Nine Pandora Spectrometer Instruments were installed at 8 sites for KORUS-AQ (Korea U.S.-Air Quality) field study from ground, aircraft, and satellite measurements. The quantities retrieved were total column measurements of ozone, nitrogen dioxide, and formaldehyde. We show the distribution of NO₂ and HCHO air pollutants vs location and time of day and comparisons with aircraft and satellite data. For some of the sites, long-term time series are available to asses changes.

Air pollution sensors are quickly proliferating for use in a wide variety of applications, with a low price point that supports use in high-density networks, citizen science, and individual consumer use. We evaluated the performance of particulate matter, ozone, and nitrogen dioxide sensors in Denver, Colorado, over a period of seven months. We found that these sensors could vary greatly in their performance, but some were able to replicate trends measured by traditional instruments.

Ambient pressure and temperature can vary with location, which implies that classifying aerosol particle mass using APM might be influenced at high-altitude sites. On the other hand, when using the APM as a particle classifier coupled with inductively coupled plasma mass spectrometry, argon would be required as the carrier gas. Therefore, air, oxygen and carbon dioxide were selected as carrier gases to evaluate the effect of gas viscosity and the mean free path on the performance of APM.

A novel neural-network-based retrieval method is proposed that combines the flexibility and computational efficiency of machine learning retrievals with the consistent treatment of uncertainties of Bayesian methods. Numerical experiments are presented that show the consistency of the proposed method with the Bayesian formulation as well as its ability to represent non-Gaussian retrieval errors. With this, the proposed method overcomes important limitations of traditional methods.

We present a campaign to address several error sources associated with rainfall estimates from microwave links in cellular communication networks. The set-up consists of three co-located links, complemented with reference instruments. We investigate events covering different attenuating phenomena: Rainfall, solid precipitation, temperature, fog, antenna wetting due to rain or dew, and clutter.

This paper aims to show the potential of an instrumented mobile platform, performing on-road remote sensing and in situ measurements, to derive aerosol properties. It is distinguished from other transportable platforms through its ability to perform measurements during movement. Its reduced size, versatility and great flexibility makes it suitable for following sudden aerosol events and for validating satellite measurements and model simulations.

MIPAS was an IR limb emission spectrometer on the Envisat platform. From 2002 to 2012, it performed pole-to-pole measurements of ozone during day and night. ESA recently released the new version 7 of Level 1 MIPAS spectra, which is expected to reduce the long-term drift of the MIPAS Level 2 data. We evaluate the long-term stability of ozone Level 2 data from the KIT IMK processor. Our results indicate that MIPAS data are now even more suited for trend studies, alone or as part of merged data.

We report differences in ozone retrievals in channels A and AB of the space-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), which amount to up to 8 %. We provide strong evidence that the bias is caused by inconsistencies in different spectroscopic databases (MIPAS, HITRAN, GEISA). We show that a major part of the differences can be attributed to inconsistent air-broadening coefficients of the ozone lines contained in the databases.

We describe a systematic approach to the calibration and uncertainty estimation of a high-resolution continuous flow analysis (CFA) water isotope (δ²H, δ¹⁸O) record from the Roosevelt Island Climate Evolution (RICE) Antarctic ice core. Our method establishes robust uncertainty estimates for CFA δ²H and δ¹⁸O measurements, comparable to those reported for discrete sample δ²H and δ¹⁸O analysis. The resulting mean total errors for the record are 0.74 ‰ and 0.21 ‰ for δ²H and δ¹⁸O, respectively.

We present two-dimensional cross sections of temperature, HNO₃, O₃, ClONO₂, H₂O and CFC-12 from measurements of the GLORIA infrared limb imager during the POLSTRACC/GW-LCYCLE/SALSA aircraft campaigns in the Arctic winter 2015/2016. GLORIA sounded the atmosphere between 5 and 14 km with vertical resolutions of 0.4–1 km. Estimated errors are in the range of 1–2 K (temperature) and 10 %–20 % (trace gases). Comparisons to in situ instruments onboard the aircraft and to Aura/MLS are shown.

