High-volume air sampling is a key measurement technique to investigate the concentration of atmospheric pollutants. Although being a mature technique, a detailed description of how to derive flow rates and how to calibrate these samplers is missing in the literature. This paper uses basics in fluid mechanics to derive the equations in question. This allows for a deeper understanding of the measurement process and opens up for a more differentiated assessment of potential error sources.

In this work we evaluate the accuracy of water vapor ground-based FTIR retrievals in the lower and upper troposphere using coincident high-quality vertically resolved balloon-borne NOAA FPH measurements. Our results suggest that highly structured water vapor vertical gradients are captured with the FTIR and found a negligible bias in the immediate layer above the instrument altitude accounting for a water vapor time variability of less than 2 %.

A new network of precipitation instruments has been established for the UK. The instruments are capable of detecting the fall velocity and diameter of each particle that falls through a laser beam. The particle characteristics are derived from the duration and amount of decrease in beam brightness as perceived by a receiving diode. 14 instruments make up the network and all instruments upload 60-second frequency data in near real time to a publicly available website with plots.

Ceilometers are often influenced by water vapor absorption in the spectral range around 910 nm. Thus, a correction is required to retrieve aerosol optical properties. Validation of this correction scheme was performed in the framework of CeiLinEx2015 for several ceilometers with good agreement in case of CL51 ceilometers. For future applications we recommend to monitor the emitted wavelength and to provide dark measurements on a regular basis to be able to correct for signal artefacts.

Based on single particle mass spectra from field measurements in the upper Rhine valley we identified characteristic particle classes, estimated their mass contributions, and achieved a better understanding of the mixing state of ambient aerosol particles. Our study opens a new way for quantitative interpretation of single particle data by comparison with complimentary bulk measurements.

An innovative method is presented for deriving particulate matter (PM) concentrations using CALIOP measurements. Deviating from conventional approaches of relying on passive satellite column-integrated aerosol measurements, PM concentrations are derived from near surface CALIOP measurements through a bulk-mass-modeling method. This proof-of-concept study shows that, while limited in spatial and temporal coverage, CALIOP exhibits reasonable skill for PM applications.

Knowledge related to sulfur isotopic composition of carbonyl sulfide (OCS or COS), the most abundant atmospheric sulfur species, remains scarce. We present a new sampling system for collecting approx. 10 nmol of OCS from ambient air coupled with a purification system. The system presented herein is useful for application of sulfur isotopic compositions for investigation of OCS sources and sinks in the troposphere to elucidate its cycle and its contribution to background stratospheric sulfate.

We study a novel remote sensing technique for atmospheric trace gases absorbing in the UV and visible spectral range. Using Fabry Perot interferometers with a spectral transmission matched to the trace gas's spectral absorption allows for imaging trace gases with high sensitivity and selectivity. The thereby achieved high spatio temporal resolution enables the study of small scale and dynamic processes in the atmosphere. We present sample calculations and a proof of concept study.

A MARGA was combined with an additional ion chromatography system specialized for the two-hourly online quantification of 12 low-molecular weight organic acids in the gas and particle phase. Low limits of detection and good precisions were achieved. The suitability for field measurements was shown. This setup reduces laboratory work and filter sampling artifacts. Diurnal profiles, sources and phase distributions of these compounds improve the knowledge of the tropospheric multiphase chemistry.

Lidars are well-suited for trend measurements of water vapour in the troposphere and lower stratosphere. The lidar's calibration can be affected by a lack of co-location between the balloon and lidar. We present a tracking calibration method which allows only periods when the balloon and lidar share a common volume of space to be used. This method allows nights with high variability in water vapour to be included in the calibration, improving the quality of the measurements for trend analysis.

A newly developed in-situ measurement method allows new insights into the propagation behaviour of aerosol particles such as pollen grains and spores, possibly improving the pollen prognosis for allergy sufferers and providing new discoveries in the propagation behaviour of fine dust particles of different origins. This publication describes the development of the unmanned multicopter based system as well as initial tests and validations to overcome various technical challenges.

In this study the consistency between MAX-DOAS measurements and radiative transfer simulations of the atmospheric O₄ absorption is investigated. The study is based on measurements (two days during the MADCAT campaign) as well as synthetic spectra. The uncertainties of all relevant aspects (spectral retrieval and radiative transfer simulations) are quantified. For one of the selected days, measurements and simulations do not agree within their uncertainties.

The paper presents a novel method to retrieve microphysical properties of cirrus clouds from the synergy of lidar and thermal infrared radiometer measurements. It highlights the advantages of combining two independent data sets resulting in a better characterization of the considered cloud type. Our algorithm may improve the description of the backscattering features of the ice crystals composing the cloud and thereby improve our understanding of their interactions with atmospheric radiation.

In this study the quality of the Total Precipitable Water (TPW) retrieved from the newly released AERONET Version 3 algorithm is assessed, through comparison with independent measurements of the TPW from a microwave radiometer and radiosondes at a station in South-Eastern Europe. The findings show that there are improvements in the estimation of TPW in Version 3, compared to Version 2 of the algorithm.

The benzene determination in ambient air is mandatory in the European Union. The reference measuring technique is by gas chromatography and it is recommended that a photometric ionisation detector is used. This study has shown that the simultaneous presence of benzene and tetrachloromethane causes a significant decrease in the GC-PID readings. Given the importance of this behaviour, a possible mechanism was proposed. This study highlights the uncertainty of measuring benzene using a GC-PID.

We present continuous in situ measurements of atmospheric CO₂ and CH₄ mole fractions at the new station Ambarchik, located in northeastern Siberia. We describe the site, measurements and quality control, characterize the signals in comparison with data from Barrow, Alaska, and show which regions the measurements are sensitive to. Ambarchik data are available on request.

