Search results for " layer"

Temperature effect on phase state and reactivity controls atmospheric multiphase chemistry and transport of PAHs

2017

Atmospheric refrigerator increases the global transport and health risks of carcinogenic PAHs.

2017

Abstract. Ozone (O3) is an important atmospheric oxidant, a greenhouse gas, and a hazard to human health and agriculture. Here we describe airborne in situ measurements and model simulations of O3 and its precursors during tropical and extratropical field campaigns over South America and Europe, respectively. Using the measurements, net ozone formation/destruction tendencies are calculated and compared to 3-D chemistry–transport model simulations. In general, observation-based net ozone tendencies are positive in the continental boundary layer and the upper troposphere at altitudes above  ∼  6 km in both environments. On the other hand, in the marine boundary layer and the middle tropospher…

Airborne observation of mixing across the entrainment zone during PARADE 2011

2016

This study presents the analysis of the structure and air mass characteristics of the lower atmosphere during the field campaign PARADE (PArticles and RAdicals: Diel observations of the impact of urban and biogenic Emissions) on Mount Kleiner Feldberg in southwestern Germany during late summer 2011. We analysed measurements of meteorological variables (temperature, moisture, pressure, wind speed and direction) from radio soundings and of chemical tracers (carbon dioxide, ozone) from aircraft measurements. We focus on the thermodynamic and dynamic properties that control the chemical distribution of atmospheric constituents in the boundary layer. We show that the evolution of tracer profiles…

The importance of stratospheric–tropospheric transport in affecting surface ozone concentrations in the western and northern tier of the United States

2011

Stratospheric–tropospheric exchange (STE) processes contribute at both high and low-elevation monitoring sites to background ozone (O3) concentrations. This study addresses the importance of stratospheric intrusions contributing to enhanced hourly average surface O3 concentrations (i.e., ≥50 ppb) at 12 O3 monitoring stations in the western and northern tier of the US for 2006, 2007, and 2008. The Lagrangian Analysis Tool (LAGRANTO) trajectory model identified specific days when stratosphere-to-troposphere transport was optimal to elevate surface O3 levels. The coincidences between the number of days with a daily maximum hourly average O3 concentration ≥ 50 ppb and stratosphere-to-tropospher…

Overview of aerosol properties associated with air masses sampled by the ATR-42 during the EUCAARI campaign (2008)

2013

Abstract. Within the frame of the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project the Météo-France aircraft ATR-42 performed 22 research flights, over central Europe and the North Sea during the intensive observation period in May 2008. For the campaign, the ATR-42 was equipped in order to study aerosol physical, chemical and optical properties, as well as cloud microphysics. During the campaign, continental air masses from Eastern and Western Europe were encountered, along with polar and Scandinavian air masses. For the 22 research flights, retroplume analyses along the flight tracks were performed with FLEXPART in order to classify air masses into five sector…

Seasonal variations in aerosol particle composition at the puy-de-Dôme research station in France

2011

Detailed investigations of the chemical and microphysical properties of atmospheric aerosol particles were performed at the puy-de-Dôme (pdD) research station (1465 m) in autumn (September and October 2008), winter (February and March 2009), and summer (June 2010) using a compact Time-of-Flight Aerosol Mass Spectrometer (cToF-AMS). Over the three campaigns, the average mass concentrations of the non-refractory submicron particles ranged from 10 μg m<sup>−3</sup> up to 27 μg m<sup>−3</sup>. Highest nitrate and ammonium mass concentrations were measured during the winter and during periods when marine modified airmasses were arriving at the site, wh…

The Asian tropopause aerosol layer within the 2017 monsoon anticyclone: microphysical properties derived from aircraft-borne in situ measurements

2021

The Asian summer monsoon is an effective pathway for aerosol particles and precursors from the planetary boundary layer over Central, South, and East Asia into the upper troposphere and lower stratosphere. An enhancement of aerosol particles within the Asian monsoon anticyclone (AMA), called the Asian tropopause aerosol layer (ATAL), has been observed by satellites. We discuss airborne in situ and remote sensing observations of aerosol microphysical properties conducted during the 2017 StratoClim field campaign within the AMA region. The aerosol particle measurements aboard the high-altitude research aircraft M55 Geophysica (maximum altitude reached of ∼20.5 km) were conducted with a modifi…

Airborne measurements of dust layer properties, particle size distribution and mixing state of Saharan dust during SAMUM 2006

2009

The Saharan Mineral Dust Experiment (SAMUM) was conducted in May/June 2006 in southern Morocco. As part of SAMUM, airborne in situ measurements of the particle size distribution in the diameter range 4 nm < Dp < 100 μm were conducted. The aerosol mixing state was determined below Dp < 2.5 μm. Furthermore, the vertical structure of the dust layers was investigated with a nadir-looking high spectral resolution lidar (HSRL). The desert dust aerosol exhibited two size regimes of different mixing states: below 0.5 μm, the particles had a non-volatile core and a volatile coating; larger particles above 0.5 μm consisted of non-volatile components and contained light absorbing material. In…

New particle formation events measured on board the ATR-42 aircraft during the EUCAARI campaign

2010

Aerosol properties were studied during an intensive airborne measurement campaign that took place at Rotterdam in Netherlands in May 2008 within the framework of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). The objective of this study is to illustrate seven events of new particle formation (NPF) observed with two Condensation Particle Counters (CPCs) operated on board the ATR-42 research aircraft in airsectors around Rotterdam, and to provide information on the spatial extent of the new particle formation phenomenon based on 1-s resolution measurements of ultra-fine particle (in the size range 3–10 nm diameter, denoted N<sub>3-10</sub> herea…

Analysing time-varying trends in stratospheric ozone time series using the state space approach

2014

Abstract. We describe a hierarchical statistical state space model for ozone profile time series. The time series are from satellite measurements by the Stratospheric Aerosol and Gas Experiment (SAGE) II and the Global Ozone Monitoring by Occultation of Stars (GOMOS) instruments spanning the years 1984–2011. Vertical ozone profiles were linearly interpolated on an altitude grid with 1 km resolution covering 20–60 km. Monthly averages were calculated for each altitude level and 10° wide latitude bins between 60° S and 60° N. In the analysis, mean densities are studied separately for the 25–35, 35–45, and 45–55 km layers. Model variables include the ozone mean level, local trend, seasonal osc…