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 upon request.

Sampling coarse-mode aerosol from a fast-moving research aircraft is challenging and can be subject to substantial losses and enhancements. We characterise these losses and enhancements for an inlet system designed to collect aerosol onto filters. We go on to present an application of this inlet system where we use electron microscopy to study the size and composition of the collected aerosol particles.

Characteristics of SAETTA lightning imager installed in Corsica are presented, with original observations of lightning activity at regional and lightning scales. SAETTA monitors thunderstorms in a maritime and mountainous region, complex for weather forecasting and sensitive to global warming. A 3-year lightning climatology highlights frequent activity over a specific region due to relief. Uncommonly high discharge in stratiform thundercloud may support a recent model of charging processes.

The Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE™) trace gas measurement system provides high-precision, long-path measurements of atmospheric trace gases including CO₂ and CH₄ over extended (0.04 km²–25 km²) areas of interest. This work provides a brief overview of the system design, a description of a newly developed bias-correction approach and the results as applied to data collected in Paris, France, over a 1-year period spanning November 2015 to December 2016.

We present a new method for retrieving temperature from pure rotational Raman (PRR) lidar measurements using an optimal estimation method. We show that the error due to calibration can be reduced significantly using our method. The new method is tested on PRR temperature measurements from the MeteoSwiss Raman Lidar for Meteorological Observations system in different sky conditions. The next step is to assimilate the temperature profiles into models to help improve weather forecasts.

In-cloud supersaturation is crucial for droplet activation, growth, and drizzle initiation but is poorly known and hardly measured. Here we provide a novel method to estimate supersaturation fluctuation in stratocumulus clouds using remote-sensing measurements, and results show that our estimated supersaturation agrees reasonably well with in situ measurements. Our method provides a unique way to estimate supersaturation in stratocumulus clouds from long-term ground-based observations.

We introduce a coaxial, low-pressure ion–molecule reaction (IMR) region for iodide-adduct chemical ionization mass spectrometry, designed to decrease the effects of IMR wall interactions with organic/inorganic gases. This IMR has 3–10 times shorter delay times than previous IMRs. We introduce a conceptual framework for understanding and subtracting the background signal due to analyte molecules interacting with IMR walls. This framework can be applied to other tubing and instrument systems.

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. A total of 14 instruments make up the network and all instruments upload 60 s frequency data in near-real time to a publicly available website with plots.

We analysed results obtained through CO and N₂O performance audits conducted within the framework of the Global Atmosphere Watch (GAW) quality management system of the World Meteorology Organization (WMO). The results reveal that current spectroscopic measurement techniques have clear advantages with respect to data quality objectives compared to more traditional methods. Further, they allow for a smooth continuation of historic CO and N₂O time series.

This study examines the effect of changes in relative humidity on measurements made by two different filter-based absorption photometers. Different filter loads, loading materials, and filter types are considered. It was found that both instruments react opposingly and with different magnitudes. One of the devices showed a variation in the dependence on the loading material. For each of the two devices, a correction approach is provided. Recommendations based on the findings are given.

This paper presents a methodology for high ice water content (HIWC) (up to 3.5 g m⁻³) retrieval from a dual-polarization side-looking X-band airborne radar. Z_dr and K_dp are used to mitigate the effects of ice crystal shape and orientation on the variation in IWC – specific differential phase (K_dp) joint distribution. Empirical analysis shows that the proposed method improves the estimation bias by 35 % and increases the correlation by 4 % on average, compared to the method using K_dp alone.

Collection of particles onto filters can be a valuable tool in several research disciplines. Here we experiment with quartz filters and their response to soot particles in an airborne and liquid state in order to better understand the sampling procedure. Soot particles in a liquid phase showed absorption of light nearly double that of airborne sampled particles.

Cloud liquid water path (LWP) is one of the target atmospheric parameters retrieved remotely from ground-based and space-borne platforms. The LWP data delivered by the satellite instruments SEVIRI and AVHRR together with the data provided by the ground-based radiometer RPG-HATPRO near St. Petersburg, Russia, have been compared. Our study revealed considerable differences between LWP data from SEVIRI and AVHRR in winter over ice-covered relatively small water bodies in this region.

Herein we report on the first successful airborne deployment of a CHARON PTR–ToF–MS instrument aboard the NASA DC–8 research aircraft. The analyzer is capable of chemically characterizing submicrometer atmospheric particles in a quantitative manner, at the near–molecular level, in real time. This brings a new and unprecedented measurement capability to the airborne atmospheric science community.

This study describes a novel application of an onion-peeling approach to MAX-DOAS measurements of shipping emissions to study the inhomogeneous NO₂ field above a shipping lane. It is shown how the method can be used to derive the approximate plume positions in the observed area, and, by using a simple Gaussian plume model, to calculate in-plume NO₂ volume mixing ratios. For validation, a comparison to airborne imaging DOAS measurements during the NOSE campaign in July 2013 is included.

The differences between the TCCON and NDACC X_CO measurements are investigated and discussed based on six NDACC–TCCON sites (Ny-Ålesund, Bremen, Izaña, Saint-Denis, Wollongong and Lauder) using data over the period 2007–2017. The smoothing errors from both TCCON and NDACC measurements are estimated. In addition, the scaling factor of the TCCON X_CO data is reassessed by comparing with the AirCore measurements at Sodankylä and Orléans.