The aim of this study is the merging of stratospheric ozone profiles from 3 satellite datasets. The merged time series is used to compute long-term changes as a function of altitude, latitude and longitude to study the evolution of the ozone layer over 1985–2018. We found positive trends in the upper stratosphere at mid-latitudes, related to the Montreal Protocol and increasing greenhouse gases, and a remarkable variability of ozone changes as a function of longitude and over the last 15 years.

This work assesses water vapour profiles acquired by Atmospheric Chemistry Experiment (ACE) satellite instruments in the upper-troposphere lower-stratosphere (UTLS) region using comparisons to radiosondes and ground-based Fourier transform infrared spectrometer measurements acquired at a Canadian high Arctic measurement site, Eureka, Nunavut. Additional comparisons are made between these Eureka measurements and other water vapour satellite datasets for context, including AIRS, MLS, and others.

The cloud base height (CBH) is important for air traffic, to describe the energy budget of the Earth and for other applications. Ground-based measurements of CBH are only punctually available, and mostly limited to land. A powerful tool for global coverage are satellites. While the cloud top height is derived operationally, the derivation of CBH from space is more difficult as the clouds hide their base. Here, we present a method to retrieve the base from multi-angle satellite data.

We demonstrate the successful adaption of a laser based spectrometer for airborne in-situ trace gas measurements to enable achieving an improved understanding of the anthropogenic influence on climate due to man made greenhouse gas emissions. The modified instrument allows for precise and simultaneous airborne observation of five climatologically-relevant gases. We further report on instrument performance during a first field deployment over the eastern and central U.S..

We implemented a prototype of a centralized system to support atmospheric observatories in data production and submission. By using the “R” Language, for several near-surface ECVs, we developed specific routines for data filtering, flagging, formatting, and creation of data products for detecting instrumental problems or special atmospheric events. Our effort would improve atmospheric data quality, accelerate the process of data submission and make the data flagging more “objective".

We use a near-infrared camera for the investigation of gravity waves. The camera observes the airglow layer which is used as a tracer for the dynamics. The images are processed, which includes the removal of the star background, and analysed with a 2D-Fast Fourier Transform and automatic derivation of the wave parameters. The results show a clear seasonal and intra-diurnal variability which is characterised in order to improve our understanding of gravity waves in the middle atmosphere.

Here, we tested lower cost CO₂ sensors in laboratory and field studies to see if they can achieve a performance target (less than 1 ppm bias with monthly calibration) that would allow using them for monitoring of atmospheric CO₂ in urban areas. We find that the commercial CO₂ sensor's readings are influenced by temperature, atm. pressure and water vapour, but this can be corrected for by adding sensors (T/p/RH) and carefully calibrating the measured CO₂ compared to a high-precision instrument.

Within the EU COST Action ES1206 we have studied the horizontal variability of the atmosphere using signals from GPS satellites, distant quasars, and a microwave radiometer. We find a consistent picture: horizontal variability over time scales of months are mainly due the atmospheric pressure, whereas water vapour is the main cause for variations over minutes to hours. An understanding of these variations helps to improve the accuracy of GPS applications in geodesy and meteorology.

In this study, we developed and applied a mobile instrument setup to determine the δ¹³CH₄ signature by measuring the plume of different CH₄ sources using a CRDS analyser. Therefore, we carefully characterised the CRDS analyser especially with regard to cross sensitivities of the gas matrix. During 21 field campaigns we determined mean δ¹³CH₄ values of three dairy farms, a biogas plant, a landfill, a wastewater treatment plant, an active deep coal mine and two natural gas facilities in Germany.

Airborne observations of ice clouds are used to validate radiative transfer simulations using a state-of-the art database of cloud ice optical properties. Simulations at these wavelenghts are required to make use of future satellite instruments such as the Ice Cloud Imager. We show that they can generally reproduce observed cloud signals, but for a given total ice mass there is considerable sensitivity to the cloud microphysics, including the particle shape and distribution of ice mass.

Airborne pollutants, such as volatile organic compounds, can present a danger to public and environmental health. We explored the potential for low-cost air quality sensors to help measure these compounds. From our deployment and the subsequent analysis, it seems these sensors can be calibrated to provide estimates of the levels of some individual and some groups of VOCs. More cost-effective ways to measure VOCs could inform actions to reduce exposure.

The version 4 (V4) release of the CALIPSO data products includes substantial improvements to the calibration of the CALIOP 1064 nm channel. In this paper we review the fundamentals of 1064 nm lidar calibration, explain the motivations for the changes made to the algorithm, and describe the mechanics of the V4 calibration technique. Internal consistency checks and comparisons to collocated high spectral resolution lidar measurements show that the V4 1064 nm calibration coefficients to within ~ 3 %.

This paper describes the temperature profiles in the stratosphere obtained from unique stellar scintillation measurements by the GOMOS instrument operated on board Envisat in 2002–2012. The high-resolution temperature profiles (HRTP) are retrieved with very good vertical resolution ~200 m and high accuracy ~1–3 K for altitudes 15–32 km and a global coverage. HRTP can be assimilated into atmospheric models and used in analyses of internal gravity waves activity.

We propose a method to assess the accuracy of turbulence measurements by sonic anemometers. The idea is to compute the ratio of the vertical to the along-wind velocity spectrum within the inertial subrange. We found that the Metek USA-1 and the Campbell CSAT3 sonic anemometers do not show the expected theoretical ratio. A wind-tunnel based correction recovers the expected ratio for the USA-1. A correction for the CSAT3 does not, illustrating that this sonic suffers of flow distortion.