Planetary wave activity measured in the mesosphere to lower thermosphere is shown to increase drastically after strong stratospheric polar cap wind reversals associated with sudden stratospheric warmings. In addition, a moderate but significant correlation was found between planetary wave enhancement in the mesosphere to lower thermosphere and all stratospheric polar cap wind reversals, irrespective of the strength of the reversal. Hide

In June 2013, a ground-based mobile lidar performed the 10,000km ride from Paris to Ulan-Ude, near Lake Baikal. Aerosols have been characterized using two intensive properties: extinction-to-backscatter ratio and particle depolarization ratio. The results highlight spatial variations in the aerosol mix, with more terrigenous particles over Russia than Europe. Wildfire and desert dust plumes were also observed, offering the first optical characterization of dust from the Caspian–Aral region. Hide

Aerosol was sampled at the Pico Mountain Observatory located at 2.2km amsl on Pico Island of the North Atlantic Azores archipelago. Two aerosol samples characterized by ultrahigh resolution mass spectrometry had biomass burning and marine emissions origins, as corroborated by collocated gas- and particle-phase measurements, air masses analyses and satellites. The paper presents the first molecular characterization of aged and processed aerosol intercepted at a remote lower free troposphere Hide

This paper presents the first highly spatially resolved simultaneous mixing ratios of VOCs, NOx and O3 in the atmospheric boundary layer above Greater London (UK) using an research aircraft. Average mixing ratios measured at 360±10 m agl over outer London were always lower than over inner London, indicative of strong local vehicular sources. The comparison of airborne mixing ratio with LAQN air quality ground monitoring stations suggests that the mixing ratios were characteristic of the surface. Hide

This study examines ozone mixing ratios over Lake Michigan as measured on the Lake Express ferry, by shoreline differential optical absorption spectroscopy (DOAS) observations in southeastern Wisconsin, and as predicted by the Community Multiscale Air Quality (CMAQ) model. Over water, ozone was determined to be an average of 3.8ppb higher than shoreline observations but overpredicted by the CMAQ model by as much as 11-16ppb midday. Hide

High ozone concentrations (up to 94.7ppbv) were frequently observed at an altitude of ~1.5--2km over Beijing during April--May 2005. Ozone due to Asian anthropogenic pollution made major contributions to the observed ozone enhancements. These enhancements typically occurred under southerly wind and warmer conditions. An earlier onset of the Asian summer monsoon would cause more ozone enhancement events in the lower troposphere over the North China Plain in late spring and early summer. Hide

Combustion ash particles nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. From this study, there is a need to quantify the atmospheric abundance of combustion ashes in order to quantitatively assess the impact of combustion ashes on mixed-phase clouds. Hide

Particle pH can affect many aerosol processes, including gas-particle partitioning, SOA formation, and mobilization of toxic redox metals. pH is challenging to directly measure and often improperly characterized by proxies like ion balances or molar ratios of measured aerosol ionic species. We present a detailed analysis predicting pH with a thermodynamic model, verify the prediction, and test pH sensitivity to model inputs based on data from the SOAS field campaign. Hide

Measurements of SO2, NOx and particle emission factors of more than 400 individual ship passages in the Gulf of Finland are presented and discussed. The measurements were conducted during two campaigns in the years 2011 and 2012 from ground-based and helicopter-based platforms. It was found that a significant number of ships use fuel oil with a fuel sulfur content below the limit of 1%. Additionally, the results of modeled data for the same ships were compared to the measurements of this study. Hide

This work details the evaluation of PM2.5 carbon, VOC precursors, and OH estimated by the CMAQ photochemical transport model using routine and special measurements from the 2010 CalNex field study. Here, CMAQ and most recent emissions inventory (2011 NEI) are used to generate model PM2.5 OC estimates that are examined in novel ways including primary vs. secondary formation, fossil vs. contemporary carbon, OH and HO2 evaluation, and the relationship between key VOC precursors and SOC tracers. Hide

By undertaking greenhouse gas emissions measurements (plus CO) in a combustion wind tunnel facility, we show that emissions from fire depend on how they spread relative to the wind. Statistically significant differences include fires spreading with the wind emitting twice as much CO as fires spreading perpendicular to or against the wind, and about 10-17% more carbon dioxide. Our results suggest that judicious use of ignition patterns could mitigate carbon emissions from forest fires. Hide

The paper presents results from data assimilation studies with the new Composition-IFS model developed in the MACC project. This system was used in MACC to produce daily analyses and 5-day forecasts of atmospheric composition and is now run daily in the EU’s Copernicus Atmosphere Monitoring Service. The paper looks at the quality of the CO, O3 and NO2 analysis fields obtained with this system, comparing them against observations, a control run and an older version of the model. Hide

This article presents a new model that simulates particle formation in vehicle exhaust. The model is used to examine particle dynamics, such as nucleation, inside a diesel exhaust laboratory sampling system. The results suggest lower slope of nucleation rate versus sulfuric acid concentration than previously found. Hide