We describe the analytical techniques used in the creation of a new background site for continuous measurements of greenhouse gases, carbon monoxide, and atmospheric oxygen in the Namib Desert. The measurement system is semi-automated and optimized for operation in a remote locale. Measurement uncertainties, gas handling, calibration schemes, drift corrections, and instrument performance are discussed.

A 29 m3 Teflon chamber was characterized and tested with oxidation experiments of toluene. Secondary organic aerosol yields of 12-42 % were obtained. These yields are comparable to those obtained in other laboratories.

The SO2 observations from OMI and OMPS satellite instruments are compared to ground-based measurements during the Icelandic Holuhraun fissure eruption in September 2014. The best agreement with the Brewer observations in Sodankylä, Finland can be found, assuming the SO2 predominantly located in the lowest levels of the atmosphere. The analysis of the SO2 surface concentrations in northern Finland supports the hypothesis that the volcanic plume was located very close to the surface.

Evaporation from precipitation gauges can bias measurements lower. The use of evaporation suppressants may not always be practical, considering the added cost of maintenance, transport, and disposal of the gauge additive. In this field study, two quality assurance methods used to evaluate depth change for the US Climate Reference Network were compared. Results from this study indicate calculation techniques can reduce the impact of gauge evaporation on precipitation measurements.

A technique for compound specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOC) is presented. It is based on selective VOC sampling onto adsorbent filled cartridges. Examples of measurements conducted demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an overrepresentation of samples that are strongly impacted by recent emissions.

Organosulfates are SOA products that have proven difficult to quantify. This study addresses the need for authentic quantification standards with a straightforward approach to synthesizing highly pure organosulfate potassium salts. New standards are used to develop a new separation protocol for small, functionalized organosulfates. Upon validation, this method is used to assess sample preparation protocols and to make new measurements of organosulfates in Centreville, Alabama.

This work presents a new iterative method for optimally selecting a vertical retrieval grid based on the location of information while accounting for inter-level correlations. Sample atmospheres initially created to parametrise the RTTOV forward model are used to compare the presented iterative vertical selection method with two other common approaches. The iterative method is shown to outperform the other methods in terms of degrees of freedom, but at the expense of simplicity.

We describe the University of Colorado 2-D-MAX-DOAS instrument and a retrieval to measure 3-D distributions of NO2. The spatial scale over which NO2 is probed is systematically varied by measuring NO2 at three different wavelengths. This has a significant effect on the comparison with the NO2 VCD as measured by OMI. The challenges and opportunities to validate satellites under inhomogeneous conditions as well as to pinpoint hydrocarbon chemistry around the measurement site are discussed.

Atmospheric aerosol is often subject to supersaturated or supercooled conditions where bulk measurements are not possible. Here we demonstrate how measurements using single particle electrodynamic levitation combined with light scattering spectroscopy allow the retrieval of thermodynamic data, optical properties and water diffusivity of such metastable particles even when auxiliary bulk data are not available due to lack of sufficient amounts of sample.

An optimised method for derivatisation of carbonyl compounds with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) in aqueous samples is described. The comprehensive optimisation of the method leads to an improvement of the detection limit up to a factor of 10 highlighting the good sensitivity of the optimised method for atmospherically relevant carbonyl compounds. The optimised method was successfully applied to detect carbonyl compounds from the aqueous phase oxidation of 3-methylbutanone.

An algorithm is presented for retrieving tropospheric NO2 vertical column densities from ground-based zenith-sky (ZS) measurements of scattered sunlight. The different steps are fully characterized and recommendations are given for each of them. The retrieval algorithm is applied on a 2-month ZS data set acquired during the CINDI campaign and on a 2-year data set acquired at the OHP NDACC station. The error budget assessment indicates that the overall error on the column values is less than 28%.

The GLORIA sounder is an airborne infrared limb-imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 research aircraft HALO during the TACTS and ESMVAL campaigns in summer 2012. This paper describes the retrieval of temperature, as well as H2O, HNO3, and O3 cross sections from GLORIA dynamics mode spectra. A high correlation is achieved between the remote sensing and the in situ trace gas measurements.

The theory of an approach for absolute radar calibration with respect to reflectivity and without a previously calibrated reference device is laid out and validated. The method requires a network of two horizontally oriented radars operating within a frequency range strongly attenuated by liquid water and a radar allowing for drop size distribution measurements with height (e.g. micro rain radar). The analysis by means of synthetic data shows potential for future practical application.

We systematically evaluated the impact of GPSRO data on typhoon track prediction over the Northwestern Pacific during 2008 to 2010. Specifically, we perform data assimilation and forecast experiments using the TWRF system at 45km resolution on 11 typhoons, with or without the use of GPSRO refractivity. The results indicate that the assimilation of GPSRO reduces the 72-hour track forecast errors by ~12km (5 %). Although this is only a modest improvement, it is statistically significant.

Source apportionment (SA) of organic aerosol mass spectrometric data measured with the Aerodyne ACSM using PMF/ME2 is a frequently used technique in the AMS/ACSM community. ME2 uncertainties due to instrument-to-instrument variations are elucidated by performing SA on ambient data from 14 individual, co-located ACSMs, recorded during the first ACTRIS ACSM intercomparison study at SIRTA near Paris (France). The mean uncertainty was 17.2%. Recommendations for future studies using ME2 are provided.

Ionization reagents suitable for accurate measurements of the atmospheric gas-phase amine vapour concentrations are needed. Based on computational results, acetone is a viable option for use as an ionization reagent in CI-APi-TOF measurements on atmospheric dimethylamine. However, comparison between the computational and experimental results revealed notable discrepancies. Further study is still required before the acetone CI-APi-TOF can be considered a viable option in practice.

The paper presents recent developments for the retrieval of sun-induced fluorescence (SIF) from medium spectral resolution space-borne spectrometers such as the Global Ozone Monitoring Experiment (GOME-2) and the Scanning Imaging Absorption SpectroMeter for Atmospheric ChartographY (SCIAMACHY). Beside using simulated radiances to evaluate the retrieval performance, the method has also been used to estimate SIF at 740 nm using real spectra from GOME-2 and for the first time, from SCIAMACHY.