The Institute for Atmospheric and Environmental Research at the University of Wuppertal designed and manufactured a prototype of the large-area blackbody for in-flight calibration of an infrared interferometer deployed onboard a long-duration balloon for stratospheric research.

During new particle formation (NPF) studies from pure isoprene oxidation in the CLOUD chamber at CERN we observed unexpected ion signals. We identified two origins of these signals: first secondary association reactions of protonated isoprene with isoprene within the PTR3 reaction chamber and, second, polymerization of isoprene inside the gas bottle. In order to study NPF from pure isoprene oxidation we had to install a cryogenic trap in the isoprene inlet line to remove polymerized isoprene.

The high potential of the MPLNET polarized Micro-Pulse LiDAR (P-MPL) is demonstrated in synergy with the POLIPHON (POlarization-LIdar PHOtometer Networking) method to retrieve the vertical separation of both the optical and mass features of the dust, smoke and pollen components mixed with other aerosols. This synergetic procedure can be easily applied to the worldwide MPLNET lidar systems and to space-borne lidars: the ongoing NASA CALIPSO/CALIOP and the forthcoming ESA EarthCARE/ATLID.

A highly portable ozone calibration source based on the photolysis of oxygen is described and evaluated. The ozone mixing ratio produced is independent of both pressure and temperature, and humidity effects are small and correctable. The resulting O₃ calibrator has a response time < 20 s, a precision of 0.4 %, and can serve as a U.S. EPA level 4 transfer standard for the calibration of ozone analyzers.

The viscosity of erythritol, a tetrol found in aerosol particles, is highly uncertain. To help resolve this uncertainty, we measured the viscosities of erythritol–water particles using rectangular-area fluorescence recovery after photobleaching and aerosol optical tweezers techniques. These results should help improve the understanding of the viscosity of secondary organic aerosol particles. In addition, we present an intercomparison of techniques for measuring the viscosity of particles.

Low-cost particulate matter sensors are promising tools for supplementing existing air quality monitoring networks but their performance under field conditions is not well understood. We characterized how well Plantower PMS3003 sensors measure PM_2.5 in a wide range of ambient conditions against different reference sensors. When a more precise reference method is used for calibration and proper RH corrections are made, our work suggests PMS3003's can measure PM_2.5 within ~ 10 % of ambient values.

In this paper we propose an innovative approach for hydrometeor de-mixing, i.e., to identify and quantify the presence of mixtures of different hydrometeor types in a radar sampling volume. It is a bin-based approach, inspired by conventional decomposition methods and evaluated using C- and X-band radar measurements compared with synchronous ground observations. The paper also investigates the potential influence of incoherency in the backscattering from hydrometeor mixtures in a radar volume.

Recently a new approach for the production of RO climatologies has been proposed. The idea is to propagate mean bending angle profiles through processing and retrieve directly climatological products of refractivity, density, pressure, and temperature. The averaging suppresses noise in the data, allowing the bending angles to be used up to 80 km without the need for background information. This work focuses on the comparison of the new climatologies between two processing centers.

It is important to correctly interpret the readings reported by low cost airborne particle sensors at high humidity. We demonstrate that deliquescent growth of particles and the formation of fog droplets in the atmosphere can lead to significant increases in particle number and mass concentrations reported by such sensors, unless they are fitted with dryers at the inlet. This is important as air quality standards for particles are specifically limited to solid particles.

Remote sensing of greenhouse gases (GHG) such as CO₂ and CH₄ in the atmosphere from space is important for studying emissions and the carbon cycle. Present-day techniques measure the absorption of light passing through the atmosphere and determine the column-averaged gas concentration in the atmosphere. Here, we draw from a well-known singular value decomposition (SVD) framework to develop a technique of extracting information about the GHG concentration profile from the column absorption.

We show the systematic application of hierarchical agglomerative clustering (HAC) to comprehensive bioaerosol and non-bioaerosol laboratory data collected with the wideband integrated bioaerosol sensor (WIBS-4A). This study investigated various input conditions and used individual matchups and computational mixtures of particles; it will help improve clustering results applied to data from the ultraviolet laser and light-induced fluorescence instruments commonly used for bioaerosol research.