it was not designed for this. The techniques developed here, based on machine learning, can also be applied to instruments already in space to speed up algorithms and reduce the effects of noise.

Vertical observation of volatile organic compounds (VOCs) is essential to study the spatial distribution and evolution patterns of VOCs in the planetary boundary layer (PBL). This paper describes multi-channel whole-air sampling equipment onboard an unmanned aerial vehicle (UAV) for near-continuous VOC vertical observation. Vertical profiles of VOCs and trace gases during the evolution of the PBL in south-western China have been successfully obtained by deploying the newly developed UAV system.

An increased social environmental awareness requires the monitoring of greenhouse gases (GHGs). We report on the development of two sampling devices (which can be mounted to a drone) and the subsequent measurement setup to analyse these gases. The functionality of the presented system was tested in the field, and the results emphasised the functionality of the sampling and measurement setup, demonstrating that it is a viable tool for monitoring GHGs and identifying their emission sources.

During a 5-week comparison campaign, we tested two set-ups to measure half hourly ammonia fluxes. The eddy covariance and flux gradient systems showed very similar results when the upwind terrain was both homogeneous and free of obstacles. We discuss the technical performance and practical limitations of both systems. Measurements from these instruments can facilitate the study of processes behind ammonia deposition, an important contributor to eutrophication and acidificationin natural areas.

Storm activity is sometimes associated with the generation of ionizing radiation. Our motivation for performing this research was to understand its origin. Using measuring cars fitted with new instruments, it was found that the duration of lightning is longer than generally thought. In most cases, lightning occurs only inside the cloud; however, rarely, it is also visible outside the cloud. In such cases, the course of emission over time can be used to assume what it looks like inside the cloud.

Accurate knowledge of the planetary boundary layer height (PBLH) is essential to study air pollution. However, PBLH observations are sparse in space and time, and PBLHs used in atmospheric models are often inaccurate. Using PBLH observations from the Aircraft Meteorological DAta Relay (AMDAR), we present a machine learning framework to produce a spatially complete PBLH product over the contiguous US that shows a better agreement with reference PBLH observations than commonly used PBLH products.

We evaluate the theoretical ability of the upcoming MicroCarb satellite to estimate urban CO₂ emissions over Paris and London. We explore the relative performance of alternative two-sweep and three-sweep city observing modes and take into account the impacts of cloud cover and urban biological CO₂ fluxes. Our results find both the two-sweep and three-sweep observing modes are able to reduce prior flux errors by 20 %–40 % depending on the prevailing wind direction and cloud coverage.

SMILE (a spectral misalignment in which a shift in the center wavelength appears as a distortion in the spectral image) was detected during our recent work. To evaluate how it affects the cloud retrieval products, we did a simulation of EarthCARE-MSI forward radiation, evaluating the error in simulated scenes from a global cloud system-resolving model and a satellite simulator. Our results indicated that the error from SMILE was generally small and negligible for oceanic scenes.