To determine gravity wave properties like wavelengths, periods and propagation directions at mesospheric altitudes (∼ 86 km) we combine lidar and airglow temperature and meteor radar wind data. By means of wavelet transformation we investigate the wave field and determine intrinsic wave properties as functions of time and period. We are able to identify several gravity wave packets by their distinct propagation and discover a superposition with possible wave–wave and wave–mean-flow interaction.

Aerosols are fine particles that are suspended in Earth’s atmosphere. A better understanding of aerosols is important to lower uncertainties in climate predictions. We propose measuring aerosols from satellites and airplanes equipped with hyperspectral cameras using an artificial neural network, a form of machine learning. We applied our neural network to hyperspectral observations from a recent airplane flight over India and find general agreement with independent aerosol measurements.

In an attempt to make cloud retrievals from the surface more common and convenient, we developed a cloud retrieval algorithm applicable for sky radiometers. It is based on an optimum method by fitting measured transmittances with modeled values. Further, a cost-effective and easy-to-use calibration procedure is proposed and validated using data obtained from the standard method. A detailed error analysis and quality assessment are also performed.

We propose a one–band XCO₂ retrieval technique which uses only the 2.06 µm band measurements from the Orbiting Carbon Observatory–2 (OCO–2) satellite. Compared to the current state–of–the–art three–band retrievals, XCO₂ retrievals using only the 2.06 µm band have similar retrieval accuracy, precision, and data yield. For future missions it may be better to replace the O₂ A band with measurements that have larger information content on aerosols, like a multi–angle polarimeter (MAP).

Determination of ecosystem exchange fluxes using the eddy covariance technique requires measurements with a fast time response. For ammonia, the time response is limited by adsorption and desorption processes on instrument surfaces, generally leading to a substantial underestimation of fluxes. Based on a 5-month flux dataset, we propose a new method to correct for the ammonia flux loss that is better suited to account for factors like surface aging and contamination than other approaches.

A new mid-infrared and ultra-portable formaldehyde (HCHO) sensor from Aeris Technologies is characterized and evaluated against well-established laser-induced fluorescence (LIF) instrumentation. The Aeris sensor displays linear behavior (R squared > 0.94) and shows good agreement with LIF instruments. While the compact sensor is not currently a replacement for the most sensitive research-grade instrumentation available, its sub-ppbv precision is sufficient for indoor and outdoor HCHO monitoring.

In 2017, an airborne mapping spectrometer (GeoTASO) was used to observe high-resolution column densities of nitrogen dioxide (NO₂) over the western shore of Lake Michigan and the Los Angeles Basin. These data were used to simulate the spatial resolution of current and future satellite NO₂ retrievals to evaluate the impact of pixel size on comparisons to ground-based observations in urban areas. As spatial resolution improves, the sensitivity to more heterogeneously polluted scenes increases.

This study developed a measurement system based on an unmanned aerial vehicle for determining the fuel sulfur content from the exhaust gas of ships. The proposed measurement could be used to determine the smoke plume at about 5 m from the funnel mouth of ships, providing a rapid high-precision monitoring of emission control areas for compliance with sulfur fuel content. The results show that, in general, the deviation of the estimated value for fuel sulfur content is less than 0.03 % (m/m).

In this study, CH₄ vertical profile is retrieved by SFIT4 code from FTIR NIR spectra based on six sites during 2016–2017. The degree of freedom for signal of the SFIT4NIR retrieval is about 2.4, with two distinct species of information in the troposphere and in the stratosphere. By comparison against other measurements, e.g. TCCON standard products, satellite observations and AirCore measurements, the uncertainties of the SFIT4NIR total column and partial columns are estimated and discussed.

We have built a triple-capillary cryostat designed to reduce potential instrumental effects that may have influenced earlier measurements and to improve our understanding of the processes responsible for ice crystal shapes and sizes. In this cryostat, a crystal forms on one of three well-separated and ultrafine capillaries. In this paper we describe the new instrument and present several observations made using the instrument to illustrate the instrument's advantages.

An automated system for the online ambient measurement of 20 biogenic volatile organic compounds (BVOCs) was successfully developed and optimized. The analytical performance was satisfying for ambient measurements. The first measurements were carried out during the LANDEX field campaign in summer 2017. The 3-week field measurements displayed the excellent performance of the method with respect to providing speciated BVOC concentration values to further investigate atmospheric BVOCs' reactivity.

This work describes the science algorithm for the recently released CALIPSO level 3 stratospheric aerosol product. It is shown that the retrieved extinction profiles capture the major stratospheric perturbations over the last decade resulting from volcanic eruptions, pyroCb smoke events, and signatures of stratospheric dynamics. An initial assessment is also provided by intercomparison with the latest aerosol retrievals from the SAGE III instrument aboard the International Space Station.

Single-particle mass spectrometer (SPMS) instruments characterize the composition of individual aerosol particles in real time. We present a new method that combines SPMS composition with independently measured particle size distributions to determine absolute number, surface area, volume, and mass concentrations of mineral dust, biomass burning, sea salt, and other climate-relevant atmospheric particle types, with a fast time response applicable to aircraft sampling.

The Cloud Aerosol Transport System (CATS) demonstrated that direct calibration of 1064 nm lidar data from a spaceborne platform is possible. By normalizing the CATS signal to a modeled molecular backscatter profile the CATS data were calibrated, enabling the derivation of optical properties of clouds and aerosols. Comparisons of the calibrated signal with airborne lidar, ground-based lidar, and spaceborne lidar all show agreement within the estimated error bars of the respective instruments.